本文選題：管道 + 消聲器�。� 參考：《哈爾濱工程大學(xué)》2014年博士論文

【摘要】：消聲器廣泛應(yīng)用于降低管道內(nèi)傳播的噪聲,其聲衰減性能的計算方法可分為兩種:頻域法和時域法。頻域法的優(yōu)點是計算速度快,其主要缺點是不能很好地考慮介質(zhì)流動和粘性對聲傳播及衰減的影響。時域方法直接求解質(zhì)量、動量和能量守恒方程,并且保留了方程中的非線性項,可以較好地處理復(fù)雜氣流流動、介質(zhì)粘性和熱傳導(dǎo)效應(yīng)對消聲器內(nèi)聲傳播及管口聲輻射的影響。為此,本文采用時域方法研究消聲器和管路系統(tǒng)的聲學(xué)特性。將時域脈沖法應(yīng)用于計算無流時簡單膨脹腔消聲器、外插進出口管膨脹腔消聲器、雙級膨脹腔消聲器、直通穿孔管消聲器、橫流穿孔管消聲器和混合膨脹腔消聲器的傳遞損失,并與實驗測量結(jié)果、有限元法計算結(jié)果進行了比較。結(jié)果表明,時域脈沖法能夠精確預(yù)測抗性消聲器的聲衰減性能。有限元計算中使用穿孔阻抗表述穿孔結(jié)構(gòu)的聲學(xué)特性,穿孔阻抗經(jīng)驗公式的準確性和適用性直接影響消聲器傳遞損失的計算精度。而時域法對于穿孔進行實體建模,在計算中可以考慮穿孔附近的非線性效應(yīng),提高了計算結(jié)果的精度。此外,時域計算中使用多孔介質(zhì)模擬吸聲材料,粘、慣性阻力系數(shù)的推導(dǎo)和多孔介質(zhì)處網(wǎng)格質(zhì)量的高低決定了時域法的預(yù)測精度。以穿孔管消聲器為例,使用時域脈沖法研究了氣流流動和溫度對于消聲器聲衰減性能的影響。通過對比分析可知,時域法預(yù)測結(jié)果與實驗測量結(jié)果吻合較好,且優(yōu)于FEM計算結(jié)果。數(shù)值計算結(jié)果表明氣流速度和溫度會影響穿孔管消聲器的聲學(xué)性能。隨著流速的增加,在多數(shù)頻率范圍內(nèi)穿孔管消聲器的傳遞損失增大。氣流溫度升高時,消聲器的傳遞損失曲線向高頻方向移動,共振峰值有所降低。使用實驗室現(xiàn)有實驗臺在無流和有流條件下測量了雙級膨脹腔消聲器的傳遞損失,并與時域脈沖法計算結(jié)果進行了對比。在考慮的頻率范圍內(nèi),測量結(jié)果和預(yù)測結(jié)果整體吻合較好,但測量曲線中有鋸齒形波動,且隨著馬赫數(shù)的增加測量精度降低。為此,對原實驗臺進行局部改動,使用快速正弦掃頻信號和同步時域平均技術(shù)以提高聲源信號的信噪比。通過對比分析可知,直通穿孔管消聲器傳遞損失的測量結(jié)果不僅與時域脈沖法的預(yù)測結(jié)果吻合較好,而且測量曲線的波動減小了。將時域脈沖法應(yīng)用于研究無流和有流條件下圓形管道的反射系數(shù)幅值,并與實驗結(jié)果、邊界元法(BEM)計算結(jié)果進行了比較。由對比分析可知,無流條件下時域法可以準確地預(yù)測管口的聲學(xué)特性,考慮氣體流動時時域法的預(yù)測結(jié)果在亥姆霍茲數(shù)較小的區(qū)域存在計算誤差,原因是計算模型的出口使用的是有反射邊界條件。氣流流動和管道出口角度對于管口的聲學(xué)特性有一定的影響。有氣流流動時,反射系數(shù)幅值隨著亥姆霍茲數(shù)的增加先升高后降低;隨著氣流馬赫數(shù)的增加,反射系數(shù)的幅值增大,曲線中峰值對應(yīng)的亥姆霍茲數(shù)也增大。相比于直切口管道而言,斜切口會降低管口的反射系數(shù),且夾角越小,反射系數(shù)下降的越快。通過用戶自定義函數(shù)(UDF)補充水密度的計算程序?qū)r域脈沖法擴展用于水管路消聲器的聲衰減性能研究。無流時分別使用時域脈沖法和FEM計算了簡單膨脹腔消聲器、外插進出口管膨脹腔消聲器、雙級膨脹腔消聲器、直通穿孔管消聲器和橫流穿孔管消聲器的傳遞損失,兩種數(shù)值結(jié)果基本吻合,峰值頻率有細微偏差,原因可以歸結(jié)為FEM計算中沒有考慮介質(zhì)粘性和可壓縮性,導(dǎo)致FEM計算中的聲速與時域計算中稍有不同。鑒于有限元法難于準確模擬消聲器內(nèi)部水流流動對其聲學(xué)性能的影響,僅僅使用時域脈沖法預(yù)測了有流時穿孔管消聲器的傳遞損失。隨著流速的增加,多數(shù)頻率下消聲器的傳遞損失有所增大。
[Abstract]:The muffler is widely used to reduce the noise propagating in the pipeline. The calculation method of acoustic attenuation performance can be divided into two kinds: frequency domain method and time domain method. The advantage of frequency domain method is that the advantages of frequency domain method are fast calculation speed, and its main disadvantage is that the effect of medium flow and viscosity on sound propagation and attenuation can not be considered well. Time domain method directly solves mass, momentum and energy. The equation of conservation of quantity and the nonlinear term in the equation are retained, which can deal with the influence of the complex flow, the viscosity of the medium and the heat conduction effect on the sound propagation in the muffler and the sound radiation of the tube. In this paper, the time domain method is used to study the acoustic characteristics of the muffler and the pipeline system. The time domain pulse method is applied to the calculation of the flow free time. The simple expansion cavity muffler, outside the inlet and outlet tube expansion chamber muffler, the double stage expansion chamber muffler, the perforated perforated tube muffler, the cross flow perforated tube muffler and the mixed expansion chamber muffler, is compared with the experimental results and the finite element method. The results show that the time domain pulse method can accurately predict the resistance elimination. Acoustic attenuation performance of an acoustic device. The finite element calculation uses the perforation impedance to express the acoustic characteristics of the perforated structure. The accuracy and applicability of the empirical formula of the perforation impedance directly affect the calculation accuracy of the transmission loss of the muffler. The time domain method is used to model the perforation, and the nonlinear effect near the perforation can be considered in the calculation. In addition, the prediction accuracy of the time domain method is determined by the use of porous media to simulate the sound absorption material in porous media, the