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Supersonic stall flutter of high speed fans. [in turbofan engines
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Jutras, R. Stevens, W. Adamczyk, J. J. |
| Copyright Year | 1981 |
| Description | An analytical model is developed for predicting the onset of supersonic stall bending flutter in axial flow compressors. The analysis is based on a modified two dimensional, compressible, unsteady actuator disk theory. It is applied to a rotor blade row by considering a cascade of airfoils whose geometry and dynamic response coincide with those of a rotor blade element at 85 percent of the span height (measured from the hub). The rotor blades are assumed to be unshrouded (i.e., free standing) and to vibrate in their first flexural mode. The effects of shock waves and flow separation are included in the model through quasi-steady, empirical, rotor total-pressure-loss and deviation-angle correlations. The actuator disk model predicts the unsteady aerodynamic force acting on the cascade blading as a function of the steady flow field entering the cascade and the geometry and dynamic response of the cascade. Calculations show that the present model predicts the existence of a bending flutter mode at supersonic inlet Mach numbers. This flutter mode is suppressed by increasing the reduced frequency of the system or by reducing the steady state aerodynamic loading on the cascade. The validity of the model for predicting flutter is demonstrated by correlating the measured flutter boundary of a high speed fan stage with its predicted boundary. This correlation uses a level of damping for the blade row (i.e., the log decrement of the rotor system) that is estimated from the experimental flutter data. The predicted flutter boundary is shown to be in good agreement with the measured boundary. |
| File Size | 1036757 |
| Page Count | 14 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19810006463 |
| Archival Resource Key | ark:/13960/t9v16vh2p |
| Language | English |
| Publisher Date | 1981-01-01 |
| Access Restriction | Open |
| Subject Keyword | Aerodynamics Dynamic Response Turbocompressors Engine Design Rotor Aerodynamics Turbomachine Blades Cascade Flow Unsteady Aerodynamics Supersonic Inlets Turbofan Engines Flutter Aeroelasticity Aerodynamic Stalling Prediction Analysis Techniques Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
