SWIFT Code Assessment for Two Similar Transonic Compressors

One goal of the NASA Fundamental Aeronautics Program is the assessment of computational fluid dynamic (CFD) codes used for the design and analysis of many aerospace systems.This paper describes the assessment of the SWIFT turbomachinery analysis code for two similar transonic compressors, NASA rotor 37 and stage 35.The two rotors have identical blade profiles on the front, transonic half of the blade but rotor 37 has more camber aft of the shock.Thus the two rotors have the same shock structure and choking flow but rotor 37 produces a higher pressure ratio.The two compressors and experimental data are described here briefly.Rotor 37 was also used for test cases organized by ASME, IGTI, and AGARD in 1994-1998.Most of the participating codes over predicted pressure and temperature ratios, and failed to predict certain features of the downstream flowfield.Since then the AUSM + upwind scheme and the k-ω turbulence model have been added to SWIFT.In this work the new capabilities were assessed for the two compressors.Comparisons were made with overall performance maps and spanwise profiles of several aerodynamic parameters.The results for rotor 37 were in much better agreement with the experimental data than the original blind test case results although there were still some discrepancies.The results for stage 35 were in very good agreement with the data.The results for rotor 37 were very sensitive to turbulence model parameters but the results for stage 35 were not.Comparison of the rotor solutions showed that the main difference between the two rotors was not blade camber as expected, but shock/boundary layer interaction on the casing.