Turbulent Diffusion in Round Tubes
Interim rept. Sep 71-Jun 72,
ARMY MOBILITY EQUIPMENT RESEARCH AND DEVELOPMENT COMMAND FORT BELVOIR VA
Pagination or Media Count:
Fully developed turbulent flow of air at Re 15000 to 30000 entered a porous tube with circular cross section. Helium and air were injected uniformly through the tube wall for 36 radii at various ratios of mass velocity through the tube wall to the average mass velocity at the entrance cross section of the tube ranging from 0.0001 to 0.0004. Measurements of the velocity field were made for air injection, and measurements of helium concentration were made for helium injection. Within the tested range of air injection, the distortion of the fully developed velocity profile was negligible. A numerical solution of the diffusion equation was obtained based upon the assumption that the nondimensional velocity distribution, uuavg, was a function of the entrance Reynolds number but independent of small wall-mass injection rates. Prandtl mixing length theory incorporating Van Driests damping factor generalized by Kinney and Sparrow for the case of wall-mass transfer was used to evaluate effective diffusivity for turbulent flow.
- Fluid Mechanics