有机混合工质对航空发动机射流预冷效果的数值研究

Numerical Study on the Effect of Organic Mixed Working Medium on Mass Injection and Pre-compressor Cooling of Aero-Engine

为了解有机混合工质进行射流预冷时的冷却特性,选用乙醇/水作为预冷工质,给定相同的边界条件,在3组不同的喷雾量(工况),通过ANSYS CFX软件进行数值模拟,探究喷雾量对冷却效果的影响。结果表明:随着喷雾量的增加,预冷段内空气的温降效果变好。喷雾量从1.641 kg/s提升到2.345 kg/s时,预冷段出口的温降系数从7.80%提升至10.23%;工况3至工况1喷雾量依次增加,预冷段内的蒸发量也随着喷雾量的增加而有所提升。工况1中蒸发量最大,达到1.286 kg/s,但蒸发率却从工况3时的58.06%降至工况1时的54%;在同一工况下,压力在喷雾杆附近损失程度最高,其中工况1压力损失系数达到了3.41%,而随着冷却工质的汽化,压力会有所补充,最终压力损失系数会有所降低;同时,工况2的压力损失系数在整个预冷段内一直为3种工况中的最低值,表明压力损失与喷雾量的大小并非呈简单的线性关系。

In order to understand the cooling performance of organic mixed working medium with mass injection and pre-compressor cooling, ethanol and water were chosen as the precooling medium.Given the same boundary condition, three groups of different amounts of spray were numerically simulated by ANSYS CFX software to explore the influence of the amount of spray on the cooling effect.The results show that the temperature drop effect of air in the precooling section will become better with the increase of the amount of spray.When the amount of spray increases from 1.641 kg/s to 2.345 kg/s, the temperature drop coefficient at the outlet of the precooling section increases from 7.80% to 10.23%.The amount of spray increases successively under the working conditions Ⅲ to Ⅰ, and the evaporation in the precooling section also enhances with the increase of the amount of spray.The evaporation reaches the maximum value of 1.286 kg/s under the working condition Ⅰ, while the evaporation rate decreases from 58.06% of the working condition Ⅲ to 54% of the working condition Ⅰ.Under the same working condition, the pressure loss near the spray rod is the highest, and the pressure loss coefficient of working condition Ⅰ reaches 3.41%.However, the pressure will be supplemented with the vaporization of the cooling medium, and the final pressure loss coefficient will be reduced.At the same time, the pressure loss coefficient of working condition Ⅱ is always the lowest value in the whole precooling section among the three working conditions, indicating that the pressure loss is not in a simple linear relationship with the amount of spray.