A research on the infrared radiation characteristics for the helicopter infrared radiation suppressor consisted of lobed nozzle and curved mixing duct is performed basing on numerical calculation.In the computation

3-D flow field computation and wall temperature computation and infrared radiation computation are combined to investigate the infrared radiation characteristics of the suppressor.Compared with the experimental data

it is indicated that the relative error between the computational and experimental results is about 15%.Spatial distribution of infrared radiation intensity has the same law as that from experiments.And a series of computations on different scale factor model are conducted to obtain the effect of model scale to the wall and plume radiations.The results indicated that the infrared radiation intensity of wall is proportional to power 2 of scale factor and the infrared radiation intensity of exhaust flume is proportional to power 2.32 of scale factor on the case of the velocity

temperature and pressure of the primary flow being keeped the same for different scaled model.