Force and Heat Transfer Measurements in Hypersonic Free-Jet Flow

The technique for aerothermodynamic measurements in free-jets is considered in the transition regime between continuum and free molecular flow. The determination of the drag and lift by electromagnetic sting balances, the determination of the total heat transfer on small models (l&#615 mm), and the determination of the overall recovery temperature is described. The advantages of a free-jet against a nozzle flow and especially the shortcomings are discussed. These are in particular: flow gradients, freezing effects of the translational degree of freedom and background pressure influences. As an extension of the free-jet technique a system under development isdescribed in which the core of a free-jets is extracted by a skimmer which works in continuum flow. It is possible to produce a shockless free-jet core up to large distances by this device