Accession Number:

ADA237572

Title:

Polymer Drag Reduction of a Zero Pressure Gradient Boundary Layer

Descriptive Note:

Technical rept. 1 Dec 89-30 Nov 90,

Corporate Author:

PURDUE UNIV LAFAYETTE IN SCHOOL OF MECHANICAL ENGINEERING

Report Date:

1991-02-01

Pagination or Media Count:

59.0

Abstract:

The objective of this portion of the program was to determine the response of a zero pressure gradient boundary layer to slot injection of drag reducing polymer solution. Attention was focused on the region far downstream of the injector. Two-component velocity data were acquired with a laser Doppler velocimeter. Mean concentration data were measured using a laser induced fluorescence technique. A 1000 ppm solution of Separan AP-273 was injected into the boundary layer at 1 and 2 times the flow rate of the linear sublayer. Results are based on two component velocity profiles and concentration profiles at four locations downstream of the slot. These locations correspond to momentum thickness Reynolds numbers of 2478, 2978, 3527 and 3935 in an unmodified Newtonian boundary layer. In dimensionless distance from the slot they vary from 52 to 144 times the boundary layer thickness at the slot and 29000 to 81000 wall units using the unmodified Newtonian inner variables at the slot. There are two major conclusions from the present data. First, the sum of the viscous shear and Reynolds stresses in polymer drag reduced boundary layers does not always account for the total shear stress in the inner region of the boundary layer. Some additional stress which is due to the polymer is present. The second conclusion is that the slope of the logarithmic region of the mean velocity profile in a polymer drag reduced flow may increase over the Newtonian slope. The latter feature may depend on the type of polymer additive.

Subject Categories:

  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE