CN118274752A - Internal runner surface quality testing and evaluating method based on pressure loss - Google Patents
Internal runner surface quality testing and evaluating method based on pressure loss Download PDFInfo
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Abstract
A method for testing and evaluating the surface quality of an inner runner based on pressure loss uses an additive manufacturing mode to manufacture standard inner runner samples with different roughness and bending angles; then, designing and manufacturing an inner runner surface quality evaluation device; and then, calibrating coefficients of a correction head loss formula: the method comprises the steps of calibrating and calculating error equation coefficients between a theoretical head loss value and an experimental head loss value by using standard inner runner roughness sample pieces with different roughness in an evaluation device; calibrating and correcting local resistance coefficients in a head loss formula by using standard inner runner bent angle sample pieces with different bent angles; finally, testing and evaluating the surface quality of the inner runner of the complex part; the invention fully considers the influence of roughness in the head loss formula and the subsequent use of the parts, can realize the nondestructive detection of the surface quality of the inner runner of the complex part, is beneficial to ensuring the processing quality of the inner runner of the complex part and improving the surface quality evaluation system of the inner runner.
Description
Technical Field
The invention relates to the technical field of internal flow path processing quality detection, in particular to a method for testing and evaluating the surface quality of an internal flow path based on pressure loss.
Background
With the vigorous development of strategic and emerging industries such as aerospace, new energy, new materials and the like, a large number of researches on cavities and internal flow channels of complex parts are carried out, and a nondestructive testing method for the surface roughness of the internal flow channels of the complex parts is a critical and indispensable key research in the field.
The traditional complex parts with the inner runner are generally produced in a casting mode, but the problems of poor casting surface quality and high die cost are difficult to effectively solve. The advent of additive manufacturing (Additive manufacturing, AM) changed this situation. The additive manufacturing is an emerging technology for subverting the traditional manufacturing, and the production mode of layer-by-layer construction enables the additive manufacturing to easily process parts with complex structures and hundreds of inner runners, and typical parts include injector shells of aerospace engines and fuel nozzles in the aerospace engines.
However, the roughness is required to be detected and evaluated whether it is a traditional casting method or an internal flow path of a complex part produced by using additive manufacturing technology. The existing method for detecting the roughness of the internal flow channel mostly needs to use a confocal microscope to carry out scanning measurement after the part is split (1, liao Yiou, feng Hui and Zhang Chongyuan. Exploration of the surface roughness measured by the laser confocal microscope, analysis and test technology and instrument, 2023,29 (02): 203-208.) the method can cause the part to fail after the part is split and can not carry out roughness evaluation on the whole batch of parts, and research on a nondestructive testing method for the surface roughness of the internal flow channel is needed to be carried out. However, the existing nondestructive testing method (2 Chinese patent publication No. CN106777830B, named as a rapid evaluation method of hydraulic friction of a pipeline, 3 Chinese patent publication No. CN116222489A, named as a pipe wall integrity detection method and device based on pressure drop loss) is not fully researched theoretically, is mainly applied to large-scale oil pipelines, and does not design related flow channel surface roughness evaluation equipment. Therefore, the existing method for detecting the roughness of the inner runner only aims at a single experimental part to effectively evaluate or aims at a large-scale oil pipeline, and the related theoretical system is not perfect enough and is not suitable for nondestructive detection of the surface roughness of the inner runner of a complex part.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a method for testing and evaluating the surface quality of an inner runner based on pressure loss, which fully considers the influence of roughness in a head loss formula and the subsequent use of complex parts with inner runners, can realize nondestructive testing of the surface quality of the inner runner of the complex parts, and is beneficial to ensuring the processing quality of the inner runner of the complex parts and improving an evaluation system of the surface quality of the inner runner.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a method for testing and evaluating the surface quality of an inner runner based on pressure loss comprises the following steps:
(a) Preparing a standard internal flow channel sample: standard inner runner samples with different roughness and different bent angles are manufactured by using an additive manufacturing mode, and a laser powder bed is selected for melting in an additive manufacturing process; the standard inner runner sample piece is divided into a standard inner runner roughness sample piece and a standard inner runner bent angle sample piece, the roughness control method of the standard inner runner roughness sample piece is to use electrolytic machining on an inner runner, select different technological parameters to produce standard sample pieces with different inner runner roughness, and the standard inner runner bent angle sample piece is manufactured after different flow runner bent angles are built in a model;
(b) Designing and manufacturing an inner runner surface quality evaluation device: the function of the evaluation device comprises that high-viscosity fluid is introduced into the inner flow channel; the temperature of the fluid is obviously changed to obtain different viscosities, and the viscosity of the fluid can be rapidly reduced and increased during surface quality detection; the high-viscosity fluid can be heated to high temperature so as to be conveniently introduced and removed; displaying the pressure difference and the flow of the two ends of the inlet and the outlet of the inner flow passage;
(c) Correcting coefficient calibration of a head loss formula: in the surface quality evaluation device, the standard internal runner roughness sample with different roughness is used for calibrating and calculating an error equation coefficient between a theoretical head loss value and an experimental head loss value; calibrating local resistance coefficients in a corrected head loss formula by using standard inner runner bent angle sample pieces with different bent angles, and finally obtaining the corrected head loss formula;
(d) Testing and evaluating the surface quality of an inner runner of a complex part: after the preparation work is finished, the complex part with the inner runner is placed into an evaluation device, the roughness of the inner runner of the part is calculated according to a correction head loss formula after the pressure loss measured by the evaluation device is brought into calibration, and the surface quality evaluation result of the inner runner is obtained.
