Experimental Validation of Numerically Optimized Short Annular Diffusers

Abstract

Short annular diffusers with negative wall angles were evaluated numerically and experi mentally with up to 40 deg inlet swirl at an inlet Reynolds number of Re, « 1.4 x 10s and Mach number ofM, » 0.16. The 80% experimental effectiveness of the 1.61 and 1.91 area ratio (AR) diffusers with 0-20 deg inlet swirl were on par with unswirled maximums reported in literature and computational fluid dynamics (CFD) predicted reasonable outlet axial velocity profiles and wall pressure distributions. The AR = 2.73 diffuser's effective ness without swirl was 13% below the maximum for the given AR and larger discrepancies occurred in the CFD results due to the incorrect prediction of the recirculation zone strength. Preference was given to the realizable k-& model on coarse grids with wall func tions that predicted performance of all cases with at least 20 deg inlet swirl to within 20%.

Design rules and applications of single-point incremental forming

“…Cerantola and Birk 24,25 performed a series of computational flow simulations on exhaust diffuser designs for gas turbines. In order to verify the simulation results, three centre bodies were produced with SPIF, shown in Figure 7, and physically tested in a wind tunnel.…”