Accession Number : ADA311019

Title :   Molecular Mixing in Shear Layers Forced by 2-D and 3-D Disturbances.

Descriptive Note : Final technical rept. 1 Jun 93-29 Feb 96,

Corporate Author : MICHIGAN STATE UNIV EAST LANSING DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : Koochesfshani, Manoochehr M.

PDF Url : ADA311019

Report Date : 30 APR 1996

Pagination or Media Count : 24

Abstract : The mixing characteristics of forced two stream shear layers and wakes have been investigated using both chemically reacting and nonreacting LIF technique. The shear layer results reveal that major modifications of the mixing field occur at relatively high values of x* > 2, and not in the enhanced growth region x* < 1. The non-dimensional downstream distance is defined by x * = x(lambda)f/U sub c where x is the downstream distance, lambda =(U1- U2)/(U1 + U2), f is the forcing frequency, and Uc = (U1+U2)/2 where U1, U2 are the high and low speed freestream velocities, respectively. The chemically reacting data provide, for the first time, the actual amount of molecularly mixed fluid and the absolute level of mixing enhancement in these forced flows. The highest value of mixed fluid fraction we have obtained to date in the forced shear layer is about 40% higher than that possible in a high Reynolds number unforced shear layer. The mixed fluid fraction at the midspan of our low Reynolds number wake with high amplitude forcing is at least a factor of two higher than that possible in high Reynolds number liquid mixing layers, and about 60% higher than in gas phase shear layers. The important conclusion is that a low Reynolds number flow, when forced appropriately, can be a better mixer' than a very high Reynolds number flow.

Descriptors :   *TWO PHASE FLOW, *SHIFTING EQUILIBRIUM FLOW, SHEAR PROPERTIES, HIGH RATE, LAYERS, LOW VELOCITY, WAKE, MIXING, RANGE(DISTANCE), AMPLITUDE, FREE STREAM, REYNOLDS NUMBER.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE