No abstract

No abstract

I T is now well known that pulsed CO 2 laser radiation can generate high pressures over a surface through formation of laser-supported detonation (LSD) waves at fluxes greater than 10 7 W/cm 2 (Refs. 1-3). It is also possible for hot, dense plasmas to be produced in the strong laser-supported combustion (LSC) wave regime at fluxes between 10 6 -10 7 W/cm 2 (Refs. 4 and 5). The impulse generated at the surface by these phenomena are reasonably well understood. 6 Previous analytical and experimental work has dealt with a static environment. The phenomenology should be different with a supersonic crossflow over the surface. This work examines the behavior of the laser/surface/supersonic flow interaction and presents impulse data from aluminum targets.

No abstract

A number of theoretical and experimental studies have heen published on convective energy transport in a high-temperature, partially ionized gas. Certain uncertainties have arisen, particularly because of effects of the surface material of the heat-transfer gage. This investigation applies a new technique to heat-transfer measurements in a shock tube at simulated flight velocities up to 50,000 fps. An infrared heat-transfer gage has been adapted to this experiment. The advantage of this gage is that the heat-transfer measuring element is a carbon surface in thermal contact only on an infrared transmitting window, and thus the gage output is electrically completely decoupled from the partially ionized gas. The difficulties of adapting the gage to the test requirements are described, as well as the calibration of the infrared cell output and response time characteristics of the measuring system. The response of the gage to the heating encountered in both shock-tube end wall and on a stagnation point of a model are discussed with emphasis on the identification of radiative heat-transfer effects. The heat-transfer data support the previous results of the authors, and the various gage surface materials used did not change the heat-transfer rates measured. NomenclatureC = specific heat Cp = gas specific heat h = enthalpy per unit mass k = thermal conductivity I = thickness Nu/(R e ) llz = heat-transfer parameter p = local pressure Pr = Prandtl number, Cpv/k Q = heat-transfer coefficient q = heat-transfer rate RN = nose radius of axisymmetric body T = temperature t = time U s = incident shock-wave velocity x = length dimension in gage measured from interface of carbon and window material p = mass density = (p 2^C2 /piA: 2 C 1 ) 1 / 2 , Eq. (2) Subscripts e = end wall s = stagnation condition w = wall 1 = carbon layer 2 = IR (infrared) transmitting window