Numerical Analysis And Optimization Research Of Welding Volutes For Centrifugal Compressors

Centrifugal compressors play an important role in power and energy, military industrial and many other fields for its special advantages of high efficiency, high reliability, compact structure and high rotate speed. High compressor efficiency is naturally required in order to save energy and cut the operating costs. In the past, research works for centrifugal compressor were mainly focused on the improvement of the impeller, while the volute and other static components were not paid appropriate attention. However, as the techniques developed to such a stage, the potential of the impeller was almost exhausted. As a result, more and more attentions were paid to the static parts of the compressor such as the volute.This thesis focused on two typical welding type volutes, namely constant breadth volute and constant height volute. A numerical analytic system was developed based on the compute aided design software Pro/Engineer, SolidWorks and computational fluid dynamics software NUMECA. The geometry model includes the impeller, the vaneless diffuser and the volute. Flow inside the last stage of centrifugal compressor was analyzed by using the simulation platform. Main features of the flow field were obtained and modifications of volute design were proposed. The efficiency of the last stage was successfully increased by 4.5% and 3.0% respectively. On the base of the research works, the specification for aerodynamic design of the welding type volute was summarized. The specification was tested on a volute which was designed by the approach in the specification. Numerical simulations prove that the specification can be used for the aerodynamic design of all welding type volutes.The research works presented in this thesis provide some guidelines for the engineering design of the volute. According to this approach, it can be estimated that the overall efficiency of the compressor unit may be increased by 1-2% approximately.