CN118013666B - Blade for high cycle fatigue crack test of air-cooled turbine blade and design method - Google Patents
Blade for high cycle fatigue crack test of air-cooled turbine blade and design method Download PDFInfo
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- CN118013666B CN118013666B CN202410417895.2A CN202410417895A CN118013666B CN 118013666 B CN118013666 B CN 118013666B CN 202410417895 A CN202410417895 A CN 202410417895A CN 118013666 B CN118013666 B CN 118013666B
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- 238000000034 method Methods 0.000 title claims abstract description 19
- 239000013078 crystal Substances 0.000 claims description 35
- 238000009661 fatigue test Methods 0.000 claims description 8
- 238000010586 diagram Methods 0.000 claims description 3
- 230000008569 process Effects 0.000 description 4
- 238000005452 bending Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000003825 pressing Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 230000004044 response Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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Abstract
The invention relates to the technical field of aeroengines, and discloses a blade and a design method for a high-cycle fatigue crack test of an air-cooled turbine blade.
Description
Technical Field
The invention relates to the technical field of aeroengines, and discloses a blade for a high-cycle fatigue crack test of an air-cooled turbine blade and a design method.
Background
The vibration characteristics and the high-cycle fatigue performance of the turbine blade are generally obtained on a vibration table, and the turbine blade cantilever is fixedly arranged on the vibration table through a pressing block to carry out the high-cycle fatigue test. During the test, vibration with large displacement amplitude is generated under the first-order bending natural frequency of the blade, so that the most dangerous section of the blade is subjected to fatigue failure due to large stress. However, when the high-stress horizontal vibration fatigue test is carried out through the vibration table in the prior art, the vibration response level on the blade cannot reach the high-cycle fatigue strength of the blade when the maximum thrust of the table surface occurs due to the overhigh frequency of the blade, so that fatigue cracks cannot occur on the blade, and the vibration table is extremely easy to damage a moving coil of the vibration table under the condition of high thrust and full load for a long time.
In addition, the boundary of the turbine blade which is fixedly arranged on the vibration table through the pressing block cantilever is different from the engine state boundary, the blade tenon is fixedly arranged on the vibration table, and the maximum vibration stress position often appears at the position of the rounding of the throat or the weaker position of the extending root, so that high-cycle fatigue cracks appear. The first-order bending vibration of the turbine blade in the engine state is affected by the damping effect, the position below the extension root is not the most dangerous position, and the stress concentration part of the blade body close to the blade root comprises a gas film hole, a split joint, a flow around column and the like, so that high-cycle fatigue cracks are more easily generated. Therefore, it is necessary to obtain the high cycle fatigue strength of the blade body part and calculate the high cycle fatigue strength reserve.
For the turbine blade with the high first-order bending frequency, the method of reducing the frequency is more, part of engineering designers transmit the blade to larger excitation energy by optimizing the tool clamp, the optimized clamp is not suitable for high-cycle fatigue test at high temperature, and the vibrating table can work under long-time high thrust during mass test. The other part of engineering designers realizes the frequency reduction by adding the weight to the blade tip position, and the method has larger problems, because the turbine blades of the high-performance engine are all of air-cooled single crystal structures, the structural integrity is destroyed by adopting a method of bolting the weight, and fatigue cracks appear in the bolt hole position preferentially; the counterweight blade is connected by adopting a welding process and can be subjected to high temperature of about 1200 ℃ once again, and the performance degradation condition of the blade can not be determined.
Disclosure of Invention
The invention aims to provide a blade for a high-cycle fatigue crack test of an air-cooled single-crystal turbine blade and a design method thereof, which can ensure that the high-cycle fatigue crack of the air-cooled single-crystal turbine blade is generated at a weak position on a blade body, so that the fatigue crack test of the air-cooled single-crystal turbine blade is more attached to an actual service scene of an engine, and an important reference basis is provided for the design of the air-cooled single-crystal turbine blade.
