Pressure recovery performance of 2-D turning diffuser by varying area ratios and inflow Reynolds numbers

Abstract

The paper aims to investigate the effects of varying area ratio, AR = 1.2 and 4.0 and inflow Reynolds number, Rein = 5.478 104 - 1.547105 on the performance of 90° two-dimensional turning diffuser. The optimum configuration area ratio and Rein to produce good pressure recovery is determined. The rig was developed to produce fully developed entrance flow by adopting arrangement of mesh net and sufficient hydrodynamic entrance length, Lh, turb = 28 Dh . Digital manometer was used to measure the inlet and outlet static pressures and Particle Image Velocimetry (PIV) to visualize the flow structure. The present results were compared with empirical solution of Asymptotic Computational Fluid Dynamics (ACFD) results to give acceptable deviation of ±7.4%. The AR=4.0 produces pressure recovery 20% more than AR=1.2 when applies low Rein<1.40 105. However, it is subjected to severe flow separation and circulation at Rein>1.40 105 that considerably disturbs the recovery. Therefore, turning diffuser of AR=1.2 is optimum applied for high Rein>1.40 105.