| The paper reports on 3D numerical and experimental study of the effects on jet's infrared signature because of the installation of cross-flap in the nozzle channel, it can be recommended from changes of jet's temperature, length, shapes of temperature field and infrared signature cures before and after fixing cross-flap.In the numerical study, changes of axisymmetric nozzle's temperature field were studied, and I found that part of jet's energy was transferred to the nozzle's wall, temperature was reduced, length was shortened, zone in high temperature was minished, isotherms were cured. These changes make for reducing jet's infrared signature.In the experimental study of axisymmetric nozzle, temperature field of a section about nozzle's exit is obtained through thermocouple harrow. In the experimental study of 2D nozzle, pressure field of a section about nozzle's exit is obtained through total pressure harrow. Heat imaging is adopted to show the length of jet. At last, jet's infrared spectrum curves are gathered through Fourier transform infrared radiometer (FTIR). All experiments are carried out before and after installation of cross-flap.The investigations of this paper prove the suppression effects of cross-flap on jet's infrared signature, and offer a new way to reduce jet's infrared signature.
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