In order to achieve the technical effects, the technical scheme adopted by the invention is as follows:
the blade design method for the high cycle fatigue crack test of the air-cooled turbine blade comprises the following steps:
analyzing and obtaining vibration characteristics of the air-cooled single-crystal turbine blade according to the campbell diagram of the air-cooled single-crystal turbine blade, wherein the vibration characteristics comprise vibration frequency and the order of the vibration frequency;
Carrying out vibration characteristics and fatigue tests on the air-cooled single-crystal turbine blade by adopting a blade vibration test bed, and judging whether fatigue cracks appear on the blade body of the air-cooled single-crystal turbine blade;
And if the blade body is free from fatigue cracks, symmetrically cutting the two sides of the tenon tooth of the tenon of the air-cooled single-crystal turbine blade to obtain a blade structure for carrying out high-cycle fatigue crack test on the air-cooled turbine blade after cutting.
Further, the cutting line is a tenon pitch line on two sides, and the tenon pitch line is a position determined by the difference value between the tooth surface width and the groove surface width of the residual tenon part of the cutting surface after cutting is less than or equal to a preset threshold value.
Further, the value range of the preset threshold value is that，/>The tooth surface length of the tenon tooth is expressed in millimeters.
In order to achieve the technical effect, the invention also provides a blade for the high-cycle fatigue crack test of the air-cooled turbine blade, and the blade is of a blade structure obtained by cutting by the blade design method for the high-cycle fatigue crack test of the air-cooled turbine blade.
Further, the cutting line at the blade tenon is a tenon tooth pitch line at two sides, and the tenon tooth pitch line is a position determined by the difference value between the tooth surface width and the groove surface width of the residual tenon tooth part of the cutting surface after cutting is less than or equal to a preset threshold value.
Further, the value range of the preset threshold value is that，/>The tooth surface length of the tenon tooth is expressed in millimeters.
Compared with the prior art, the invention has the following beneficial effects: according to the invention, by symmetrically cutting the two sides of the tenon tooth of the tenon of the air-cooled single-crystal turbine blade, which does not have fatigue cracks, after the tenon tooth is cut, the holding position of the air-cooled single-crystal turbine blade on the vibration table is reduced, and the vibration frequency of the air-cooled single-crystal turbine blade is greatly reduced, so that the high-cycle fatigue cracks of the air-cooled single-crystal turbine blade are transferred to the weak position on the blade body from the throat of the tenon, and the fatigue crack test of the air-cooled single-crystal turbine blade is more attached to the actual use scene of the engine, thereby providing an important reference basis for the design of the air-cooled single-crystal turbine blade.
Drawings
FIG. 1 is a schematic illustration of various cutting patterns for a dovetail of an air-cooled turbine blade according to an embodiment;
FIG. 2 is a schematic view of a blade dovetail configuration for use in a high cycle fatigue crack test for an air cooled turbine blade after cutting in an example;
FIG. 3 is a schematic view of the mounting structure of the tenon in the fixture according to the embodiment;
wherein, 1, tenon; 2. mortises; 3. a fixed block; 4. a tongue and groove; 5. a limit bump; 6. tension bolts.
Detailed Description
The present invention will be described in further detail with reference to the following examples and drawings. It should not be construed that the scope of the above subject matter of the present invention is limited to the following embodiments, and all techniques realized based on the present invention are within the scope of the present invention.
Examples
Referring to fig. 1-3, a blade design method for a high cycle fatigue crack test of an air cooled turbine blade, comprising:
analyzing and obtaining vibration characteristics of the air-cooled single-crystal turbine blade according to the campbell diagram of the air-cooled single-crystal turbine blade, wherein the vibration characteristics comprise vibration frequency and the order of the vibration frequency;
Carrying out vibration characteristics and fatigue tests on the air-cooled single-crystal turbine blade by adopting a blade vibration test bed, and judging whether fatigue cracks appear on the blade body of the air-cooled single-crystal turbine blade;
And if the blade body is free from fatigue cracks, symmetrically cutting the two sides of the tenon tooth 2 of the tenon 1 of the air-cooled single-crystal turbine blade to obtain a blade structure for carrying out high-cycle fatigue crack test of the air-cooled turbine blade after cutting.
