Research On Optimizing And Matching Of Complex Oil-gas Separator

The oil-gas separator is a critical part of the positive crankcase ventilation(PCV) system which can separate the oil drops from the crankcase gas. It can not only decrease the total consumption of the oil, but also avoid the pollution to the intake pipes and other components during the crankcase gas flowing into the cylinders. Meanwhile, the emission of the particle for the engine can be reduced at the same time. Therefore, an oil-gas separator with high efficiency performance is significant to the engine. With the increasingly stringent emission regulations, most of the one-stage oil-gas separator cannot meet the requirement of the market any longer. The multi-stage oil-gas separator has aroused people’s attention. The complex oil-gas separator studied in this paper is just a kind of multi-stage oil-gas separator. It is composed of the active part and the negative part. In addition to the characteristic of the high efficiency, the complex oil-gas separator can adapt to the variation of the engine operations by adjusting the rotation speed of impeller in the active part. In this way the strict oil-gas separation requirement of the engine can be demanded.This paper mainly deals with the structure optimization of the active part and the matching between the complex oil-gas separator and the engine. The specific content is as follows:(1) Designed the critical structures of the complex oil-gas separator’s active part. Various optimum proposals were put forward, then the computation models were established based on the CFD simulation method. Finally, the gas phase flow field and the two-phase flow field of each model were analyzed and compared and the best proposals were selected as the final solution.(2) Completed the matching design work between the complex oil-gas separator and the GW4D20 diesel engine. According to the distribution of the volume flow rate for the crankcase gas in all conditions of the engine, a series of computation models corresponding different flow rates and different rotation speeds were established, then by analyzing the gas phase flow field and the two-phase flow field of each model and taking the oil-gas separation efficiency and the pressure loss into consideration, the optimum matching rotation in each volume flow rate of the crankcase gas was defined. Finally the matching designs in all conditions of the engine were completed.(3) Verified the matching simulation results. The engine test bench was built and the complex oil-gas separator sample was made, then the oil-gas separation efficiency and the crankcase pressure in different engine conditions were measured. Compared the test results with the simulation results, the variation trends were basically same, the matching simulation results were validated.