Cooling and infrared radiation characteristics of diversion shielding at exhaust outlet of double-layer mixing duct
In order to reduce the temperature and infrared radiation intensity of the diverter at the outlet of the mixing duct of the integrated infrared suppressor,a double mixing duct and a diverter with cooling structure were designed.Through CFD and numerical simulation of the spatial distribution of infrared radiation intensity,the effects of inlet flow rate of forced cooling,outlet shape of deflector and number of valves on the infrared radiation intensity of exhaust jet and exhaust mixing duct were studied.The calculation results showed that compared with the reference model(single-layer mixing duct,no cooling of the deflector),the structure of double-layer mixing duct and deflector can effectively reduce the visible surface high-temperature region of the deflector,and the infrared radiation intensity of the deflector itself can be reduced by 82.9％.The wave disc at the outlet of the deflector can induce streamwise vortex pairs,and the enhanced cooling air can be mixed with the exhaust wake at the outlet of the mixing duct.Compared with the benchmark model,the infrared radiation intensity of the exhaust can drop up to 68.2％,and the overall radiation intensity of the mixing duct and its exhaust can drop up to 86.4％.The exhaust infrared radiation intensity and the overall radiation intensity decreased gradually with the decrease of the number of valves and the excessive number of valves at the outlet of the diverter was not conducive to the development of streamwise vortex.The overall radiation intensity of the mixed duct gradually decreased with the increase of the forced cooling airflow flow rate.When the ratio of the cooling airflow flow rate to the main flow rate was 0.1,the overall radiation intensity decreased by a peak of 68.3％compared with the situation without cooling airflow.
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