FIFTH INTERNATIONAL CONGRESS ON SOUND AND VIBRATION

The problem of broadband noise generated by turbulence @om a rotor imping”ng on a downstream stator is examined from a theoretical viewpoint. Equations are derived giving sound power spectra in terms of the 3 dimensional turbulence wavenumber spectrum. Particular attention is g“ven to issues of turbulence inhomogeneity related to separation of individual blade wakes in the near~eld of the rotor. It is shown that this inhomogeneity can be handled rigorously with no additional complexity in the noise equations. A procedure for measurement of turbulence at a stator inlet with a 2-probe &ta system is studied. In the process, formulas are derived to compute the 3D turbulence spectrum via transforms of measured cross-spectra and estimates are given for the requiredprobe spacing.