CN105650392A - 90-degree rectangular silencing and denoising elbow used for window-mounted fan and elbow silencing treatment method - Google Patents

Abstract

The invention discloses a 90-degree rectangular silencing and denoising elbow used for a window-mounted fan and an elbow silencing treatment method. The 90-degree rectangular silencing and denoising elbow for the window-mounted fan comprises a top plate, a bottom plate, an outer cambered surface and an inner cambered surface, wherein a quarter-circle arc-shaped pipe is encircled by using the top plate, the bottom plate, the outer cambered surface and the inner cambered surface as four sides; the top plate is identical to the bottom plate; the top plate, the bottom plate and the inner cambered surface are all divided into a high-noise zone, a middle-noise zone and a low-noise zone; and silencing materials are arranged on the surfaces, positioned in the 90-degree rectangular silencing and denoising elbow, of the high-noise zone and the middle-noise zone for different thicknesses. Silencing treatment is carried out in different noise zones by using different silencing materials, and each part needing to be treated can be specially and accurately treated, so that the silencing effect is effectively improved.

Description

The window load blower fan noise elimination processing method of 90 �� of rectangle silencing noise reduction elbows and elbow

Technical field

The invention belongs to air conditioner field, be specifically related to a kind of rectangular elbow and elbow processing method, particularly a kind of window load blower fan noise elimination processing method of 90 �� of rectangle silencing noise reduction elbows and elbow.

Background technology

Noise is one of influence factor of Indoor Environmental Quality, and person works's efficiency can be produced impact by noise, especially the impact of Precision Machining workman or brain worker is become apparent from: it can disperse the attention of people even to damage health. In ventilation and air conditioning system, air-flow can produce regenerated noise when flowing in airduct elbow, and the more big regenerated noise of wind speed is more big. Noise is propagated by airduct, and the noise produced in airduct elbow is positioned at after the acoustic filter of ventilation and air conditioning system, and acoustic filter is helpless. Therefore, in ventilation and air conditioning system, bend pipe is noise control becomes the interior noise control very crucial problem of building.

At present, controlling bend pipe noise mainly has two ways: a kind of method be in air conditioner designs by the flow speed control of air main in 8m/s, with the noise that the tube wall vibration alleviating friction between air-flow and pipeline and air-flow excites produces. But, in fluid delivery pipeline, the pipe fitting changing the fluid flow direction that 90 �� of rectangular elbow right and wrong are usually shown in. Due to the turning of fluid, occur in that from the center of curvature to the centrifugal force of bend pipe extrados, this allow for fluid from the straight pipeline of pipeline be transitioned into bending tube section time, extrados pressure increase and the pressure of intrados reduce. So, the flow velocity at extrados place fluid reduces, and the flow velocity of intrados place fluid correspondingly increases, it is easy to producing the flow velocity more than 8m/s at some position, being difficult to the noise eliminated in indoor generation, thus affecting the physical and mental health of indoor occupant. Another kind of method is all to apply deadener at pipe interior to lay and eliminate the noise, and so not only results in pipeline internal resistance and becomes very big, it is necessary to energy expenditure increase, the equipment such as breeze fan also to select relatively large number, increases first cost and installation difficulty. And it is all very big currently to have airduct area in the building concentrating air conditioner, it is necessary to use substantial amounts of deadener, costly.

Summary of the invention

For defect or the deficiency of prior art, it is an object of the invention to, it is provided that a kind of 90 �� of rectangle bend mufflers.

For realizing above-mentioned technical assignment, the present invention adopts following technical proposals to be achieved:

A kind of 90 �� of rectangle silencing noise reduction elbows, including upper plate, lower shoe, extrados and intrados; Upper plate, lower shoe, extrados and intrados surround the curved pipe obtaining one 1/4 circle as four faces; Upper plate is identical with lower shoe; Described upper plate, lower shoe and intrados are all divided into high noisy district, middle noise regions and the low noise range of sound; At the deadener that described high noisy district has thickness different with the surface configuration being positioned at 90 �� of rectangle silencing noise reduction elbows of middle noise regions.

Further, the deadener of the surface configuration being positioned at elbow in described strong noise district is polyurethane rubber.

Further, following formula is utilized to calculate the thickness of described deadener:

$H_h={\mathrm{\γ}}_1\×\mathrm{\δ}\×INT\[\frac{L_p}{L_{h-m}}\×\frac{L_{max-h}}{L_{h-m}}\]$

In formula, H_hFor the thickness that high noisy district polyurethane rubber is smeared, mm; �� is 90 �� of rectangular bend wall thickness, mm; L_max-hFor the maximum sound pressure level value in plate face, dB; L_h-mFor dividing the sound pressure level threshold value in high noisy district and middle noise regions, dB; L_PFor the sound pressure level at arbitrfary point place, dB in high noisy district; ��₁For high noisy district thickness constant coefficient, 1�ܦ�₁�� 6; One numerical value is rounded downwards the function into immediate integer by INT.

Further, the deadener of the surface configuration being positioned at elbow of described middle noise regions is resin modified asphalt.

Further, the thickness of described deadener:

$H_m={\mathrm{\γ}}_2\×\mathrm{\δ}\×INT\[\frac{L_p}{L_{m-l}}\×\frac{L_{h-m}}{L_{m-l}}\]$

In formula, H_mFor the thickness that middle noise regions resin modified asphalt is smeared, mm; �� is 90 �� of rectangular bend wall thickness, mm; L_h-mFor dividing the sound pressure level threshold value in high noisy district and middle noise regions, dB; L_m-lFor the sound pressure level threshold value in noise regions and the low noise range of sound, dB in dividing; L_PFor the sound pressure level at arbitrfary point place, dB in middle noise regions; ��₂For middle noise regions thickness constant coefficient, 1�ܦ�₂�� 6; One numerical value is rounded downwards the function into immediate integer by INT.

