CONCENTRATION MEASUREMENTS IN DENSE ISOTHERMAL GAS CLOUDS WITH DIFFERENT STARTING CONDITIONS

Experimental results are presented for instantaneous finite-volume den se-gas releases in a channel of 20 m length. The gases used were argon and argon-air mixtures with density ratios relative to air varying fr om 1.15 to 1.35. The aspect ratio (height to length) of the initial vo lume was varied from 0.42 to 1.68 with gas volumes from 1.89 to 3.78 m (3). Measurements with 50 fast-response gas sensors (aspirated hot-wir es) gave concentration signals with good resolution in time and space. The data obtained allow the air entrainment rates (both local and glo bal) to be determined and give detailed information on the influence o f the initial aspect ratio. Comparisons with theoretical solutions fro m the shallow-layer approximation (code SHALADIS) and with a dynamic i ntegral model (adapted from Van Ulden, 1986, J. Hat. Mat. 16, 411-425) are also included. In view of the limitations of the models, the agre ement was good for both. Copyright (C) 1996 Elsevier Science Ltd.