Effects of Heat Release at the Small Scales of Turbulent Flows
Abstract
Effects of density changes due to heat release by exothermic reactions in turbulent flows are known to alter the outer variable scalings, and thereby affect the resulting entrainment and mixing rates achieved by the flow, even in the absence of any buoyancy effects. There are additional effects of heat release at the small scales of reacting turbulent flows, due among other things to changes in the transport properties of the fluid with temperature, and to the volume source field induced by dilatation. The significance of these heat release effects at the small scales is not known. It is the latter effect that is considered here. We present results from simultaneous PIV and CH PLIF imaging measurements in turbulent jet diffusion flames that resolve the small scales of the flow. Regions of exothermicity as marked by CH concentration fields are compared with those identified by dilatation fields from the PIV measurements. Effects of anisotropy in vector orientations are accounted for, and the resulting comparisons of the velocity gradients induced by the vorticity field and by the dilatation field are obtained. These provide direct insights into the relative significance of dilatation effects in exothermic turbulent reacting flows.
- Publication:
-
APS Division of Fluid Dynamics Meeting Abstracts
- Pub Date:
- November 1999
- Bibcode:
- 1999APS..DFD..FF07M