Cooling of exhaust gases as a possibility to increase stealth properties of military helicopters

Helicopters, in comparison to other aircrafts, have much lower flight speeds and manoeuvrability, which makes them easy targets for actual combat assets like ground to air or air-to-air infrared-guided missiles. Current techniques aim to increase the combat effectiveness and lifetime of military helicopters performing combat missions by reducing the possibility of their detection on battlefield, thereby increasing their flight time without fire attack and reduce effects of potential strike. When designing new helicopter types, especially for combat applications, it is essential to pay enormous attention to infrared emissions of the solid parts composing the helicopter’s structure, as well as to exhaust gases egressing from the engine’s exhaust system. Due to their high temperature, exhaust gases, egressed to the surrounding are a major factor in infrared radiation emission level and, in consequence, detectability of a helicopter performing air combat operations. This article presents the possibility to decrease the infrared radiation level that is emitted to the environment by helicopter in flight, by cooling hot exhaust in special ejective cooler. Article presents also the exhaust cooler operation principles and results of numeric analysis of concept exhaust cooler adapted to cooperate with PA-10W turbine engine. Numeric analysis presented promising results in decreasing the infrared emission level by PA W-3 helicopter in flight, as well as increasing its stealth properties