本实验用化学示踪剂浓度法测量了压水堆燃料组件定位格架的交混长度。流体流过定位格架后的总交混系数用贝克莱数的形式来表示。实验结果表明,贝克莱数随定位格架下游距离的增大而逐渐减小,到一定距离后,贝克莱数基本上不再变化了,把这个距离定义为定位格架的交混长度。实验测得定位格架的交混长度约为70倍流道当量直径。 In this experiment, the chemical tracer concentration method was used to measure the mixing length of the positioning grid of PWR fuel assembly. The total cross mixing coefficient of the fluid flowing through the spacer grid is expressed in the form of a Berkeley number. The experimental results show that the Berkeley number decreases gradually with the distance downstream of the positioning grid. After reaching a certain distance, the Berkeley number basically does not change any more. This distance is defined as the mixing length of the positioning grid. The experimental results show that the cross-section length of the spacer grid is about 70 times the equivalent diameter of the runner.