Experimental Measurements and Numerical Simulation of Pulsating Flow in a Vehicle's Exhaust Pipe

• Main Authors: Sheng-Feng Wang, 王聖丰
• Other Authors: Shen-Min Liang
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/99545892799026529790

碩士 === 國立成功大學 === 航空太空工程學系碩博士班 === 94 === The process of power stroke of a vehicle’s engine produces exhaust gas which flows through the exhaust pipe into the atmosphere. The exhaust gas of high temperature and high pressure has pulsating waves. These pulsating waves induce oscillation of pressure and oscillation of flow velocity. We use a simplified exhaust pipe for numerical simulation and experiments to study the flow field properties of a basic flow and the propagation of the pulsating blast waves. For the pressure measurement, a PCB pressure sensor is used to measure pressure variations at these check points for different engine speeds. We use a U-shape tube to measure the time-mean pressure at pipe’s entrance. For the temperature measurement, K-type thermocouples are used for measuring six check-point temperatures simultaneously. For the flow speed measurement, a pitot tube and a U-shape tube are used to measure the flow speed at the outlet for the exhaust pipe. A time-dependent one-dimensional Euler system with source terms of friction force and heat transfer is solved by using a high-resolution method of a fifth-order weighted essential non-oscillation scheme for spatial derivatives and a forth-order Runge-Kutta method for time integration. We adopt two different dimensionless time-scaling strategies to simulate the basic flow and the propagation of pulsating blast waves. Computed results are compared with the experimental data, it is found that the present numerical simulation well predicts the aforementioned flow properties of the exhaust pipe at these check points under different engine speeds.