MechE Seminar Series: Anupam Sharma

Speaker: Anupam Sharma

Title: Dynamic stall onset and its prediction

Abstract: Dynamic stall occurs on helicopter rotor blades, wind turbine blades, and rapidly maneuvering aircraft wings, producing unsteady aerodynamic loads through leading-edge vortex shedding. Although insects and hummingbirds exploit this mechanism for enhanced lift at very low Reynolds numbers, dynamic stall at moderate-to-high Re generates unsteady forces and moments that risk fatigue or catastrophic structural failure. Stall control is most effective at onset, marked by the emergence of the dynamic stall vortex (DSV), making accurate onset prediction critical for both practical applications and reduced-order modeling — yet challenging due to the small-scale boundary-layer events involved. This talk examines dynamic stall onset in three parts. The first presents wall-resolved large-eddy simulations (LES) at moderate Re, highlighting the role of the laminar separation bubble (LSB) and the influence of airfoil thickness on the stall mechanism. The second introduces a novel vorticity-based parameter for estimating stall incipience across different dynamic stall regimes at both low and high Re. The third addresses ongoing work on cost-effective hybrid RANS-LES prediction, augmented through machine learning with LES and experimental data.

About the Speaker: Anupam Sharma is Professor of Aerospace Engineering at Iowa State University. His research spans unsteady aerodynamics, with particular emphasis on aeroacoustics and dynamic stall. He received his B.Tech. from IIT Bombay and his M.S. and Ph.D. in Aerospace Engineering from Penn State University. Prior to joining academia, he spent seven years at GE Global Research in New York, working on aircraft engines and wind turbines. Prof. Sharma is an AIAA Associate Fellow and the recipient of the 2016 NSF CAREER Award and the Early Achievement in Teaching Award at Iowa State University. His research is supported by the NSF, DOE, DOD, and various state and industry partners.