Dynamics of Large Buoyant Clouds Generated by Rocket Launches

Abstract

Motion pictures of launches of Titan III solid rocket motors were used, in conjunction with conservation equations and knowledge of rocket plume properties, to determine the initial temperature and mass of the large cloud that is generated during these launches. These initial conditions were applied to a mathematical model which accounted for buoyancy, drag and entrainment. The model predicted the radius, altitude, temperature and mass of the cloud as a function of time. The results showed fair agreement with size and altitude data extracted from the movies. This methodology was applied with limited success to smaller scale rocket clouds generated at test stands. The model was also used to predict the behavior of large exhaust clouds under various external temperature profiles. There is some experimental evidence that the model correctly accounts for unstable profiles, and the predictions of cloud rise during inversion conditions agree with what intuition would predict.