Research On The Partial Inlet Variable Geometry Turbine

With the modern vehicle engines towards higher coefficient of torque reserve, higher power, higher economical efficiency, lower noise and lower pollution, the conventional fixed turbocharger is found with its narrow operating range, the boost pressure cann’t be regulated, and the resulting problems are more and more outstanding. Variable geometry turbocharger technology has been proved to be an ideal solution at home and abroad. A lot of research have been done and obtained many useful result. But the present variable geometry turbochargers need to future research because of its poor reliability, low turbine efficiency and high cost.This paper presents a new type of variable geometry partial inlet turbine which was used variable flow channel structure. In low speed condition, the inlet control value of the turbine is closed, only the internal flow channel is opened, and then the sectional area is reduced, the turbine inlet pressure and the useful work is improved, so the boost pressure is increased. In the high speed condition, the value is adjusted its opening according to the different performance requirements, the flow sectional area is changed, so the turbine can match with all the engine conditions well. A full stage simulation has been done by a software named NUMECA, the turbine internal flow have been analyzed, the working characteristics and the mechanism of internal flow loss are definited, the optimization design of the turbine structure is put forward.In this paper, the processing problem of rotor-stator interface which has great influence on result has been studied. Under the premise of calculating accuracy and saving calculation time, the frozening rotor-stator interface method is selected. And then the turbine performance with different inlet angles which at low speed condition are studied. Compared to the experiment results, the appropriate calculation model is established, the flow characteristics of the various inlet angle schemes are mastered, also the efficiency and flow characteristics are obtained. This provides an evidence for the matching with different engines. In this paper, the value as an important component is analyzed. Biased and middle value structure schemes at different opening value degrees are studied, the flow regulation relationship between the two schemes are found. This paper presents the total pressure loss coefficient and flow angle to evaluate the turbine flow condition, through the detailed analysis for the different degrees of two value schemes, the reason of turbine loss is analyzed. According to the low turbine efficiency when the value under small openings, the sectional area of external flow channel is reduced, and the modified model was calculated at different value degrees. Compared to the modified and unmodified model, the modified model significantly improves the turbine efficiency and reduces the flow loss of external flow channel at small opening as5and10degrees.