高速气流场中鼻锥仿真及其声学特性研究

发布时间：2018-07-04 22:18

本文选题：鼻锥 + 气动噪声　；参考：《北京化工大学》2014年硕士论文

【摘要】：鼻锥是一种装配在传声器前身用于保护传声器膜片的装置。随着气流速度的提高,鼻锥表面的气动噪声变得越来越明显,会影响常规的声学实验,限制声学实验的气流速度。因此降低鼻锥表面的气动噪声已经成为声学风洞实验的关键之一,研究高速气流场中鼻锥表面的气动噪声是十分有必要的。本文从数值模拟和风洞实验两方面出发,对鼻锥表面的气动噪声进行了研究。主要工作有： (1)高速气流场中鼻锥表面气动噪声的数值计算。建立了不同形状的鼻锥的儿何模型,应用Ansys软件对鼻锥表面的流场进行了模拟计算,以流场的计算结果作为初值,应用Virtual.Lab声学仿真软件对鼻锥表面的气动噪声声场进行仿真计算。对各个风速下的几种鼻锥模型的气动噪声进行对比分析。分析结果表明鼻锥在高速气流场中的气动噪声主要集中在中低频,随着频率的增加,噪声声压级下降,并且在低频下降的比较快。通过对儿种鼻锥模型的对比可以看出,椭球状的鼻锥的降噪效果优于半球状的鼻锥,并且在较高气流速度下椭球形鼻锥气动噪声声压级在大多数频率上低于两种商业鼻锥。 (2)传声器高声压下的测量校准研究。介绍了一种基于谐振耦合腔原理的高声压源以及以此为核心的高声压校准装置(BK一9719),给出了传声器高声压级下性能参数的校准原理、校准方法和校准结果分析,并对国内外同等类型的传声器的动态上限进行了测量,与其出厂数据进行对比,对比结果表明厂家提供的动态上限参数满足相应的测试标准的要求。并且由于校准系统的高声压发声源的失真度很小,可以实现对传声器在高声压下的线性度偏差的校准,其测量不确定度优于0.20dB。 (3)声学风洞中鼻锥表面气动噪声的测量实验。设计并加工了几种形状的鼻锥模型,并在声学风洞中对其气动噪声进行测量,与数值计算结果进行对比分析,分析结果表明数值计算的结果与实际测量结果在趋势和量级上有很好的一致性,验证了数值仿真模型的可行性。并且通过实验的方法探究影响鼻锥声学特性的因素。
[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.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB53

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