Education

Research Description

Dr. Gopalarathnam is presently 1) developing adaptive aerodynamics for morphing aircraft, 2) developing aerodynamic prediction techniques for flight dynamics simulations, and 3) studying unsteady and post-stall aerodynamics of aircraft, helicopters, micro-aerial vehicles, and flight in nature. In MAE, Dr. G works with Dr. Edwards, Dr. Wu, and Dr. Peters.

Publications

Flow criticality governs leading-edge-vortex initiation on finite wings in unsteady flow

Hirato, Y., Shen, M., Gopalarathnam, A., & Edwards, J. R. (2021), JOURNAL OF FLUID MECHANICS, 910. https://doi.org/10.1017/jfm.2020.896

Aeroelastic inverse: Estimation of aerodynamic loads during large amplitude limit cycle oscillations

Kirschmeier, B., Pash, G., Gianikos, Z., Medina, A., Gopalarathnam, A., & Bryant, M. (2020), JOURNAL OF FLUIDS AND STRUCTURES, 98. https://doi.org/10.1016/j.jfluidstructs.2020.103131

Amplitude Annihilation in Wake-Influenced Aeroelastic Limit-Cycle Oscillations

Kirschmeier, B. A., Gianikos, Z., Gopalarathnam, A., & Bryant, M. (2020), AIAA JOURNAL, 58(9), 4117–4127. https://doi.org/10.2514/1.J058942

Artificial Lumbered Flight for Autonomous Soaring

Powers, T. C., Silverberg, L. M., & Gopalarathnam, A. (2020), JOURNAL OF GUIDANCE CONTROL AND DYNAMICS, 43(3), 553–566. https://doi.org/10.2514/1.G004397

Limit cycle characterization of an aeroelastic wing in a bluff body wake

Gianikos, Z. N., Kirschmeier, B. A., Gopalarathnam, A., & Bryant, M. (2020), JOURNAL OF FLUIDS AND STRUCTURES, 95(0). https://doi.org/10.1016/j.jfluidstructs.2020.102986

Variation of leading-edge suction during stall for unsteady aerofoil motions

Narsipur, S., Hosangadi, P., Gopalarathnam, A., & Edwards, J. R. (2020), JOURNAL OF FLUID MECHANICS, 900. https://doi.org/10.1017/jfm.2020.467

Aerodynamic Sails for Passive Guidance of High-Altitude Balloons: Static-Stability and Equilibrium Performance

Waghela, R., Yoder, C. D., Gopalarathnam, A., & Mazzoleni, A. P. (2019), JOURNAL OF AIRCRAFT, 56(5), 1849–1857. https://doi.org/10.2514/1.C035353

Low-Order Model for Prediction of Trailing-Edge Separation in Unsteady Flow

Narsipur, S., Gopalarathnam, A., & Edwards, J. R. (2019), AIAA JOURNAL, 57(1), 191–207. https://doi.org/10.2514/1.J057132

Model Reduction in Discrete-Vortex Methods for Unsteady Airfoil Flows

SureshBabu, A. V., Ramesh, K., & Gopalarathnam, A. (2019, April), AIAA JOURNAL, Vol. 57, pp. 1409–1422. https://doi.org/10.2514/1.J057458

Vortex-Sheet Representation of Leading-Edge Vortex Shedding from Finite Wings

Hirato, Y., Shen, M., Gopalarathnam, A., & Edwards, J. R. (2019), JOURNAL OF AIRCRAFT, 56(4), 1626–1640. https://doi.org/10.2514/1.C035124

View all publications via NC State Libraries

Grants

Control of Aeroelastic Structures via Prescribed Aerodynamic Disturbances

National Science Foundation (NSF)(7/01/20 - 6/30/23)

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Control of Aeroelastic Structures via Prescribed Aerodynamic Disturbances

Sponsor: National Science Foundation (NSF)