It is a further object of the invention to provide a kind of noise processing method to 90 �� of rectangular elbow, comprise the following steps:

Step 1: solve equation of continuity and the N-S equation of momentum partial differential equations of 90 �� of rectangular elbow, and determine 90 �� of rectangular elbow stable state turbulent-velocity field U (x, y, z) and pressure field P (x, y, z);

Step 2: the 90 �� of rectangular elbow stable state turbulent-velocity field U (x obtained according to step 1, y, z) with pressure field P (x, y, z), substitute into formula 1, then formula 1 is carried out single order upstreame scheme discretization, and solve the formula after discretization 1, obtain the components of flow u of acoustics pulsation partial differential equation_a(x, y, z) and P_a(x, y, z), and then obtain the dissipative shock wave �� of turbulent fluctuation kinetic energy k and turbulent fluctuation kinetic energy;

$\frac{\∂u_{ai}}{\∂t}+U_j\frac{\∂u_{ai}}{\∂x_j}+u_{ai}\frac{\∂U_i}{\∂x_j}+\frac{1}{\mathrm{\ρ}}\frac{\∂P_a}{\∂x_i}-\frac{{\mathrm{\ρ}}_a}{{\mathrm{\ρ}}^2}\frac{\∂P}{\∂x_i}=-U_j\frac{\∂{u^{\′}}_i}{\∂x_j}-{u^{\′}}_j\frac{\∂U_i}{\∂x_j}-{u^{\′}}_j\frac{\∂{u^{\′}}_i}{\∂x_j}-\frac{1}{\mathrm{\ρ}}\frac{\∂P^{\′}}{\∂x_i}-\frac{\∂{u^{\′}}_i}{\∂t}$ (formula 1)

In formula, t is the time, s; I and j is the durection component of rectangular coordinate system; �� is atmospheric density, kg/m³; ��_aFor the atmospheric density on plate face, kg/m³; U' is fluctuation velocity, m/s; P' is fluctuation pressure, Pa; U is 90 �� of rectangular elbow stable state turbulent velocities, m/s; P is 90 �� of rectangular elbow pressure, Pa;

Step 3: solve the dissipative shock wave �� of turbulent fluctuation kinetic energy k and the turbulent fluctuation kinetic energy obtained according to step 2, calculate the sound pressure level L of intrados, upper plate and lower shoe respectively_P, obtain the respective sound pressure level scope of intrados, upper plate and lower shoe;

Step 4: the sound pressure level scope according to intrados, upper plate and lower shoe that step 3 obtains, calculates the sound pressure level threshold value L dividing high noisy district and middle noise regions obtaining each plate face respectively_h-m, dB;Calculate the sound pressure level threshold value L in noise regions and the low noise range of sound in the division obtaining intrados, upper plate and lower shoe simultaneously_m-l, dB; By L_h-mCurve corresponding on plate face is as strong noise district envelope curve; By L_m-lCurve corresponding on plate face is as middle noise range envelope curve;

Step 5: respectively the middle low noise region envelope curve on each plate face that step 4 obtains, senior middle school's noise range envelope curve takes multiple discrete point, and obtain the coordinate figure of these discrete points; The coordinate figure of the discrete point on centering low noise region envelope curve, senior middle school's noise range envelope curve is fitted, and obtains original fit curve equation; Then adopt general Global Optimization Method that original fit curve equation is processed, obtain middle low noise region envelope curve, fit curve equation that senior middle school's noise range envelope curve is corresponding;

Step 6: step 5 is obtained every fit curve equation in each plate face as the demarcation line of each noise regions on plate face, obtain the high noisy district in each plate face, middle noise regions and the low noise range of sound;

Step 7: in the surface smear polyurethane rubber being positioned at 90 �� of rectangle silencing noise reduction elbows in the high noisy district in each plate face that step 6 obtains, at the surface smear resin modified asphalt being positioned at 90 �� of rectangle silencing noise reduction elbows of middle noise regions.

Further, in described step 3, following formula is utilized to calculate the sound pressure level L of intrados, upper plate and lower shoe respectively_P:

$L_P=10log\[\frac{{\mathrm{\α}}_{\mathrm{\ϵ}}\mathrm{\ρ}\mathrm{\ϵ}{\left(2k\right)}^{\frac{5}{2}}}{P_{ref}{{\mathrm{\α}}_0}^5}\]$

In formula: ��_��For reduced scale constant, study according to Sarkar&Hussaini isotropic turbulence DNS analog calibration, take 0.1; P_refFor reference sound power, W/m³, ��₀For the local velocity of sound under the status of criterion, m/s; �� is atmospheric density, kg/m³��

Further, in described step 4, formula 3 is utilized to respectively obtain the sound pressure level threshold value L dividing high noisy district and middle noise regions in each plate face_h-m; Utilize formula 4 to obtain the sound pressure level threshold value L in noise regions and the low noise range of sound in the division of intrados, upper plate and lower shoe simultaneously_m-l;

$L_{h-m}=L_{max-h}-\left(\frac{L_{max-h}-L_{\min -l}}{3}\right)\mathrm{\β},1\≤\mathrm{\β}\≤3$ (formula 3)

$L_{m-l}=L_{\min -l}+\left(\frac{L_{max-h}-L_{\min -l}}{3}\right)\mathrm{\&alpha;},0<\mathrm{\&alpha;}\&le;1$ (formula 4)

In formula, L_max-h��L_min-lThe respectively maximum sound pressure level value in plate face and minimal sound pressure levels value, dB; ��, �� are that region divides constant, 0.5 < ����1,1�ܦ¡�2.