In the embodiment, the blade vibration test bed is used for carrying out vibration characteristics and fatigue tests on the air-cooled single-crystal turbine blade, symmetrical cutting is carried out on two sides of the tenon tooth 2 of the tenon 1 of the air-cooled single-crystal turbine blade, so that the holding position of the air-cooled single-crystal turbine blade on the vibration bed is reduced after the tenon tooth 2 is cut, the vibration frequency of the air-cooled single-crystal turbine blade can be greatly reduced, and therefore, high-cycle fatigue cracks of the air-cooled single-crystal turbine blade are transferred to the weak position on the blade body from the throat part of the tenon 1, and the practical use scene of the engine, which is more attached to the fatigue crack test of the air-cooled single-crystal turbine blade, is provided with important reference for the design of the air-cooled single-crystal turbine blade.
In the embodiment, a clamp is used for clamping and fixing the tenon tooth 2 of the tenon 1 after the air-cooled single crystal turbine blade is cut in the test process, the clamp comprises a fixed block 3, a tenon groove 4 is formed in the fixed block 3, and a limit lug 5 matched with the throat part of the tenon tooth 2 of the tenon 1 after the cutting is arranged in the tenon groove 4; the fixing block 3 is fixed on the mounting position of the test stand through a compression bolt. The mortises 4 are in interference fit with the mortises 2 of the cut tenons 1, and the interference fit tolerance range is 0.3mm-0.6mm. Tension screw holes are formed in the two sides of the fixed block 3, and tension bolts 6 matched with the tension screw holes are used for pulling the mortise 4 open to clamp and fix or detach the blade.
If the cutting line is near the root location (as in FIG. 1) The clamping system of the clamp may be unstable, so that the tenon 1 gradually breaks away from the clamp during the vibration test, and the maximum vibration stress occurs in the throat; if the cutting line is located close to the tooth tip (as/>, in FIG. 1) The reduction amplitude of the vibration frequency of the blade is reduced, and larger vibration energy is required to ensure that cracks are generated and the generated vibration energy cannot be stored; cracks appear at the blade body location. To sum up, the cutting line in this embodiment is the two-sided tooth 2 pitch line/>The tenon tooth 2 pitch line/>Tooth surface width/>, of the remaining tooth 2 part of the cut faceAnd groove face width/>The difference value is smaller than or equal to the position determined by the preset threshold value. By coupling the tenon tooth 2 to the line/>Cutting line, pitch line/>, defined as tooth 2 of tenon 1The upper tooth thickness and the tooth slot width are basically equal, the strength of the fixture of the tenon tooth 2 and the stability of a clamping system can be guaranteed, the rigidity of the hollow tenon tooth 2 in the blade vibration fatigue test process can be guaranteed, the problem that the throat and the extension root of the tenon 1 are greatly increased to generate cracks due to large deformation in the clamping process of the cut tenon 1 is avoided, the cooling cavity inside the tenon 1 cannot be made to be a weak link to generate cracks, and the position where the cracks are generated on the blade body is further guaranteed.
In this embodiment, the range of values of the preset threshold is，/>The tooth surface length of the tenon tooth is expressed in millimeters, so that the cutting line is ensured to be overlapped with the pitch line as much as possible.
