PIV와 CFD를 이용한 디젤엔진용 매연여과장치 내부유동 특성 연구

Abstract

Ejectors is a fluid transportation device for which a principle is used that high-pressure fluid are spouted through driving pipe and the pressure of low-pressure fluid is increased through exchange of momentum with low-pressure gas. As it inducts solid as well as fluid and gas, it can be applied for many industries and construction areas such as heat organs, fluid machinery power station, air conditioning duct, petroleum chemistry, food industry and environment industry. Steam-steam ejectors have been widely used for suction, mixture and dehydration, and have been considered as the most important to control various kinds of harmful gases and for air conditioning to generate pleasant air. Ejectors can be simple irregardless of size and installed easily. They can be easily used in places where fluid moves and expenses are reasonable. In addition, it is a semi-permanent fluid device as it needs little maintenance. This study is to analyse characteristics of flow according to volume of driving pipe and expanded pipe, and Reynolds number through experiments and numerical analysis (CFD). This study compares and analyses mean velocity of compound pipe, distribution of static pressure, distribution of total pressure, turbulent flow energy, turbulent viscosity, dissipation energy and concludes as follows:

1). In measuring PIV, as Reynolds number increases because of influence of shearing force of wall, vortex of velocity vector is formed near the wall. 2). When suction occurs at branch pipe, vortex that is formed at the joint of branch pipe with curvature (R= 28mm) and expanded pipe increases as velocity increases. 3). To increase suction efficiency, nozzle configuration should be realized at proper place of expanded pipe as a means to decrease dissipation of energy. 4) About 93% of the values of PIV measurement test and dimensionless velocity distribution by and CFD numerical analysis are identical. 5). Flux efficiency decrease as diameter of driving pipe increases, and it increases as Reynolds number increases. 6). Flux efficiency is the highest when the ratio of diameter of driving pipes is 1: 2.3, and flux efficiency increase to = 50%, = 69% and = 75% according to velocity ratio.