Experimental And Numerical Study On Flow Resistance Of Equipment Components In Reactor System

In the research and design of innovative reactor type, the pressure drop in primary circuit isone of the major factors which determine the flow rate and head of the primary pump. And pressuredrop in reactor core and steam generator is the main contributor to the total in the primary circuit.Experimental studies are performed to investigate flow resistance of lower supporting plate offuel assembly, as well as the inlet and outlet nozzles in primary side of a10:1scaled steam generatormodel. With the aid of flow visualization experiments are carried out for the lower supporting plate.Characteristics of flow resistance and flow field in the different cases are obtained. Complementedby numerical study, the following conclusions are drawn:(1) The flow resistance coefficient of the lower supporting plate and lower tube socket is19.2and7.2respectively. It becomes25.15when both of them are connected to the test section at thesame time, which means that the summation of flow resistance is relatively conservative. Theexperiment results show that the inlet flow direction shows weak effect on the flow resistance ofsupporting plate and tube socket. Hence, the influence of flow direction in lower plenum can beignored. The flow resistance coefficient given by the existing correlation is about10%larger thanthat obtained from experiment, which implies the correlation is conservative.(2) The flow resistance coefficient of the inlet and outlet nozzles in the scaled steam generatormodel is0.71and0.22respectively, which are smaller than that in typical sudden expansion andcontraction structure. Installed with the tube plate, the coefficient of the inlet nozzle changessignificantly, but the plate doesn’t affect the coefficient of the outlet nozzle.(3)Flow visualization results are obtained in the downstream of lower supported plate testsection using laser-induced fluorescence method. The jet flow area and eddy area are recognizable inthe downstream of lower supported plate. The vortices show obvious unsteady characteristics, andthe lower tube socket mixes the flow very well.(4)The flow field near the lower supporting plate and inlet/outlet of the steam generator arestudied using computational fluid dynamics (CFD) method. The discrepancy is less than5%between calculated form drag coefficient and the measured one. It reveals that the CFD method can be used in the calculation of flow resistance for the design of main components in primary circuit.Large eddy simulation (LES) depicting complex vortex structure better predicts similar resultscompared with experiments. The flow field and pressure distribution show poor uniformity in theinlet area of steam generator heat transfer tube plate, which may adversely affect flow distribution inthe heat transfer tubes. Flow rate difference varies linearly with pressure difference between twooutlet tubes, and pressure fluctuation shows significant effect. Thus, this type of pressure differencebetween the outlet tubes should be avoided in actual engineering application.