Further, in described step 7, the thickness smearing polyurethane rubber in high noisy district is determined according to formula 5:

$H_h={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{L_p}{L_{h-m}}\&times;\frac{L_{max-h}}{L_{h-m}}\&rsqb;$ (formula 5)

In formula, H_hFor the thickness that high noisy district polyurethane rubber is smeared, mm; �� is 90 �� of rectangular bend wall thickness, mm; L_max-hFor the maximum sound pressure level value in plate face, dB; L_h-mFor dividing the sound pressure level threshold value in high noisy district and middle noise regions, dB; L_PFor the sound pressure level at arbitrfary point place, dB in high noisy district; ��₁For high noisy district thickness constant coefficient, 1�ܦ�₁�� 6; One numerical value is rounded downwards the function into immediate integer by INT.

Further, in described step 7, the thickness smearing resin modified asphalt in middle noise regions is determined according to formula 6:

$H_m={\mathrm{\&gamma;}}_2\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{L_p}{L_{m-l}}\&times;\frac{L_{h-m}}{L_{m-l}}\&rsqb;$ (formula 6)

In formula, H_mFor the thickness that middle noise regions resin modified asphalt is smeared, mm; �� is 90 �� of rectangular bend wall thickness, mm; L_h-mFor dividing the sound pressure level threshold value in high noisy district and middle noise regions, dB; L_m-lFor the sound pressure level threshold value in noise regions and the low noise range of sound, dB in dividing; L_PFor the sound pressure level at arbitrfary point place, dB in middle noise regions; ��₂For middle noise regions thickness constant coefficient, 1�ܦ�₂�� 6; One numerical value is rounded downwards the function into immediate integer by INT.

Present invention have the advantage that

(1) method by solving acoustics pulsation partial differential equation, it is possible to be accurately positioned the noise size distribution in 90 �� of rectangular elbow plate faces, carry out noise reduction process with a definite target in view, it is possible to the noise effectively reducing airduct elbow produces.

(2) upper plate, lower shoe and intrados are respectively divided high noisy district, middle noise regions and the low noise range of sound, different deadeners is selected to carry out noise elimination process in high noisy district and middle noise regions, can be processed each targetedly and exactly and need position to be processed, improve soundproof effect.

(3) smearing thickness in high noisy district, the deadener of middle noise regions is carried out Precise spraying, not only to different noise regional choice difference deadeners, and in same noise region, different sections select different smearing thickness, can significantly improve soundproof effect by the suitable thickness after designing.

Accompanying drawing explanation

Fig. 1 is existing 90 �� of rectangular bend schematic diagrams;

Fig. 2 is that intrados noise reduction processes schematic diagram;

Fig. 3 is that upper plate noise reduction processes schematic diagram;

Fig. 4 is that lower shoe noise reduction processes schematic diagram;

Fig. 5 is sound pressure level field schematic diagram in existing 90 �� of rectangular elbow;

Fig. 6 is existing 90 �� of rectangular elbow upper plate high noisies, middle noise and low noise range of sound figure;

Fig. 7 is existing 90 �� of rectangular elbow lower shoe high noisies, middle noise and low noise range of sound figure;

Fig. 8 is existing 90 �� of rectangular elbow intrados high noisies, middle noise and low noise range of sound figure;

Fig. 9 is existing 90 �� of rectangular elbow (a) and sound-deadening and noise-reducing elbow (b) the upper plate sound pressure level profiles versus of the present invention schemes;

Figure 10 is existing 90 �� of rectangular elbow (a) and sound-deadening and noise-reducing elbow (b) the lower shoe sound pressure level profiles versus of the present invention schemes;

Figure 11 is existing 90 �� of rectangular elbow (a) and sound-deadening and noise-reducing elbow (b) the intrados sound pressure level profiles versus of the present invention schemes.

Each label implication in figure: 1-entrance; 2-extrados; 3-upper plate; 4-lower shoe; 5-exports; 6-flange; 7-intrados; The 8-intrados low noise range of sound; Noise regions in 9-intrados; 10-intrados high noisy district; 11-upper plate low noise region; Noise regions in 12-upper plate; 13-upper plate high noisy district; The 14-lower shoe low noise range of sound; Noise regions in 15-lower shoe; 16-lower shoe high noisy district.

Detailed description of the invention

As it is shown in figure 1, the main body of the sound-deadening and noise-reducing elbow of the present invention adopts 90 �� of common rectangular elbow, 90 �� of common rectangular elbow include upper plate 3, lower shoe 4, extrados 2 and intrados 7; Upper plate 3, lower shoe 4, extrados 2 and intrados 7 surround the curved pipe obtaining one 1/4 circle as four faces. Upper plate 3 is identical with lower shoe 4.

In order to effectively eliminate elbow noise, the upper plate 3 of 90 �� of common rectangular elbow, lower shoe 4 and intrados 7 are carried out noise elimination process respectively. Owing to the noise figure of extrados 2 is very low, extrados 2 is not carried out noise elimination process by the present invention. Noise elimination processes specific as follows:

Upper plate 3, lower shoe 4 and intrados 7 are all divided into high noisy district, middle noise regions and the low noise range of sound. Specifically: the surface being arranged in 90 �� of rectangular elbow of upper plate 3 is divided into high noisy district 13, noise regions 12 and the low noise range of sound 11; The surface being arranged in 90 �� of rectangular elbow of lower shoe 4 is divided into high noisy district 16, noise regions 15 and the low noise range of sound 14; Intrados 7 is arranged in the surface of 90 �� of rectangular elbow and is divided into high noisy district 10, noise regions 9 and the low noise range of sound 8. Owing to the noise figure in the low noise range of sound is very low, therefore do not do noise elimination and process. Only high noisy district, middle noise regions are carried out noise elimination process.

