CFD를 이용한 디젤 엔진용 공기 정화기 성능에 관한 연구

Abstract

The cyclones which employ a centrifugal force generated by a spinning gas stream to separate dusts from the carrier gas are one of the most useful dust collectors. They have the advantages of simple design, low cost and very low maintenance operation cost. However, cyclones directly employ a centrifugal force to separate dusts, so they have the advantages to collect the larger size of particles relatively. These are why they are used as pre-cleaners for more expensive final control devices such as bag houses or electrostatic precipitators. Inner flows of cyclones have very complicated features such as mechanically strong eddy, cavity region which has backflows in specific case and so on. Thus, experiments on inner flow of cyclone, approaches of many theories, methodology using numerical modeling were performed many times. Research conducted by Zhou & Soo showed 30% improvement of pressure drop, increase of collection efficiency when a special shaped geometric body was employed at center of cyclone inside. Chun & Ohm performed the numerical analyses with several parameters such as vortex finder diameter, effective dust exit diameter, vortex finder length, inlet type and showed that the simulation results with k-ε turbulence model were in good agreement with empirical knowledge. Gimbun & Chuah showed that CFD(Computational Fluid Dynamics) predicted the cyclone cut-off size for all operating conditions with a deviation of 3.7% from the experimental data. It also produced the better result than other empirical models'. In this study, we present an application of CFD to predict the dust collection efficiency according to various dimensional parameters such as shape of helical guide vanes, length of cylindrical part, dimension of inner diameter. With above numerical results, the experiments are performed to replace the old cyclone model according to KS R 1041 which is identical to ISO 5011.