高功率微波管收集极的散热分析

Heat dissipation analysis of high power microwave tubes collector

利用欧拉两相流模型和沸腾换热模型计算了高功率微波管收集极的散热问题。在给出电子束能量沉积规律的基础上，得到了热源项在收集极及冷却水中的分布形式。利用CFD软件计算了脉宽为45ns、重频为5OHz、平均功率为27kW电子束作用下的收集极温度分布，重点研究了冷却水流速对散热效果的影响。研究结果表明，冷却水流速为1．5m／s时，内壁面稳态峰值温度超过了收集极材料的熔点，会导致一定时间后收集极损坏；散热峰值处对流换热大约占总换热量的71．7％，激冷换热大约占28．1％，相变换热占0．2％。冷却水流速小于5m／s时，收集极最高温度随流速增加快速下降；5～10m／s时，温度下降缓慢；超过10m／s后，温度下降速度增大。针对该电子束条件，收集极安全工作要求冷却水流速不得低于5m／s。

In the paper,the heat dissipation of high power microwave tubes collector is calculated by using Euler two-phase model and the boiling model.Based on the electron beam sink rule,the distribution of heat source in collector material and cooling water is obtained.Then,the collector temperature is calculated by using the CFD software under electron beam duration of 45 ns,a repetitive frequency of 50 Hz and an average power of 27 kW.The effect of flow velocity of the cooling water on heat dissipation is analyzed.The results indicate that the max temperature of the collector is beyond the material melting point when the cooling water flow velocity is 1.5m/s,and the collector will be damaged after some time.At the top of the heat dissipation,the convection heat transfer is about 71.7% of the total heat transfer.The quenching heat transfer is 28.1%,and the phase transition heat transfer is 0.2%.When the cooling water flow velocity is less than 5m/s or more than 10m/s,the maximum temperature of the collector will decrease quickly as the flow velocity increases;when the cooling water flow velocity is 5-10m/s,the temperature will decrease slowly as the flow velocity increases.For the electron beam condition in the paper,it is requested that the cooling water flow velocity is 5m/s at least for collector safety.