论文标题:扫描声强法测量声功率的几个关键问题研究
Research on Some Key Problems of the Measurement of Sound Power by Scanning Sound Intensity
论文作者 周广林
论文导师 陈心昭,论文学位 博士,论文专业 机械设计及理论
论文单位 合肥工业大学,点击次数 79,论文页数 150页File Size7903k
2004-12-01论文网 http://www.lw23.com/lunwen_98610182/ 声强测量;系统误差;不确定度;双传声器;扫描;声功率;误差分析;声压;算术平均声压;几何平均声压;实验
Sound intensity measurement; system error; uncertainty; two-microphone; scanning; sound power; error analysis; sound pressure; arithmetic averaging sound pressure; geometrical averaging sound pressure; experiments
声强就是声场中的声波强度,它等于通过与能流方向垂直的单位面积上的声能量。由于声强本身是一个矢量,用声强描述声场有声压无法相比的优点。用声强法测量声源的声功率可以分为离散点测量法和扫描测量法。本文选择矩形测量面,对方形、直线加半圆形和锯齿形扫描路径的收敛性进行理论上的证明,研究扫描测量声功率误差与扫描速度、扫描面大小、扫描面到声源的距离、扫描线密度的关系。对双传声器声强测量系统测量误差进行分析和评定,指出减小测量误差的途径,并对测量系统进行修正。针对基于算术平均声压计算的声强值存在着高频止限问题,文中选取较多种声源类型,对基于几何平均声压的声强计算方法与基于算术平均声压的声强计算方法进行比较,指出两种声强计算方法的特点和应用范围。分别在普通环境和半消声室选择矩形测量面对声强测量系统的有效性和三种扫描路径的收敛性进行实验研究,证明理论研究的正确性。 第一章阐明研究的意义,回顾分析声强测量技术的发展历史及研究现状,明确需要解决的问题,确定本论文的主要研究内容。 第二章介绍波动方程、声能、声能流密度、声强及度量方法、双传声器互谱声强测量原理。对双传声器声强测量系统的原理误差、仪器制造误差及随机误差进行详尽的分析,并应用不确定度理论对测量系统进行评定,指出减小测量误差的途径。根据传递函数推导出双传声器声强测量系统的误差特征函数,采用残余声强方法对声强测量系统进行修正。 第三章对扫描声强法测量声功率的收敛性进行研究,证明在矩形测量面上,方形、直线加半圆形和锯齿形扫描路径均为真实的扫描路径的正确性,同时研究是否还存在其它能够获得精确测量结果的真实扫描路径;研究扫描路径的真实性与扫描速度的关系;研究直线加半圆形、方形、锯齿形三种扫描路径声功率测量误差的收敛速度与扫描路径的形式和扫描速度的关系;研究扫描面的大小与扫描误差的关系。给出矩形测量面锯齿形扫描路径三种声源不同误差值时不同扫描线密度所对应的扫描测量面到声源的距离的最小值或取值范围。 第四章针对基于算术平均声压计算的声强值存在着高频止限这一问题,选取多种声源类型(点声源、平面声场、单极子、偶极子、四极子、作振动的球声源、两同相小球源及声柱),对基于几何平均声压的声强计算方法与基于算术平均声压的声强计算方法进行比较,找出这两种计算方法的适用范围,并从计算精度和计算量上对其进行比较。 第五章验证自制扫描声强测量系统的有效性;分析扫描声强测量参数对声功率测量误差的影响;研究直线加半圆形、方形、锯齿形三种扫描路径收敛速
Sound Intensity is the sound wave intensity in sound field, which equals sound energy through the unit area perpendicular to the energy flow direction. Since the sound intensity is a vector in nature, which has the priority to sound pressure when used to describe sound field. Sound power determination using sound intensity methods can be categorized into the discrete point and scanning measurement methods. In this dissertation, the rectangle measurement plane is chosen, and convergence of rectangle, linear plus half circle and saw-tooth shaped scanning ways has been verified in theory. Meanwhile the relationships between the sound power measurement error and the scanning velocity, the size of the scanning plane, the distance from sound source to scanning plane, the scanning density have been investigated deeply. The errors of the two-microphone sound intensity measurement system have been analyzed and evaluated, the reduction methods of the measurement error has been described and utilized to correct the measurement system. In order to solve the high frequency cut-off problem that exists in the sound intensity determination using arithmetic-averaging sound pressures, many types of sound source have been adopted and sound intensity determination methods using arithmetic averaging and geometrical-averaging sound pressures have been compared. As a result of the analysis, the applicable scopes and characteristics of these two methods have been given in this dissertation. To testify the theoretical research, some experimental researches on the effectiveness of selecting rectangle measurement plane and the convergence of the three scanning ways have been conducted in the common and half-anechoic chambers respectively.In chapter one, the research meaning has been described, and the development history and current status of the sound intensity measurement technology have been reviewed, and the contents of this dissertation have been determined.In chapter two, wave motion equation, sound energy, sound energy flux density, sound intensity and its scaling method and the theorem of two-microphone sound intensity have been introduced. The theoretical, manufacture and random errors of the two-microphone sound intensity measurement has been analyzed in details, and the measurement reduction method has been given based on the evaluation of the measurement system using uncertainty theorem. The error functions of the two-microphone sound intensity measurement system has been deduced according to the transfer function, and the residual sound intensity method has been used to correct the sound intensity measurement system.In chapter three, the convergence of scanning sound intensity method determining sound power has been investigated, and the correctness of the rectangle, line plus half circle and saw tooth shaped scanning ways have been verified to be real scanning ways on a rectangle measurement plane. Meanwhile, this dissertation study if there are other real scanning ways that can be used to precise measurement results, the relationship between the reality of the scanning ways and the scanning velocity, the relationship between the sound power measurement convergence velocity when using the three scanning method aforementioned and the scanning type and scanning velocity, the relationship between the size of the scanning plane and the scanning errors. When the saw-tooth shaped scanning method is used on the rectangle measurement plane, the minimum value and value scope have been given according to three different sound source error values.In chapter four, in order to solve the high frequency cut-off problem that exists in the sound intensity determination using arithmetic-averaging sound pressures, the calculation methods based on the arithmetic and geometrical averaging sound pressures have been compared at the aspects of the calculating precision and quantity, and their applicable scopes have been given, where different kinds of sound sources are selected such as point source, planar sound field, monopole, dipole, quad-pole, vibrati
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