授予学位单位：西安交通大学
授予时间：1997年12月

二级学科名称：机械电子工程
指导教师：史维祥

博士论文题目：间歇性排气噪声特性及其控制理论的研究

摘 要

作者根据噪声起伏性大小，首次将排气噪声分为稳定性排气噪声、周期性排气噪声和间歇性排气噪声三大类，从而提出间歇性排气噪声的新概念。本文对间歇性排气噪声特性及其控制理论进行了深入的研究。
机械压力机气动摩擦离合器（PFC）和气动摩擦制动器（PFB）产生的排气噪声是典型的间歇性排气噪声，作者将机械压力机噪声特性及其控制作为应用背景。对机械压力机噪声特性、产生机理及其控制方法进行了全面深入的研究，提出了间歇性排气噪声控制用消声器应满足的条件。作者对机械压力机噪声对操作工人身心健康的伤害进行了普查及分析研究。指出PFC和PFB排气噪声是导致操作工人身心健康的伤害的关键因素。首次指出1Cr18Ni9不锈钢纤维是理想的用于间歇性排气噪声控制消声器使用的吸声材料，对1Cr18Ni9不锈钢纤维的吸声性能进行了深入的分析研究，并成功地用于实际的间歇性排气噪声控制之中。作者指出间歇性排气过程的空气动力模型可简化为两级气缸串联的排气问题，编制的数值计算程序真实地模拟了排气过程中的空气动力学特性，建立了消声器膨胀消声室体积大小计算的表达式。研究了间歇性排气噪声产生机理及其组成，指出下游喷口噪声是由单极子和四极子源组成,并且排气阀打开速度越快,排气噪声中的低频成份就越大,建立了间歇性排气噪声辐射规律的表达式。
间歇性排气噪声可通过小孔喷注、膨胀吸声室及滤波隔声三种方式的不同组合来控制，作者系统地研究了各种滤波单元及其组合应用于间歇性排气噪声控制时的特性及相应的三种理论模型，建立的四种间歇性排气噪声控制用消声器总成，在工厂实际中大面积推广应用，具有30~38dB(A)的降噪量，使单机纯排气噪声达到了国家标准规定的90dB（A）的要求，阻力损失小，不影响机器正常工作，并具有良好的抗恶劣使用环境的能力，性能稳定，寿命长，值得在实际中推广应用。

关 键 词： 机械压力机，排气噪声，空气动力学，吸声材料，消声器

Subject: Study in Control Theories and Characteristics of Intermittence Exhaust Noise

Speciality: Xi’an JiaoTong University Fluid Power Transmission and Control

Name: Zhao Shengdun

Supervisor: Shi Weixiang

ABSTRACT

According to noise fluctuation value, a new concept of intermittence exhaust noise is put forward, and exhaust noise is firstly divided into steadiness exhaust noise, periodicity exhaust noise and intermittence exhaust noise. In this paper, characteristics and control theories of intermittence exhaust noise are thoroughly studied.

Exhaust noise generated by PFC and PFB of mechanical power press is typical example of intermittence exhaust noise. The noise characteristics of mechanical power press and the noise control are regarded as applied background of this paper study. The characteristics, mechanism and control methods of the noise generated by mechanical power press are comprehensively and thoroughly studied. The exhaust noise generated by PFC and PFB action is the main noise source of the press. Requirements that the muffler controlling the intermittence exhaust noise is satisfied with are put forward. Harm conditions caused by the noise of the press for the worker are investigated and analyzed. The exhaust noise caused by PFC and PFB action is the key factor which leads to the harm of worker health. It is firstly pointed out that 1Cr18Ni9 stainless steel fiber is the ideal absorbing material which is used for controlling intermittence exhaust noise. The absorbing noise properties of stainless steel fiber are thoroughly analyzed and studied. The fiber are successfully used in the practical noise control. The model of aerodynamics in the course of the intermittence exhaust is simplified into exhaust problem of two stage series cylinder. Digital calculation program which can really imitate aerodynamics characteristics in the exhaust process is established. A simple formula which can be used for calculating the volume of the silencer expansion chamber is established. Mechanism generating intermittence exhaust noise and the noise composition are researched. It is suggested that the downstream jet noise is composed of the noise generated by the annupole source and quadrupole source, and the faster the opening speed of exhaust valve is, the more the low frequency components in the exhaust noise are. formula about the radiation law of intermittence exhaust noise is established.

The intermittence exhaust noise is controlled by the different combination way by small hole jet, expansion absorbing noise chamber, filter and sound insulation. characteristics about all kinds of filtering unit and their combination for controlling intermittence exhaust noise are systematically studied. The three kinds of theoretical model of reducing intermittence exhaust noise are put forward. Four types of total structure silencer for controlling intermittence exhaust noise have noise reduction of 30~38dB(A). Now they are used widely in the factories. The pure exhaust noise generated by a single press reaches nation standard requirement that numerical value of the noise is not greater than 90dB(A), and its impedance loss is small, which doesn’t have influence on the normal action of the press ,and it has the ability to resist bad conditions, its characteristics being stable, its life being long. So such silencer is worth using in real production.

Key words: Mechanical power press, Exhaust noise, aerodynamics, Absorbing materials, Muffler