Numerical investigation of air entrainment and wall temperature of a real-scale infrared suppression device with slots of gradient height

The high-temperature funnel walls of the infrared suppression (IRS) device are significant sources of infrared radiation on warships, so that the cooling of the funnel walls becomes indispensable for achieving infrared stealth. In this study, the air entrainment and wall temperature distribution of a real-scale IRS device are investigated in detail. Numerical computations are performed to solve the relevant governing equations in a 2D computational domain. The RNG turbulence model and the enhanced wall treatment are used in the simulations. The present work innovatively proposes to optimize the performance of the IRS device by varying the height ratio of slots between funnels. The results show that the device has the optimal air entrainment rate and temperature distribution on the funnel walls for a slot height ratio of 1.6. In addition, the impacts of nozzle Reynolds number, funnel and nozzle overlap on the air suction and funnel wall temperature are discussed as well. When the nozzle Reynolds number gets higher, an increment in air entrainment and a decrement in funnel wall temperature are observed. The negative funnel overlap and negative nozzle overlap increase the air entrainment, but adversely affect the cooling of the funnel walls.