A study was conducted to investigate the effects of temperature rate of change on the environmental stress screening (ESS) of printed wiring assemblies (PWAs). The related effects of chamber air velocity and temperature dwell time on module temperature response also were evaluated.Tests were conducted to investigate the effects of varying thermal cycling parameter levels. The effects of various chamber air temperature rates of change and velocity levels on the temperature responses of two vastly different PWAs were measured. A thermal cycling analysis of a PWA of the same construction as one of the two PWAs tested in the present investigation also was performed. A comparison of the results of a portion of the test was made with the analytical predictions.
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CARL R. HALBACHÂdvanced Rocket Technology (ARTCOR), Irvine, Calif.Viscous effects on the performance of biowaste resistojet microthrusters are calculated using Rae's numerica method for low-Reynolds number flow in a nozzle. Results are presented for a 25-mlb thruster suitable for space station attitude control using CO 2 , CH 4 , and H 2 O as propellants. Nozzle exit plane data (such as Mach number, velocity, and temperature profiles) useful for computations of plume contamination are also presented. The performance predictions are compared with experimental data which were available from laboratory firings of a 10-mlb thruster having a trumpet-shaped nozzle with CO 2 , CH 4 , H 2 O and H 2 as propellants.
Nomenclature
B= Reynolds number [see Eq.(specific enthalpy I sp = specific impulse M<£ = centerline Mach number MW = molecular weight m = mass flow rate P = power Pr = Prandtl number p = pressure R = universal gas constant r = radial coordinate, measured from nozzle axis r*,r w = nozzle throat, local nozzle radius T = temperature u = velocity x -z/r* z = axial coordinate, measured from nozzle throat y = specific-heat ratio A V = velocity increment 8 L = boundary-layer displacement thickness € = nozzle area ratio r] = r/r w or over all total power efficiency 61 = nozzle inlet convergence half angle (see Fig. 4) IJL = viscosity p = density co = exponent in the relation p.oc T 03 Subscript ( ) 0 = conditions in chamber, i.e., downstream end of heater Presented as Paper 72-450 at the
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