CAJ | 학술논문

针对液氢预冷火箭发动机自然循环回路的流动与传热过程,建立了一维非稳态均相模型来研究预冷过程中管路的温降特性.在膜态沸腾阶段引入过渡膜态沸腾,保证了弥散流膜态沸腾向反环状流膜态沸腾的合理过渡.一般流体的膜态沸腾起始壁温T_L大于核态沸腾最高壁温T_(CHF),而氢的T_L小于T_(CHF),使得氢的沸腾曲线不同于其他流体,造成计算时传热与流型转换的不连续,因此考虑以T_(CHF)作为膜态沸腾起始壁温,以T_L作为核态沸腾最高壁温,通过增加过渡沸腾区来确保计算顺利进行.计算发现:预冷过程中,回路管壁温沿流动方向表现出从高到低的逆向分布规律,最高壁温点位于反环状流向弥散流过渡区间处,最高壁温点位置随时间逐渐向下游推进.
침대액경예랭화전발동궤자연순배회로적류동여전열과정,건립료일유비은태균상모형래연구예랭과정중관로적온강특성.재막태비등계단인입과도막태비등,보증료미산류막태비등향반배상류막태비등적합리과도.일반류체적막태비등기시벽온T_L대우핵태비등최고벽온T_(CHF),이경적T_L소우T_(CHF),사득경적비등곡선불동우기타류체,조성계산시전열여류형전환적불련속,인차고필이T_(CHF)작위막태비등기시벽온,이T_L작위핵태비등최고벽온,통과증가과도비등구래학보계산순리진행.계산발현:예랭과정중,회로관벽온연류동방향표현출종고도저적역향분포규률,최고벽온점위우반배상류향미산류과도구간처,최고벽온점위치수시간축점향하유추진.
A set of one-dimensional unsteady homogenous models for flow and heat transfer process of a natural circulation precooling loop of a rocket engine is established to study the cooldown characteristic of the pipeline when liquid hydrogen flows in the pipeline. A transition filming boiling model is adopted to ensure the reasonable transition from dispersed filming boiling to inverted filming boiling. T_(CHF) and T_L are viewed as the onset temperature of film boiling and the temperature of critical heat flux, respectively, to achieve the continuity of heat transfer and flow regime transition in the calculation. The computing results show that the inverse temperature distribution exists at the loop along the flow direction during the precooling process. The maximum wall temperature is located at the transition from inverted flow to dispersed flow. In addition, the location of the maximum wall temperature moves downstream with time gradually.