Numerical Study In Work Process Of Air-powered Rotary Engine

With the emphasis o n environmental protection, saving energy and the continuously tightening vehicle emission standards, more new-generation cars with ultra- low emissions, clean, energy-saving and consuming no fossil fuels are paid more attention. Among them is the air-powered engine, the pressure energy of the air-powered engine changes into mechanical energy without emitting any pollutants. It has a promising market application prospect. Combine with the advantages of light weight, high power weight ratio, and smooth operat ion from the rotary engine that many others that reciprocating engines don’t have.It has important significance in some specified field. Therefore, it is very meaningful to get a research on air-powered rotary engine.This paper based on FLUENT software, combined with multiple UDF modules to realize dynamic simulation.Analyzed the effects of valve timing, inlet angles and rotor structure on the performance of air-powered rotary engine. The results provide a preliminary theoretical foundation for design and improvement of the engine.The main conclusions and innovations of the paper:(1)Based on a second development of the Fluent CFD software, the two-dimensional dynamic mesh of air-powered rotary engine was achieved by UDF modules. Reasonable turbulence model and boundary conditions are selected and established. And the relevant mathematics models were validated by comparing with result of reference.(2)The air inflow and flow field of the air-powered rotor engine were impacted by changing valve timing. So, the dynamic performance and the economic performance also are impacted importantly. Study shows that, the power first increases then decreases with the increase of the intake advance angle. However, the specific steam consumption(SSC) is decreased; With the increase of intake duration angle, the in-cylinder pressure increases in the expansion stage, the power increases, and the specific steam consumption increases; With the increase of exhaust advance angle, the fluctuation of in-cylinder pressure decreases that reduces the negative work in the expansion stage, and the specific steam consumption decreases; The power is increased while the specific steam consumption decreases at first and then increases with the increase of exhaust duration angle.(3)The valve timing is studied further by the orthogonal design The result shows that the greatest impact is intake duration angle, exhaust advance angle secondly, intake advance angle followed by, exhaust duration angle is the least important for the dynamic performance of the Wankel rotor air-powered engine. The optimal valve-timing is acquired in the case. Simultaneously, the greatest impact is the exhaust advance angle, the intake duration angle secondly, the exhaust duration angle followed by and the intake advance angle is the least important for the economic performance. The optimal valve-timing is acquired in the case.(4)when valve timing had no changes, the distributions of flow field and pressure field are decided by chamber shape, then work process is affected. The result shows that the pit have a small impact on flow field distribution in intake phase, the air-powered rotary engine with inclined inlet is to promote the back vortex and the front vortex is squeezed to decrease the vortex intensity, finally the dynamic is increased. Because of the pit, the SSC is increased. Straight inlet or inclined inlet has little impact on the SSC of air-powered rotary engine without pit. Straight inlet or inclined inlet has a big impact on the SSC of air-powered rotary engine with pit. The inclined inlet air-powered rotary engine without pit is best.