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凝胶推进剂虽然兼具有液体推进剂流量可控和固体推进剂长期可储存等优点,但凝胶喷雾液滴蒸发燃烧问题却一直困扰着凝胶推进剂研制及燃烧室设计工作,阻碍了凝胶推进剂实际工程应用.设计实现了凝胶单液滴蒸发燃烧实验系统,通过某型有机凝胶偏二甲肼(UDMH)单液滴在四氧化二氮蒸气中的蒸发燃烧实验现象,进一步深入分析了凝胶液滴蒸发燃烧机理.根据实验中凝胶单液滴在不同阶段的蒸发特性,建立了有机凝胶喷雾液滴在胶凝剂膜形成、膨胀、破裂三个不同蒸发阶段的多组分蒸发模型,采用初步选定的模型参数及物性参数对凝胶单液滴在高温气体环境中的蒸发全过程进行了仿真计算,并与常规液体液滴的仿真结果进行了对比分析.结果表明,凝胶喷雾液滴表面胶凝荆含量在蒸发初期增加比较缓慢,但在某临界时刻后的极短时间内迅速升高至形成胶凝剂膜的质量分数95%,导致表面质量流率迅速下降至0,表面温度则快速上升至UDMH推进剂沸点.胶凝剂膜形成后,液滴半径及表面UDMH蒸气质量分数出现了实验现象中凝胶液滴反复膨胀-破裂的震荡现象,液滴表面温度维持在略高于沸点的某温度范围内,凝胶液滴内部的沸腾蒸发明显强于液体液滴表面稳态蒸发流率,使得凝胶喷雾液滴生存时问小于常规液体液滴.
Although the gel propellant has the advantages of controllable flow rate of liquid propellants and long-term storage of solid propellants, the problem of evaporation and evaporation of gel spray droplets has haunted the development of gel propellants and the design of combustion chambers, hindering Gel propellant.A experiment system was designed and implemented to study the single droplet evaporation combustion experiment of gel.According to the experimental results of vaporization and combustion of a single droplet of UDMH in dinitrogen monoxide vapor, The mechanism of evaporation and evaporation of gel droplets was further analyzed.According to the evaporation characteristics of single gel droplets in different stages in the experiment, the droplets of organic gel were established in three different evaporation stages of gel film formation, expansion and rupture The multi-component evaporation model was used to simulate the whole evaporation process of gel single droplets in a high-temperature gas environment by using the preliminarily selected model parameters and physical parameters. The results were compared with the simulation results of conventional liquid droplets The results showed that the content of gelation on the surface of gel spray droplets increased slowly at the beginning of evaporation, but rapidly increased to the formation of gellant film in a very short period of time after some critical time The volume fraction of 95%, resulting in the rapid decline of the surface mass flow rate to 0, the surface temperature is rapidly rising to the boiling point of UDMH propellants.After the formation of gel film, the droplet radius and surface UDMH vapor mass fraction appeared in the experimental phenomenon gel Drop repeated swelling - rupture phenomenon, the droplet surface temperature is maintained at a temperature slightly higher than the boiling point of the boiling within the gel boiling evaporation was significantly stronger than the liquid droplet surface steady state evaporation rate, so that the gel spray Droplets survive less than conventional liquid droplets.