Trailing Edge Flow and Aerodynamic Sound. Part 1. Tonal Pressure and Velocity Fluctuations. Part 2. Random Pressure and Velocity Fluctuations.

摘要

The turbulent field quantities at the trailing edges of lifting surfaces consist of two components. Locally-generated random fluctuations are generated by separation of the turbulent boundary layers and these fluctuations account for weakly correlated surface pressure fields. The second contribution is periodic, or nearly periodic, and is generated by the structured vortex pressure field. The aerodynamic properties of each of these contributions are examined for various trailing edge configurations, and the aeroacoustic qualities of each are explored. Rules are given for the prediction of the onset of either predominately tonal or predominantly random pressure fields. Relationships are given for estimating aerodynamic sound levels from the surface pressures for each class of aerodynamic excitation.