材料构件在气动噪声环境下的声载荷场分析方法研究

发布时间：2018-06-06 13:36

本文选题：气动噪声 + 气流背景噪声抑制　；参考：《北京科技大学》2017年博士论文

【摘要】：飞行器在高速服役过程中,空气与飞行器结构产生剧烈的相互作用,使飞行器结构表面的空气压力产生脉动,由此产生气动噪声。气动噪声会使飞行器结构产生声疲劳失效问题,威胁飞行器的服役安全。因此,在飞行器的研发和设计过程中,需要对材料构件的气动噪声的载荷场进行分析,为飞行器服役安全性能的评价和降噪设计提供数据支撑。通常,在地面模拟实验环境中开展气动噪声的研究,会遇到如下困难:气流背景噪声严重,导致材料构件气动噪声的信噪比低;环境中布置阵列的孔径有限,使声源定位的辨识能力不足;声波在气流传播中发生路径偏折,改变了声传播时延,造成声场重构准确度的下降;在恶劣的高速气流近场环境下,难以实现材料构件实时声载荷信号的近场测量,也就无法对材料构件的服役状态给出准确评价。本文以现有的声场分析和信号处理理论作为基础,以气动噪声环境下的材料构件所承受的气动噪声载荷为研究对象,开展材料构件在气动噪声环境下的声载荷场分析方法研究,可以为飞行器材料构件的服役安全评估和降噪设计提供更为可靠的评价数据,对保证飞行器的服役安全具有十分重要的意义。论文具体内容如下:(1)提出基于集合经验模态分解的气流背景噪声抑制方法。在气流环境中,材料构件的气动噪声被高强气流背景噪声淹没,使材料构件的气动噪声信噪比被降低,难以在声源定位云图中对材料构件的气动噪声源进行正确辨识。针对气动噪声环境中高强气流背景噪声抑制问题,提出基于集合经验模态分解(EEMD)的气流背景噪声抑制方法。首先在气流空吹工况下采集纯气流背景噪声信号;之后将试件安装在气流中,采集到试件的气动噪声和气流背景噪声的混合信号,并对混合信号进行EEMD分解,得到各IMF分量;计算各IMF分量与纯气流背景噪声信号的相关系数,将相关系数小于阈值的IMF分量进行还原,实现气流背景噪声抑制,提高强气流背景噪声干扰下测试件气动声源定位的辨识度。在声学风洞中开展了对扬声器声源和机翼模型尾缘气动噪声源的气流背景噪声抑制实验,利用新方法使淹没在气流背景噪声中的目标声源在声源定位云图中凸显出来,验证了方法的有效性。(2)提出基于互谱矩阵拟合的气动噪声源定位新方法。在气动噪声模拟实验装置中,有限的传声器阵列布阵空间限制了气动声源定位的辨识能力,运动的气流降低了声源定位的准确度。针对飞行器构件的气动噪声源高精度定位问题,提出基于互谱矩阵拟合的气动噪声源定位方法(Amiet-IMACS)。首先利用Amiet方法对气流环境下的阵列流形矩阵进行修正;之后在原始互谱矩阵拟合方法的基础上,提出一种新的稀疏化约束条件,能够自适应改变稀疏化约束参数,改善声源辨识度,提高计算效率。在声学风洞环境中开展相关双声源和机翼模型尾缘脱涡噪声源的定位实验,利用新方法提高了对声源的辨识能力和定位准确度,验证了新方法对气动噪声源定位的有效性。(3)提出基于Amiet解析被动时间反转镜的气动声载荷信号还原方法。在高速气流环境下难以实现材料构件实时声载荷信号的近场测量,也就无法对材料构件的服役状态给出准确评价。针对气动噪声环境下材料构件的近场气动声载荷信号的还原问题,提出基于Amiet解析被动时间反转镜(Amiet-AP-TR)的气动声载荷信号还原方法。首先,提出新的时间反转声传播模型,即在对传声器阵列信号进行时间反转的基础上,将气流的方向也进行虚拟反向;其次,利用Amiet气流修正方法,计算了气流环境下时间反转声波的路径和时延,修正了时间反转镜的解析表达式;最后,将时间反转的阵列信号代入解析表达式中,可获得声载荷场的实时声压信号,实现高时间分辨的气动噪声载荷场分析。在声学风洞环境中,利用新方法提高了扬声器还原信号与真值信号的相关系数,并实现对机翼模型气动噪声载荷场的高时间分辨分析,验证了新方法对气动噪声载荷信号还原的有效性。(4)开展超音速气流环境下典型构件气动噪声载荷场分析研究。在流速为4Ma,环境压力为5kPa的超音速气流环境下,搭建基于传声器阵列的气动噪声载荷分析系统,实现对超音速气流环境下典型构件的气动噪声载荷阵列信号的高速同步采集和声场重构分析,利用基于EEMD的气流背景噪声抑制方法、Amiet-IMACS高分辨率声源定位方法和Amiet-AP-TR声载荷信号还原方法,对平板试件和球柱试件特征频段的气动噪声载荷进行全面的精细化分析,可以获得典型构件气动噪声载荷的特征频段、强度、位置和实时分布等特征规律。
[Abstract]:During the high-speed service of the aircraft, the air and the structure of the aircraft produce violent interaction, which causes the air pressure of the surface of the aircraft structure to produce pulsation, resulting in aerodynamic noise. The aerodynamic noise will cause the problem of acoustic fatigue failure of the aircraft structure and threaten the service safety of the aircraft. Therefore, the process of research and design and design of the aircraft is in the process of designing and designing the aircraft. It is necessary to analyze the aerodynamic noise load field of the material components and provide data support for the safety performance evaluation and noise reduction design of the aircraft. Usually, the research of aerodynamic noise in the ground simulation experiment environment will meet the following difficulties: the air background noise is serious, which leads to the low signal to noise ratio of the aerodynamic noise of the material components; The aperture of the array is limited, which makes the identification ability of the sound source localization is insufficient; the sound wave has a path deflected in the air flow, and the sound propagation delay is changed, and the accuracy of the sound field reconstruction is reduced. It is difficult to realize the near field measurement of the real time sound load signal of the material components under the bad high-speed airflow near field environment, and the material can not be used to the material. On the basis of the existing sound field analysis and signal processing theory, this paper takes the aerodynamic noise load under the pneumatic noise environment as the research object, and studies the analysis method of the acoustic load field of the material components under the aerodynamic noise environment, which can be used as the material components of the aircraft. The service safety assessment and noise reduction design provide more reliable evaluation data, which is of great significance to ensure the safety of the aircraft in service. The contents of this paper are as follows: (1) a method of airflow background noise suppression based on collective empirical mode decomposition is proposed. In the air flow environment, the aerodynamic noise of the material components is caused by the background noise of high strength air flow. It is difficult to correctly identify the aerodynamic noise source of the material components in the sound source positioning cloud, and it is difficult to identify the aerodynamic noise source of the material components in the sound source positioning cloud. In view of the suppression of the background noise of the high strength air flow in the aerodynamic noise environment, the air background noise suppression method based on the collective empirical mode decomposition (EEMD) is proposed. The