Cumpsty, N. A. and Marble, F. E. (1977) The Interaction of Entropy Fluctuations with Turbine Blade Rows; A Mechanism of Turbojet Engine Noise. Proceedings of the Royal Society A: Mathematical, physical, and engineering sciences, 357 (1690). pp. 323-344. ISSN 1364-5021 http://resolver.caltech.edu/CaltechAUTHORS:20101213-114306465
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The theory relating to the interaction of entropy fluctuations ('hot spots'), as well as vorticity and pressure, with blade rows is described. A basic feature of the model is that the blade rows have blades of sufficiently short chord that this is negligible in comparison with the wavelength of the disturbances. For the interaction of entropy with a blade row to be important, it is essential that the steady pressure change across the blade row should be large, although all unsteady perturbations are assumed small. A number of idealized examples have been calculated, beginning with isolated blade rows, progressing to single and then to several turbine stages. Finally, the model has been used to predict the low-frequency rearward-radiated acoustic power from a commercial turbojet engine. Following several assumptions, together with considerable empirical data, the correct trend and level are predicted, suggesting the mechanism to be important at low jet velocities.
|Additional Information:||© 1977, Royal Society. Communicated by Sir William Hawthorne, F.R.S. Received 23 November 1976. The authors wish to express their gratitude for the assistance provided by the Boeing Airplane Company, Pratt & Whitney Aircraft, and Rolls-Royce Ltd., in making data available. They would also like to express the individual assistance by D. S. Whitehead of Cambridge University as well as R. R. Dils and E. M. Greitzer of Pratt and Whitney Aircraft.|
|Group:||Guggenheim Jet Propulsion Center|
|Other Numbering System:|
|Official Citation:||Cumpsty, N. A. and F. E. Marble (1977). "The Interaction of Entropy Fluctuations with Turbine Blade Rows; A Mechanism of Turbojet Engine Noise." Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences 357(1690): 323-344. doi:10.1098/rspa.1977.0171|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||15 Dec 2010 19:43|
|Last Modified:||26 Dec 2012 12:45|
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