Research Papers

Mechanisms for Wide-Chord Fan Blade Flutter

[+] Author and Article Information
Mehdi Vahdati

 Imperial College London MED, Exhibition Road, London SW7 2AZ, UKm.vahdati@imperial.ac.uk

George Simpson

 Rolls-Royce PLC, P.O. Box 31, Derby DE24 8BJ, UK

Mehmet Imregun

 Imperial College London MED, Exhibition Road, London SW7 2AZ, UK

J. Turbomach 133(4), 041029 (Apr 27, 2011) (7 pages) doi:10.1115/1.4001233 History: Received August 19, 2009; Revised October 28, 2009; Published April 27, 2011; Online April 27, 2011

This paper describes a detailed wide-chord fan blade flutter analysis with emphasis on flutter bite. The same fan was used with three different intakes of increasing complexity to explain flutter mechanisms. Two types of flutter, namely, stall and acoustic flutters, were identified. The first intake is a uniform cylinder, in which there are no acoustic reflections. Only the stall flutter, which is driven by flow separation, can exist in this case. The second intake, based on the first one, has a “bump” feature to reflect the fan’s forward pressure wave at a known location so that detailed parametric studies can be undertaken. The analysis revealed a mechanism for acoustic flutter, which is driven by the phase of the reflected wave. The third intake has the typical geometric features of a flight intake. The results indicate that flutter bite occurs when both stall and acoustic flutters happen at the same speed. It is also found that blade stiffening has no effect on aero-acoustic flutter.

Copyright © 2011 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.



Grahic Jump Location
Figure 10

(a) Total aerodamping (left) and (b) aerodamping due to bump only

Grahic Jump Location
Figure 3

1F/2ND assembly vibration mode

Grahic Jump Location
Figure 4

Aerodamping with plain intake

Grahic Jump Location
Figure 5

Steady-state pressure and stall regions on suction surface (S/S)

Grahic Jump Location
Figure 6

Unsteady pressure amplitude on the blade surface (left) and time histories at points A and B (dx: motion, dp: pressure)

Grahic Jump Location
Figure 7

Aerodamping as a function of the bump position

Grahic Jump Location
Figure 8

Displacement and modal force time histories for X1 and X2

Grahic Jump Location
Figure 9

Unsteady pressure waves: (a) unsteady pressure, (b) forward pressure wave, and (c) backward pressure wave

Grahic Jump Location
Figure 11

Domain used for flutter analysis—real intake

Grahic Jump Location
Figure 1

Computational domain

Grahic Jump Location
Figure 2

Computed characteristic

Grahic Jump Location
Figure 12

Characteristic computed with flight intake

Grahic Jump Location
Figure 13

Aerodamping along high working line HWK

Grahic Jump Location
Figure 14

1D forward and backward waves (104 Pa)

Grahic Jump Location
Figure 15

(a) Amplitude and (b) phase of the reflected wave

Grahic Jump Location
Figure 16

Aerodamping as a function of the blade frequency—plain intake

Grahic Jump Location
Figure 17

Aerodamping as a function of blade frequency—80% speed, flight intake



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In