加减速流条件下棒束通道阻力特性研究

Resistance Characteristics of Rod Bundle Channel under Acceleration and Deceleration Flows

压水反应堆的启动、停堆、事故等多种工况会使反应堆堆芯内部冷却剂产生加减速流,影响反应堆的热工水力特性。在雷诺数(Re)700<Re<20000范围内针对加减速流条件下棒束通道内的阻力特性进行了试验研究。结果表明,受流体黏性与惯性影响,流体在充分发展区与定位格架下游区域,由瞬态进入稳态流动时沿程压降会产生突变,该突变随着加速度的减小而减小。加减速流条件下,沿程阻力系数与局部阻力系数随雷诺数呈顺时针闭合曲线变化,与稳态值的偏移量随雷诺数的增大而减小,随加速度的增大而增大。减速流中,当雷诺数较低(Re<4000)时,局部阻力系数与沿程阻力系数的变化趋势相差较大。

The start-up,shutdown and accident of PWR will make the coolant flow in the reactor core accelerate and decelerate,which will affect the thermal-hydraulic characteristics of the reactor.Experimental study on the resistance characteristics of the rod bundle in the Reynolds number range of 700<Re<20000 under acceleration and deceleration flow conditions were carried out.The results show that,under the influence of fluid viscosity and inertia,when the fluid moves from the transient state to the steady state flow in the full development region and the downstream region of the spacer grid,the frictional pressure drop along the flow will suddenly change,and the sudden change will decrease with the decrease of the acceleration.Under the condition of acceleration and deceleration flows,the frictional resistance coefficients and the local resistance coefficients change in a clockwise closed curve with the Reynolds number,and the offset from the steady state value decreases with the increase of Reynolds number and increases with the increase of acceleration.In the decelerating flow,when the Reynolds number is low(Re<4000),the variation trend of the local resistance coefficients is quite different from that of the frictional resistance coefficients.