Condensation in free jet expansions from sonic orifices is studied with nitrogen, water vapor, and argon as test gases. The stagnation temperature T0 is varied from 80 to 450 K by a liquid nitrogen cooler or a hot water bath, and in the case of water vapor by an electric driven steam generator. The stagnation pressure p0 was changed between 0.2 to 3 bar. The nozzle throat diameters are 5 and 10 mm. Static pressures are measured along the center line of nitrogen jets and the static temperatures are calculated by isentropic theory up to condensation onset. The condensation onset points on the center line of all free jets are detected by laser light scattering. The nitrogen laser data from free jets fit perfectly to static pressure measurements which are also compared to the classical homogeneous nucleation theory; the argon laser data are compared to experiments in free jets, nozzles, and shock tubes.

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A plume flow model has been developed to calculate the impingement forces and heat transfer caused by the firing of attitude control thrusters on satellites. Its validity for the inviscid core flow was tested and verified by an experimental study including pitot pressure and velocity measurements in plumes with different pure test gases. Measurements in real hydrazine thruster plumes allowed the determination of essential data (especially an effective ratio of specific heats) necessary for the description of this flowfield.x,y y b Nomenclature = cross section of nozzle exit = plume constant 1 = plume constant, determined by experiment = factor of proportionality in Eq. (12) = specific heats at constant pressure and volume, respectively = surface element = diameter of pitot probe = distance from nozzle throat to nozzle exit = mass flow = molecular mass = Mach number = surface normal vector = stagnation pressure = pitot pressure = pitot pressure on centerline = (specific) gas constant = nozzle Reynolds number, = radius, polar coordinate = nozzle throat radius = nozzle exit radius = stagnation temperature = velocity = velocity at nozzle throat = velocity at nozzle exit (isentropic flow) = velocity determined by experiment = maximum gas velocity V2/c/(/c-1) -R-T Q = virtual source point of streamlines = coordinates = plume boundary coordinate = boundary-layer thickness at nozzle exit angle, polar coordinate = angle between plume axis and streamline, which separates the isentropic core and the boundary-layer expansion region = maximum expansion angle = angle between surface normal and streamline ( Fig. 9) = ratio of specific heats -viscosity Presented as Paper 85-0933 at

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