Turbine noise generation, reduction and prediction

REVIEW—A Critical Review of Turbomachinery Noise

“…Kazin and Matta [74] also report perhaps the only example of systematic tests of turbine noise in the open literature. A three stage low pressure turbine was run at a range of pressure ratios for the design speed and then at a range of speeds for the design pressure ratio.…”

“…For turbines it is common to have thick trailing edges, and this may negate this effect somewhat. Experiments have shown the rapid reduction in tone level with increased spacing, for example Kazin and Matta [74], and a change in sound pressure level of 10 log (spacing/chord) appears to be the favored correlation. Just as for fans and compressors, the tones are amenable to acoustic-cut-off.…”

“…The haystacking of tones is primarily brought about by the radiation of the tones through the jet, and modification to the exhaust geometry has been demonstrated to alter its extent, Mathews and Perachio [78], Kazin and Matta [74], It appears that the acoustic power in a tone is more or less unaltered by this, but is merely redistributed. Comparative measurements on one turbine by Fletcher and Smith [79] show a sharp tone in the duct but no more than a broad band hump in the far field spectrum.…”

“…Kazin and Matta [74] made large increases to the turbulence and radial nonuniformity at the inlet to a single stage turbine with choked nozzle guide vanes, but there was no perceptible change in the noise. It is probable that the scale of turbulence is as important as the intensity, and it is possible that the wrong scale was used here.…”

“…The flow deflections in turbine blade rows are 90 deg or more, and the flow acceleration is typically from Mach numbers as low as 0.2 up to close to unity. Nevertheless Kazin and Matta [74] describe such a method in which the usual assumptions are made, in particular the lift fluctuations are calculated by a method for incompressible flow about a nonlifting flat plate and the fluctuating lifting line becomes a line acoustic source. The wake is represented by the Silverstein, et al [33] profile, derived for low camber and low Mach number isolated airfoils, with the blade aerodynamics appearing in the loss of pressure.…”