Fluid Flow Analysis Through a Variable Diameter Infra-Red Suppression Device

Abstract

An Infra-red suppression device(IRS) is used for suppression of heat signatures from the exhaust of the ships or aero planes, thus facilitating in the stealth operation. In the past, studies have been performed on multiple funnel type, lobed shaped as well as straight funnel type IRS device. In the present study an attempt has been made to suggest a variable diameter IRS device which works on the principle of mass suction due to drop in pressure resulting from the high velocity exhaust fluid. The multiple funnel type IRS device has been modified into an inverted fulcrum like device with holes present on the periphery of device for suction of fluid. Two types of computational studies have been performed. In the first study, the suction is occurring through the bottom as well as the holes on the periphery of funnel wall. In the second study, suction is occurring only through the holes on the funnel wall and bottom of funnel has been kept closed. The mass suction ratio has been calculated for varying Reynolds number (3000≤ R ≤ 7000). The effect on suction due to position of holes, number of holes and distance of the holes from the nozzle, effect of bidirectional flow etc. has been computed. It is found that the mass suction ratio is more when suction is occurring through the bottom of the funnel along with the holes on the funnel wall periphery.