Optionally, strong noise district smears polyurethane rubber, the thickness of polyurethane rubber:

$H_h={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{L_p}{L_{h-m}}\&times;\frac{L_{max-h}}{L_{h-m}}\&rsqb;$

Optionally, middle noise regions is smeared resin modified asphalt, the thickness of resin modified asphalt:

$H_m={\mathrm{\&gamma;}}_2\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{L_p}{L_{m-l}}\&times;\frac{L_{h-m}}{L_{m-l}}\&rsqb;.$

The present invention gives the noise processing method to 90 �� of rectangular elbow, comprises the following steps:

Step 1: for 90 �� of common rectangular elbow, solves its equation of continuity and N-S equation of momentum partial differential equations, it is determined that 90 �� of rectangular elbow stable state turbulent-velocity field U (x, y, z) and pressure field P (x, y, z);

Optionally, above-mentioned equation of continuity, solving of N-S equation of momentum partial differential equations are to adopt based on the Pressurebased RNGk-�� turbulence model solved and carry out in conjunction with simple algorithm.

Step 2: the 90 �� of rectangular elbow stable state turbulent-velocity field U (x obtained according to step 1, y, z) with pressure field P (x, y, z), substitute into the acoustics pulsation partial differential equation shown in formula 1, then formula 1 is carried out single order upstreame scheme discretization, and utilize the formula 1 after your iterative discretization of Gauss-Saden, obtain the components of flow u of acoustics pulsation partial differential equation_a(x, y, z) and P_a(x, y z), and then obtain the dissipative shock wave �� (%) of turbulent fluctuation kinetic energy k (J) and turbulent fluctuation kinetic energy.

$\frac{\&part;u_{ai}}{\&part;t}+U_j\frac{\&part;u_{ai}}{\&part;x_j}+u_{ai}\frac{\&part;U_i}{\&part;x_j}+\frac{1}{\mathrm{\&rho;}}\frac{\&part;P_a}{\&part;x_i}-\frac{{\mathrm{\&rho;}}_a}{{\mathrm{\&rho;}}^2}\frac{\&part;P}{\&part;x_i}=-U_j\frac{\&part;{u^{\&prime;}}_i}{\&part;x_j}-{u^{\&prime;}}_j\frac{\&part;U_i}{\&part;x_j}-{u^{\&prime;}}_j\frac{\&part;{u^{\&prime;}}_i}{\&part;x_j}-\frac{1}{\mathrm{\&rho;}}\frac{\&part;P^{\&prime;}}{\&part;x_i}-\frac{\&part;{u^{\&prime;}}_i}{\&part;t}$ (formula 1)

In formula, t is the time, s; I and j is the durection component of rectangular coordinate system; �� is atmospheric density, kg/m³; ��_aFor the atmospheric density on plate face, kg/m³; U' is fluctuation velocity, m/s; P' is fluctuation pressure, Pa; U is 90 �� of rectangular elbow stable state turbulent velocities, m/s; P is 90 �� of rectangular elbow pressure, Pa.

Optionally, the defining method of acoustics pulsation partial differential equation is as follows: the flow variables in the N-S equation of momentum partial differential equations described in step 1 is decomposed, obtains time-average flow, instantaneous pulsation and acoustics and pulse three parts; Time-average flow part and the components of flow of instantaneous pulsatile portion it is far smaller than due to the components of flow of acoustics pulsatile portion, by magnitude comparative approach, cast out time-average flow part and the components of flow of instantaneous pulsatile portion, obtain the acoustics pulsation partial differential equation shown in above-mentioned formula 1.

Step 3: solve the dissipative shock wave �� of turbulent fluctuation kinetic energy k and the turbulent fluctuation kinetic energy obtained according to step 2, utilize formula 2 to calculate the sound pressure level L of intrados, upper plate and lower shoe respectively_P(dB), thus obtaining the respective sound pressure level scope of intrados, upper plate and lower shoe;

$L_P=10log\&lsqb;\frac{{\mathrm{\&alpha;}}_{\mathrm{\&epsiv;}}\mathrm{\&rho;}\mathrm{\&epsiv;}{\left(2k\right)}^{\frac{5}{2}}}{P_{ref}{{\mathrm{\&alpha;}}_0}^5}\&rsqb;$ (formula 2)

In formula: ��_��For reduced scale constant, study according to Sarkar&Hussaini isotropic turbulence DNS analog calibration, take 0.1; P_refFor reference sound power, W/m³, ��₀For the local velocity of sound under the status of criterion, m/s; �� is atmospheric density, kg/m³��

Step 4: the sound pressure level scope according to intrados, upper plate and lower shoe that step 3 obtains, is utilized respectively formula 3 and obtains the sound pressure level threshold value L dividing high noisy district and middle noise regions in each plate face_h-m, dB; Utilize formula 4 to obtain the sound pressure level threshold value L in noise regions and the low noise range of sound in the division of intrados, upper plate and lower shoe simultaneously_m-l, dB; By L_h-mCurve corresponding on plate face is as the strong noise district in plate face and demarcation line, middle noise range, i.e. strong noise district envelope curve; By L_m-lCurve corresponding on plate face is as the middle noise range in plate face and low noise region demarcation line, noise range envelope curve in namely;

$L_{h-m}=L_{max-h}-\left(\frac{L_{max-h}-L_{\min -l}}{3}\right)\mathrm{\&beta;},1\&le;\mathrm{\&beta;}\&le;3$ (formula 3)

$L_{m-l}=L_{\min -l}+\left(\frac{L_{max-h}-L_{\min -l}}{3}\right)\mathrm{\&alpha;},0<\mathrm{\&alpha;}\&le;1$ (formula 4)

In formula, L_max-h��L_min-lThe respectively maximum sound pressure level value in plate face and minimal sound pressure levels value, dB; ��, �� are that region divides constant, and beta/alpha is more big, and the strong noise district scope of division is more big, low noise range of sound scope is more little, it is necessary to the regional extent of noise processed is more big, and elbow soundproof effect is more good, but the resistance of ducting increasing generation of deadener can increase, and expense also can increase accordingly. Through verification experimental verification, choosing 0.5 < ����1,1�ܦ¡�2 can effectively reduce the resistance of ducting, it is achieved preferably soundproof effect. Wherein, plate face refers to upper plate 3, lower shoe 4, extrados 2 or intrados 7.

