消声器结构对排气噪声和发动机性能的影响

利用GT-Power软件建立了汽油机与其排气系统的耦合模型,模拟分析主消声器和副消声器的结构对排气噪声、发动机性能以及排气系统参数的影响.最后,根据模拟结果,选择合适的主消声器和副消声器的结构形式,设计出性能优越的排气系统.     

汽车排气消声器结构形式对压力损失的影响

使用GT-POWER软件计算了3种抗性消声器的压力损失,并与FLUENT软件的计算结果进行了比较以验证软件的计算精度,分析了气流流速变化对消声器压力损失的影响.使用GT-POWER软件建立了发动机和排气消卢器的耦合模型,研究了消声器对发动机性能的影响.     

Application of dual reciprocity boundary element method to predict acoustic attenuation characteristics of marine engine exhaust silencers

In marine engine exhaust silencing systems, the presence of exhaust gas flow influences the sound propagation inside the systems and the acoustic attenuation performance of silencers. In order to investigate the effects of three-dimensional gas flow and acoustic damping on the acoustic attenuation characteristics of marine engine exhaust silencers, a dual reciprocity boundary element method （DRBEM） was developed. The acoustic governing equation in three-dimensional potential flow was derived first, and then the DRBEM numerical procedure is given. Compared to the conventional boundary element method （CBEM）, the DRBEM considers the second order terms of flow Mach number in the acoustic governing equation, so it is suitable for the cases with higher Mach number subsonic flow. For complex exhaust silencers, it is difficult to apply the single-domain boundary element method, so a substructure approach based on the dual reciprocity boundary element method is presented. The experiments for measuring transmission loss of silencers are conducted, and the experimental setup and measurements are explained. The transmission loss of a single expansion chamber silencer with extended inlet and outlet were predicted by DRBEM and compared with the measurements. The good agreements between predictions and measurements are observed, which demonstrated that the derived acoustic governing equation and the DRBEM numerical procedure in the present study are correct.     

高温气流对穿孔管消声器声学性能的影响

使用GT-POWER软件计算了直通穿孔管消声器和三通穿孔管消声器静态时的传递损失,并与实验测量结果进行了比较以验证软件的计算精度和适用范围.计算并分析了有高温气流存在时上述2种消声器的传递损失.为改善三通穿孔管消声器的低频消声性能,还研究了有端部共振器的三通穿孔管消声器的声学性能.     

汽车发动机空气滤清器消声特性研究

以某型轿车空气滤清器为研究对象,使用有限元法计算并分析其消声特性.将滤纸看作为吸声材料,利用阻抗管系统测量滤纸的复阻抗和复波数,并将其导人声学软件SYSNOISE中,进而计算出空气滤清器的传递损失.与实验测量结果比较表明,空气滤清器的声学有限元处理方法是合理的.     

提高柴油机排气消声器消声性能的试验研究

针对柴油机排气消声器，将流体计算软件用于阻力特性分析，并采用对试验件进行静态放声试验的方法，优化消声器的声学设计以提高消声效果。     

车客渡船舱室噪声预报与控制

针对新设计的100 m级海峡车客渡船开展舱室噪声预报和控制研究。使用统计能量分析（SEA）软件VA One预报所有舱室的噪声,由经验公式得到喷水激励、主辅机、泵体和风机等设备的结构噪声和空气噪声,并加载间接式通风空调口振动的实测值。采用特性分析的方法讨论结构噪声和空气噪声的传播方式,结果表明,结构噪声比空气噪声传播得更远。分析不同舱室的主要噪声来源,发现船舶下层结构,即艏楼甲板以下舱室的噪声主要来自机舱内,而上层建筑舱室的主要噪声则间接来自通风空调口。对于噪声超标的舱室,采取敷设阻尼材料和吸声材料以及加装消声器的减振降噪措施。研究表明,统计能量法适用于船舶设计阶段的噪声预报和声学优化计算,所得数据可为今后100 m级实船设计提供参考依据。