Radiation of spalled particles in shock layers

Abstract

The behavior of solid particles ejected into a shock layer from an ablating carbonaceous heat shield is investigated theoretically in order to explain the results of an experiment conducted in an are-jet facility. The experiment found that a laser beam made to pass through the shock layer over an ablating flat-faced model is attenuated in the shock layer.The likely cause of the attenuation is the presence of solid carbon particles due to spallation. The equation of motion of the solid particles, accounting for their vaporization, is integrated for different combinations of size and ejection velocity. The assumed quantity of ejected particles and the distributions of the size and ejection velocity are varied until the calculated pattern of laser-beam attenuation matched the experimental data. The radiative heat flux reaching the wall is calculated to be up to 170 W/cm(2) in the arc-jet experiment. If this phenomenon occurs also during the entry flight of the Stardust vehicle, the wall-heating rates are predicted to be up to 8% greater than without radiating carbon particles in the shock layer.