Step 5: respectively the middle low noise region envelope curve on each plate face that step 4 obtains, senior middle school's noise range envelope curve takes fully more than enough (no less than 200) discrete point, and obtain the coordinate figure of these discrete points;The coordinate figure adopting the discrete point on Levenberg-Marquardt algorithm centering low noise region envelope curve, senior middle school's noise range envelope curve is fitted, and obtains original fit curve equation; Then adopt general Global Optimization Method that original fit curve equation is processed, obtain middle low noise region envelope curve, fit curve equation that senior middle school's noise range envelope curve is corresponding.

Can be seen that from the coordinate figure of the point envelope curve, on envelope curve, change in value amplitude is uncertain, parameter amount is more, when adopting all kinds of iterative method conventional in optimization calculating field, initial parameter value set loaded down with trivial details and calculate be difficult to restrain, correct result cannot be tried to achieve, inventors performed lot of experiments checking, find to adopt the general global optimization approach of Levenberg-Marquardt+, can start to try to achieve correct result from arbitrary random starting values, and then can be derived that the fit curve equation of the high accuracy that each envelope curve is corresponding, low residual error.

Step 6: step 5 is obtained every fit curve equation in each plate face as the demarcation line of each noise regions on plate face, obtain the high noisy district in each plate face, middle noise regions and the low noise range of sound.

Step 7: smear polyurethane rubber in the high noisy district in each plate face that step 6 obtains, smear resin modified asphalt in middle noise regions, the kinetic energy of the vibrations of air layer is converted into thermal energy consumption and falls, with the effect that raising abates the noise. Specific as follows:

The thickness smearing polyurethane rubber in high noisy district is determined according to formula 5, and middle noise regions is smeared the thickness of resin modified asphalt and determined according to formula 6. By formula 5, formula 6 it can be seen that the deadener thickness smeared in same noise regions is along with sound pressure level L_PSize and different, therefore, the different noise sections calculated deadener thickness in same noise regions is one or more.

$H_h={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{L_p}{L_{h-m}}\&times;\frac{L_{max-h}}{L_{h-m}}\&rsqb;$ (formula 5)

$H_m={\mathrm{\&gamma;}}_2\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{L_p}{L_{m-1}}\&times;\frac{L_{h-m}}{L_{m-l}}\&rsqb;$ (formula 6)

In formula, H_hFor the thickness that high noisy district polyurethane rubber is smeared, mm; H_mFor the thickness that middle noise regions resin modified asphalt is smeared, mm; �� is 90 �� of rectangular bend wall thickness, mm; L_max-hFor the maximum sound pressure level value in plate face, dB; L_h-mFor dividing the sound pressure level threshold value in high noisy district and middle noise regions, dB; L_m-lFor the sound pressure level threshold value in noise regions and the low noise range of sound, dB in dividing; L_PFor the sound pressure level at arbitrfary point place, dB in high noisy district or middle noise regions; ��₁����₂Respectively high noisy district, middle noise regions thickness constant coefficient because daily design requiring, deadener thickness is 3 �ġ�6 ��, so 1�ܦ�₁�� 6,1�ܦ�₂�� 6; One numerical value is rounded downwards the function into immediate integer by INT.

Need to smear the thickness of deadener in each noise regions according to calculated each plate face, polyurethane rubber is smeared in high noisy region, resin modified asphalt is smeared in middle noise region, in same noise regions, the different-thickness according to deadener is smeared, it is possible to reduce the resistance of ducting and Master Cost further.

Embodiment 1

Specific embodiments of the invention given below, it is necessary to explanation is to the invention is not limited in specific examples below, and all equivalents done on technical scheme basis each fall within protection scope of the present invention.

Defer to technique scheme, the cross section of the entrance and exit of 90 �� of rectangular elbow in the present embodiment is 320mm �� 250mm, the thickness of upper plate, lower shoe, intrados and extrados is 0.5mm, intrados radius is 320mm, extrados radius is 640mm, before 90 �� of rectangular elbow entrances, it is terminated with the straight length of 2m length, after outlet, is terminated with the straight length of 2m length.Being 5��6.5m/s according to airduct main leg's wind speed in " civil buildings heating ventilator and In Air Conditioning Design specification ", the maximum requirement less than 8m/s, entrance front end straight length inlet velocity is taken as 6m/s.

Adopt following steps that above-mentioned 90 �� of rectangular elbow are carried out noise elimination process:

Step 1: for 90 �� of rectangular elbow, adopt based on the Pressurebased RNGk-�� turbulence model solved and in conjunction with simple algorithm, solve equation of continuity and N-S equation of momentum partial differential equations, and determine 90 �� of rectangular elbow stable state turbulent-velocity field U (x, y, z), pressure field P (x, y, z).

Step 2: by 90 �� of rectangular elbow stable state turbulent-velocity field U (x, y, z), pressure field P (x, y, z) acoustics pulsation partial differential equation are substituted into, then formula 1 is carried out single order upstreame scheme discretization, and utilizes your iteration of Gauss-Saden that formula 1 is solved, obtain the components of flow u of acoustics pulsation partial differential equation_a(x, y, z) and P_a(x, y z), and then obtain the dissipative shock wave �� (%) of turbulent fluctuation kinetic energy k (J) and turbulent fluctuation kinetic energy.

