Evaluation on the flow characteristics of helium working fluid in generation Ⅳ nuclear power station

Abstract

This paper investigates the fundamental flow behaviors of helium, aiming at supporting the helium turbomachinery design optimization in generation Ⅳ nuclear power station. The applicability of hydrodynamics theory to helium has been discussed from many aspects including continuous medium, Newtonian fluid, Stokes hypotheses, and perfect gas state. The Reynolds average N-S method (RANS) with the γ-θ transition model is used for solving the compressible helium boundary layer. The influence of the Reynolds number on the helium boundary layer transition is explored. With the increasing Reynolds number, the transition of boundary layer occurs in advance on the plate. On the other side, the boundary layers under different Reynolds numbers have uniformity in the comparison of dimensionless parameters. The free stream turbulence (FST) is a main influence factor on the transition. Both the enhanced turbulence intensity and the large turbulence scale can make the transition be triggered in advance and reduce the onset Reynolds number. For the fluids with different specific heat ratios, the helium transition lags behind the air under the same Mach number. When under the same Reynolds number, the helium boundary layer is identical to the air. They share the same mean velocity profile and agree with the theory solution and experimental data simultaneously.