低温液体火箭发动机预冷自然循环回路的流动与传热特性研究

针对低温液体火箭发动机预冷自然循环回路的流动与传热过程，建立了一维非稳态均相流数学模型，采用反环状流和弥散流两种流型描述膜态沸腾流型及传热特性。数值计算结果表明：自然循环预冷回路中推进剂流量的不稳定特性是由驱动力——循环回路释热量的不稳定性造成的；预冷过程约80％的管路壁面温度下降由膜态沸腾所引起；反环状流和弥散流膜态沸腾流型的引入，可较好解释回流管壁面温度在预冷过程中的逆向分布规律。

Studies on Flow and Heat Transfer Characteristics of Natural Circulation Precooling Loop

One set of one-dimensional unsteady homogenous mathematic models for flow and heat process of natural circulation precooling loop of cryogenic liquid rocket engine was established, and especially, both inverted annular model and dispersed model were introduced for the prediction of filming boiling region. Results indicate the unstable characteristics of circulation flow rate in precooling process is caused by the unstable characteristics of natural circulation driving force, that is, the heat flux transferred to the cryogenic liquid from the natural circulation precooling loop. Moreover, about 80% of wall temperature decrease takes place in filming boiling region, and the inverted temperature distribution law of the return pipe is well interpreted by introducing the two filming boiling models mentioned above.