A research on the internal aerodynamic and infrared radiation characteristics for the helicopter infrared radiation suppressor consisted of lobed mixer-ejector and curved mixing duct is performed basing on CFD technique. In the computation, 3-D flow field computation and wall temperature computation and infrared radiation computation are combined. Compared with the experimental data, it is indicated that the relative error between the computational and experimental results is about 15%. In the aerodynamic computation, the inlet of the primary flow uses the velocity boundary condition. The total pressure boundary condition is applied to the inlet of the second flow and the static pressure boundary condition is applied to the outlet of the mixing flow, both are defined as ambient pressure. The pressure outlet is set at the region far away from the outlet of mixing duct. Based on this way of the boundary condition,pumping ratio can be forecasted through numerical computation. The effects of flow caused by curved mixing duct wall on internal gas flow can be revealed from numerical computation results. And a series of computations are conducted to obtain the effects of mixing-duct parameters on pumpingmixing performance. There is an optimum performance design for the particular mixer-ejector system. Spatial distribution of infrared radiation intensity from infrared radiation computations has the same law as that from experiments. And a series of infrared radiation computations are conducted to obtain the effects of model scale to the wall and plume radiations. The results show that:(1)the infrared radiation intensity is proportional to power four of primary flow temperature on the condition of equal primary flowrate and pressure;(2) the infrared radiation intensity is proportional to power two of scale on the condition of equal primary velocity、 temperature and pressure. These results are verified with the physics nature.
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