The preparation method of the standard inner runner roughness sample piece in the step (a) comprises the following steps: and (3) carrying out post-treatment on the flow passage in the sample piece manufactured by melting the laser powder bed, selecting an electrolytic machining process, and controlling parameters such as discharge power, discharge time and the like during electrolytic machining to obtain a standard sample piece with specific roughness. The preparation method of the standard inner runner bent angle sample piece in the step (a) comprises the following steps: and planning different inner runner bent angles of the model inner runner in the model construction stage, and selecting a laser powder bed for melting by a specific additive process to obtain a standard sample at a specific angle.
The standard inner flow channel roughness sample in the step (a) is used in the following manner: putting the standard inner flow path roughness sample into an evaluation device, and introducing high-viscosity fluid into the standard inner flow path roughness sample to read the pressure loss of the standard inner flow path roughness sample; heating the device to a new platform temperature, and reading the pressure difference at the moment to obtain new pressure loss when the pressure difference and the flow speed are stable; repeating the above steps at least five times to remove the high viscosity fluid. And then the standard inner runner roughness sample is split, and a laser confocal microscope is used for measuring the real surface roughness of the standard inner runner roughness sample.
The using method of the standard inner runner bent angle sample piece in the step (a) comprises the following steps: placing a standard inner flow path bent angle sample into an evaluation device, introducing high-viscosity fluid into the inner flow path, and reading the pressure difference to obtain pressure loss when the pressure difference and the flow speed are stable; removing fluid in the inner flow passage, cutting a standard inner flow passage bent angle sample piece, measuring the absolute roughness of the inner flow passage by using a laser confocal microscope, solving an on-way resistance loss term in pressure loss, and calculating to obtain a local resistance coefficient; and repeatedly putting the standard inner flow passage bent angle sample pieces with different bent angles for a plurality of times to obtain a series of local resistance coefficients.
The standard internal flow channel sample was used for: the standard inner runner roughness sample piece is used for calibrating an error equation coefficient between a theoretical head loss value and an experimental head loss value of a head loss formula; the standard inner runner bent angle sample piece is used for calibrating a local resistance coefficient influenced by an angle in the corrected head loss formula, and finally the corrected head loss formula is obtained.
The inner runner surface quality evaluation device designed in the step (b) comprises four functions: the temperature is quickly increased and decreased to change the viscosity of the fluid, the high-viscosity fluid is introduced, the pressure loss of the inlet and the outlet of the inner flow passage is read, and the high-viscosity fluid is removed.
The evaluation device comprises an insulation box 4, wherein a sleeve 13 is connected inside the insulation box 4, the sleeve 13 is arranged outside a part, an induction heating coil 12 is arranged outside the sleeve 13, and the induction heating coil 12 and the sleeve 13 have the functions of quickly raising the temperature of the part and the fluid and maintaining the temperature at a specific temperature so as to realize the functions of quickly raising the temperature and reducing the viscosity of the fluid; the part inlet is connected with an oil pump 10 and a water pump 9 through an inlet pipeline 11 and an inlet electromagnetic valve 8; the outlet of the part is connected with an oil tank 16 and a water tank 15 through an outlet pipeline 14 and an outlet electromagnetic valve 17; the oil pump 10 enables high-viscosity fluid to enter the part through the inlet electromagnetic valve 8 and the inlet pipeline 11, and then the fluid is led to the outlet electromagnetic valve 17 from the outlet pipeline 14 to enter the oil tank 16, so that the function of leading in the high-viscosity fluid is realized; the water pump 9 is used for leading water into the part through the inlet electromagnetic valve 8 and the inlet pipeline 11, removing high-viscosity fluid in the inner flow passage of the part, leading the high-viscosity fluid from the outlet pipeline 14 to the outlet electromagnetic valve 17 and leading the high-viscosity fluid into the water tank 15, and realizing the function of removing the high-viscosity fluid; the inlet pressure gauge 2 and the outlet pressure gauge 7 record the pressure difference, the inlet flow gauge 3 and the outlet flow gauge 6 record the fluid flow rate of an inlet and an outlet, and the function of reading the pressure difference and the flow of the inlet and the outlet of the inner runner is realized; the sleeve 13 and the induction heating coil 12 are adjacent to a liquid nitrogen outlet 5 connected with the interior of the heat preservation box 4, the liquid nitrogen outlet 5 is connected with a liquid nitrogen bottle 1 outside the heat preservation box 4, and the function of rapid cooling is realized through liquid nitrogen; the sleeve 13 is connected with a temperature sensor 18, and the temperature sensor 18 displays the temperatures of the parts and fluid in the sleeve 13 in real time.
The temperature control flow of the evaluation device is as follows: inputting the given temperature into an evaluation device, and controlling the induction coil and the liquid nitrogen outlet to act according to the temperature rise and the temperature drop after the temperature controller receives the given temperature; heating the induction coil when heating is needed, opening a liquid nitrogen outlet when cooling is needed, changing the temperature of parts and fluid, and feeding back the temperature to a temperature sensor; the temperature sensor collects the temperature, amplifies and converts the signal, and returns to the temperature controller; and the controller adjusts according to the temperature deviation to complete feedback control of the temperature in the evaluation device.
The evaluation device needs to be filled with high-viscosity fluid: the surface quality of the inner flow passage is measured by using fluid, and the influence of roughness on the head loss is increased according to a head loss formula, namely, the along-path resistance loss term is increased, so that the roughness of the inner flow passage can be obtained more accurately, and therefore, the high-viscosity fluid is selected, and the viscosity-temperature characteristic of the fluid is required to be changed severely and conveniently to be introduced and removed. The currently selected high-viscosity fluid mainly comprises two types, namely waxy crude oil and high-viscosity lubricating oil with the brand of LVI-1200.
