引气结构对二元塞式喷管冷却和红外辐射特性的影响

Effects of Air Intake Structures on Cooling and Infrared Radiation Characteristics of Two-Dimensional Plug Nozzle

关键词:  二元塞式喷管  塞锥冷却  引气结构  冷却特性  红外辐射特性  数值仿真

Key words:  2-D plug nozzle  Plug cooling  Air intake structure  Cooling performance  Infrared radiation characteristic  Numerical simulation

摘要:

为降低加力状态下二元塞锥表面温度和喷管红外辐射强度，对塞锥进行冷却结构设计。采用数值模拟的方法对比分析了引气结构、冷却通道高度和冷气入口总压比对塞锥冷却和喷管红外辐射特性的影响。结果表明：塞锥冷却后其表面温度和喷管红外辐射强度显著降低；引气腔内无冲击板时，引气角度的改变引起射流核心区位置的变化，造成塞锥头部和前缘展向温度分布差异明显，引气角度为90°时塞锥表面最高温度要比30°和60°的模型高50K；加装冲击板后，冷却通道内的流量分配和塞锥前缘的展向温度分布得到有效改善、塞锥头部的换热得以增强，但同时会引起较大的总压损失，因此相同入口总压比下，加装冲击板后冷却流量降低、塞锥外表面温度升高；随着冷却通道高度增大，冷气流量增加、流速降低，故存在一个最佳通道高度使得塞锥冷却效果最好；以塞锥无冷却为基准，入口总压比为1.0~1.8时，塞锥外表面最高温度降低了470~590K，0°探测角上红外辐射强度降低了25%~33%。

Abstract:

In order to reduce the surface temperature of two-dimensional plug and the infrared radiation intensity of nozzle in the state of afterburning， the cooling structure of plug was designed. A series of numerical simulations were performed to investigate the effects of air intake structure， cooling channel height and total pressure ratio of inlets on the plug cooling and nozzle infrared radiation performances. The calculation results indicate that： the surface temperature of plug and the infrared radiation of nozzle have dropped significantly after the plug is cooled. The change of air intake angle leads to different core region of jet when there is no impact plate in the air intake chamber， which caused remarkable difference in the spanwise temperature distributions of the plug head and leading edge. While the air intake angle is 90°， the maximum temperature of the plug surface is 50K higher than that of 30° and 60°. After the impact plate is installed， the flow distribution in the cooling channel and the spanwise temperature distribution of the plug leading edge are effectively improved as well as the heat transfer of the plug head， however， a large total pressure loss is also caused. Therefore， the mass flow of cooling air decreases and the external surface temperature of the plug increases when an impact plate existed in a fixed total pressure ratio of inlets. A higher cooling channel brings a bigger mass flow rate and a less flow velocity of cooling air， so there is an optimal height of the passage to make the cooling effect on the plug best. Compared with the situation of un-cooled plug， with the total pressure ratio of inlets varying from1.0 to 1.8， the maximum temperature of the external surface of plug decreases by 470K to 590K and the infrared radiation intensity decreases by 25% to 33% at the detection angle of 0°.