The Highly Loaded Aerodynamic Design and Performance Enhancement of a Helium Compressor

A design study of the multistage axial helium compressor of a 300MWe nuclear gas turbine is presented in this paper. Helium compressor is characterized by shorter blades, narrow flow channels, numerous stages and longer slim rotor, which result in losses due to blade surface and end wall boundary layers growths, secondary flows and clearance leakage flows, any occurrence of flow separation and stage mismatch. Therefore, the purpose of this paper is to improve and optimize the aerodynamic design of the helium compressor. The property of helium is different from that of air, so how to choose the design parameters of a helium compressor is discussed first. And then how to shorten the length of the helium compressor or how to decrease the number of stages for a certain pressure ratio by increasing the stage loading are investigated. The new highly loaded helium compressor of larger flow coefficient and high reaction is designed and optimized. The three-dimensional flow patterns in a helium stage are simulated with CFD software (NUMECA). Adjusting the position of blade maximum camber deflection position; redistributing radial compression work; modifying the configuration of blade at inlet and outlet; using CDA technique to optimize blade profile; 3D blading techniques to mitigate end wall boundary layers and corner separation have improved the performance of the first stage of the helium compressor cascades.