Experimental and analytical evaluation of flow in a square-to-square wind tunnel contraction

Flow characteristics within a square-to-square contraction are investigated numerically and experimentally so as to gain additional insight into the c ontraction design. Measurements of cross-sectional velocity profiles and lo ngitudinal pressure distributions along the wall centerlines are carried ou t in a contraction prototype and the results are compared to those predicte d by the numerical simulations. Finally, the applicability of the nozzle de sign method, proposed by Fang (ASME J. Fluid Eng. (1997) 454), is assessed. Results show that although the inviscid calculation fails to simulate corr ectly the part of the nozzle flow near the contracting walls, the general b ehavior of the flow in the regions away from the wall is in reasonable agre ement with the predicted behavior. On the other hand, the relative friction losses along the wall centerlines are about 4.3% relative to the total pre ssure drop through the contracting duct. After an adjustment is made in the normalization scheme, the measured pressure distributions are in good agre ement with the numerically based distribution. (C) 2001 Elsevier Science Lt d. All rights reserved.