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S = Eq. (8) T = absolute temoerature u = x-component of velocity v = y component of velocity x = distance along meridian profile of body y = distance normal to body surface V = Eq. (6) 0 = Eq. (8) \x = absolute viscosity * = Eq. (5) p = mass density a = Prandtl Number c p fx/kA method of predicting laminar heat-transfer rates to blunt, highly cooled bodies with constant wall temperature in dissociated air flow is developed. Attention is restricted to the case of axisymmetric bodies at zero incidence, although two-dimensional bodies could be treated the same way. The method is based on the use of the "local similarity" concept and an extension of the ideas used by Fay and Riddell. 1 A simple formula is given for predicting the ratio of local heat-transfer rate to stagnation-point rate. It depends on wall conditions and pressure distribution, but not on the thermodynamic or transport properties of the hot external flow, except at the stagnation point.Experimental heat-transfer rates obtained with correct stagnation-point simulation and high wall cooling in shock tubes are also presented and compared with the theoretical predictions. On the whole, the agreement is good, although in regions of rapidly varying pressure there is evidence that the local similarity assumption breaks down, and the theory underestimates the actual heat-transfer rate by up to 25 per cent. SYMBOLS Ci Cp D DT f g h h hi 0 h D H k I Li U T L M 8 P Pi = = = = = = = = = = = = = = = = = = = mass fraction of ith component Vd(dhi/dT) diffusion coefficient thermal diffusion coefficient Eq.(7) Eq.(8) enthalpy per unit mass of ith component enthalpy per unit mass of the mixture, including dissociation energy, Xci(hi -hi 0 ) heat evolved in the formation of component i at 0°K., per unit mass average atomic dissociation energy times atom mass fraction in external flow h + (l/2)u 2 thermal conductivity PM/' PwP y = differentiation with respect to indicated variable oo = free-stream conditions o = local similarity solution E = equilibrium (1) INTRODUCTION T HE THEORY of heat transfer at a stagnation point in a dissociating gas has been discussed by Fay and Riddell. 1 They considered the mechanism of heat transfer, with the pertinent physical and chemical effects which arise because of gas dissociation. It was shown ...

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A heat transfer gauge suitable for measuring extremely high heat transfer rates under the quasi-transient conditions occurring in shock tubes has been developed. The instrument is based on a calorimetric principle and is made possible by the short steady state times inherent in shock tubes. The technique developed extends, verifies, and supplements the shock tube heat transfer measurements made by thin film resistance thermometers. The operating principles and experimental experiences with calorimeter heat transfer gauges are reported in some detail. Much heat transfer data obtained with calorimeter gauges has been collected and published. Experimental measurements of laminar and turbulent heat transfer rates at velocities up to satellite speeds, approximately 26 000 ft/sec, have been reported. Heat transfer rates as high as 40 kw/cm2 have been encountered in these experiments.

For the study of high-temperature gas dynamics, shock-tube techniques have been developed earlier to produce shock waves strong enough to heat gases to high and accurately known enthalpy (for argon up to 18 000°K or 40 percent ionization at equilibrium). This paper reports a study of the visible radiation from the highly luminous argon following strong shock waves. Preliminary spectrograms showed a strong continuum and that the prominent argon lines were broadened and shifted to the red. Correlation of the frequency shifts with theoretical treatments permitted an evaluation of the ion density in the gas. Development of a drum camera spectrograph (film speed 700 ft/sec) in which time effects could be resolved to about 1 μsec indicated that equilibrium ion density was reached rapidly, and provided a rough measurement of the rate of decline of ion density due to cooling. Absolute photoelectric spectrophotometric measurements of the continuum radiation were made and correlated with theoretical expectations. Confirmation of the expected variation of continuum intensity with wavelength and temperature was obtained and an undetermined factor on the theoretical intensity was evaluated. Determinations of the cooling rate of the high-temperature argon from time variation of the continuum intensity, the line shift, and the electrical conductivity (by others) are in agreement and show that continuum radiation was the dominant heat loss.