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MAE PhD Defense – Shreyas Narsipur
March 16, 2017 @ 1:30 pm
Low-Order Modeling of Dynamic Stall on Airfoils in Incompressible Flow
(Advisor: Dr. Ashok Gopalarathnam)
Unsteady aerodynamics has been a topic of research since the late 1930’s and has increased in popularity among researchers studying dynamic stall in helicopters, insect/bird flight, micro air vehicles, wind-turbine aerodynamics, and flow-energy harvesting devices. Several experimental and computational studies have helped researchers gain a good understanding of the unsteady flow phenomena, but have proved to be expensive and time-intensive for rapid design and analysis purposes. The aim of the current work is to develop a low-order model capable of simulating incompressible dynamic-stall type flow problems with a focus on accurately modeling the unsteady flow physics with the aim of reducing empirical dependencies. The lumped-vortex-element (LVE) algorithm was used as the baseline unsteady inviscid model to which augmentations were applied to model unsteady viscous effects. The current research was divided into two phases. The first phase focused on augmentations aimed at modeling pure unsteady trailing-edge boundary-layer separation and stall without leading-edge vortex (LEV) formation. The second phase was targeted at including LEV shedding capabilities to the LVE algorithm and combining with the trailing-edge separation model from phase one to realize a holistic, optimized, and robust low-order dynamic stall model. Results from the final low-order model compared excellently with CFD and experimental solutions, both in terms of aerodynamic loads and vortex flow pattern predictions. Overall, the final combined dynamic stall model that resulted from the current research was successful in accurately modeling the physics of unsteady flow thereby helping restrict the number of empirical coefficients to just two variables while successfully modeling the aerodynamic forces and flow patterns in a simple and precise manner.
Shreyas Narsipur was born to N.R. Kumar and Meenakshi Kumar on January 11th, 1989 in Bangalore, India. In 1993, Shreyas and his family moved to Dubai, U.A.E. where he spent 11 years before moving back to Bangalore in 2004. He graduated National Public School in 2006 and went on to pursue a bachelor’s degree in Mechanical Engineering at Amrita Vishwa Vidyapeetham, Kollam, India. He graduated with honors in 2010 and moved to Illinois, U.S.A. in the Fall of 2010 to attend the University of Illinois at Urbana-Champaign in pursuit of a master’s degree in Aerospace Engineering. He had the opportunity to conduct research in UIUC’s Applied Aerodynamics Research Group under the guidance of Dr. Michael Selig and graduated with a M.S. degree in the Spring of 2012. Shortly afterwards, he began working towards a PhD degree under the guidance of Dr. Ashok Gopalarathnam at the North Carolina State University on low-order method development for analyzing unsteady airfoil aerodynamics. He will be receiving his PhD in Aerospace Engineering with a minor in Electrical Engineering in May, 2017 and intends to pursue a long and fulfilling career in the aerospace industry.