Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 07, 2019 - November 08, 2019
When the temperature of automobile exhaust gas is low, the catalyst becomes inactive and this phenomenon is one of causes of environmental pollution. This study focuses on the pulsating flow in the exhaust pipe of the internal engine for heating up the catalyst and causing its activation. The flow through the exhaust pipe of the engine is modeled as the air flow which is pulsated by a rotary valve in test pipe and the relation between the wave phenomena and the fluid temperature is examined in this study. The change with time of the opening area of the valve is designed to be same as that of the exhaust port of an actual engine and an obstacle simulating a catalyst is installed in the test pipe. As test pipes, a straight pipe, a rectangular pipe, and two types of semiellipse pipes are used in this study, and pressure and temperature are measured using pressure transducers and thermocouples at some points in pipe. As a result, when the pulsation frequency is high, the pressure waves are found to merge into the shock wave upstream of the obstacle in the cases of all four types of test pipes, and the shock becomes relatively strong in the straight pipe. Furthermore, it is found that the fluid temperature most increases at the location where the shock wave grows and becomes strongest. In addition, when a semiellipse pipe is used, high pressure and high temperature is obtained at the focal point of the ellipse.
