状态方程对煤油液滴高压蒸发计算的影响

分别基于RK、SRK和PR等不同真实流体状态方程(EoS)建立了包含亚临界和超临界两种不同机制的瞬态液滴高压蒸发模型。针对我国新一代高压补燃液氧/煤油发动机，对煤油液滴在高压N 2 环境下的蒸发过程进行数值研究，重点分析了不同状态方程对N 2 -C 12 H 26 二元系统高压气液相平衡，及进一步对煤油液滴高压蒸发计算的影响。结果表明：对液滴蒸发速率影响最大的参数是液滴表面蒸气质量分数，而对该参数影响最大的则是所选取的状态方程。基于SRK和PR EoSs的高压气液相平衡及液滴高压蒸发计算结果均与试验数据符合较好，可正确描述液滴高压蒸发特性；而基于RK EoS的相平衡计算结果显著高估液滴表面蒸气质量分数和环境气体溶解度，并低估临界混合温度和偏摩尔相变热，进而在亚临界蒸发状态下高估蒸发速率，在超临界蒸发状态下低估蒸发速率。另外，基于RK EoS的计算中液滴发生跨临界转变所需的环境温度显著低于基于SRK和PR EoSs的。

Effects of Equation of States on Numerical Calculation of High Pressure Evaporation of Kerosene Droplet

The transient droplet high-pressure evaporation model including both sub- and super-critical mechanism is established based on the RK, SRK and PR real-fluid equation of states (EoS) respectively. The evaporation processes of the kerosene droplets under high-pressure nitrogen gas are studied numerically with emphasis on the effects of different EoS on the high-pressure vapor-liquid phase equilibrium of N 2 -C 12 H 26 binary system and high-pressure evaporation calculation aimed at high-pressure staged-combustion liquid oxygen/kerosene rocket engine. The results indicate that the most influencing parameter of the droplet evaporation rate is the mass fraction of vapor on the droplet surface, which is mainly affected by the chosen EoS. The calculated results of the high-pressure vapor-liquid phase equilibrium and high-pressure evaporation rate using both SRK and PR EoSs agree overall with the experimental data, and the evaporation characteristics at high pressure could be described well. In contrast, the results using the RK EoS over-predict mass fraction of vapor on the droplet surface and solubility of the ambient N 2 into the liquid phase, whereas under-predict the critical mixing temperature and partial molar heat of the phase change, consequently, over-predict the subcritical evaporation rate, whereas under-predict the supercritical evaporation rate. In addition, the minimum ambient temperature required for the trans-critical transition of the C 12 H 26 droplets based on RK EoS is lower than those based on SRK and PR EoSs.