Supercritical helium cold circulators for nuclear fusion machines: A comparative overview of different hydrodynamic design approaches

Abstract

Cold circulators play a critical role in dynamic heat load mitigation across various operational scenarios to ensure stable performance of fusion reactor cryogenic system. The hydrodynamic design is a crucial parameter that critically influences the performance of these machines especially considering the future reactors with large superconducting magnets which would be handling high mass flow rates. The present study highlights quantitatively the effect of different blading schematics on the hydrodynamic performance of the pump impeller wheel, based on detailed analytical calculation and numerical analysis. The necessity and advantage of using impeller wheel with double curvature blades over single curvature blades is analysed qualitatively and quantitatively. It is observed that double curvature blades with blade hub ingress ratio larger than one deliver favourable performance and with an increase in the number of blades, this ratio decreases. It is seen that within the same wheel design parameters, optimally designed double curvature blades result in lower effective blade loading as compared to single curvature counterparts leading to better hydraulic performance. The temperature rise across pump due to viscous dissipative effects in fluid alone is more pronounced in impellers with single curvature blades as compared to the double curvature counterparts.