High Fidelity Code-to-Code Comparison of Rotor Performance in Hover and Forward Flight

Abstract

High fidelity code-to-code comparisons have been made between the University of Glasgow HMB3 code and the HPCMP CREATE™-AV Helios code under The Technical Cooperation Program collaboration project, Next Generation Rotor Blade Design. The comparisons are made for two model-scale rotors - Langley baseline (LBL) rotor and Pressure Sensitive Paint (PSP) rotor. Hover and forward flight performance results are compared against test data. For the LBL rotor, hover performance is in a good agreement between the test data and HMB3 results over a full range of CT. However, the comparison between the HMB3 and Helios results at a CT of 0.0084 shows the difference in Figure of Merit (FM) by approximately 2 counts (2.2-3.2%). In forward flight, the HMB3 and Helios performance results overpredict the test data at the low advance ratios but improve the predictions at the high advance ratios. At an advance ratio of 0.31, the code-to-code comparison indicated that the Helios torque was lower by 2.8-3.1% compared with the HMB3 torque. For the PSP rotor, the FM trend computed using the Helios-OVERFLOW code agrees well with the fully-turbulent test data. The Helios-OVERFLOW result shows that the fuselage interaction effect is favorable for rotor performance. For a code-to-code comparison, the HMB3 FM result shows about 3.0 counts (4.0%) lower than the HeliosOVERFLOW result at a CT/σ of 0.091. In forward flight, the HMB3 rotor result agrees well with the test data whereas the Helios rotor result underpredicts by 2-3 counts in CP/σ (3.5-5.7%) at the high advance ratios although it was significantly improved at the low advance ratio. Overall, the code-to-code comparisons are successfully conducted for both the LBL and PSP rotors.