A Burgers equation model is applied to predict nonlinear propagation of helicopter high-speed impulsive noise. The Burgers equation model is validated against an analytic solution for a sinusoidal wave and then applied to a model-scale rotor noise. The Euler CFD data is used to extract the starting signal and to validate the prediction obtained by the Burgers equation. It is found that the prediction agrees very well with the CFD data. The sensitivity of the starting position in the proximity of the blade tip to the prediction is investigated. In addition, a difference between linear and nonlinear propagations is shown for long distances. The effect of the atmospheric absorption in comparison with the nonlinear propagations is also examined. Finally, the nonlinearity indicator is used to identify the energy transfer in the frequency domain and to explain the SPL distribution.
|Original language||English (US)|
|Number of pages||11|
|Journal||Annual Forum Proceedings - AHS International|
|State||Published - 2010|
|Event||66th Forum of the American Helicopter Society: "Rising to New Heights in Vertical Lift Technology", AHS Forum 66 - Phoenix, AZ, United States|
Duration: May 11 2010 → May 13 2010
All Science Journal Classification (ASJC) codes