Accession Number : AD0703741

Title :   INTERACTION OF GRID TURBULENCE WITH A UNIFORM MEANSHEAR.

Descriptive Note : Final rept. 1 May 66-28 Feb 69,

Corporate Author : VIRGINIA UNIV CHARLOTTESVILLE RESEARCH LABS FOR THE ENGINEERING SCIENCES

Personal Author(s) : Rose,William G.

Report Date : MAR 1970

Pagination or Media Count : 27

Abstract : Experiments were performed to explore the effect of initial disturbance length-scale on turbulence developed in the presence of a uniform mean-shear. Flows with nearly the same mean-shear (8.6/sec) and initially different turbulent scales are generated in a windtunnel test-section by placing grids just downstream of a honeycomb of uniform cell-diameter (1/4 in) and nonuniform cell-length. Both round-rod grids of uniform square-mesh and parallel-rod construction with roughly equal solidity (0.34) are used. Grid mesh-sizes range from 1/24 to 2 in. From the results it is concluded that for a given value of mean shear the imposed length scale fixes the energy level of the resulting turbulence, provided the scale is sufficiently large. When it is reduced below some minimum value the turbulence decays. Also, it is found that two-dimensional flow-generator geometries are more effective than are three-dimensional geometries in producing a roughly homogeneous turbulent field with a higher fluctuation level in a shorter distance. (Author)

Descriptors :   (*TURBULENCE, *SHEAR STRESSES), INTERACTIONS, TEST EQUIPMENT, SCALE, TWO DIMENSIONAL FLOW, THREE DIMENSIONAL FLOW

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE