Announcing the Final Examination of David Smerina for the degree of Master of Science
The contributions of vortex stretching, dilatation, baroclinic torque, and viscous diffusion to vorticity transport are experimentally investigated in a high-Reynolds number cavity combustor using high-speed particle image velocimetry and broadband chemiluminescence. An adaptive wall geometry forming converging, diverging, and nominal configurations is implemented to study the effects of pressure gradient on local flow physics and vorticity dynamics. The spatial profiles of the
local turbulence terms are conditioned on the mean flame front to characterize the influence of the pressure gradient field and exothermic heat release on vortex dynamics in the cavity. In addition to isolate the influence of combustion on the flow, a nonreacting analysis is performed and a correlation is made between combustor geometry and the turbulence transport
processes. Vorticity transport through dilatation was found to be significant relative to the other transport terms across all the configurations studied. These results contrast with direct numerical simulations of high Reynolds number flows in homogeneous isentropic turbulence. In addition, a scaling is proposed to quantify the significance of the flow induced vorticity and pressure fields on dilatation and baroclinic torque vorticity production. Experimental studies of similar confined
combustors show a similar trend to the numerical studies with baroclinic torque dominating the transport mechanisms, motivating this study to understand the dependence of vorticity transport on the underlying flow physics.
Committee in Charge:
Kareem Ahmed (Chair)
Samik Bhattacharya
Sagnik Mazumdar
Read More