| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 92 === Because an exhaust flow is a kind of pulsating flow, it is unsteady, highly non-linear and is not easiy to accurately predict pressure oscillations by a traditional linear acoustic theory. In this study, we establish a non-linear compressible flow model for investigating pressure oscillations inside the exhaust pipe, which are closely related to the noise generated by the exhaust pipe.
In order to study the pressure oscillations inside the exhaust pipe associated with a HS-2L car provided by YULOM MOTOR Co. We use a one-dimensional non-linear compressible flow model with and without viscous effects. A 5th-order WENO scheme is used for discretizing convective terms, and a 4th-order Runge-Kutta scheme for time integration. In addition, experimental facilities of pressure, temperature, velocity of the pipe flow have been set up. To validate the computed temperature and pressure results inside the exhaust pipe, we conduct experiments to measure the pressure and flow velocity at some specific points for different engine speeds. It is found that the present one-dimensional, non-linear, viscous flow model is reasonably accurate to predict the pressure peak and the flow speed inside the exhaust pipe at different engine speeds.
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