Experimental and numerical investigation on the hydraulic characteristics of orifice plate throttle for sodium-cooled fast reactor

As an important throttling component for Sodium-cooled Fast Reactor (SFR), the orifice plate throttles are widely used for the pressure adjustment of coolant pipelines. The complicated flow phenomena are the common issues encountered in similar engineering applications, which need to be further investigated. In this work, a new orifice plate throttle applied to outlet pressure adjustment of main vessel cooling system is specifically designed and manufactured based on the design requirements of SFR. The full-scale verification experiment and numerical simulation are employed to investigate its hydraulic characteristics and geometrical parameter effect. The experiment results indicate that the orifice plate throttle with the throttling diameter ratio of 0.516 meets the design requirements, where this improved design has also been verified. Moreover, several empirical correlations of resistance coefficient and outflow coefficient related to the geometrical parameters are obtained by regression analysis of experiment data, which can be used to preliminarily predict the hydraulic characteristics of orifice plate throttle. As a comprehensive supplement, the numerical results with the SST turbulence model are in good agreement with the experiment results, as the maximum error less than 8%. Furthermore, the effect of geometrical parameters on the hydraulic characteristics has been numerically analyzed, such as the throttling diameter ratio, throttling orifice shape and chamfer angle. It is evident that the throttling effect of the orifice plate throttle with the upstream chamfer is superior to other. Meanwhile, reasonable chamfer angle configuration can improve the throttling effect of orifice plate throttle. After evaluation, increasing the chamfer angle by 5 degrees can result in an increase of approximately 3% in pressure drop. As for the upstream chamfer orifice plate throttle, the chamfer angle of 45 degrees has excellent throttling effect. This investigation reports a promising design modification, as the potential structure optimization for the orifice plate throttles of SFR.