Effects of energy release on near field flow structure of gas jets

The primary objective is to understand how buoyancy affects the structure of the shear layer, the development of fluid dynamic instabilities, and formation of the coherent structures in the near-nozzle regions of gas jets. The secondary objectives are to study the role of buoyancy in lifting and reattachment process of diffusion flames, to evaluate the scaling behavior of diffusion flames, and to aid development and/or validation of theoretical models by providing quantitative data in the absence of buoyancy. Fast reacting hydrogen or hydrogen-inert fuels are used to isolate the effects of buoyancy on fluid dynamics without masking the flame behavior by soot and radiative heat transfer. This choice of fuel also permits an evaluation of simulating low gravity in low pressure ground experiments because the similarity constraints are relaxed for the fast reacting, nonsooting diffusion flames. The diagnostics consists primarily of a color schlieren system coupled with computer generated rainbow filters, video recording, and image analysis. The project involves (1) drop tower experiments, (2) ground experiments, and (3) theoretical analysis