Helicopter Noise Prediction: The Current Status and Future Direction

The current status of helicopter noise prediction is examined in this paper. A brief history is given, followed by a discussion of the status of prediction for each source mechanism. The acoustic analogy approach, and specifically, theories based on the Ffowcs Williams-Hawkings equations are the most widely used for deterministic noise sources. Thickness and loading noise can be routinely predicted given good blade motion and blade loading inputs. Blade-vortex interaction (BVI) noise can also be predicted well with measured input data, but prediction of airloads with the high spatial and temporal resolution required for BVI is still difficult. No efficient prediction method for high speed impulsive noise is currently available, but much progress has been made. The best broadband noise prediction currently depends on semi-empirical methods.