Based on the same inventive concept, the embodiment also provides a blade for high cycle fatigue crack test of an air-cooled turbine blade, wherein the blade is a blade structure for performing high cycle fatigue crack test of the air-cooled turbine blade after cutting by symmetrically cutting the two sides of the tenon tooth 2 of the tenon 1 of the air-cooled single crystal turbine blade.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (4)
1. The blade design method for the high cycle fatigue crack test of the air-cooled turbine blade is characterized by comprising the following steps of:
analyzing and obtaining vibration characteristics of the air-cooled single-crystal turbine blade according to the campbell diagram of the air-cooled single-crystal turbine blade, wherein the vibration characteristics comprise vibration frequency and the order of the vibration frequency;
Carrying out vibration characteristics and fatigue tests on the air-cooled single-crystal turbine blade by adopting a blade vibration test bed, and judging whether fatigue cracks appear on the blade body of the air-cooled single-crystal turbine blade;
if the blade body is free from fatigue cracks, symmetrically cutting the two sides of the tenon tooth of the tenon of the air-cooled single-crystal turbine blade to obtain a blade structure for carrying out high-cycle fatigue crack test on the air-cooled turbine blade after cutting; the cutting line is a tenon tooth pitch line on two sides, and the tenon tooth pitch line is a position determined by the difference value between the tooth surface width and the groove surface width of the residual tenon tooth part of the cutting surface after cutting is smaller than or equal to a preset threshold value.
2. The blade design method for high cycle fatigue crack test of an air cooled turbine blade according to claim 1, wherein the preset threshold value is in a range of values of，/>The tooth surface length of the tenon tooth is expressed in millimeters.
3. A blade for use in a high cycle fatigue crack test of an air-cooled turbine blade, characterized in that the blade is a blade structure cut by the blade design method for use in a high cycle fatigue crack test of an air-cooled turbine blade as set forth in claim 1.
4. A blade for a high cycle fatigue crack test for an air cooled turbine blade as in claim 3, wherein the predetermined threshold value is in the range of，/>The tooth surface length of the tenon tooth is expressed in millimeters.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202410417895.2A CN118013666B (en) | 2024-04-09 | 2024-04-09 | Blade for high cycle fatigue crack test of air-cooled turbine blade and design method |
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| CN202410417895.2A CN118013666B (en) | 2024-04-09 | 2024-04-09 | Blade for high cycle fatigue crack test of air-cooled turbine blade and design method |
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| CN118013666B true CN118013666B (en) | 2024-06-18 |
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| CN103196644B (en) * | 2013-04-09 | 2015-10-21 | 中国航空动力机械研究所 | integral impeller blade vibration fatigue test device and test method |
| CN103558072A (en) * | 2013-11-14 | 2014-02-05 | 北京航空航天大学 | Complex structure type precrack machining method |
| CN104535438B (en) * | 2014-12-31 | 2017-07-04 | 北京航空航天大学 | A kind of all Combined Fatigue Crack Propagation pilot systems of testpieces high temperature height and measuring method |
| CN106644490B (en) * | 2016-12-31 | 2018-08-03 | 北京航空航天大学 | A kind of all Combined Fatigue Crack Propagation life-span prediction methods of turbine mortise structure height |
| CN108890053B (en) * | 2018-06-29 | 2020-02-21 | 南京航空航天大学 | Double-channel tube electrode and electrolytic cutting method thereof |
| CN110426171A (en) * | 2019-08-13 | 2019-11-08 | 中国航发贵阳发动机设计研究所 | A kind of fixture and its application method of turbine blade vibration fatigue test |
| CN111579396B (en) * | 2020-04-29 | 2021-08-06 | 南京航空航天大学 | Optimization method of turbine joggling fretting fatigue test piece |
| CN114875347B (en) * | 2022-03-21 | 2022-12-06 | 西安交通大学 | Low-speed temperature-rising reversion heat treatment method for blade tenon |
| CN115640673A (en) * | 2022-09-23 | 2023-01-24 | 中国航发北京航空材料研究院 | Potential method-based method for testing fatigue crack state of tenon tooth simulation part |
| CN116202716A (en) * | 2022-12-31 | 2023-06-02 | 中国航发沈阳发动机研究所 | Turbine blade root extension vibration fatigue test piece and construction method thereof |
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| Title |
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| 航空发动机自由涡轮盘低循环疲劳寿命试验研究;魏勇等;《航空发动机》;20200615;第46卷(第3期);第31-34页 * |
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