發(fā)布時(shí)間：2018-07-04 22:18

  本文選題：鼻錐 + 氣動(dòng)噪聲�。� 參考：《北京化工大學(xué)》2014年碩士論文

【摘要】：鼻錐是一種裝配在傳聲器前身用于保護(hù)傳聲器膜片的裝置。隨著氣流速度的提高,鼻錐表面的氣動(dòng)噪聲變得越來(lái)越明顯,會(huì)影響常規(guī)的聲學(xué)實(shí)驗(yàn),限制聲學(xué)實(shí)驗(yàn)的氣流速度。因此降低鼻錐表面的氣動(dòng)噪聲已經(jīng)成為聲學(xué)風(fēng)洞實(shí)驗(yàn)的關(guān)鍵之一,研究高速氣流場(chǎng)中鼻錐表面的氣動(dòng)噪聲是十分有必要的。本文從數(shù)值模擬和風(fēng)洞實(shí)驗(yàn)兩方面出發(fā),對(duì)鼻錐表面的氣動(dòng)噪聲進(jìn)行了研究。主要工作有： (1)高速氣流場(chǎng)中鼻錐表面氣動(dòng)噪聲的數(shù)值計(jì)算。建立了不同形狀的鼻錐的兒何模型,應(yīng)用Ansys軟件對(duì)鼻錐表面的流場(chǎng)進(jìn)行了模擬計(jì)算,以流場(chǎng)的計(jì)算結(jié)果作為初值,應(yīng)用Virtual.Lab聲學(xué)仿真軟件對(duì)鼻錐表面的氣動(dòng)噪聲聲場(chǎng)進(jìn)行仿真計(jì)算。對(duì)各個(gè)風(fēng)速下的幾種鼻錐模型的氣動(dòng)噪聲進(jìn)行對(duì)比分析。分析結(jié)果表明鼻錐在高速氣流場(chǎng)中的氣動(dòng)噪聲主要集中在中低頻,隨著頻率的增加,噪聲聲壓級(jí)下降,并且在低頻下降的比較快。通過(guò)對(duì)兒種鼻錐模型的對(duì)比可以看出,橢球狀的鼻錐的降噪效果優(yōu)于半球狀的鼻錐,并且在較高氣流速度下橢球形鼻錐氣動(dòng)噪聲聲壓級(jí)在大多數(shù)頻率上低于兩種商業(yè)鼻錐。 (2)傳聲器高聲壓下的測(cè)量校準(zhǔn)研究。介紹了一種基于諧振耦合腔原理的高聲壓源以及以此為核心的高聲壓校準(zhǔn)裝置(BK一9719),給出了傳聲器高聲壓級(jí)下性能參數(shù)的校準(zhǔn)原理、校準(zhǔn)方法和校準(zhǔn)結(jié)果分析,并對(duì)國(guó)內(nèi)外同等類(lèi)型的傳聲器的動(dòng)態(tài)上限進(jìn)行了測(cè)量,與其出廠數(shù)據(jù)進(jìn)行對(duì)比,對(duì)比結(jié)果表明廠家提供的動(dòng)態(tài)上限參數(shù)滿足相應(yīng)的測(cè)試標(biāo)準(zhǔn)的要求。并且由于校準(zhǔn)系統(tǒng)的高聲壓發(fā)聲源的失真度很小,可以實(shí)現(xiàn)對(duì)傳聲器在高聲壓下的線性度偏差的校準(zhǔn),其測(cè)量不確定度優(yōu)于0.20dB。 (3)聲學(xué)風(fēng)洞中鼻錐表面氣動(dòng)噪聲的測(cè)量實(shí)驗(yàn)。設(shè)計(jì)并加工了幾種形狀的鼻錐模型,并在聲學(xué)風(fēng)洞中對(duì)其氣動(dòng)噪聲進(jìn)行測(cè)量,與數(shù)值計(jì)算結(jié)果進(jìn)行對(duì)比分析,分析結(jié)果表明數(shù)值計(jì)算的結(jié)果與實(shí)際測(cè)量結(jié)果在趨勢(shì)和量級(jí)上有很好的一致性,驗(yàn)證了數(shù)值仿真模型的可行性。并且通過(guò)實(shí)驗(yàn)的方法探究影響鼻錐聲學(xué)特性的因素。
[Abstract]:The nose cone is a device assembled in front of the microphone to protect the microphone diaphragm. With the increase of airflow velocity, the aerodynamic noise on the surface of nasal cone becomes more and more obvious, which will affect the conventional acoustic experiments and limit the airflow velocity of acoustic experiments. Therefore, reducing the aerodynamic noise of the nasal cone surface has become one of the key points in acoustic wind tunnel experiments. It is necessary to study the aerodynamic noise of the nasal cone surface in the high speed air flow field. In this paper, the aerodynamic noise of nasal cone surface is studied from the aspects of numerical simulation and wind tunnel experiment. The main works are as follows: (1) numerical calculation of aerodynamic noise on nasal cone surface in high speed airflow field. The model of different shape nose cone is established, and the flow field on the surface of nose cone is simulated by Ansys software. The result of flow field is taken as the initial value. The acoustical simulation software Virtual.Lab is used to simulate the aerodynamic noise sound field on the nasal cone surface. The aerodynamic noise of several nasal cone models under different wind speeds is compared and analyzed. The results show that the aerodynamic noise of the nasal cone in the high speed airflow field is mainly concentrated in the middle and low frequency. With the increase of the frequency, the noise sound pressure level decreases, and the noise pressure level decreases rapidly at the low frequency. By comparing the model of infantile nasal cone, we can see that the noise reduction effect of ellipsoid nasal cone is better than that of hemispherical nose cone. And the acoustic pressure level of the ellipsoid nose cone is lower than that of the two commercial nasal cones at most frequencies at higher air velocity. (2) the measurement and calibration of the microphone under high sound pressure. This paper introduces a hypersonic pressure source based on the principle of resonant coupling cavity and a hypersonic pressure calibration device (BK- 9719) based on it. The calibration principle, calibration method and calibration results of the performance parameters under high acoustical pressure level of microphone are presented. The dynamic upper limits of the same types of microphones at home and abroad are measured and compared with the factory data. The comparison results show that the dynamic upper limit parameters provided by the manufacturers meet the requirements of the corresponding test standards. Because the distortion of the sound source of the calibration system is very small, the linearity deviation of the microphone under the high sound pressure can be calibrated. The uncertainty of measurement is better than 0.20 dB. (3) the measurement of aerodynamic noise on nasal cone surface in acoustic wind tunnel. Several nasal cone models with different shapes were designed and processed, and the aerodynamic noise was measured in acoustic wind tunnel. The results were compared with the numerical results. The analysis results show that the numerical results are in good agreement with the actual measurement results in the trend and order of magnitude. The feasibility of the numerical simulation model is verified. The factors that influence the acoustic characteristics of nasal cone were investigated by experimental method.
【學(xué)位授予單位】：北京化工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TB53

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