挡板构型对直升机红外抑制器气动与红外辐射特性影响研究

设计了一种具有引射结构的挡板用以遮挡红外抑制器内部高温部件,同时挡板结构引射环境冷气对其自身表面降温,以大幅度降低红外抑制器红外辐射。采用数值模拟的方法研究了弓形挡板构型对红外抑制器气动性能、温度场与红外辐射强度空间分布的影响。结果表明:与无挡板结构(Case0)相比较,挡板结构将二元引射喷管的引射系数提高115%,红外抑制器的热混合效率增加273%,但红外抑制器总压恢复系数降低7%,红外抑制器3~5 μm波段壁面和气体辐射强度峰值分别降低46%和72%。与单层弓形挡板(Case1)结构相比,设计较优的双层弓形挡板(Case3)可以引射环境冷气,引射系数达到0.1左右,并将其冷端表面平均温度从638 K降低到415 K,红外抑制器3~5 μm波段壁面辐射强度峰值降低84%,气体辐射强度峰值降低80%。总体来看,弓形挡板冷端表面温度受双层弓形挡板内部引射气流、弓形挡板冷端下游滞止涡和二元混合管窄边出口附近的回流冷气三者共同影响。

Effect of baffle configuration on aerodynamic and infrared radiation characteristics of helicopter infrared suppressor

In this paper, a baffle with an ejector structure is designed to block the high-temperature parts in the infrared suppressor. At the same time, the baffle structure injects ambient cold air to cool its own surface to significantly reduce the infrared radiation of the infrared suppressor. The effects of bow-shaped baffle configuration on the aerodynamic performance, temperature field, and spatial distribution of infrared radiation intensity of the infrared suppressor are studied by numerical simulation. The results show that compared with the nonbaffle structure (Case 0), the baffle structure increases the pumping coefficient of the two-dimensional ejector nozzle by 115% and the thermal mixing efficiency of the infrared suppressor by 273%. Nevertheless, the total pressure recovery coefficient of the infrared suppressor decreases by 7%, and the peak values of the wall and gas infrared radiation intensity are reduced by 46% and 72% within the 3-5 μm band, respectively. Compared with the single bow-shaped baffle (Case 1) structure, the better-designed double bow-shaped baffle (Case 3) can eject ambient cold air with a pumping coefficient of approximately 0.1 and reduce the average surface temperature of its cold side from 638 K to 415 K. The peak values of the wall and gas radiation intensity decrease by 84% and 80% within the 3-5 μm band. In general, the surface temperature of the bow-shaped baffle cold side is affected by the internal eject flow of the double bow-shaped baffle, the stagnation vortex downstream of the bow-shaped baffle cold side, and the cold backflow at the narrow edge end face of the two-dimensional mixing duct.