A fluid dynamic pump without moving elements is called an ejector. Traditional ejector systems move energy from a high velocity primary stream to a lower energy secondary stream via viscous forces. Such ejector systems can cool jet engines' exhaust systems and provide IR (Infrared) suppression. In this paper, experiments are carried out to determine the ideal compressible subsonic air ejector design for use as an IR suppression tool. Using the Particle Image Velocimetry (PIV) technique, the flow field of the problem under consideration is experimentally measured. The obtained results provide the best guidance for exhaust ejector design and aid in understanding the flow behaviors and physical phenomena that occur in the flow through ejectors. In addition, the optimum exhaust mixed air temperature is achieved for an ejector with length-to-diameter ratio of LE/DE = 7, mixing suction to nozzle exit area ratio ARE = 36, and the axial position of primary nozzle relative to the ejector inlet LS = - 0.5 DE. Under these conditions the exhaust mixed air temperature reduces by 40% about no ejector case. At this optimum exhaust mixed air temperature; the emissive power is suppressed to 330 %.