Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 18
Book Description
Resonance Effects in the NASA Transonic Flutter Cascade Facility
Author: Resonance Effects in the NASA Transonic Flutter Cascade Facility
Author: National Aeronautics and Space Administration (NASA)Publisher: Createspace Independent Publishing Platform
ISBN: 9781721587414
Category :
Languages : en
Pages : 32
Book Description
Investigations of unsteady pressure loadings on the blades of fans operating near the stall flutter boundary are carried out under simulated conditions in the NASA Transonic Flutter Cascade facility (TFC). It has been observed that for inlet Mach numbers of about 0.8, the cascade flowfield exhibits intense low-frequency pressure oscillations. The origins of these oscillations were not clear. It was speculated that this behavior was either caused by instabilities in the blade separated flow zone or that it was a tunnel resonance phenomenon. It has now been determined that the strong low-frequency oscillations, observed in the TFC facility, are not a cascade phenomenon contributing to blade flutter, but that they are solely caused by the tunnel resonance characteristics. Most likely, the self-induced oscillations originate in the system of exit duct resonators. For sure, the self-induced oscillations can be significantly suppressed for a narrow range of inlet Mach numbers by tuning one of the resonators. A considerable amount of flutter simulation data has been acquired in this facility to date, and therefore it is of interest to know how much this tunnel self-induced flow oscillation influences the experimental data at high subsonic Mach numbers since this facility is being used to simulate flutter in transonic fans. In short, can this body of experimental data still be used reliably to verify computer codes for blade flutter and blade life predictions? To answer this question a study on resonance effects in the NASA TFC facility was carried out. The results, based on spectral and ensemble averaging analysis of the cascade data, showed that the interaction between self-induced oscillations and forced blade motion oscillations is very weak and can generally be neglected. The forced motion data acquired with the mistuned tunnel, when strong self-induced oscillations were present, can be used as reliable forced pressure fluctuations provided that they are extracted from
Proceedings of the ASME Turbo Expo ...
Author: Scientific and Technical Aerospace Reports
Author: Aeronautical Engineering
Author: Applied Mechanics Reviews
Author: NASA Scientific and Technical Publications
Author: Aeronautical Engineering: A Cumulative Index to a Continuing Bibliography (supplement 300)
Author: International Aerospace Abstracts
Author: Handbook of the Acoustic Characteristics of Turbomachinery Cavities
Author: Michael J. LucasPublisher: American Society of Mechanical Engineers
ISBN:
Category : Science
Languages : en
Pages : 288
Book Description
A guide for mechanical engineers to identifying flow-induced noise and vibration sources within machinery that could cause catastrophic failure. Explains methods for computing frequencies for self-sustained oscillations, and presents formulae to calculate the acoustic resonant modes for ducts and cavities. Considers the general types of flow configurations that are known to produce self-sustained oscillations and includes a complete collection of models. Annotation copyrighted by Book News, Inc., Portland, OR