失重和重力条件液态金属绕流管束对流传热特性对比

Comparison of convective heat transfer characteristics of liquid metals flowing across tube bundles between gravity and zero-gravity conditions

液态金属绕流管束对流换热能力强,其应用有助于换热设备小型化,是空间动力反应堆主换热器设计的较好选择。失重是空间环境的典型特征,失重和重力条件下液态金属绕流管束流动传热特性的异同尚不清楚,阻碍了液态金属用于空间反应堆的发展进程。为此,通过雷诺时均数值模拟方法,对比研究了失重和重力条件下液态金属绕流管束湍流传热特性,获得了局部温度与速度分布,得到了流动传热性能变化规律。结果表明:竖直向下流动时,液态金属对流传热性能在失重和重力条件下表现不同;重力条件下浮力影响了流场和温度场,相比失重条件,阻力和换热性能最大偏差约10%。

Liquid metal flowing across tube bundles accompanies with strong convective heat transfer ability.Its application is conducive to the miniaturization of heat exchanger equipment and is a good choice for the main heat exchanger design of space reactor.Weightlessness is a typical characteristic of space environment.However,it is not clear in the similarities and differences of the flow and heat transfer characteristics between gravity and zero-gravity conditions in the process of liquid metal flowing across tube bundles,which hinders the development process of liquid metal used in space reactors.Therefore,the turbulent heat transfer characteristics of liquid metal flowing across tube bundles between gravity and zero-gravity conditions are investigated by employing the Reynolds averaged numerical method.The temperature and the velocity distribution are displayed in the local area,and the convective heat transfer characteristics are obtained.It is shown that the convective heat transfer performance is different under the gravity and zero-gravity conditions with liquid metal flowing vertically downward.Under the gravity condition,the buoyancy affects the flow and temperature fields,thereby causing a maximum deviation of 10%for friction factor and heat transfer ability compared with the zero-gravity condition.