瓦状塞式喷管的设计和试验分析

Design and experimental analysis of tile-shaped aerospike nozzles

为了分析瓦状塞式喷管的气动特性,提出轴对称内喷管和塞锥的型面设计方法,设计了两单元的模型发动机,内喷管面积比为5.81,总面积比为24.36、29.43、33.88、37.58。采用高压空气为介质对模型发动机进行冷流试验,分析内喷管倾角和底部二次流变化、以及有无底部盖板对推力性能和底部压强的影响情况。介绍了试验发动机的结构与设计参数,给出了试验模型照片、测量参数曲线和性能数据处理。结果表明:瓦状塞式喷管模型的高度补偿效果较为明显,在整个工作高度有较高的推力系数效率,20°模型的最高效率为96%;底部压强曲线反映出了底部气动特性由开放状态到闭合的转变过程;内喷管倾角增大,底部压强增大即增加底部推力,但存在一个优化性能的最佳倾角;底部加入二次流可以增加底部压强,提高性能,但其影响范围在1%～2%,少量的二次流对增加性能的效果较好;底部盖板会影响底部的气动特性,底部压强是否受环境压强的影响取决于底部处于开放或闭合状态。

Simple design methods of the tile-shaped aerospike nozzle with the axisymmetric thrust cell and the concave plug were presented, and the two-module experimental models were designed. The area ratio of internal nozzle is 5.81 and the total area ratios of the aerospike models are 24.36, 29.43, 33.88 and 37.58. Cold-flow tests on the tile-shaped models were carried out using highly pressurized air. The effects of the variations of the inclination angle and the amount of base bleed on the performance and the base pressure were examined in the tests. Test apparatus, structures photographs and design parameters of the main parts of the experimental engine were introduced. Chamber pressure, thrust and ambient pressure were acquired and the data analyses were al- so delivered. It is shown that good altitude compensation capacities and high efficiencies were obtained in the tests. The maximum nozzle thrust efficiency of the tile-shaped nozzles tested here is 96%. The base pressure increases when the inclination angle becomes bigger and there is an optimum angle for the optimum performance. The bleed can increase the base pressure, the effect of bleed on the performance is within 1%-2% and a little bleed can improve the performance effectivly. The effects of base sidewalls on base pressure were also analyzed. The results indicate that whether the base pressure changes with the ambient backpressure or not depends on the base region is working at open or closed condition.