Blast waves with heat transfer

Abstract

A model is given for blast waves which are dominated by heat transfer rather than by shock heating and adiabatic expansion. The wave motion is attributed to a net heat flow W (watts/cm2) from the expanding hot core to the surrounding cold gas (density ρ1). The surface of the hot core is initially a supersonic heat wave without a shock. It changes into a subsonic heat wave with a leading shock after quickly passing through the detonation mode. A quantitative analysis of the space time trace near the detonation point yields the enthalpy hf and other parameters of the hot core, the thermal response function hf=f (W) of the background medium, and the blast wave energy E0=const ρ1V2sr3H (where Vs is the shock front velocity and rH is the radius of the hot core). The analysis shows the steady transition of such a blast wave from the early stage of a ’’thermal’’ wave with negligible mass motion to the late stage (which approaches ’’classical’’ blast waves) with negligible heat transfer. Applications to laser spark plasmas are discussed.