一种带抽吸狭缝的新型短隔离段数值研究

Numerical investigation of a new short isolator with bleed slots

关键词:  超燃冲压发动机  隔离段  激波串  抽吸狭缝  壁面压力

Key words:  Scramjet  Isolator  Shock train  Bleed slot  Wall pressure

摘要:

为了缩短超燃冲压发动机隔离段长度以及提高它的耐反压能力,采用数值模拟方法研究了一种带抽吸狭缝的新型短隔离段,获得了隔离段的缩短程度以及耐反压能力提高的程度。结果表明,通过流向狭缝抽吸隔离段角流区内的低能附面层,可不降低隔离段耐反压能力而将其长度缩短30%左右。同一隔离段采用狭缝抽吸后,能够承受的最大反压从来流静压的3.46倍上升到3.74倍,提高了8%左右。合理的狭缝位置应在厚附面层一侧的隔离段前部角流区内,前倾角对隔离段性能的影响呈非线性特征,抽吸背压在亚临界范围时对隔离段性能的影响较明显,而在超临界范围时的影响则不明显。

Abstract:

An isolator with bleed slots was designed to reduce the length of the isolator and to improve the isolator maximum back pressure. The slots were placed on the corner of the lower wall at the isolator entrance. Computational fluid dynamic simulations were performed on the isolator. Numerical results indicated that the overall length of the isolator could be reduced by 30% for the isolator with bleed slots at the same back pressure. The maximum back-pressure is improved by 8% for the isolator with a bleed slot which can withstand a maximum back-pressure of 3.74 times static pressure, but the baseline isolator could only withstand a maximum back-pressure of 3.46 times static pressure. The reasonable position of slots should be near the corner in the forepart of the isolator. The performance of the isolator does not change lineally when the inclined angle of the slots alters. When the bleed slot works as supercritical operation, the bleed pressure has great influence on the isolator performance. When the bleed slot works as subcritical operation, the bleed pressure has little influence on the isolator performance.