Start Date: 7/01/20

End Date: 6/30/23

Abstract

The primary innovations of the proposed project will be: (1) a novel method of exercising control over the response of aeroelastic structures through prescribing upstream vortical flow disturbances; (2) an understanding of the mechanisms and governing parameters of unsteady wing force generation in response to impinging vortices; and (3) knowledge of the relationships between desired aeroelastic wing behavior and the appropriate spatial and temporal features of impinging flow disturbances. The current knowledge and understanding of the motion of elastic structures in response to impinging flow disturbances like vortices remains rudimentary and ad-hoc. Both natural and engineered systems offer numerous examples of vortical wakes and flow disturbances interacting with elastic structures. These examples range from fish adopting specialized swimming gaits to improve efficiency when in vortical wakes, to marine mammals sensing and following wake vortices of upstream prey via flexible whisker sensors, to oscillating fluid-elastic energy harvesters passively synchronizing and enhancing power extraction via constructive wake-coupled interactions. While these examples serve as motivating proofs of concept, engineering systems to exploit such interactions and use them as control mechanisms requires understanding of the nonlinear governing relationships between the flow disturbances and the structural dynamics. Our proposed aims will expand knowledge of the fundamental physics that facilitates these fluid-structure interactions such that we can tailor and control vortical disturbances to affect desired dynamic response from fluid-elastic structures. Our proposed work will create the required analytical framework, reveal the fundamental relationships between vortical flow feature parameters and wing forces, formulate control algorithms that produce desired aeroelastic wing responses on demand, and generate reproducible experimental validations that will enable engineers and scientists to understand, exploit, and control the interactions of elastic structures and vortical wake flows.

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Development of a Fast Low-Order Aerodynamic Prediction Method for Aircraft Configurations in Post-Stall Flight

National Aeronautics & Space Administration (NASA)(1/01/18 - 8/15/18)

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Development of a Fast Low-Order Aerodynamic Prediction Method for Aircraft Configurations in Post-Stall Flight

Sponsor: National Aeronautics & Space Administration (NASA)

Start Date: 1/01/18

End Date: 8/15/18

Abstract

The research proposed in this effort aims to combine the prediction techniques and knowledge gained from the past efforts into developing a fast low-order aerodynamic prediction method for full-aircraft configurations (wing+tails+fuselage) and assess the suitability of this method for use in real-time simulation of flight dynamics.

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Further Aerodynamic Modeling of Aerial Refueling Tanker and Receiver Interactions

US Navy(10/16/17 - 3/15/21)

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Further Aerodynamic Modeling of Aerial Refueling Tanker and Receiver Interactions

Sponsor: US Navy

Start Date: 10/16/17

End Date: 3/15/21

Abstract

In this project we will continue further research on aerodynamic modeling of close formation flight of aircraft and their interactions.

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Aerodynamic and Aeroelastic Behavior of Wings in the Presence of Upstream Vortical and Viscous Disturbances

US Air Force - Office of Scientific Research (AFOSR)(7/01/17 - 6/30/21)

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Aerodynamic and Aeroelastic Behavior of Wings in the Presence of Upstream Vortical and Viscous Disturbances

Sponsor: US Air Force - Office of Scientific Research (AFOSR)

Start Date: 7/01/17

End Date: 6/30/21

Abstract

In this research, we propose to study the effects of upstream vortical and viscous flow disturbances on the unsteady aerodynamics of airfoils undergoing prescribed motions and on the aeroelastic characteristics of flexible airfoils.

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Aerodynamic Modeling of Aerial Refueling Tanker and Receiver Interactions

US Navy(6/02/16 - 8/28/17)

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Aerodynamic Modeling of Aerial Refueling Tanker and Receiver Interactions

Sponsor: US Navy

Start Date: 6/02/16

End Date: 8/28/17

Abstract

In this research effort, we will develop a vortex lattice method for determining the incremental loads on one aircraft flying in the vicinity of another, for the purposes of developing aerodynamic models for simulation.

