Expanding Helicopter Noise Simulation Scope, based on High-Fidelity CFD

Based on a previous high fidelity CFD simulation of descent flight for acoustic evaluation, the two other certification points of takeoff and flyover have been investigated. Selected simulation results are compared to flight test data and among each other, investigating commonalities as well as deviations. Special consideration was given to the separate analysis of blade harmonics and broadband noise, expecting the latter to be less accessible to CFD. However, the accuracy of results varies for both shares, ranging from excellent to leaving room for considerable improvement. An old empirical model for broadband noise did not deliver the upgrade hoped for. For takeoff, an alternative data set with a slightly different, but equally plausible trim condition was analyzed, resulting in a rough sensitivity estimate. Summing up, acoustic evaluation of high fidelity CFD can give valuable qualitative information, and in some, albeit not all, cases match flight tests and parameter dependencies also quantitatively.