控制棒水压驱动系统落棒减速部件三维流场分析

3D Numerical Analysis of Hydraulic Deceleration Device Flow Channel of Control Rod Hydraulic Drive System

控制棒水压驱动系统是清华大学为低温核供热堆研制的新型内置式控制棒驱动技术,控制棒水力减速部件是水压驱动系统的关键部件之一,在保证落棒时间的前提下,通过其对落棒过程进行减速,降低控制棒快速落棒过程的冲击力,避免控制棒十字翼的变形和损坏。本文分析了控制棒水压驱动系统落棒减速机理,利用CFD软件FLUENT对驱动系统水力减速箱流道进行了三维流场数值分析,并分析了对应不同落棒位置水力减速箱流道在不同边界条件下的流场分布特性。在流场分析结果的基础上计算得到了水力减速箱侧壁孔流道和底部缓冲腔流道流量系数随落棒位移的变化,将该结果与驱动系统落棒减速理论模型联立,获得了控制棒落棒位移曲线,理论计算结果同冷态落棒性能实验结果符合得很好,从而验证了流场分析结果的正确性,在此基础上分析了落棒过程减速箱内外差压和落棒速度与水力减速箱流量系数的关系,为控制棒水压驱动系统落棒减速部件的设计和优化提供了指导。

Control rod hydraulic drive system（CRHDS）,which is invented by Institute of Nuclear and New Energy Technology,Tsinghua University,is a new type of internal control rod drive technology for the nuclear heating reactor（NHR）.Control rod hydraulic deceleration device（CRHDD）is one of the main components of the CRHDS.The CRHDD performs the rod dropping deceleration function to reduce the peak impact force acting upon the control rod and prevent the cruciform blade from being deformed or damaged.The working mechanism of the CRHDD was presented and analyzed.The three dimensional flow field analysis of the CRHDD flow channels was carried out using the computational fluid dynamics（CFD）program FLUENT.The relationship betweenthe flow coefficients of the hydraulic deceleration cylinder side wall flow channel and the cushion chamber flow channel and the control rod scram displacement was obtained on the basis of the flow field analysis results,which was substituted into the theoretical rod drop model to obtain the control rod scram displacements.The theoretical results agree well with the CRHDS scram test results under room temperature which verifies the validity of the flow field analysis results.Then the model was applied to study the transient pressure inside the hydraulic deceleration cylinder and the scram speed versus the flow coefficients of the flow channels.The research results can give guidance for the design and optimization of the CRHDD.