The function of changing the viscosity of the fluid by rapidly increasing and decreasing the temperature is as follows: because the high-viscosity fluid flows in the inner flow channel difficultly, the device is required to be quickly heated and kept at the temperature, and the fluid has lower viscosity and good fluidity at high temperature; the viscosity of the fluid needs to be increased during experimental measurement, the device can be rapidly cooled and maintained, the viscosity is high at low temperature, the on-way resistance loss is large, and the surface quality of the inner runner is accurately evaluated.
The function of introducing the high-viscosity fluid is as follows: the high-viscosity fluid is heated to a certain temperature, the viscosity of the fluid is reduced, good fluidity is obtained, the device introduces the high-viscosity fluid into the part until the fluid completely enters the inner flow passage of the complex part, and the next stage is carried out after the pressure difference between the inlet and the outlet is stable and the flow is stable.
The function of reading the pressure loss of the inlet and the outlet of the inner runner part is as follows: when the fluid state in the internal flow channel is stable, the liquid nitrogen is used for rapidly reducing the temperature; the viscosity of the high-viscosity fluid rises after the temperature is reduced, and the pressure difference between an inlet and an outlet of the inner runner is increased; after the temperature is stable, the pressure difference is stable and the flow is stable, the pressure loss is obtained by reading, and then the surface quality of the inner runner is evaluated according to a formula.
The function of removing the high-viscosity fluid is as follows: after the pressure loss of the fluid passing through the inner flow passage is obtained, an inlet-outlet switching pipeline is arranged, wherein the fluid in the pipeline is water; raising the temperature, reducing the viscosity of the high viscosity fluid, and increasing the solubility of the oil in water, the water removes the high viscosity fluid from the internal flow path.
The coefficient calibration of the head loss correction formula in the step (c) is divided into two steps: firstly, calculating an error equation coefficient between a theoretical head loss value and an experimental head loss value by using a standard internal runner roughness sample piece calibration head loss formula; and then calibrating and correcting local resistance coefficients mainly related to the angle of the inner runner in the head loss formula by using a standard inner runner bent angle sample piece.
Calculating an error equation between a theoretical head loss value and an experimental head loss value, namely a head loss error equation for short, and calibrating coefficients, wherein the steps are as follows:
Placing the standard inner runner roughness sample into an evaluation device, introducing high-viscosity fluid until the temperature is stable, the pressure difference is stable, and recording the pressure loss after the flow rate is stable; heating by the evaluation device, raising the temperature of the high-viscosity fluid until the temperature of the fluid is stabilized at a new platform temperature after heating, and recording new pressure loss when the pressure difference is stabilized and the flow speed is stabilized; repeating the steps for at least five times to obtain experimental pressure loss values of five groups of roughness samples of the same standard internal flow channel;
after the experiment is finished, the standard inner runner roughness sample piece is split, the real roughness value is measured under a laser confocal microscope, and the theoretical head loss value can be calculated by using the real roughness value and the runner parameters through a formula; and calibrating error equation coefficients between the theoretical head loss and the experimental head loss.
The principle and formula for calculating the error equation coefficient calibration between the theoretical head loss value and the experimental head loss value are as follows:
The head loss in the inner runner mainly comes from two parts, and one part is the along-way resistance loss h f generated by the viscosity effect;
The other part is the local resistance loss h j which is the result of the cross action of various factors, and the regularity result of the local loss factors is difficult to obtain through theoretical analysis and analytic calculation, and the regularity result is generally measured by experiments and has a certain relation with the bending angle of the flow channel;
The comparison between the experimental result and the theoretical calculation result shows that an error exists between the calculation value of the head loss formula and the head loss value obtained by experimental test, and the error is a function of the logarithm lgRe of the Reynolds number:
Wherein h w is the theoretical head loss, and the unit is m; h e is the experimental head loss, and the unit is m; re is the Reynolds number, dimensionless;
performing quadratic polynomial fitting on the error function:
hw＝he·f(lgRe)＝he[a(lgRe)2+blgRe+c]
Wherein a, b and c are coefficients to be calibrated in the error function;
theoretical calculation formula of left-side water head loss
Wherein lambda is the along-path resistance coefficient; l is the length of the pipeline, and the unit is m; d is the inner diameter of the pipeline, and the unit is m; v is the average flow rate in m/s; g is gravity acceleration, and the unit is m/s 2;kθ is the along-way resistance coefficient.
The temperature is obviously increased by using the function of changing the temperature of the evaluation device, the viscosity of the fluid in the inner flow channel is changed along with the temperature, the Reynolds number Re is also changed, but the flow velocity V is controlled to be unchanged so as to calibrate the three coefficients a, b and c in the quadratic polynomial. Subtracting the i-th experimental actual measurement value from the i+1-th experimental actual measurement value, and eliminating the partial resistance loss term which is not calibrated:
Wherein lambda i is the on-way resistance coefficient of the ith experiment; h i is the actual measurement head loss value of the ith experiment; re i is the Reynolds number of the ith experiment;
Repeating the heating of the part and fluid to different plateau temperatures at least five times
Wherein A is a coefficient matrix;
And solving the second order polynomial coefficients a, b and c between the theoretical head loss value and the experimental head loss value through the head loss recorded by the experiment and the flow channel parameters of the sample.