pure air background noise signal is collected under the working condition; then the specimen is installed in the air flow to collect the mixed signal of the aerodynamic noise and the air background noise of the specimen, and the mixed signal is decomposed by EEMD, and each IMF component is obtained; the correlation coefficient of the IMF component and the pure air background noise signal is calculated, and the correlation coefficient is less than the threshold value of the IMF component. In the acoustic wind tunnel, the air background noise suppression experiment on the sound source of the loudspeaker and the tail edge of the wing model is carried out in the acoustic wind tunnel, and the new method is used to make the target sound submerged in the background noise of the airflow. The source is highlighted in the sound source mapping, and the effectiveness of the method is verified. (2) a new method of locating the aerodynamic noise source based on the cross spectrum matrix fitting is proposed. In the pneumatic noise simulation experiment device, the finite microphone array space restricts the identification energy of the pneumatic sound source positioning, and the moving air flow reduces the accuracy of the sound source location. In view of the high precision positioning of aerodynamic noise sources of aircraft components, an aerodynamic noise source localization method based on cross spectral matrix fitting (Amiet-IMACS) is proposed. First, Amiet method is used to modify the array manifold matrix in the airflow environment, and then a new sparsity constraint bar is proposed on the basis of the original cross spectral matrix fitting method. It can adaptively change the sparse constraint parameters, improve the identification of sound source and improve the calculation efficiency. In the acoustic wind tunnel, the localization experiment of the related dual source and the tail edge vortex noise source of the wing model is carried out, and the identification and positioning accuracy of the sound source are improved by the new method, and the new method is verified for the positioning of the aerodynamic noise source. (3) (3) a method for the reduction of the acoustic load signal based on the passive time reversal mirror is proposed. It is difficult to realize the near field measurement of the real time acoustic load signal of the material components under the high speed air flow environment, and it is impossible to give an accurate evaluation of the service state of the material components. The reduction of load signal is proposed, and a new method is proposed based on Amiet to analyze passive time reversal mirror (Amiet-AP-TR). First, a new time reversal sound propagation model is proposed, that is, on the basis of time reversal of the microphone array signal, the direction of the air flow is also virtual reverse; secondly, the Amiet air flow is used to repair it. In the positive method, the path and time delay of the time reversal sound wave in the airflow environment are calculated and the analytic expression of the time reversal mirror is corrected. Finally, the time reversal array signal is replaced in the analytic expression, and the sound pressure signal of the acoustic load field can be obtained to realize the high time resolved aerodynamic noise load field analysis. In the acoustic wind tunnel environment, the benefit is obtained. A new method is used to improve the correlation coefficient between the loudspeaker reduction signal and the true value signal, and the high time resolution analysis of the aerodynamic noise load field of the wing model is realized. The effectiveness of the new method to the reduction of the aerodynamic noise load signal is verified. (4) the analysis of the aerodynamic noise load field of the typical component under supersonic airflow environment is studied. The velocity is 4. Ma, under the environment pressure of 5kPa supersonic airflow, an aerodynamic noise load analysis system based on microphone array is set up to achieve high speed synchronous acquisition and sound field reconstruction analysis of the aerodynamic noise load array signals of typical components under supersonic airflow, and Amiet-IMACS high score is used to suppress the air background noise based on EEMD. The acoustic source localization method and the Amiet-AP-TR acoustic load signal reduction method are used to analyze the aerodynamic noise load of the characteristic frequency section of the plate specimen and the ball column specimen, and the characteristics of the characteristic frequency, intensity, position and real-time distribution of the aerodynamic noise load of typical components can be obtained.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：V250.2;V214

【参考文献】