Unsteady aerodynamics of advanced ducted fan
Abstract
A three-dimensional linear frequency domain panel method has been extended to study the unsteady aerodynamics, aeroelasticity, and aeroacoustics of advanced ducted fans. Additional contributions are to extend and improve previous lifting surface theory to include for stator rows and planar supersonic tip Mach numbers, and radiated noise estimation. A two-dimensional viscous wake model is incorporated to account for the influence of the viscous wake generated by the upstream blade impinging on the downstream blade. In order to verify the procedure, several test cases, most of which have been investigated by researchers, were examined and compared with the existing measurements and theoretical predictions for a rectangular wing, single rotation fans, a counter rotation propeller and advanced ducted fans. Subsequently, studies are performed to examine the unsteady aerodynamics, aeroelastic response, and aeroacoustics of ducted fans, where most of them have not been extensively studied, such as resonance conditions predicted by the two-dimensional strip theory, the effect of ducting the fan on aeroelasticity of a ducted eight-bladed SR3 fan, the significance of unsteady interaction of ducted (2x2) counter rotation Purdue model propeller, and unsteady aerodynamics of ducted rotor-stator $E\sp3$ fan. A non-compact loading noise calculation based on Farassat's formulation 1A is developed for analyzing acoustic field generated by fans operating at subsonic tip Mach number. The noise calculation procedure is verified with existing acoustic measurements and theoretical predictions. Finally, applications to the noise characteristics of counter rotation propellers, both acoustic interference and aerodynamic interference, are demonstrated.
Degree
Ph.D.
Advisors
Williams, Purdue University.
Subject Area
Aerospace materials|Mechanical engineering
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