尺度效应下大功率伺服电机再生冷却通道超临界态甲烷传热特性研究

Heat Transfer Investigation of Supercritical Methane in Regenerative Cooling Channel of High-Power Servo Motor under Scale Effect

关键词:  超临界态甲烷  大功率伺服电机  再生冷却  传热特性  浮升力  尺度效应

Key words:  Supercritical methane  High-power servo motor  Regenerative cooling  Heat transfer characteristics  Buoyancy force  Scale effect

摘要:

针对飞行器电动执行机构的大功率伺服电机强化散热问题，建立了不同尺度的电机缠绕式螺旋管再生冷却通道数值模型，对超临界态甲烷在尺度效应影响下的传热特性和机理进行研究，探讨了不同尺度冷却通道中超临界态甲烷所受重力浮升力和离心浮升力对传热性能的影响。结果表明，离心浮升力及重力浮升力均受到超临界态甲烷热物性剧烈变化的影响；在相同热质比下，尺度效应对流体温度影响较小，但壁面温度存在明显差别，小尺度冷却通道的传热强化效果更为显著；小尺度时热物性引起的重力浮升力相比于离心浮升力对传热影响较大，大尺度冷却通道的重力浮升力及离心浮升力对传热影响均显著增强；此外，小尺度下大比热区后流动加速更为明显。

Abstract:

The numerical model of supercritical methane in regenerative cooling channel of high-power servo motor in flight vehicle actuator is built for the problem of heat dissipation， the thermal performance and heat transfer mechanism of supercritical methane in helically coiled tube are investigated， and the scale effect on heat transfer is explored by evaluating the domination of gravitational buoyancy force and centrifugal buoyancy force. The simulation results reveal that both the two buoyancy forces are affected by the thermophysical properties of supercritical methane significantly. Under the constant thermal mass ratio， the gap of bulk temperature is not obvious， while the dramatic difference exists between the inner wall temperature， and the superiority of small-scale tube on heat transfer is revealed. The important role of thermophysical properties contributed to the gravitational buoyancy force on heat transfer is illustrated， while the effect of centrifugal buoyancy force is not dramatical. Meanwhile， both the two buoyancy forces affect the heat transfer of supercritical methane remarkably under large scale tube. Moreover， the flow acceleration is obvious after the large specific heat region under small scale tube.