Effect of trailing edge thickness on the performance of a helium turboexpander used in cryogenic refrigeration and liquefaction cycles

26th International Cryogenic Engineering Conference & International Cryogenic Materials Conference 2016

材料科学;物理学

Sam, Ashish Alex^1 ; Ghosh, Parthasarathi^1

Cryogenic Engineering Centre, Indian Institute of Technology Kharagpur, 721302, India^1

关键词: Computational fluid dynamics analysis;    Cryogenic refrigeration;    Cryogenic turboexpanders;    Dynamic loadings;    Efficiency degradation;    Flow charac-teristics;    Performance characteristics;    Pressure recovery;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/171/1/012021/pdf
DOI  :  10.1088/1757-899X/171/1/012021

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

Turboexpanders in cryogenic refrigeration and liquefaction cycles, which is of radial inflow configuration, constitute stationary and rotating components like nozzle, a rotating wheel and a diffuser. The relative motion between the stationary and rotating components and the interactions of secondary flows and vortices at different stages make the turboexpander flow unsteady. Computational Fluid Dynamics (CFD) analysis of this flow is essential to identify the scope for improvement in efficiency. The trailing edge vortex formed due to the mixing of the pressure and suction side streams is an important phenomenon to analyse, as this leads to efficiency degradation of the machine. Additionally, there are mechanical vibrations and dynamic loading associated with. This flow non-uniformity at the exit should be suppressed as this may affect the pressure recovery process in the diffuser and thereby the turboexpander's performance. The strength of this vortex depends upon the geometrical parameters like trailing edge shape, thickness etc. In this paper, transient CFD analyses of a cryogenic turboexpander designed for helium refrigeration and liquefaction cycles using Ansys CFX®were performed to investigate the effect of trailing edge thickness on the turboexpander performance and the performance characteristics and the flow patterns were compared to understand the flow characteristics in each case.