Gas Pulsation And Reducing Methods Research Of Roots Supercharger

Roots supercharger is a displacement fluid machinery, applied to supercharging technology of automobile engine. Its excellent low speed torque characteristic, good transient response, makes the engine play a unique advantage of traffic in the city. But roots supercharger exists gas pulsation, which causes vibration, noise and other issues in the system, it has seriously affected the work performance of roots supercharger. In this paper, gas pulsation and reducing methods of Roots supercharger are studied. The main research contents are as follows:(1) The working principle of Roots supercharger was analyzed.The main reason caused gas pulsation was the high pressure gas at exhaust end of Roots supercharger flowed to the element volume.(2) The gas pulsation models of Roots supercharger was set up.The forecast about the transient exhaust flux at different turning angle of Roots supercharger was achieved from writing program of MATLAB language. The characteristics of gas pulsation was achieved through comparing fluctuation curve under difference working condition.(3) With the help of computational fluid dynamics software FLUENT Dynamic grid and UDF technology were adopted to simulate the inside flow field of Roots supercharger. The instantaneous pressure distribution and velocity distribution was achieved at different turning angle of Roots supercharger, Revealed the changes of air flow with the rotation of the rotors. The phenomenon of small pulsation caused by vortex development and changes was captured.(4) Measures of countercurrent cooling technique and gradually expanding gap inflow structure was put forward to reduce gas pulsation, The best improvement measure was got by theory analysis and simulation research,.(5) The gas pulsation experiment platform of Roots supercharger was built. The software of experiment and control system was established combining with virtual instrument programs based on Lab VIEW platform. The experiment verified the feasibility of the cooling technique measure of gas flow pulsation reduction.