derivation of the viscosity, the inertia resistance coefficient and the quality of the meshes at the porous medium. The time domain pulse method is used to study the acoustic attenuation performance of the flow and temperature of the muffler. The results of the time domain method are in good agreement with the experimental results, and it is better than the FEM results. The numerical results show that the velocity and temperature of the air flow can affect the acoustic performance of the perforated tube muffler. The transmission loss curve of the muffler moves to the high frequency direction and the resonance peak is reduced. The transmission loss of the double stage chamber muffler is measured under the current laboratory test bench under the condition of no flow and flow, and the results are compared with the time domain pulse method. The overall agreement is good, but the measurement curve has the zigzag fluctuation and the measurement precision decreases with the increase of the Maher number. Therefore, a local change is made to the original experimental platform. The signal to noise ratio of the sound source signal is improved by the fast sinusoidal sweep frequency signal and the synchronization time domain average technique. Through the contrast analysis, the direct through perforated tube muffler transfer the loss. The measurement results are not only in good agreement with the prediction results of the time domain pulse method, but also reduce the fluctuation of the measurement curves. The time domain pulse method is applied to the study of the amplitude of the reflection coefficient of a circular pipe under the condition of flow without flow and flow. The results are compared with the experimental results, and the results of the boundary element method (BEM) are compared. The method can accurately predict the acoustic characteristics of the pipe mouth, considering the prediction results of the gas flow time domain method in the smaller area of Helmholtz. The reason is that the calculation model has reflected boundary conditions. The air flow and the outlet angle of the pipe have a certain influence on the acoustic characteristics of the pipe mouth. When the Helmholtz number increases, the amplitude of the reflection coefficient increases and then decreases with the increase of the number of Helmholtz. With the increase of the Maher number of the airflow, the amplitude of the reflection coefficient increases, and the number of Helmholtz corresponding to the peak in the curve is also increased. The oblique incision will reduce the anti ejection coefficient of the pipe, and the smaller the angle, the faster the reflection coefficient decreases. The time domain pulse method is extended to study the sound attenuation performance of water pipe silencers by using the user defined function (UDF) to supplement the water density. Time domain pulse method and FEM are used to calculate the simple expansion cavity muffler, external plug and import tube expansion chamber muffler, double expansion chamber muffler, straight through perforated tube muffler. The transmission loss of the perforated perforated tube muffler is basically consistent with the two numerical results, and the peak frequency has a slight deviation. The reason can be attributed to the fact that the FEM calculation does not consider the viscosity and compressibility of the medium. The sound velocity in the FEM calculation is slightly different from the time domain calculation. In view of the difficulty of the finite element method, it is difficult to accurately simulate the flow of flow inside the muffler. With the effect of acoustic performance, the transmission loss of the perforated tube muffler is predicted by the time domain pulse method only. With the increase of flow velocity, the transmission loss of the muffler at most frequency increases.

【學(xué)位授予單位】：哈爾濱工程大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TB535.2

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