Mathematic simulation of AL-31F powerplant radiation in the IR range

The paper is devoted to the modeling of aircraft power plant radiation. The object of investigation is the AL-31F aircraft afterburning turbojet bypass engine. The results of research dealing with the calculation of spatial distribution of radiation from complex radiators are presented. A complex method of calculating the infrared radiation based on mathematic simulation of radiant energy spatial distribution is proposed. An algorithm using the probabilistic Monte Carlo method is developed, which makes the modeled process of the beam emission and reflection similar to the physical one. A new method of calculating the indicator function in an absorbing medium from complex radiators is used. Calculations of temperature distribution inside the nozzle and modeling of the power plant geometry are performed. Spatial distribution of infrared radiation is determined on the basis of the computations made. A device for reducing the intensity of radiation over a wide angle range is developed, the analysis of its efficiency is carried out. The device proposed makes it possible to reduce the design level of infrared radiation by more than 90% in the range of the solid angle of the rear hemisphere. The results of calculating the direct (without reflections of radiation inside the nozzle) and complete (including reflections) radiation from the central ellipsoidal body are presented. The results of the comparison of these calculations are also presented.