高温超导电缆用波纹管内液氮流动特性的数值研究

Study of the flow characteristics of the sub-cooled liquid nitrogen in corrugated tubes used for HTS power cable

随着超导技术的发展,高温超导电缆在电力输运中逐渐得到重视并进行了广泛的研究。由于波纹管具有良好的柔韧性和收缩性,在高温超导电缆中作为杜瓦放置电缆,冷却超导体用的液氮需流经波纹管。在系统设计中,需要对液氮在波纹管中的流动特性加以了解。为了研究液氮在波纹管内的流动特性,对其进行了数值计算及理论分析。分析表明:压力损失随入口速度的增大而增大;在波纹内形成了涡旋流;在所考察的雷诺数范围内,雷诺数对摩擦系数的影响不大,而波纹尺寸对摩擦系数具有主要的影响。摩擦系数随s/t的增大而减小。。

With the development of the superconductor technology, high temperature superconducting cable has been developed. Liquid nitrogen passes through the corrugated tubes for cooling the high temperature superconductor. The detailed flow characteristics of the liquid nitrogen in corrugated tubes are investigated by numerical simulation for different inlet fluid velocities and tube geometries, i.e. different sizes of the pitch and depth of corrugation. The pressure and velocity field contour plots are obtained and analyzed. The pressure drop increases with the velocity. The results of friction factor show that the influences of pitch and corrugation depth are significant but the dependency on the Reynolds number is not severe. The friction factor decreases while the s/t increases.