The step of calibrating and correcting the local resistance coefficient in the head loss formula by using standard inner flow passage bent angle sample pieces with different bent angles comprises the following specific steps:
Fixing a standard inner flow passage bent angle sample piece into an evaluation device, and introducing high-viscosity fluid into the standard inner flow passage bent angle sample piece; when the pressure difference between the inlet and the outlet of the inner runner is stable, the flow speed is stable, and the experimental pressure loss value is obtained by reading the pressure difference; then raising the temperature, and introducing water to remove the high-viscosity fluid; cutting a standard inner runner bent angle sample piece, measuring roughness of the standard inner runner bent angle sample piece under a laser confocal microscope, and calculating the on-way resistance loss in head loss; finally, the partial resistance coefficient is solved after the partial resistance coefficient is brought into a water head loss formula; and replacing a plurality of standard inner flow passage bent angle sample pieces with different angles to obtain a series of corresponding local resistance coefficients, using a least square fitting curve, and completing the calibration of the local resistance coefficient k θ when the deviation between the curve fitting k θ Estimation of and the experiment k θ is smaller than a certain range.
The principle and formula of using standard inner runner bend sample pieces with different bend angles to calibrate local resistance coefficients in a head loss formula are as follows:
Obtaining an inlet-outlet pressure difference delta p of a standard inner flow channel bent angle sample piece in an evaluation device, and bringing the inlet-outlet pressure difference delta p into a water head loss error equation:
wherein h f is the along-the-way resistance loss, and the unit is m; h j is the local drag loss in m; Δp is the pressure difference between the fluid inlet and the fluid outlet in the internal flow path, and the unit is Pa;
After the standard inner flow passage bent angle sample piece is split, measuring roughness of the standard inner flow passage bent angle sample piece by using a laser confocal microscope, and calculating the in-process resistance loss h f in water head loss; subtracting the on-way resistance loss from the total water head loss to obtain a local resistance loss h j; and carrying out a local resistance loss calculation equation, and solving a local resistance loss coefficient k θ after the term transfer:
And replacing a plurality of standard inner flow passage bent angle sample pieces with different angles to obtain a series of corresponding local resistance coefficients, fitting a curve by using a least square method, and completing the calibration of the local resistance coefficients when the deviation between the curve fitting k θ Estimation of and the experiment k θ is smaller than a certain range.
The inner runner surface quality test and evaluation steps of the complex part in the step (d) are as follows: installing the complex part into an evaluation device, increasing the temperature of the fluid, reducing the viscosity of the fluid, improving the fluidity, and introducing the high-viscosity fluid into an inner runner of the complex part; when the flow speed of the fluid is stable, the liquid nitrogen is used for reducing the temperature of the fluid and the parts, increasing the viscosity of the high-viscosity fluid, increasing the on-way resistance loss of the fluid in the inner flow passage, enabling the calculation of the roughness to be more accurate, and obtaining the experimental pressure loss by reading the pressure difference; then heating, and introducing water to remove fluid in the inner flow path; and (5) carrying the measured experimental pressure loss into a formula to obtain the surface quality evaluation result of the inner runner of the complex part.
The inner runner surface quality test calculation principle and formula of the complex part in the step (d) are as follows:
Reading out the pressure difference deltap and the flow velocity V of an inlet and an outlet of an inner flow passage of a complex part in the evaluation device, and carrying out a calibrated correction water head formula to calculate the on-way resistance loss h f of the high-viscosity fluid in the inner flow passage:
Wherein k θ is the local resistance loss coefficient after calibration;
the term of transfer solves for the along-path drag coefficient λ:
obtaining an on-way resistance coefficient lambda, and solving the absolute roughness epsilon of the surface of the flow path in the complex part by using a Kelbuck-white formula:
Where ε is the absolute roughness of the inner flow channel and the unit is m.
And finally, solving a formula to finish nondestructive testing and evaluation of the surface quality of the flow path in the complex part.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention fully considers the limitations of the existing internal flow channel surface quality detection method, and provides a pressure loss-based internal flow channel surface quality testing and evaluating method.
(2) The invention improves on the basis of the head loss formula, and uses the standard inner runner sample to calibrate the error equation coefficient between the experimental head loss and the theoretical head loss and the local resistance loss coefficient, so as to obtain the calibrated correction head loss formula, thereby leading the formula to be more in line with the actual situation and leading the surface quality evaluation of the inner runner of the complex part to be more accurate.
(3) The internal runner surface quality evaluation device adopted by the invention can complete all steps of internal runner surface quality test and evaluation of complex parts, and is beneficial to improving the internal runner surface quality evaluation efficiency; and the device can remove residual high-viscosity fluid in the flow channel in the part after evaluation, and does not influence subsequent experiments of the part.
Drawings
Fig. 1 is a general flow chart of the present invention.
FIG. 2 is a flow chart of the preparation of a standard internal flow channel sample of the present invention.
FIG. 3 is a flow chart of the correction head loss formula coefficient calibration of the present invention.
FIG. 4 is a schematic view of an apparatus for evaluating the surface quality of an internal flow path according to the present invention.
FIG. 5 is a flow chart showing the temperature control of the apparatus for evaluating the surface quality of an inner flow passage according to the present invention.
FIG. 6 is a flow chart of the flow path surface quality test and evaluation in a complex part according to the present invention.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings.
