Over recent years, engine designs have moved increasingly toward low specific thrust cycles to deliver significant specific fuel consumption (SFC) improvements. Such fan blades may be more prone to aerodynamic and aeroelastic instabilities than conventional fan blades. The aim of this paper is to analyze the flutter stability of a low-speed/low pressure ratio fan blade. By using a validated computational fluid dynamics (CFD) model (AU3D), three-dimensional unsteady simulations are performed for a modern low-speed fan rig for which extensive measured data are available. The computational domain contains a complete fan assembly with an intake duct and the downstream outlet guide vanes (OGVs), which is a whole low-pressure (LP) domain. Flutter simulations are conducted over a range of speeds to understand flutter characteristics of this blade. Only the first flap (1F) mode is considered in this work. Measured rig data obtained by using the same fan set but with two different lengths of the intake showed a significant difference in the flutter boundary for the two intakes. AU3D computations were performed for both intakes and were used to explain this difference between the two intakes, and showed that intake reflections play an important role in flutter of this blade. This observation indicates that the experiment with the long intake used for the performance test may be misleading for flutter. In the next phase of this work, two possible modifications for increasing the flutter margin of the fan blade were explored: changing the mode shape of the blade and using acoustic liners in the casing. The results show that it is possible to increase the flutter margin of the blade by either decreasing the ratio of the twisting to plunging motion in 1F mode or by introducing deep acoustic liners in the intake. The liners have to be deep enough to attenuate the flutter pressure waves and hence influence the stability. The results indicate the importance of reflection in flutter stability of the fan blade and clearly show that intake duct needs to be included in flutter study of any fan blade.
Skip Nav Destination
Article navigation
July 2017
Research-Article
Numerical Study on Aeroelastic Instability for a Low-Speed Fan
Mehdi Vahdati
Mehdi Vahdati
Imperial College London,
Mechanical Engineering Department,
London SW7 2AZ, UK
e-mail: m.vahdati@imperial.ac.uk
Mechanical Engineering Department,
London SW7 2AZ, UK
e-mail: m.vahdati@imperial.ac.uk
Search for other works by this author on:
Kuen-Bae Lee
Mark Wilson
Mehdi Vahdati
Imperial College London,
Mechanical Engineering Department,
London SW7 2AZ, UK
e-mail: m.vahdati@imperial.ac.uk
Mechanical Engineering Department,
London SW7 2AZ, UK
e-mail: m.vahdati@imperial.ac.uk
Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received September 27, 2016; final manuscript received November 29, 2016; published online February 23, 2017. Editor: Kenneth Hall.
J. Turbomach. Jul 2017, 139(7): 071004 (8 pages)
Published Online: February 23, 2017
Article history
Received:
September 27, 2016
Revised:
November 29, 2016
Citation
Lee, K., Wilson, M., and Vahdati, M. (February 23, 2017). "Numerical Study on Aeroelastic Instability for a Low-Speed Fan." ASME. J. Turbomach. July 2017; 139(7): 071004. https://doi.org/10.1115/1.4035569
Download citation file:
Get Email Alerts
Evaluating Thin-Film Thermocouple Performance on Additively Manufactured Turbine Airfoils
J. Turbomach (July 2025)
Thermohydraulic Performance and Flow Structures of Diamond Pyramid Arrays
J. Turbomach (July 2025)
Related Articles
On the Importance of Engine-Representative Models for Fan Flutter Predictions
J. Turbomach (August,2018)
A Simple Model for Identifying the Flutter Bite of Fan Blades
J. Turbomach (July,2017)
Geometrical Modification of the Unsteady Pressure to Reduce Low-Pressure Turbine Flutter
J. Turbomach (September,2017)
An Aerodynamic Parameter for Low-Pressure Turbine Flutter
J. Turbomach (May,2016)
Related Chapters
Occlusion Identification and Relief within Branched Structures
Biomedical Applications of Vibration and Acoustics in Therapy, Bioeffect and Modeling
Aerodynamic Performance Analysis
Axial-Flow Compressors
Fans and Air Handling Systems
Thermal Management of Telecommunications Equipment