Structural Design and Optimization of High-Speed Radial Compressor Wheels for Light Gases

Proceedings

Abstract

The use of radial compressors for the compression of hydrogen introduces notable challenges due to its unique characteristics. One significant challenge is the requirement for the circumferential speed at the rotor outlet to approach the sonic speed for achieving high compression efficiency. Furthermore, hydrogen can adversely affect the physical properties of many metallic materials. The circumferential speed is inherently constrained by the material properties of the impeller and rotor dynamics, with the density-to-tensile strength ratio playing a critical role in material selection. Moreover, rotor dynamics are influenced by factors such as the impeller’s weight and the center of gravity’s position. A promising approach to improve both without altering the impeller’s flow-path, is the modification of the internal topology. Additive manufacturing technologies emerge as the ideal choice for producing partially hollow impellers without changing the external shape of the impeller. However, many high-strength and hydrogen-resistant materials may not be suitable for state-of-the-art additive manufacturing. This paper presents a comprehensive design and optimization process for light gas centrifugal compressor impellers. The design process incorporates computer aided topology optimization considering material properties as well as rotor dynamic boundary conditions to attain maximum circumferential speed. The most common topology optimization algorithms are evaluated, and the density-based approach is identified as the most suitable algorithm. The presented design process is applied to a state-of-the-art high-speed impeller design, resulting in a reduction in mass by 27% and a reduction in maximum stress by 30-40%. The optimized topology features multiple cavities within the impeller and a strongly modified backside contour. The finite element analysis of the optimized impeller indicates a more uniform stress distribution in the highly stressed hub area in comparison to the benchmark geometry.

Authors 2

1. Marvin A. Schwarz Aachen Institute of Power Plant Technology

   RWTH Aachen University

   Affiliation as printed

   Aachen , NRW , Germany

   Institute of Power Plant Technology, Steam and Gas Turbines , RWTH Aachen University

2. Manfred Wirsum Aachen Institute of Power Plant Technology

   RWTH Aachen University

   Affiliation as printed

   Institute of Power Plant Technology, Steam and Gas Turbines , RWTH Aachen University