EFFECTS OF INITIAL PROFILE IN THE LAMINAR MIXING LAYER.
XEROX ELECTRO-OPTICAL SYSTEMS PASADENA CA
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The velocity and enthalpy distributions in the laminar mixing layer were calculated for a wide range of initial profiles. The profiles correspond to a Blasius velocity distribution and Crocco integral enthalpy distribution on a body just before separation. A simple model of the separation process assumes that the outer inviscid flow turns such that the Mach number increases from Me2 on the body to Me3 after separation, while the boundary layer flow expands isentropically along streamlines from the corresponding body pressure P2 to a mixing layer pressure P3. The effects of viscosity are neglected during the expansion, and at high Mach numbers, the generation of a significant pressure gradient across the former boundary layer during the expansion is not included. The calculations were performed for wall enthalpy ratios ranging from 0 cold wall to 1 adiabatic wall, and expansions ranging from Me2Me3 .4 to Me2Me3 1. The dividing streamline velocity at a downstream point in the mixing layer depends strongly on the profile distortion, but, the dividing streamline enthalpy functions are affected only slightly. An overall energy balance was used to find the mixing layer inner edge dimensionless enthalpy and the dividing streamline dimensionless enthalpy at the downstream end of the mixing layer. For the case of negligible net energy transport across the dividing streamline, these quantities were only slightly affected by the variation of initial profile shapes, suggesting the use of a single averaged curve for these quantities for all degrees of profile distortion.
- Fluid Mechanics