【作者】 吴亚瑾；

【导师】 杨逢瑜；

【作者基本信息】 兰州理工大学 ， 机械电子工程， 2009， 硕士

【摘要】 大型飞机要突破的10项关键技术中,民用大型飞机总体设计技术、民用大型飞机的噪声预测和减噪措施是两项重要内容。其中,液压系统的噪声控制是一项重要内容。飞机主供压系统、应急供压系统、起落架收放系统、襟翼收放系统、前轮转弯系统、主轮刹车系统、风挡雨刷刮水系统等都用到液压系统,其中的液压元件会产生中高频噪声。本文围绕液压系统产生的噪声对机舱的影响,讨论噪声的基本特性及详细的表征参数。介绍了噪声的数值仿真分析方法有限元(FE)分析法、边界元分析法(BEM)、统计能量法(SEA)。其中,三种方法中有限元方法是确定性的求解方法,用于低频振动环境的预示,可以得到结构的整体模态参数。与边界元方法结合可以预示结构的振动以及内外声场的噪声辐射强度。有限元方法求解高频问题时,由于波长很小且模态密集,要准确求解需要网格精细程度足够高,因此模型的规模会变得非常大,求解的时间变得非常的长,反而没有了数值仿真高效的特点。再次,由于结构的高阶模态参数对许多不确定的原始参数以及许多结构细节非常的敏感,但是结构细节又不太好确定,使得有限元方法求解的精度大打折扣。另外,结构声振分析既存在振动引起的噪声辐射问题,又存在噪声引起的结构振动问题,传统的有限元方法在解决二者的耦合时比较困难。因此有限元方法通常只是用于求解低频振动噪声环境的预示。统计能量分析(SEA)从统计的角度分析统计密集模态平均的振动能量传递水平,因而模态愈是密集,统计精度就愈高,振动响应分析的精度也就愈高,其适用的分析频带较有限单元法宽得多。通过数值仿真,集成上述三种分析方法对噪声进行分析,并通过实验验证了周期性SEA方法在蒙皮桁条结构中应用的精确性,利用混合边界层法对侧墙+底板结构进行建模,验证了机身侧墙上部到底板的传递路径的正确性。针对液压系统的噪声分析,在液压控制系统设计过程中对合理使用液压元件,设计液压控制电路有着很高的指导作用。更多还原

【Abstract】 In the 10 key technologies to break in the designing technology of large-scale civil aircraft, noise prediction and noise reduction measures are two important elements. Noise control of hydraulic systems is one of the most important. Main oil supply pressure systems, emergency oil supply pressure systems, undercarriage control systems, flap control systems, front-wheel steer systems, main-wheel braking systems and windshield wiper systems of the airo are based on hydraulic systems, the hydraulic component in the systems cause high-frequency noise.This paper describes the basic characteristics of the noise and the parameters of characterization around the hydraulic systems’ impact of noise on the cabin. Introduce three numerical simulation methods about noise analysis, which including finite element (FE) analysis, boundary element method (BEM), statistical Energy Analysis (SEA). Finite element method is a deterministic method for low frequency vibration noise’s prediction; get the overall modal parameters of the structure. Combined with the boundary element method(BEM),it can indicate the structure of the vibration and radiation of the noise inside and outside the sound field. For solving high frequency problems, because of the small-wavelength and the mode-intensive, it is necessary to accurately solve the needs of the grid high enough precision, and the size of the model will become very large, need a very long time, high-performance characteristics of Numerical simulation could not work. Secondly, because parameters of the higher-order modal are very sensitive to many uncertain original parameters and many details of the structure, but it is not good to determine the structure of the details, so it is not easy to get great accuracy by using finite element method. In addition, the problems of acoustic vibration of the structure include both the acoustic radiation and vibration caused by noise; the coupling of the traditional finite element method is more difficult. Therefore the finite element method is usually used to solve the problems of low-frequency vibration and noise. Statistical Energy Analysis(SEA) from the statistical point predict the statistics-intensive mode of vibration of the average level of energy transfer, which mode is more intensive, higher statistical accuracy, the accuracy of vibration analysis is the higher ,frequency band of its application is much wider than finite element method.Through numerical simulation, integrate the three analytical methods for analysis of noise. Through experimental method show a confidence of application on the stressed-skin construction by using the periodic SEA method. Model structure of sidewall and the bottom by using the method of hybrid FE-SEA, verify the correctness of the transmission path from the upper plate of the fuselage to the bottom.更多还原