【作者】 刘丽媛；

【导师】 季振林；

【作者基本信息】 哈尔滨工程大学 ， 动力机械及工程， 2010， 硕士

【摘要】 进气噪声是增压型发动机的主要噪声源,本文介绍了增压型发动机进气噪声的研究现状和方法,阐述了进气噪声源特性、产生机理以及控制方法。本文根据涡轮增压器中主要噪声源特性,设计了两套进气消声器。由于能改善消声效果和保护吸声材料不被气流吹出,穿孔元件在阻性消声器中广泛应用。为预测消声器的声学性能,首先需要确定贴附有吸声材料的穿孔元件的声学特性。本文将针对消声器声学性能的计算方法和贴附有吸声材料的穿孔元件的声学特性开展系统研究。采用有限元方法研究贴附有吸声材料的穿孔元件的声学特性,首先需建立穿孔板声阻抗的有限元模型,分析各种结构参数对穿孔板声学厚度修正系数的影响,并根据计算结果给出贴附有吸声材料的穿孔板声学厚度修正系数的近似公式。以长纤维玻璃丝棉作为吸声材料实验样品,验证两载荷法测量吸声材料声学特性方法的正确性,并测量出硅酸铝岩棉的声学特性参数——复波数和复阻抗。以设计的两套进气消声器为研究对象,建立其有限元模型,将本文获得的贴附有吸声材料的穿孔声阻抗新模型和所测得的硅酸铝的声学特性参数导入声学软件SYSNOISE,通过声学仿真预测进气消声器的传递损失,并与实验测量结果比较,可验证对进气消声器模型的处理是合理的。研究各种结构参数对进气消声器声学特性的影响,结果表明,可以通过调整穿孔率、吸声材料填充密度、吸声材料的厚度等参数来改善进气消声器的消声性能。更多还原

【Abstract】 The induction noise is a major noise source of turbocharged engine. This thesis introduced the situation and methods of turbocharged engine intake system noise study, explained the source characteristics and generation mechanisms as well as the control method of intake noise. The present works design two kinds of intake silencers according to the source characteristics of intake system noise. The perforated elements are commonly used in dissipative silencers to improve the acoustic attenuation and protect the absorbing material from running. To predict the acoustic attenuation performance of silencers, the acoustic characteristics of perforated elements in contact with fibrous material need to be determined first. Therefore, the present thesis will investigate in detail the calculation methods of acoustic attenuation performance of silencers and the acoustic characteristics of perforated elements in contact with fibrous material.The acoustic characteristics of perforated elements in contact with fibrous material are studied by using finite element methods. The finite element model for determination of the acoustic impedance of perforation is first built, and then the effect of various structure factors on the acoustic thickness correction coefficient of perforated element is investigated. A curve-fitting expression for the end correction coefficient is obtained based on the numerical results.According to the principle of Two-Load method, the fiber glass was used to verify the methods of measuring the acoustic characteristic parameters of absorptive material, and then the characteristic impedance and complex wavenumber of aluminium silicate had also been measured.The finite element models of intake silencer were created based on the physical model of the two mufflers. The models for the acoustic impedance of perforation in contact with fibrous material and the acoustic characteristic parameters of aluminium silicate were imported to software SYSNOISE. The transmission loss of intake silencer had been calculated and compared with the measured results. The results indicated that the model created for intake silencer was reasonable. The effects of various structure factors on the intake silencer are studied. The results indicated that the desired acoustic attenuation performance of intake silencer can be obtained by accommodating porosity, the density of sound-absorbing material, thickness of sound-absorbing material and so on.更多还原