Referring to fig. 1, a method for testing and evaluating the surface quality of an inner flow path based on pressure loss includes the steps of:
(a) Preparing a standard internal flow channel sample: because a large error exists between the theoretical head loss calculated by the head loss formula and the experimental head loss, a batch of standard sample pieces are required to be used for carrying out coefficient calibration on the corrected head loss formula, and standard inner runner sample pieces with different roughness and different bent angles are manufactured by using an additive manufacturing mode; the standard inner runner sample piece is divided into two types, one is a standard inner runner roughness sample piece and the other is a standard inner runner bent angle sample piece, wherein the standard inner runner roughness sample piece and the standard inner runner roughness sample piece are prepared by a laser powder bed melting process, the difference is that the standard inner runner roughness sample piece is manufactured after the inner runner is subjected to electrolytic machining and different process parameters are selected to control the roughness of the inner runner, and the standard inner runner bent angle sample piece is manufactured after different flow runner bent angles are constructed in a model;
(b) Designing and manufacturing an inner runner surface quality evaluation device: a set of evaluation device is needed to ensure the repeatability and efficiency of the surface quality test of the inner runner, the coefficient calibration of the correction head loss formula is also needed to be carried out in the evaluation device, and the functions of the evaluation device comprise that high-viscosity fluid is introduced into the inner runner; the temperature of the fluid is obviously changed to obtain different viscosities, so that the viscosity of the fluid can be quickly reduced and increased during surface quality detection, and the high-viscosity fluid can be heated to high temperature for convenient removal; displaying the flow and pressure difference of the two ends of the inlet and the outlet of the inner flow channel;
(c) Correcting coefficient calibration of a head loss formula: in order to reduce the error between the theoretical calculated head loss and the experimental head loss and ensure the accuracy of the surface quality evaluation result of the inner runner, the coefficient calibration of the correction head loss formula is required; the calibration comprises two parts: the method comprises the steps of calibrating and calculating error equation coefficients between a theoretical head loss value and an experimental head loss value by using standard inner runner roughness sample pieces with different roughness in an evaluation device; the local resistance coefficient in the head loss correction formula is calibrated by using standard inner flow channel bent angle sample pieces with different bent angles, so that a final head loss correction formula is obtained;
(d) Testing and evaluating the surface quality of an inner runner of a complex part: on the basis of correcting a head loss formula and an internal runner surface quality evaluation device, putting a complex part with an internal runner into the evaluation device, heating the evaluation device, introducing high-viscosity fluid into the internal runner of the complex part, cooling by using liquid nitrogen after introducing, increasing the viscosity of the fluid, stabilizing the pressure difference and stabilizing the flow speed, and reading the pressure difference to calculate the pressure loss; the temperature of the evaluation device is raised again, and water is introduced to remove fluid in the inner flow path; and finally, bringing the pressure loss into a head loss correction formula, and solving and finishing the surface quality test and evaluation of the inner runner of the complex part.
Referring to fig. 2, the preparation of the standard internal flow channel sample includes the preparation of the standard internal flow channel roughness sample and the preparation of the standard internal flow channel corner sample, both of which are manufactured using a laser powder bed fusion process, but with different treatments. The standard inner runner roughness sample is a standard sample which is obtained by using electrolytic machining on the inner runner and selecting different technological parameters including discharge power, discharge time and the like so as to obtain specific roughness; the standard inner runner corner sample is a standard sample with different inner runner corners planned for the model inner runner before preparation so as to obtain a specific angle.
Referring to fig. 3, the method of using the standard internal flow channel roughness sample is: placing the prepared standard inner flow path roughness sample into an evaluation device, introducing high-viscosity fluid into the inner flow path, and reading the pressure difference to obtain pressure loss when the pressure difference and the flow speed are stable; heating the evaluation device to a new platform temperature, and reading the pressure difference at the moment to obtain new pressure loss after the evaluation device is stabilized; repeating the steps for at least five times, then raising the temperature, improving the fluidity of the fluid, and introducing water to remove the fluid in the flow channel; and finally, cutting a standard inner flow channel roughness sample piece, and measuring the absolute roughness of the inner flow channel under a laser confocal microscope.
Referring to fig. 3, the standard inner flow channel corner sample piece is used in the following method: placing a standard inner flow path bent angle sample into an evaluation device, introducing high-viscosity fluid into the inner flow path, and reading the pressure difference to obtain pressure loss when the pressure difference and the flow speed are stable; then, the standard inner flow passage bent angle sample piece is cut open to measure the absolute roughness of the inner flow passage, the on-way resistance loss in the head loss is solved, and the local resistance coefficient is calculated; and repeatedly putting the standard inner runner bent angle sample pieces with different bent angles for a plurality of times, and calculating to obtain a series of local resistance coefficients.
Referring to fig. 3, the principle and steps of equation calculation of the error equation coefficient between the theoretical head loss value and the experimental head loss value are:
Certain error exists between the theoretical head loss value and the experimental head loss value, and the error is a function of the logarithm lgRe of the Reynolds number; fitting by using a quadratic polynomial to obtain an error function between a theoretical head loss value and an experimental head loss value:
hw＝he·f(lgRe)＝he[a(lgRe)2+blgRe+c]
Wherein h w is the theoretical head loss, and the unit is m; h e is the experimental head loss, and the unit is m; a, b and c are coefficients of the error function to be calibrated; re is the Reynolds number, dimensionless;
theoretical calculation formula of left side brought water head loss:
Wherein lambda is the along-path resistance coefficient; l is the length of the pipeline, and the unit is m; d is the inner diameter of the pipeline, and the unit is m; v is the average flow rate in m/s; g is gravity acceleration, wherein the unit is m/s 2;kθ and the unit is the along-way resistance coefficient;
Then, an evaluation device is used for changing the temperature, but the flow velocity V of the control fluid is unchanged, the temperature is changed, the viscosity of the fluid in the inner flow channel is changed, the resistance loss along the way is changed, and the local resistance loss term is unchanged; therefore, subtracting the i-th experimental measured value from the i+1-th experimental measured value, and eliminating the partial resistance loss term which is not calibrated:
Wherein lambda i is the on-way resistance coefficient of the ith experiment; h i is the actual measurement head loss value of the ith experiment; re i is the Reynolds number of the ith experiment;
The heating of the part and fluid temperatures to different plateau temperatures was repeated at least five times:
wherein A is a coefficient matrix:
and solving the flow channel parameters of the water head loss and the sample piece recorded through experiments to calculate the second order polynomial coefficients a, b and c between the theoretical water head loss value and the experimental water head loss value:
Thus, the error equation between the theoretical head loss value and the experimental head loss value, the head loss error equation for short, and the calibration of the coefficient are completed.