Step 3: solve the dissipative shock wave �� of turbulent fluctuation kinetic energy k and the turbulent fluctuation kinetic energy obtained according to step 2, utilize formula 2 to calculate the sound pressure level L of intrados, upper plate and lower shoe_P(dB), thus obtaining the sound pressure level scope of intrados, upper plate and lower shoe, as shown in Figure 5.

Step 4: take ��=��=1, utilizes formula 3 to obtain the sound pressure level threshold value L dividing high noisy district and middle noise regions of intrados, upper plate and lower shoe_h-mIt is respectively as follows: 29dB, 22dB, 22dB; Formula 4 is utilized to obtain the sound pressure level threshold value L in noise regions and the low noise range of sound in the division of intrados, upper plate and lower shoe_m-lIt is respectively as follows: 24.5dB, 12dB, 12dB. By L_h-mCurve corresponding on plate face is as the strong noise district in plate face and demarcation line, middle noise range, i.e. strong noise district envelope curve; By L_m-lCurve corresponding on plate face as the middle noise range in plate face and low noise region demarcation line, noise range envelope curve in namely, such as Fig. 6,7 and shown in 8.

Step 5: respectively the middle low noise region envelope curve on each plate face that step 4 obtains, senior middle school's noise range envelope curve takes 200 discrete points, and obtain the coordinate figure of these discrete points; The coordinate figure adopting the discrete point on Levenberg-Marquardt centering low noise region respectively envelope curve, senior middle school's noise range envelope curve is fitted, and obtains original fit curve equation; Then adopt the intelligent optimization that original fit curve equation is independent of initial value by general Global Optimization Method to process, obtain the correlation coefficient middle low noise region envelope curve more than 0.99, fit curve equation that senior middle school's noise range envelope curve is corresponding.

Obtain each plate face upper low noise region envelope curve, fit curve equation that senior middle school's noise range envelope curve is corresponding, in Table 1. Upper plate high noisy region envelope curve equation is 1, and middle noise region envelope curve equation is 2; Lower shoe high noisy region envelope curve equation is 3, and middle noise region envelope curve equation is 4; Intrados high noisy region envelope curve equation is 5, and middle noise region envelope curve equation is 6.

The fit curve equation that table 1 envelope curve is corresponding

(x^*And y^*For dimensionless coordinate, whereinR is elbow radius)

Step 6: step 5 is obtained every fit curve equation in each plate face as the demarcation line of each noise regions on plate face, obtain the high noisy district in each plate face, middle noise regions and the low noise range of sound.

Step 7: smear polyurethane rubber in the high noisy district in each plate face that step 6 obtains, smear resin modified asphalt in middle noise regions.Specific as follows:

According to formula 5, calculate noise elimination material thickness (see table 2) in the high noisy district of intrados, upper plate and lower shoe respectively; Visible, the thickness that different sections in the high noisy district of upper plate and lower shoe obtain is different;

According to noise elimination material thickness, being positioned on the surface of elbow and smearing polyurethane rubber in the high noisy district of intrados in calculated intrados high noisy district. Being positioned on the surface of elbow deadener and be divided into two kinds of thickness to smear in upper plate high noisy district, the deadener in lower shoe high noisy district is divided into two kinds of thickness to smear.

According to formula 6, calculate noise elimination material thickness in the middle noise regions of intrados, upper plate and lower shoe respectively; According to noise elimination material thickness in noise regions in calculated intrados, being positioned on the surface of elbow and smearing resin modified asphalt in the middle noise regions of intrados. Being positioned on the surface of elbow deadener and be divided into two kinds of thickness to smear of noise regions in upper plate, in lower shoe, in noise regions, deadener is divided into two kinds of thickness to smear. Deadener and one-tenth-value thickness 1/10 such as table 2.

Table 2 each noise regions deadener and thickness

Such as: the thickness H that upper plate high noisy district polyurethane rubber is smeared_hAsk for as follows:

The high noisy region of upper plate is 22-32dB, now L_h-m=22dB (L_h-mFor dividing the sound pressure level threshold value in high noisy district and middle noise regions), L_max-h=32dB (L_max-hMaximum sound pressure level value for plate face). L_PSpan be exactly 22-32dB.

The first step: first take L_PIt is known that=22dB substitutes into formula 5:

$H_h={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{L_p}{L_{h-m}}\&times;\frac{L_{max-h}}{L_{h-m}}\&rsqb;={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{22}{22}\&times;\frac{32}{22}\&rsqb;={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;1.4545\&rsqb;$

Because INT is a numerical value rounds downwards the function into immediate integer,

So INT [1.4545]=1,

So H_h=��₁����

Second step: in like manner: take L successively_PIt is known that=23-31dB substitutes into formula 5:

H_h=��₁����

3rd step: take L_PIt is known that=31dB substitutes into formula 5:

$\begin{array}{c}{H}_h={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{L_p}{L_{h-m}}\&times;\frac{L_{max-h}}{L_{h-m}}\&rsqb;={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{31}{22}\&times;\frac{32}{22}\&rsqb;={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;2.04958\&rsqb;\\ ={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;2\end{array}$

Take L_PIt is known that=32dB substitutes into formula 5:

$\begin{array}{c}{H}_h={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{L_p}{L_{h-m}}\&times;\frac{L_{max-h}}{L_{h-m}}\&rsqb;={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{32}{22}\&times;\frac{32}{22}\&rsqb;={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;2.1157\&rsqb;\\ ={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;2\end{array}$

So calculating: H_hDuring 22-30dB region in upper plate high noisy region (22-32dB), H_h=��₁����

H_hDuring 31-32dB region in upper plate high noisy region (22-32dB), H_h=��₁�� �� �� 2 are so the deadener thickness that the different noise sections that calculate in same noise regions are smeared can be different.

