脉动热管气液塞初始分布可视化实验研究

Experimental Study on Initial Distribution of Liquid Plug and Vapor Slug in Pulsating Heat Pipe

脉动热管中气液塞的初始位置和长度的分布对于理论模型的精确性和启动性能有很大的影响。针对此,本文搭建了内径2 mm脉动热管的可视化实验装置,研究了气液塞初始分布位置和长度的规律,以及气液塞初始分布对脉动热管启动性能的影响。脉动热管充注统计规律显示,中间管段较容易出现长气塞,其他管段气液塞分布较为均匀;分次充注和增大充液率有利于提高脉动热管内气液塞分布的均匀性。在0.3～0.7充液率下,液塞长度均集中在1～10 mm范围内,其中,2～4 mm长度范围内的液塞出现频率最高。根据启动试验,初始气液塞的均匀分布有助于脉动热管的有效启动。脉动热管蒸发段气液塞初始分布较为均匀时,管内气液塞能够在较小的加热热流下开始振动。

The initial distribution and length of the vapor slugs and liquid plugs in pulsating heat pipes have a great influence on the accuracy of the theoretical model and the starting performance of pulsating heat pipe. For this problem, a visualized experimental device for pulsating heat pipe with an inner diameter of 2 mm was built. The rule of initial distribution and the influence of initial distribution of liquid plugs on starting performance were investigated. The statistical law of initial distribution in pulsating heat pipe showed that the middle sections in the horizontal direction were prone to appear long vapor slugs, and the distribution of vapor-liquid plugs in other sections was more uniform. The increase of liquid filling ratio(FR) was helpful to improve the uniformity of vapor-liquid plugs distribution in pulsating heat pipes. When the filling ratio was between 0.3~0.7, the length of liquid plugs was mainly in the range of 1~10 mm, the liquid plugs in the length range of 2~4 mm accounted for the largest percentage of liquid plugs. According to the test of start-up performance,the uniform distribution of the initial vapor-liquid plugs was helpful to the effective start-up of the pulsating heat pipe. When the initial distribution of the vapor-liquid plugs in the evaporation section of the pulsating heat pipe was more uniform, the vapor slugs and liquid plugs can begin to oscillate under the lower heat flux.