Referring to fig. 3, the steps and principles for calibrating the local resistance coefficient mainly related to the inner flow path bend on the basis of the head loss error equation using the standard inner flow path bend sample are as follows:
The local resistance loss in the head loss is the result of the cross action of various factors, and the regularity result of the local loss factors is difficult to obtain through theoretical analysis and analytic calculation; they are generally determined experimentally and have a relationship with the channel bend; therefore, the standard inner flow passage bent angle sample piece is used for calibrating the local resistance coefficient, so that the calculation of the local resistance loss is more accurate, and the subsequent calculation of the roughness is also more accurate;
placing the standard inner runner bent angle sample piece into an inner runner surface quality evaluation device, heating the inner runner, and introducing high-viscosity fluid into the inner runner until the fluid pressure difference and the fluid flow rate are stable; liquid nitrogen is introduced into the evaluation device, so that the temperature of the high-viscosity fluid is reduced, the viscosity is increased, and the on-way resistance loss of the fluid in the inner flow passage is improved; after the temperature is stable, the pressure difference is stable and the flow speed is stable at low temperature, reading the pressure difference to obtain experimental pressure loss; and then, obtaining an experimental pressure loss value of the standard inner runner bent angle test piece in the evaluation device, and carrying the experimental pressure loss value into a water head loss error equation:
wherein h f is the along-the-way resistance loss, and the unit is m; h j is the local drag loss in m; Δp is the pressure difference between the fluid inlet and the fluid outlet in the internal flow path, and the unit is Pa;
After the standard inner flow passage bent angle sample piece is split, measuring roughness of the standard inner flow passage bent angle sample piece by using a laser confocal microscope, calculating the along-way resistance loss h f in water head loss, and subtracting the along-way resistance loss by using the total water head loss to obtain local resistance loss; and carrying out a local resistance loss calculation equation, and solving a local resistance loss coefficient k θ after the term transfer:
And replacing a plurality of standard inner flow passage bent angle sample pieces with different angles to obtain a series of corresponding local resistance coefficients, fitting a curve of the local resistance coefficients along with the change of the inner flow passage bent angle by using a least square method, and when the deviation between the curve fitting k θ Estimation of and the experiment k θ is smaller than a certain range, completing the calibration of the local resistance coefficients k θ.
Referring to fig. 4, the evaluation device includes a liquid nitrogen bottle 1, an inlet pressure gauge 2, an inlet flow meter 3, an incubator 4, a liquid nitrogen outlet 5, an outlet flow meter 6, an outlet pressure gauge 7, an inlet solenoid valve 8, a water pump 9, an oil pump 10, an inlet pipe 11, an induction heating coil 12, a sleeve 13, an outlet pipe 14, a water tank 15, an oil tank 16, an outlet solenoid valve 17, and a temperature sensor 18; the inside of the heat preservation box 4 is connected with a sleeve 13, the sleeve 13 is arranged outside the part, an induction heating coil 12 is arranged outside the sleeve 13, and the induction heating coil 12 and the sleeve 13 have the functions of quickly raising the temperature of the part and the fluid and maintaining the temperature at a specific temperature, so that the function of quickly raising the temperature and reducing the viscosity of the fluid is realized; the inlet of the inner runner is connected with an oil pump 10 and a water pump 9 through an inlet pipeline 11 and an inlet electromagnetic valve 8; the outlet of the inner flow passage is connected with the oil tank 16 and the water tank 15 through an outlet pipeline 14 and an outlet electromagnetic valve 17; the oil pump 10 leads high-viscosity fluid into the part through the inlet electromagnetic valve 8 and the inlet pipeline 11, and then the fluid is led to the outlet electromagnetic valve 17 from the outlet pipeline 14 to enter the oil tank 16, so that the function of leading the high-viscosity fluid is realized; the water pump 9 is used for leading water into the part through the inlet electromagnetic valve 8 and the inlet pipeline 11, removing high-viscosity fluid in the inner flow passage of the part, leading the high-viscosity fluid from the outlet pipeline 14 to the outlet electromagnetic valve 17 and leading the high-viscosity fluid into the water tank 15, and realizing the function of removing the high-viscosity fluid; the inlet pressure gauge 2 and the outlet pressure gauge 7 record the pressure difference, the inlet flow gauge 3 and the outlet flow gauge 6 record the fluid flow rate of an inlet and an outlet, and the function of reading the pressure difference and the flow of the inlet and the outlet of the inner runner is realized; the sleeve 13 and the induction heating coil 12 are adjacent to a liquid nitrogen outlet 5 connected with the interior of the heat preservation box 4, the liquid nitrogen outlet 5 is connected with a liquid nitrogen bottle 1 outside the heat preservation box 4, and the function of rapid cooling is realized through liquid nitrogen; the sleeve 13 is connected with a temperature sensor 18, and the temperature sensor 18 displays the temperatures of the parts and fluid in the sleeve 13 in real time.
