采用数值模拟的方法，研究了混合管出口宽高比以及混合管出口掺混距离对红外抑制器整体气动性能和红外辐射特性影响，在研究参数范围内得到如下结论：相对于椭圆出口的混合管，矩形出口混合管的引射系数显著增加，且垂直方向3~5 μm红外辐射强度峰值降低10.7％；随着矩形出口宽高比从2.2增大到4.6，抑制器总引射系数增大，而总压恢复系数几乎不变；延长混合管出口掺混距离，有助于提高抑制器引射能力，且压力损失几乎没有增加；无论是增加混合管出口宽高比还是增加出口掺混距离，红外抑制器水平方向和垂直方向3~5 μm波段红外辐射强度都呈现逐渐减小趋势。

Based on CFD/IR numerical simulations, the effects of aspect ratio as well as relative space out of mixing duct on helicopter aerodynamics and infrared radiation characteristics were studied systematically. Conclusions can be drawn as follows according to the present simulation conditions: In comparison with IR suppressor with oval outlet, suppressor with rectangular outlet owns a stronger ejecting capacity, and its 3-5 μm infrared radiation intensity is relatively lower, which is exemplified by the fact that the maximum infrared radiation intensity decreased by 10.7％ by changing the shape of mixing duct outlet from oval to rectangle. With the aspect ratio of mixing duct exit rising from 2.2 to 4.6, the pumping ratios of the IR suppressors come to increase, but the total pressure recovery coefficients of those suppressors only change slightly. It can be the instrument of enhancing the pumping capacity when the relative space out of mixing duct is extended, which hardly contributes to greater pressure loss on the other hand. Whether the aspect ratio of the mixing duct exit is increased or relative space out of mixing duct is extended, the infrared radiation intensity(3-5 μm) for IR suppressors is going to decrease gradually in both horizontal and vertical planes.