波纹结构对纵向波纹隔热屏冷却特性影响的数值研究

Numerical Investigation on Influence of Wave Structure on the Cooling Characteristics of Longitudinal Ripple Heat Shield

针对冲压发动机燃烧室纵向波纹隔热屏热防护技术,通过改变波纹的几何结构,开展了隔热屏近壁流场结构调控的研究,采用数值模拟获得了波形对纵向波纹隔热屏流场结构和冷却特性的影响规律。研究结果表明,增加单周期内的冷流迎风侧长度占比更有利于冷流动压进气,充分利用火焰筒内外压差,同时减小了入射冷气流与热流的夹角,减小近壁卷吸涡尺度,降低近壁区的湍流强度,削弱冷、热流掺混,显著增强波谷冷气对下游波峰的保护作用;随着迎风侧长度占比增加,隔热屏的平均综合冷效显著提高。

Aiming at the thermal protection technology of longitudinal ripple heat shield of ramjet combustion chamber,numerical simulation was carried out to study the influence of the field structure in nearwall region and cooling characteristics by changing the geometry of wave.The results show that increasing the proportion of the coolant on the windward side in a single cycle is more conducive for coolant to using dynamic pressure intake and making full use of the pressure difference between the inside and outside of the flame tube.Which decreases the angle between the incident coolant and the hot gas,reduces the vortex scale and the turbulence intensity in the nearwall region,weakens the mixing of coolant and hot gas,and significantly enhances the protection of the trough coolant to the downstream peaks;as the proportion of the windward side increases,the average overall film cooling effectiveness of the heat shield increases significantly.