Referring to fig. 5, the temperature control flow of the evaluation device is: inputting the given temperature into an evaluation device, and controlling the induction coil and the liquid nitrogen outlet to act according to the temperature rise and the temperature drop after the temperature controller receives the given temperature; heating the induction coil when heating is needed, opening a liquid nitrogen outlet when cooling is needed, changing the temperature of parts and fluid, and feeding back the temperature to a temperature sensor; the temperature sensor collects the temperature, amplifies and converts the signal, and returns to the temperature controller; and the controller adjusts according to the temperature deviation to complete feedback control of the temperature in the evaluation device.
Referring to fig. 6, the principle and the steps of the inner runner surface quality test and evaluation of the complex part in the step (d) are as follows:
Installing the complex part with the inner runner into an evaluation device, increasing the temperature of the fluid, reducing the viscosity of the fluid, improving the fluidity, and introducing the high-viscosity fluid into the inner runner of the complex part; when the pressure difference and the flow speed are stable, liquid nitrogen is introduced, the temperature of the fluid and the parts is reduced, the viscosity of the high-viscosity fluid is increased, the on-way resistance loss of the fluid in the inner flow passage is increased, and the calculation of the roughness is more accurate; after the temperature is stable, the pressure difference is stable and the flow speed is stable at low temperature, the pressure difference is read, and the experimental pressure loss is obtained through calculation; then heating, and introducing water to remove fluid in the flow channel;
Bringing the experimentally measured pressure difference deltap and the flow velocity V into a corrected head loss formula after calibration, and calculating the on-way resistance loss h f of the high-viscosity fluid in the inner flow passage:
Wherein k θ is the calibrated local resistance loss coefficient;
solving the following resistance coefficient lambda after the term transfer:
after the along-the-way resistance coefficient lambda is obtained, the Kelbuck-Huai Tegong is used for solving the surface roughness epsilon of the inner flow passage of the part:
Where ε is the absolute roughness of the inner flow channel and the unit is m.
And finally solving the formula to finish nondestructive testing and evaluation of the surface quality of the flow path in the complex part.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the scope of the present invention should be included in the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims (6)
1. The method for testing and evaluating the surface quality of the inner runner based on the pressure loss is characterized by comprising the following steps of:
(a) Preparing a standard internal flow channel sample: standard inner runner samples with different roughness and different bent angles are manufactured by using an additive manufacturing mode, and a laser powder bed is selected for melting in an additive manufacturing process; the standard inner runner sample piece is divided into a standard inner runner roughness sample piece and a standard inner runner bent angle sample piece, the roughness of the standard inner runner roughness sample piece is controlled by using electrolytic machining on the inner runner, different process parameters are selected to control the roughness of the inner runner, and the standard inner runner bent angle sample piece is manufactured after different flow runner bent angles are constructed in a model;
(b) Designing and manufacturing an inner runner surface quality evaluation device: the function of the evaluation device comprises that high-viscosity fluid is introduced into the inner flow channel; the temperature of the fluid is obviously changed to obtain different viscosities, and the viscosity of the fluid can be rapidly reduced and increased during surface quality detection; the high-viscosity fluid can be heated to high temperature so as to be conveniently introduced and removed; displaying the pressure difference and the flow of the two ends of the inlet and the outlet of the inner flow passage;
(c) Correcting coefficient calibration of a head loss formula: in the surface quality evaluation device, the standard internal runner roughness sample with different roughness is used for calibrating and calculating an error equation coefficient between a theoretical head loss value and an experimental head loss value; calibrating local resistance coefficients in a corrected head loss formula by using standard inner runner bent angle sample pieces with different bent angles, and finally obtaining the corrected head loss formula;
(d) Testing and evaluating the surface quality of an inner runner of a complex part: after the preparation work is finished, the complex part with the inner runner is placed into an evaluation device, the roughness of the inner runner of the part is calculated according to a correction head loss formula after the pressure loss measured by the evaluation device is brought into calibration, and the surface quality evaluation result of the inner runner is obtained.
2. The method of claim 1, wherein the standard internal flow channel roughness sample in step (a) is prepared by: performing post-treatment on a flow passage in a sample manufactured by melting a laser powder bed, selecting an electrolytic machining process, and controlling discharge power and discharge time parameters during electrolytic machining to obtain a standard sample with specific roughness; the preparation method of the standard inner runner bent angle sample piece in the step (a) comprises the following steps: and planning different inner runner bent angles of the model inner runner in the model construction stage, and selecting a laser powder bed for melting by a specific additive process to obtain a standard sample at a specific angle.
3. The method according to claim 1, wherein the evaluation device in the step (b) comprises an insulation box (4), a sleeve (13) is connected inside the insulation box (4), the sleeve (13) is arranged outside a standard inner runner sample, and an induction heating coil (12) is connected outside the sleeve (13), so that the function of changing the viscosity of fluid by rapid temperature rise is realized; the inlet of the standard inner flow passage sample is connected with an oil pump (10) and a water pump (9) through an inlet pipeline (11), an inlet electromagnetic valve (8), and an outlet pipeline of the inlet electromagnetic valve (8) is connected with an inlet pressure gauge (2) and an inlet flowmeter (3); the outlet of the standard inner flow passage sample is connected with the oil tank (16) and the water tank (15) through the outlet pipeline (14) and the outlet electromagnetic valve (17), so that the function of introducing high-viscosity fluid and the function of removing the high-viscosity fluid are realized; an inlet pipeline of the outlet electromagnetic valve (17) is connected with an outlet flowmeter (6) and an outlet pressure gauge (7), so that the functions of reading the pressure difference and the flow of an inlet and an outlet are realized; the sleeve (13) and the induction heating coil (12) are opposite to a liquid nitrogen outlet (5) connected with the inside of the heat preservation box (4), and the liquid nitrogen outlet (5) is connected with a liquid nitrogen bottle (1) outside the heat preservation box (4), so that the standard inner flow passage sample piece and the fluid can be cooled rapidly; the sleeve (13) is connected with a temperature sensor (18), and the temperature sensor (18) displays the temperature of the parts and the fluid in the sleeve (13) in real time.
