Numerical Study of a Transonic Aircraft Wing for the Prediction of Flutter Failure
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TECHNICAL ARTICLE—PEER-REVIEWED
Numerical Study of a Transonic Aircraft Wing for the Prediction of Flutter Failure Indrajeet Singh . R. K. Mishra . P. S. Aswatha Narayana
Submitted: 10 July 2016 ASM International 2016
Abstract In the present paper, computational analysis has been carried out to assess the coupled fluid–structure interaction using NASTRAN finite element approach. A straight swept wing of aluminum material is studied at transonic zone. Analysis has been carried out to find the natural frequency by fluid–structure interaction, then adopting its natural frequency to calculate the reduced frequency for analyzing the flutter effectiveness. A typical case study of plate has been carried out for better understanding the flutter which was then adopted for the swept wing. A fluid–structure interaction phenomenon provides an additional energy to the moving object in terms of frequency in transonic zone. In this speed zone, the divergence speed results a drag that leads to the object to be in a stronger twisting mode resulting in catastrophic failure of the aircraft. The study has defined the flutter boundary of the wing in terms of velocity and frequency which will be very useful in preventing the flutter failure of the aircraft wing through appropriate design improvement or through restriction operational regime. Keywords Flutter Fluid–structure interaction Mode shapes Vibration
I. Singh P. S. Aswatha Narayana Jain University International Institute for Aerospace Engineering and Management, Bangalore, Karnataka, India R. K. Mishra (&) Regional Center for Military Airworthiness (Engines), Bangalore, Karnataka, India e-mail: [email protected]
Introduction Flutter is a self-feeding and potentially destructive vibration where aerodynamic forces on an object couple with a structure’s natural mode of vibration to produce rapid periodic motion. Flutter can occur on any object with an intense fluid flow, under the conditions that a positive feedback occurs between the structure’s natural vibration and the aerodynamic forces. The vibrational effect on the object increases aerodynamic load, which in turn drives the structure to move further. If the energy input by the aerodynamic excitation in a cycle is larger than that dissipated by the damping in the system, amplitude of vibration increases, resulting in self-exciting oscillation. A fluid– structure interaction phenomenon provides an additional energy to the moving object in terms of frequency in transonic zone. In this speed zone, the divergence speed results in a drag that leads to the object to be in a stronger twisting mode resulting in catastrophic failure of the aircraft [1–3]. Flutter is an unstable phenomenon occurring in a fraction of second causing structural failure and has raised serious concern to the operational safety of aircrafts. This has initiated many researches all over for the effective prediction, suppression, and control of flutter in aircraft wings [4–6]. Effectual means of flutter prevention has also become mandatory in
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