截短单边膨胀喷管的试验和数值模拟

Experimental and Numerical Study of the Truncated SERN

关键词:  截短单边膨胀喷管  试验  数值模拟  推力性能

Key words:  Truncated SERN  Experiment  Numerical simulation  Thrust performance

摘要:

基于最短长度理论喷管设计程序,获得了设计点为马赫数6.5时单边膨胀喷管(Single Expansion Ramp Nozzle,SERN)等熵膨胀型线,并对其截短70%后的喷管进行模型设计和加工。通过试验和数值模拟结合的方法,研究了模型喷管在不同压比下的流场结构和性能。结果表明:喷管长度截短70%对推力性能影响不大,在所有典型压比下,喷管截短70%后推力系数与原喷管相差不超过1%。该喷管截短70%后,其推力系数在落压比大于60时仍能达到0.95以上,随着喷管压比的继续降低,喷管推力系数迅速降低,性能恶化,喷管在过膨胀状态下的性能应该得到重点关注。

Abstract:

The isentropic contour of an optimum Single Expansion Ramp Nozzle (SERN) with 70% truncation at a design Mach number of 6.5, based on the Method of characteristics (MOC), was obtained. Then, cold flow static test and numerical simulation were conducted to investigate the nozzle internal performance characteristics and flowfield structure varying with nozzle pressure ratio (NPR). The results indicate that seventy percent truncation has little effect on the nozzle thrust performance and the nozzle thrust coefficient difference is less than one percent between the perfect nozzle and the truncated nozzle. The nozzle thrust coefficient remains over 0.95 till the NPR falls to 60.With further decreasing of NPR, the nozzle internal performance is deteriorated sharply. Further studies should be conducted in order to improve the SERN internal performance under serious over-under expansion condition. 