Jet Engine Safety Concerns: Low-Pressure Turbine Flutter

Joshua Waite (MEMS)
Friday, March 28, 2014 - 12:00pm
Hudson 208. Friday, March 28th, 11:45 AM. Lunch Provided.

Joshua Waite

Jet Engine Safety Concerns: Low-Pressure Turbine Flutter

Friday, March 28th, 11:45 AM.  Hudson 208. Lunch Provided


Successful, efficient turbine design requires a thorough understanding of the underlying physical phenomena. This paper investigates the flutter phenomenon of low pressure turbine (LPT) blades seen in aircraft engines and power turbines. CFD analysis will be conducted in a two-dimensional sense using a frequency domain RANS solver on a publicly available LPT airfoil geometry: EPFL’s Standard Configuration 4. An emphasis is placed on revealing the underlying physics behind the threatening LPT flutter mechanism. To this end, flutter sensitivity analysis is conducted on three key parameters: reduced frequency, mode shape, and Mach number. Additionally, exact two-dimensional acoustic resonance inter-blade phase angles (IBPAs) are analytically predicted as a function of reduced frequency. Made evident via damping vs. IBPA plots, the CFD model successfully captures the theoretical acoustic resonance predictions. Studies of the decay of unsteady aerodynamic influence coefficients away from a reference blade are also presented. The influence coefficients provide key insights to the harmonic content of the unsteady pressure field. Finally, this work explores methods of normalizing the work per cycle by the exit dynamic pressure.


Joshua is a Ph.D. student in Mechanical Engineering and Material Science at Duke University. He grew up in Maine and completed his undergraduate studies there. At the University of Maine, Joshua graduated with a B.S. in Mechanical Engineering and a minor in Mathematics in 2010. During these earlier years, Joshua had two engineering internships: one studying Magneto-Rheological fluid dynamics and the other working alongside the Department of Defense Atmospheric Diving System team at Portsmouth Naval Shipyard. Joshua received his M.S. degree in Mechanical Engineering from Duke University in 2013. His nonlinear dynamics specialization highlighted a thesis that investigated the initial condition sensitivity of nonlinear structural systems.  For his Ph.D. studies, Joshua is studying turbomachinery aeroelasticity with Dr. Robert Kielb. In 2013, he won the National Defense Science and Engineering Graduate (NDSEG) fellowship. His current aeromechanical collaborations include industrial jet engine manufacturers and the Department of Defense.