Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : March 18, 2019 - March 19, 2019
The research and the development of ultra micro gas turbine (UMGT) which possesses both high power density and high energy density have been performed continuously for the usage as the electric power sources. The main components of UMGT are a compressor, a combustor and a turbine, and the compressor is the most important among them to establish the gas turbine cycle and to generate the output. Numerical analysis is more suitable for such investigation than experiment because of the small size of ultra micro centrifugal compressor (UMCC). However, numerical analysis often gives unrealistic results by inadequate settings of the boundary condition or the boundary location. In this study, in order to investigate the adequate setting of the outlet boundary location applied at the diffuser outlet, the flows in three types of calculation model for UMCC were analyzed numerically. The first model is the basic model which is constructed by the impeller and the parallel wall vaneless diffuser. In the second and the third model, the calculation region with constant cross-sectional area in radial direction (CAR) is added to the diffuser outlet of the first model to reduce the pressure rise near the outlet boundary. The second model is different from and the third model in the radial length of CAR. The computed results clarified that the addition of CAR was effective to prevent the appearance of reversed flow at the outlet boundary and to give more realistic results.
