To meet the detailed slot-inlet-layout design requirement for the top-surface of an infrared-suppressor-integrated rear airframe, we propose four schemes by changing the slot-inlet locations and areas. Based on the simplified main-rotor downwash and tail-rotor flow models, numerical simulations are performed regarding the conjugated flow and heat transfer around the rear airframe. A forward-backward ray-tracing method is used to calculate the infrared radiation spatial-distribution in 3-5 μm and 8-14 μm bands. The current study illustrates preliminarily the effects of slot-inlet layouts on the internal flow organization and infrared radiation characteristics of an infrared-suppressor-integrated rear airframe. The results show that the impact roles of the main-rotor downwash on the exhaust plumes are distinct on both sides of the rear airframe. The presence of the tail-rotor flow aggravates the local heating effect of the exhaust flow on the exhaust-outlet nearby the rear airframe. The slot-inlet position affects the through-flow mass flow rate of the rotor downwash entering the rear airframe and the internal flow fields inside the rear airframe. When the slot-inlet is located far away from the central plane of the rear airframe, the through-flow mass flow rate is relatively smaller. However, when the slot-inlet is located near the central plane of the rear airframe, the flow in the local space between the mixing duct and the rear airframe wall is seriously weakened, leading to a local high-temperature zone. Enlarging the slot-inlet area helps to reduce the hot spots at the rear airframe, yet leads to an obvious increase of the infrared radiation emitting in the top direction. Therefore, the location and the area of the slot-inlet are identified as important geometric parameters affecting the internal flow organization and infrared radiation characteristics of an infrared-suppressor-integrated rear airframe. A proper internal flow organization could provide a more efficient cooling on the mixing duct and thermal protection on the rear airframe surface, improving the infrared radiation spatial-distribution in 3-5 μm and 8-14 μm bands.
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