Sound pressure level field distribution such as Fig. 9 of 90 �� of rectangle bend mufflers after the said method of the present invention carries out noise elimination process, 10 and 11. Through comparing, the soundproof effect of the sound-deadening and noise-reducing elbow of the present invention is obvious, the highest by 33.5dB, the noise in high noisy region is reduced to 16dB, and noise decibel is reduced 52%, the noise in middle noise region is reduced to 11.0dB by 20dB, noise decibel is reduced 45%. Meanwhile, the method for Varying-thickness effectively reduces the resistance of ducting making consumption and generation thereof of deadener, reduces initial cost cost.

Claims (10)

1. window load blower fan is with 90 �� of rectangle silencing noise reduction elbows, including upper plate, lower shoe, extrados and intrados; Upper plate, lower shoe, extrados and intrados surround the curved pipe obtaining one 1/4 circle as four faces; Upper plate is identical with lower shoe; It is characterized in that, described upper plate, lower shoe and intrados are all divided into high noisy district, middle noise regions and the low noise range of sound; There is the deadener that thickness is different with the surface configuration being positioned at elbow of middle noise regions in described high noisy district.

2. window as claimed in claim 1 carries 90 �� of rectangle silencing noise reduction elbows of blower fan, it is characterised in that the deadener of the surface configuration being positioned at elbow in described strong noise district is polyurethane rubber.

3. window as claimed in claim 1 or 2 carries 90 �� of rectangle silencing noise reduction elbows of blower fan, it is characterised in that utilize following formula to calculate the thickness of described deadener:

$H_h={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{L_p}{L_{h-m}}\&times;\frac{L_{max-h}}{L_{h-m}}\&rsqb;$

In formula, H_hFor the thickness that high noisy district polyurethane rubber is smeared, mm;�� is 90 �� of rectangular bend wall thickness, mm; L_max-hFor the maximum sound pressure level value in plate face, dB; L_h-mFor dividing the sound pressure level threshold value in high noisy district and middle noise regions, dB; L_PFor the sound pressure level at arbitrfary point place, dB in high noisy district; ��₁For high noisy district thickness constant coefficient, 1�ܦ�₁�� 6; One numerical value is rounded downwards the function into immediate integer by INT.

4. window as claimed in claim 1 carries 90 �� of rectangle silencing noise reduction elbows of blower fan, it is characterised in that the deadener of the surface configuration being positioned at elbow of described middle noise regions is resin modified asphalt.

5. the window as described in claim 1 or 4 carries 90 �� of rectangle silencing noise reduction elbows of blower fan, it is characterised in that the thickness of described deadener:

$H_m={\mathrm{\&gamma;}}_2\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{L_p}{L_{m-l}}\&times;\frac{L_{h-m}}{L_{m-l}}\&rsqb;$

In formula, H_mFor the thickness that middle noise regions resin modified asphalt is smeared, mm; �� is 90 �� of rectangular bend wall thickness, mm; L_h-mFor dividing the sound pressure level threshold value in high noisy district and middle noise regions, dB; L_m-lFor the sound pressure level threshold value in noise regions and the low noise range of sound, dB in dividing; L_PFor the sound pressure level at arbitrfary point place, dB in middle noise regions; ��₂For middle noise regions thickness constant coefficient, 1�ܦ�₂�� 6; One numerical value is rounded downwards the function into immediate integer by INT.

6. the noise processing method to 90 �� of rectangular elbow, it is characterised in that comprise the following steps:

Step 1: solve equation of continuity and the N-S equation of momentum partial differential equations of 90 �� of rectangular elbow, and determine 90 �� of rectangular elbow stable state turbulent-velocity field U (x, y, z) and pressure field P (x, y, z);

Step 2: the 90 �� of rectangular elbow stable state turbulent-velocity field U (x obtained according to step 1, y, z) with pressure field P (x, y, z), substitute into formula 1, then formula 1 is carried out single order upstreame scheme discretization, and solve the formula after discretization 1, obtain the components of flow u of acoustics pulsation partial differential equation_a(x, y, z) and P_a(x, y, z), and then obtain the dissipative shock wave �� of turbulent fluctuation kinetic energy k and turbulent fluctuation kinetic energy;

$\frac{\&part;u_{ai}}{\&part;t}+U_j\frac{\&part;u_{ai}}{\&part;x_j}+u_{ai}\frac{\&part;U_i}{\&part;x_j}+\frac{1}{\mathrm{\&rho;}}\frac{\&part;P_a}{\&part;x_i}-\frac{P_a}{{\mathrm{\&rho;}}^2}\frac{\&part;P}{\&part;x_i}=-U_j\frac{\&part;{u^{\&prime;}}_i}{\&part;x_j}-{u^{\&prime;}}_j\frac{\&part;U_i}{\&part;x_j}-{u^{\&prime;}}_j\frac{\&part;{u^{\&prime;}}_i}{\&part;x_j}-\frac{1}{\mathrm{\&rho;}}\frac{\&part;P^{\&prime;}}{\&part;x_i}-\frac{\&part;{u^{\&prime;}}_i}{\&part;t}$ (formula 1)

In formula, t is the time, s; I and j is the durection component of rectangular coordinate system; �� is atmospheric density, kg/m³; ��_aFor the atmospheric density on plate face, kg/m³; U' is fluctuation velocity, m/s; P' is fluctuation pressure, Pa; U is 90 �� of rectangular elbow stable state turbulent velocities, m/s; P is 90 �� of rectangular elbow pressure, Pa;

