Publication de 6 numéros par an
ISSN Imprimer: 1948-2590
ISSN En ligne: 1948-2604
DEVELOPMENT OF EQUALIZING GRIDS WITH LOW DRAG COEFFICIENCTS FOR WIND TUNNELS
RÉSUMÉ
The activities described in the paper are aimed at studying flow characteristics in the T-128 wind tunnel. The goal of this study is to work out recommendations on using new equalizing and protective grids with low drag coefficients in the T-128 wind tunnel and to analyze grid characteristics depending on specific features of their structure and flow parameters at places of grid mounting. An improved method of calculating drag coefficients of individual elements of the T-128 wind tunnel (honeycomb, grids, and air cooler) with due allowance for the Reynolds number effect is presented. Refined drag coefficients of these wind tunnel elements are given with the Mach number in the T-128 test section varying from 0.2 to 1.5. A new equalizing grid with the cell size M =10 mm and wire diameter b = 2 mm is proposed. The drag coefficient of this grid is lower than the drag coefficient of the grid currently mounted in T-128 by a factor of 1.76, but the efficiency of flow turbulence suppression in the T-128 test section is the same. The use of a coarser equalizing grid in T-128 also assists in more effective smoothing of possible cross-flow nonuniformity of velocities of the mean and fluctuating components of velocity. A comparison of the total pressure recovery coefficients obtained with the existing and recommended equalizing and protective grids in the range of Mach numbers in the T-128 test section from 0.2 to 1.5 testifies that the recommended grids ensure noticeably lower hydraulic losses.