Coupling Simulation And Characteristics Analysis Of Low-speed Diesel Engine And Intake/Exhaust Systems

Low-speed diesel engines are widely used as the marine propulsion power plant,and their intake and exhaust noise are the main noise source,which have an important impact on ship comfort.In the present study,a coupled simulative model of low-speed diesel engine with the intake and exhaust systems was established to predict and analyze the intake and exhaust noise levels,then the influences of compressor and turbine on the intake and exhaust noise was studied,and the method of extracting acoustic source impedance was investigated.Numerical simulation software GT-Power was employed to establish a model of marine low-speed diesel engine,which was verified with the test data firstly.In this process,flow and noise parameters are obtained to study the influence of turbocharger structure on intake and exhaust noise.The method of extracting acoustic source impedance of low-speed diesel engine was studied,the reasons for errors caused in the acoustic source impedance extraction by using the two-load method are analyzed and then the reasonable selection and combination of loads is proposed for the error reduction in the acoustic source impedance extraction.With this method,the effects of engine rotating speed and load on the intake and exhaust acoustic source impedance were studied.The intake and exhaust silencing systems were designed according to the intake and exhaust parameters of diesel engine,the air cleaner was installed in the intake system,while the silencer and the after treatment device were installed in the exhaust system,and then the transmission loss of the silencing elements were calculated by using GT-Power software.Finally,a coupled model of low-speed diesel engine with the associated intake and exhaust silencing systems was established,and the influence of silencing elements on the engine performance,as well as the intake and exhaust noise levels were calculated and analyzed.