Gas Engine Labyrinth Oil-Gas Separator Numerical Simulation Research

With China increasingly strict China Ⅲ, China Ⅳ, China Ⅴ diesel emissions regulations were promulgated, the closed crankcase ventilation system that inhale the crankcase emissions to the combustion chamber to burn has become an important technology. This paper analyzes the application of modern computational fluid dynamics numerical simulation of oil-gas separator, according to the engineering, building the structure cooperate of orifice plate and baffle, coarse filter and fine filter combination labyrinth oil-gas separator geometry, then generate grid mesh. To set relevant boundary conditions of gas phase field model and discrete phase model. The influence which the change of boundary conditions and structural parameters on the separation efficiency and pressure loss is studied, and the result shows that the collision process, which oil droplet hit the wall so that the velocity decreases sharply and adsorbs on the wall, is an important mechanism for oil-gas separation. The separation efficiency of the separator increases with the increase of oil droplet size. Besides, separation efficiency and pressure loss increase with the increase of separator’s gas leakage and degree of vacuum of outlet, while decrease with the increase of spacing between perforated plate and baffle plate as well as the pore diameter of coarse filter hole and fine filter hole, however, the effect of temperature changes and concentration variation of engine oil content of blow-by gas within a certain range on separation efficiency is not obvious. Compared with the straight holes, gradually expanded holes are negative to oil-gas separation, while the tapered holes on perforated plate can improve the separation efficiency in small amplitude. According to the research above, this paper focuses on the design of construction and dimensions for the new labyrinth oil-gas separator with the consideration for the balance of the separation efficiency and the pressure drop. Then the experimental verification is carried out as well. The separation efficiencies of the new labyrinth oil-gas separator are 79.8%,83.3% and 86.7% respectively, The corresponding blow-by flows are 100L/min,122L/min and 179L/min. The calculation and analysis of the microcosmic field show that the cavum between the plates are beneficial to the formation of vortex when the blow-by flow is 122L/min. Furthermore, the position of the prefiltration pore plates influence the gas velocity significantly. However, each hole of the refined filtration pore plates distribute equably as the impact on air velocity is slighter. Further, the key position that affects turbulent dissipation rate is the refined filtration pore plates and baffle plate. The pressure loss around the prefiltration’s place occurs at the gap between the pore plate and baffle plate. The pressure loss around the refined filtration’s place occurs at the anteroposterior position of the pore plate. The pressure loss around the refined filtration’s place is triple that of the pressure loss around the prefiltration’s place.The smaller the droplet size is, it is more easier along with the flow and difficult to separate, the greater the droplet size is the more easy to separate. Compared with the original separator, when the particle size is 3 microns the separation efficiency is best and increase rate of 3%, pressure loss reduce 121pa. The research result of this paper aims to reality the innovation of the two-phase flow separation mechanism research on gas engine labyrinth oil-gas separator, strive to provide close to the engineering practice of theoretical guidance and method support to promote the efficiency of oil separation for oil-gas separator.