Performance Analysis And Optimazation Of High Pressure Stage Centrifugal Compressor For A MW Level Gas Turbine

Distributed energy is an important component of the future energy system.It has become a key task of the 13 th Five-Year Plan for electric power development in China.Micro-sized gas turbine is an important facility in distributed energy systems.Compressor is one of the three majo r components of the gas turbine.It is very important for the efficiency and stable operation of the gas turbine.In micro-sized gas turbine,centrifugal compressor is widely used for its simple structure and high single stage pressure ratio.In this paper,the aerodynamic performance of centrifugal compressor is studied.The high pressure stage centrifugal compressor of a MW level gas turbine is chosen as the object.This centrifugal compre ssor consists of three rows of vanes: inlet guide vanes,closed impeller and vaned diffuser.Because its performance parameters such as pressure ratio and efficiency are lower than a similar unit,this paper carried out a detailed analysis in order to find the design flaws,and then to optimize the design on this basis.Using the method of computational fluid dynamics,the overall performance parameters and the detailed flow field distribution of this centrifugal compressor are calculated under different rotating speed and different flow rate.This centrifugal compressor has a fine off-design performance.Under a wide range of flow rate,except near the flow blockage,the performance of this centrifugal compressor changes slightly.In the design conditions,the flow fleid in the inlet vane and impeller is in a good condision.The flow field in the vaned diffuser is also stable from the middle region to the tip.But in the area near the hub,serious flow separation appears in the second half of the suction side,which is the main reason for the performance decreasing.Based on the above analysis results,the vaned diffuser is optimized.In blade profiling,the Bezier curve is used to fit the mean camber line.The influence of four different factors of the blade on the performance of centrifugal compressor are discussed: geometric inlet angle,length,quantity and thickness.According to the results,a final optimization scheme is decided.Compared with the original scheme,the final optimization scheme has a significant higher performance in the design rotating speed,and change slightly in the other rotating speed.