Abstract: The design of a reaction control system requires fundamental information concerning the process of transverse Jet Interaction (JI) with a crossflow. The effects of JI properties on hypersonic aerodynamic interference, have been the subject of several wind tunnel experimental investigations. In wind tunnel facilities, it is more convenient to perform JI tests with jet fluids of different compositions and with test models of scaled size from those of the actual vehicle. There are a myriad of scaling issues/differences from flight to wind tunnel, and a review of scaling theories has been presented and verified, with calibrated computational fluid dynamics simulations based on HB-1 standard model, as well as NASA Space Shuttle flight data from open literatures. In this work it is found that, in the case of strong jet flow that can penetrate the incoming shock wave, the momentum ratio as the scaling parameter is appropriate, while in the case of weak jet flow that cannot penetrate the incoming shock wave, the mass flow ratio is more suitable as the scaling parameter.