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CFD and Experimental Studies to Aid Development of Low-Order Aerodynamic Prediction Methods for Post-Stall Flight

National Aeronautics & Space Administration (NASA)(1/01/16 - 9/15/17)

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CFD and Experimental Studies to Aid Development of Low-Order Aerodynamic Prediction Methods for Post-Stall Flight

Sponsor: National Aeronautics & Space Administration (NASA)

Start Date: 1/01/16

End Date: 9/15/17

Abstract

We propose the development of low-order aerodynamic prediction methods for aircraft configurations at post-stall conditions, using computational fluid dynamics to help guide the development.

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Angelfish: Initial Planning and Project Management

Defense Advanced Research Projects Agency (DARPA)(6/19/14 - 1/31/16)

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Angelfish: Initial Planning and Project Management

Sponsor: Defense Advanced Research Projects Agency (DARPA)

Start Date: 6/19/14

End Date: 1/31/16

Abstract

The objective of Project Angelfish is to develop a dual-purpose (air and water) unmanned system, referred to as Angelfish. The system to be developed will be capable of locomotion and controlled maneuvering in both the aerial and subsurface domains. The air-purpose performance (flight distance, duration, etc.) is to be minimally compromised by the water-purpose requirements, and the transition between air and water are to be as reliable as possible, again with minimal performance penalty (power). The goal of the effort is to develop alternative designs that lie throughout the trade space and to focus the further development on the most promising design or set of designs.

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Evaluation of Flexible Micropost Arrays for Shear Stress Measurement

National Aeronautics & Space Administration (NASA)(7/10/14 - 7/09/16)

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Evaluation of Flexible Micropost Arrays for Shear Stress Measurement

Sponsor: National Aeronautics & Space Administration (NASA)

Start Date: 7/10/14

End Date: 7/09/16

Abstract

Micropillar arrays will be developed for shear stress measurement in NCSU subsonic wind tunnel. Micropillar array sensors will be characterized first, and then assembled into a test model and calibrated in the wind tunnel. Such a measurement device enables new aerodynamics research needed to design more fuel efficient, quieter aircraft with improved dynamics for smoother and safer flight.

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Aerodynamic Sensing using Miniature Transducers

General Electric Co.(3/01/13 - 12/31/13)

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Aerodynamic Sensing using Miniature Transducers

Sponsor: General Electric Co.

Start Date: 3/01/13

End Date: 12/31/13

Abstract

In this project we will develop aerodynamic sensing on an airfoil using miniature pressure transducers.

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Harnessing Fluid-Structure Interaction in Wind Power and Sustainable Air Transport

University Global Partnership Network (UGPN)(3/01/13 - 2/28/14)

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Harnessing Fluid-Structure Interaction in Wind Power and Sustainable Air Transport

Sponsor: University Global Partnership Network (UGPN)

Start Date: 3/01/13

End Date: 2/28/14

Abstract

A research collaboration between Dr Joseba Murua (University of Surrey) and Prof Ashok Gopalarathnam (North Carolina State University) is hereby proposed for the second call for proposals of the University Global Partnership Network (UGPN). The collaboration will tackle the multi-physics interaction between fluids and structures, focusing on the development of design-oriented modelling tools applicable to both wind turbines and aerospace vehicles. The aerodynamic efficiency of aircraft and wind turbines can be maximised using low-weight and slender wings/blades operating at conditions just short of aerodynamic stall. However, light, slender and thus flexible structures exhibit coupled fluid-structure behaviour, increasing the likelihood of reaching stall, a sub-optimal flow regime. A design-oriented computational tool that captures this fluid-structure interaction and accounts for stall is proposed, integrating the so-called decambering approach into a flexible aircraft model. The resulting multidisciplinary framework will be applicable to a wide range of current and novel systems in both aerospace and wind power, filling a niche area for fast yet accurate simulation capability. The project will be based on the placement of a PhD student, and the outcome of the research will be published in a flagship international aerospace conference and a high-impact journal. The project is also expected to establish the foundations of a long-term collaboration that will focus on exploiting fluid-structure interaction to optimise aerodynamic performance in next-generation technologies.

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