【作者】 周恺；

【导师】 邓兆祥；

【作者基本信息】 重庆大学 ， 车辆工程， 2010， 硕士

【摘要】 汽车工业发展迅速,使得汽车噪声污染日益严重。减少进排气噪声是降低汽车噪声的关键,而安装消声器作为减少进排气噪声的主要方法,它的设计方法已经引起广泛重视,传统的设计为了满足消声量的要求,必须不断修改结构尺寸进行反复计算和实验,工作量很大,因此如何在缩短设计周期与设计成本的前提下设计出一个性能优良的消声器并预测其性能是需要解决的关键问题。本文基于传统声学理论,从消声器设计需要出发,以ANSYS软件作为二次开发平台,通过对声学有限元理论和APDL程序参数化语言的学习研究,实现消声器声学性能的自动分析计算,并最终以VB.NET和DirectX9.0为开发工具,初步建立了以用户可视化建模界面为主的消声器设计系统。该系统包含用户参数化建模模块,声学性能自动仿真模块及声学性能评价模块。设计人员只需通过操作系统主界面工具栏中对消声器子结构的组合即可进行消声器的结构设计,并通过后台程序驱动ANSYS仿真计算,所有计算过程都不需要用户干预,计算完毕自动反馈给用户声学性能曲线;用户还可以选择不同频带范围的消声量作为评价指标,以消声器的某些子结构尺寸作为设计变量,进行消声器的灵敏度分析和结构优化。接着本文在消声器传统声学性能指标基础上,进行了声学性能评价技术的研究。在传声损失评价方面,主要评价参数包括传声损失曲线包围的面积值、任意消声频率范围下的传声损失、比容传声损失、整个频段传声损失曲线存在的消声低谷、消声不足量频带及曲线波动率;在插入损失评价方面,包括各转速下插入损失声压级及消声器出口端噪声A计权总声压级和响度级的线性度。本文最后通过几个设计实例,把实验得到的传声损失和插入损失曲线与本系统的计算结果对比,发现具有较高的吻合度,从而证明了系统的正确性和工程实用性。更多还原

【Abstract】 The automobile noise pollution is becoming more and more severe with the development of automobile industry. The critical point of reducing the noise emission is to fix a muffler, the design of which has been extensively emphasized. Traditional design requires people to carry out the simulation and experiment repeatedly with diverse sizes of structures in order to meet the demand of noise loss, which is definitely a very painstaking manual labor. Thus, it quicly become a crutial issue needed to handle ungently that how to shorten the periodic time to obtain the muffler with great performance based on the minimal cost in budget.Taking three dimensional finite element simulation as the muffler’s design approach, ANSYS is regarded as an second development tool with the support of traditional acoustics theory in this thesis. Through studying on the FEM theory the APDL language, the establishment of finite element model and automatic acoustic simulation of muffler come true. Finallly,by using the VB.NET and DirectX9.0, the muffler design sisyem including the visual modeling module, acustic performance simulation module and evaluation of acoustic behaivor model are building up.Among these different modules, all parameters in visual modeling module are transmitted to the next module with the type of correspond class enclosing.Based on the research in area of automatic analytical technology and evalution technology as well as mutual penetrating in each module,users only operates the toolbars in main interface,which will achieve the purpose of design. Then the outcome of acoustic performance running by ANSY due to the control of programme will present to the user without any manual interruption. After that, choosing trasmission loss in different rang of frequency as evaluation stardard and picking out several structure’s parameters which are used to be design variables, users can implement further research in term of analysis of structures’sensitive degree and structures’optimization.To continue, this article also focuses on the research regarding to the evaluative technology of acoustic behaivor in term of transmission loss and insertion loss. In the area of transmission loss, the square measure of TL curve, TL value in given frequency range, TL of specific volume, detail about the low point and frequency band of insufficient noise elimination as well as waving rate are presented. In the area of insertion loss, taking the toal value of insertion loss and linear degree of muffler outlet’s sound pressure level into consideration would be a good way to reflect the IL performance. Combining with all parameters mentioned above will achive the comprehensive assessment of muffler’s acoustic behaivor.At last, the outcome of this system accords with the experiment by comparing with acoustic performance curves in the same muffler, which can prove that the study on this thesis is accurate and meaningful.更多还原