Step 3: solve the dissipative shock wave �� of turbulent fluctuation kinetic energy k and the turbulent fluctuation kinetic energy obtained according to step 2, calculate the sound pressure level L of intrados, upper plate and lower shoe respectively_P, obtain the respective sound pressure level scope of intrados, upper plate and lower shoe;

Step 4: the sound pressure level scope according to intrados, upper plate and lower shoe that step 3 obtains, calculates the sound pressure level threshold value L dividing high noisy district and middle noise regions obtaining each plate face respectively_h-m; Calculate the sound pressure level threshold value L in noise regions and the low noise range of sound in the division obtaining intrados, upper plate and lower shoe simultaneously_m-l; By L_h-mCurve corresponding on plate face is as strong noise district envelope curve; By L_m-lCurve corresponding on plate face is as middle noise range envelope curve;

Step 5: respectively the middle low noise region envelope curve on each plate face that step 4 obtains, senior middle school's noise range envelope curve takes multiple discrete point, and obtain the coordinate figure of these discrete points; The coordinate figure of the discrete point on centering low noise region envelope curve, senior middle school's noise range envelope curve is fitted, and obtains original fit curve equation; Then adopt general Global Optimization Method that original fit curve equation is processed, obtain middle low noise region envelope curve, fit curve equation that senior middle school's noise range envelope curve is corresponding;

Step 6: step 5 is obtained every fit curve equation in each plate face as the demarcation line of each noise regions on plate face, obtain the high noisy district in each plate face, middle noise regions and the low noise range of sound;

Step 7: in the surface smear polyurethane rubber being positioned at 90 �� of rectangle silencing noise reduction elbows in the high noisy district in each plate face that step 6 obtains, at the surface smear resin modified asphalt being positioned at 90 �� of rectangle silencing noise reduction elbows of middle noise regions.

7. the noise processing method to 90 �� of rectangular elbow as claimed in claim 6, it is characterised in that in described step 3, utilize following formula to calculate the sound pressure level L of intrados, upper plate and lower shoe respectively_P:

$L_P=10\log \&lsqb;\frac{{\mathrm{\&alpha;}}_{\mathrm{\&epsiv;}}\mathrm{\&rho;}\mathrm{\&epsiv;}{\left(2k\right)}^{\frac{5}{2}}}{P_{ref}{{\mathrm{\&alpha;}}_0}^5}\&rsqb;$

In formula: ��_��For reduced scale constant, study according to Sarkar&Hussaini isotropic turbulence DNS analog calibration, take 0.1; P_refFor reference sound power, W/m³, ��₀For the local velocity of sound under the status of criterion, m/s; �� is atmospheric density, kg/m³��

8. the noise processing method to 90 �� of rectangular elbow as claimed in claim 6, it is characterised in that in described step 4, utilizes formula 3 to calculate the sound pressure level threshold value L dividing high noisy district and middle noise regions obtaining each plate face respectively_h-m; Utilize formula 4 to calculate the sound pressure level threshold value L in noise regions and the low noise range of sound in the division obtaining intrados, upper plate and lower shoe simultaneously_m-l;

$L_{h-m}=L_{max-h}-\left(\frac{L_{max-h}-L_{\min -l}}{3}\right)\mathrm{\&beta;},1\&le;\mathrm{\&beta;}\&le;3$ (formula 3)

$L_{m-l}=L_{\min -l}+\left(\frac{L_{max-h}-L_{\min -l}}{3}\right)\mathrm{\&alpha;},0<\mathrm{\&alpha;}\&le;1$ (formula 4)

In formula, L_max-h��L_min-lThe respectively maximum sound pressure level value in plate face and minimal sound pressure levels value, dB; ��, �� are that region divides constant, 0.5 < ����1,1�ܦ¡�2.

9. the noise processing method to 90 �� of rectangular elbow as claimed in claim 6, it is characterised in that in described step 7, the thickness smearing polyurethane rubber in high noisy district is determined according to formula 5:

$H_h={\mathrm{\&gamma;}}_1\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{L_p}{L_{h-m}}\&times;\frac{L_{max-h}}{L_{h-m}}\&rsqb;$ (formula 5)

In formula, H_hFor the thickness that high noisy district polyurethane rubber is smeared, mm; �� is 90 �� of rectangular bend wall thickness, mm; L_max-hFor the maximum sound pressure level value in plate face, dB; L_h-mFor dividing the sound pressure level threshold value in high noisy district and middle noise regions, dB; L_PFor the sound pressure level at arbitrfary point place, dB in high noisy district; ��₁For high noisy district thickness constant coefficient, 1�ܦ�₁�� 6; One numerical value is rounded downwards the function into immediate integer by INT.

10. the noise processing method to 90 �� of rectangular elbow as claimed in claim 6, it is characterised in that in described step 7, the thickness smearing resin modified asphalt in middle noise regions is determined according to formula 6:

$H_m={\mathrm{\&gamma;}}_2\&times;\mathrm{\&delta;}\&times;INT\&lsqb;\frac{L_p}{L_{m-l}}\&times;\frac{L_{h-m}}{L_{m-l}}\&rsqb;$ (formula 6)

In formula, H_mFor the thickness that middle noise regions resin modified asphalt is smeared, mm; �� is 90 �� of rectangular bend wall thickness, mm; L_h-mFor dividing the sound pressure level threshold value in high noisy district and middle noise regions, dB; L_m-lFor the sound pressure level threshold value in noise regions and the low noise range of sound, dB in dividing; L_PFor the sound pressure level at arbitrfary point place, dB in middle noise regions; ��₂For middle noise regions thickness constant coefficient, 1�ܦ�₂�� 6; One numerical value is rounded downwards the function into immediate integer by INT.