4. The method of claim 1, wherein the step (c) of correcting the coefficient calibration of the head loss equation is divided into two steps: firstly, calculating an error equation coefficient between a theoretical head loss value and an experimental head loss value by using a standard internal runner roughness sample piece calibration head loss formula; then calibrating a local resistance coefficient related to the angle of the inner runner on the basis of correcting a head loss formula by using a standard inner runner bent angle sample piece;
An error exists between the theoretical head loss value and the experimental head loss value, the error is a function of the logarithm lgRe of the Reynolds number, and a quadratic polynomial is used for fitting to obtain an error function between the theoretical head loss value and the experimental head loss value:
hw＝he·f(lgRe)＝he[a(lgRe)2+blgRe+c]
Wherein h w is the theoretical head loss, and the unit is m; h e is the experimental head loss, and the unit is m; a, b and c are coefficients of the error function to be calibrated; re is the Reynolds number, dimensionless;
theoretical calculation formula of left side brought water head loss:
Wherein lambda is the along-path resistance coefficient; l is the length of the pipeline, and the unit is m; d is the inner diameter of the pipeline, and the unit is m; v is the average flow rate in m/s; g is gravity acceleration, wherein the unit is m/s 2;kθ and the unit is the along-way resistance coefficient;
Then, an evaluation device is used for changing the temperature, but the flow velocity V of the control fluid is unchanged, the temperature is changed, the viscosity of the fluid in the inner flow channel is changed, the resistance loss along the way is changed, and the local resistance loss term is unchanged; therefore, subtracting the i-th experimental measured value from the i+1-th experimental measured value, and eliminating the partial resistance loss term which is not calibrated:
Wherein lambda i is the on-way resistance coefficient of the ith experiment; h i is the actual measurement head loss value of the ith experiment; re i is the Reynolds number of the ith experiment;
The heating of the part and fluid temperatures to different plateau temperatures was repeated at least five times:
wherein A is a coefficient matrix:
and solving the flow channel parameters of the water head loss and the sample piece recorded through experiments to calculate the second order polynomial coefficients a, b and c between the theoretical water head loss value and the experimental water head loss value:
Thus, the calibration of the error equation, abbreviated as the head loss error equation coefficient, between the theoretical head loss value and the experimental head loss value is completed.
5. The method of claim 4, wherein the step (c) uses standard internal flow channel corner samples of different corners to calibrate the local drag coefficient in the corrected head loss equation is specifically:
Placing the standard inner runner bent angle sample piece into an evaluation device, and introducing high-viscosity fluid into the inner runner; when the pressure difference and the flow rate of the fluid are stable; introducing liquid nitrogen into the evaluation device to reduce the temperature and increase the viscosity of the high-viscosity fluid; after the temperature is stable, the pressure difference is stable and the flow speed is stable at low temperature, reading the pressure difference data to calculate the experimental pressure loss; obtaining an experimental pressure loss value of a standard inner flow passage bent angle sample piece in an evaluation device, and carrying into a water head loss error equation:
wherein h f is the along-the-way resistance loss, and the unit is m; h j is the local drag loss in m; Δp is the pressure difference between the fluid inlet and the fluid outlet in the internal flow path, and the unit is Pa;
after the standard inner flow passage bent angle sample piece is split, measuring roughness of the standard inner flow passage bent angle sample piece by using a laser confocal microscope, and calculating the in-process resistance loss h f in water head loss; subtracting the on-way resistance loss from the total loss of the water head to obtain local resistance loss; and carrying out a local resistance loss calculation equation, and solving a local resistance loss coefficient k θ after the term transfer:
And replacing a plurality of standard inner flow passage bent angle sample pieces with different angles to obtain a series of corresponding local resistance coefficients, fitting a curve of the local resistance coefficients changing along with the angles by using a least square method, and completing the calibration of the local resistance coefficients k θ when the deviation between the curve fitting k θ Estimation of and the experiment k θ is smaller than a certain range.
6. The method of claim 1, wherein the surface quality testing and evaluation of the flow channels in the complex part of step (d) is specifically:
Installing the complex part with the inner runner into an evaluation device, increasing the temperature of the fluid, reducing the viscosity of the fluid, improving the fluidity, and introducing the high-viscosity fluid into the inner runner of the complex part; when the pressure difference and the flow speed are stable, liquid nitrogen is introduced, the temperature of the fluid and the parts is reduced, the viscosity of the high-viscosity fluid is increased, the on-way resistance loss of the fluid in the inner flow passage is increased, and the calculation of the roughness is more accurate; after the temperature is stable, the pressure difference is stable and the flow speed is stable at low temperature, the pressure difference is read, and the experimental pressure loss is obtained through calculation; then heating, and introducing water to remove fluid in the flow channel;
Bringing the experimentally measured pressure difference deltap and the flow velocity V into a corrected head loss formula after calibration, and calculating the on-way resistance loss h f of the high-viscosity fluid in the inner flow passage:
Wherein k θ is the calibrated local resistance loss coefficient;
solving the following resistance coefficient lambda after the term transfer:
after the along-the-way resistance coefficient lambda is obtained, the Kelbuck-Huai Tegong is used for solving the surface roughness epsilon of the inner flow passage of the part:
wherein epsilon is the absolute roughness of the inner runner and the unit is m;
And finally solving the formula to finish nondestructive testing and evaluation of the surface quality of the flow path in the complex part.
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