Turbulent Shear Flow Velocity Profiles Behind a Grid of Parallel Rods of Variable Spacing.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
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An experimental study was conducted to investigate the turbulent shear flow velocity profiles generated by a parallel-rod grid with adjustable spacing designed to produce an artificial boundary layer. The study was conducted in a low turbulence wind tunnel with a 9 x 9 x 37 inch test cabin. Data was collected using a hot-wire anemometer in conjunction with a correlator. The turbulence parameters reported are the development and distribution of mean velocities, fluctuating velocities, Reynolds stresses, microscales and integral scales at 32, 112, and 232 rod diameters downstream of the grid. Results show that stable power-law velocity profiles can be generated with negligible diffusion of the shear layer along the length of the test cabin. Turbulence intensity plots show that 75 of the grid generated turbulence decayed within 100 rod diameters downstream from the grid. The microscale and integral scales showed their minimum values close to the grid and increased in value downstream. Also, the ratio of the spatial integral scale to the spatial microscale was approximately 3.0 throughout the test cabin. Author
- Fluid Mechanics