NUMERICAL METHODS FOR THE INVESTIGATION OF THE AERODYNAMIC NOISE OF A HELICOPTER ROTOR
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Abstract
In this paper, the main numerical methods for modeling the aerodynamically
generated rotor noise of helicopter are considered. In particular, finite difference schemes for steady
and unsteady 2-dimensional potential flows are given, on the basis of which a model of sound
generation of aerodynamic origin of a helicopter rotor blade is built. Examples of the solution of the
problem for 3-dimensional potential unsteady flow are considered. It should be noted that until
recently there was no general finite difference scheme for solving problems of helicopter rotor
acoustics. The numerical-analytical method developed by the author of this paper showed the ability
to solve problems of aeroacoustics of a helicopter blade for different types of flow models, both
potential and non-potential. The paper gives examples of the solution of similar problems, analyses
the application of the numerical-analytical method and compares it with existing finite difference
methods. In particular, the calculation schemes for the application of the method for a 2D steady flow
and a 3D unsteady flow are presented and the peculiarities of the selection of the number of points in
the calculation molecule are explained. Depending on the characteristics of a problem, the number of
computational grid points can vary both along the span and across the blade. This makes it possible to
adapt the numerical-analytical method for each of the problems to be solved. At the same time, a
stable calculation is performed based on the idea of the numerical analytical method itself, and the
convergence of the method is performed automatically each time.
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