To reduce the temperature on helicopter nacelle skin and lower the helicopter infrared radiation

numerical investigation was conducted to study the temperature distribution on the nacelle skin and the helicopter infrared radiation characteristics for helicopter under hovering state in consideration of the rotor down wash.Several improved schemes for the nacalle were presented based on the baseline nacalle configuration

such as adopting radiation shelter

adding ventilation slots

improving trailing edge of mixed exhaust duct

and making thermal resistance layer. The effects of above treatments on the temperature distribution and infrared radiation characteristics were assessed.Conclusions can be listed as follows:(1) With the adopted radiation shelter

infrared radiation intensity of the helicopter is enhanced by 25% in 3-5μm band but remained almost the same in 8-14μm band.(2) With the added ventilation slots

infrared radiation intensity of the helicopter is reduced by 12% in 3-5μm band but remained almost the same in 8-14μm band.(3) With the added ventilation slots

improved trailing edge and thermal resistance layer

infrared radiation intensity of the helicopter is reduced by 70% and 10%

respectively

in 3-5μm and in 8-14μm bands.