Education

Research Description

Dr. Granlund's long term goal is to gain a deeper understanding of separated unsteady, separated flows and develop physics-based low-order force models for maneuvering and control of air vehicles. Unsteady fluid mechanics exist in in several different areas such as helicopter rotor aerodynamics, wind turbines, Micro Air Vehicle flapping flight, high-rate maneuvering conventional aircraft, where the object is unsteady, as well as gusting air with unsteady inflow. In many of these research problems, the freestream has rarely been varied; it is usually assumed to be constant and uniform. Dr. Granlund's research expands the knowledge of how streamwise velocity fluctuations affect "standard" unsteady fluid dynamic problems.

Publications

Experimental analysis of dual coaxial turbines in skew

Metoyer, R., Chatterjee, P., Elfering, K., Bryant, M., Granlund, K., & Mazzoleni, A. (2020), Ocean Engineering, 215, 107877. https://doi.org/10.1016/j.oceaneng.2020.107877

Dual-Actuator Disc Theory for Turbines in Yaw

Khatri, D. N., Chatterjee, P., Metoyer, R., Mazzoleni, A. P., Bryant, M., & Granlund, K. O. (2019), AIAA JOURNAL, 57(5), 2204–2208. https://doi.org/10.2514/1.J057740

Passive flow control for drag reduction in vehicle platoons

Jacuzzi, E., & Granlund, K. (2019), JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS, 189, 104–117. https://doi.org/10.1016/j.jweia.2019.03.001

Stochastic Store Trajectory of Ice Models from a Cavity into Supersonic Flow

Chin, D., Granlund, K., Maatz, I., Schmit, R. F., & Reeder, M. F. (2019), JOURNAL OF AIRCRAFT, Vol. 56, pp. 1313–1319. https://doi.org/10.2514/1.C035104

Leading-edge flow criticality as a governing factor in leading-edge vortex initiation in unsteady airfoil flows

Ramesh, K., Granlund, K., Ol, M. V., Gopalarathnam, A., & Edwards, J. R. (2018), Theoretical and Computational Fluid Dynamics, 32(2), 109–136. https://doi.org/10.1007/s00162-017-0442-0

Experiments and computations on the lift of accelerating flat plates at incidence

Stevens, P. R. R. J., Babinsky, H., Manar, F., Mancini, P., Jones, A. R., Nakata, T., … Ol, M. V. (2017), AIAA Journal, 55(10), 3255–3265. https://doi.org/10.2514/1.j055323

Non-linearity of apparent mass for multi-element bodies

Granlund K., O. M., & L., B. (2016), AIAA Journal, 54(2), 771–776.

Streamwise oscillation of airfoils into reverse flow

Granlund, K., Ol, M. V., & Jones, A. R. (2016), AIAA Journal, 54(5), 1628–1636. https://doi.org/10.2514/1.j054674

Unsteady aerodynamic characteristics of a translating rigid wing at low Reynolds number

Mancini P., M., F., A. J. A., Granlund, K., & Ol, M. (2015), Physics of Fluids (Woodbury, N.Y.), 27(123102).

Unsteady aerodynamic characteristics of a translating rigid wing at low Reynolds number

Mancini, P., Manar, F., Granlund, K., Ol, M. V., & Jones, A. R. (2015), Physics of Fluids, 27(12), 123102. https://doi.org/10.1063/1.4936396

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Grants

LEG-h: Long Endurance Glider, Heavy

Defense Advanced Research Projects Agency (DARPA)(2/24/20 - 1/25/21)

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LEG-h: Long Endurance Glider, Heavy

Sponsor: Defense Advanced Research Projects Agency (DARPA)

Start Date: 2/24/20

End Date: 1/25/21

Abstract

Our vehicle features an organic kite for energy harvesting. The kite is hydrodynamically integrated with the blended wing-body. Unique to our kite concept is a focus on very low-speed flight startup, with operational current speeds as low as 0.25m/s. Central to the design’s low cur-rent power-production capabilities is the use of high-speed cross-current flight, which, for the design of Figure 1, enables more than an order of magnitude of power production than a comparably-scaled fixed turbine. Also unique to our kite is a high-efficiency power takeoff (PTO) device tuned for low-power operations that temporarily stores kinetic energy from kite motions as potential energy before releasing it through a motor generator. The kite will have zero surface expressions, and low noise signature as a result of housing the PTO and generator in the hull of the UUV. Our team’s kite concept development and risk mitigation leverages the ongoing Department of Energy funded research at the NCSU and its affiliates (see Related Experience).

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Device Design and Robust Periodic Motion Control of an Ocean Kite System for Hydrokinetic Energy Harvesting

US Dept. of Energy (DOE) - Energy Efficiency & Renewable Energy (EERE)(5/01/19 - 10/31/20)

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Device Design and Robust Periodic Motion Control of an Ocean Kite System for Hydrokinetic Energy Harvesting

Sponsor: US Dept. of Energy (DOE) - Energy Efficiency & Renewable Energy (EERE)

Start Date: 5/01/19

End Date: 10/31/20

Abstract

This project will focus on the model-based design, flight characterization, robust periodic control, 1/10-scale prototyping, and testing of a rigid kite-based ocean current and tidal energy harvesting system. The system is intended for areas of moderate flow in relatively shallow waters, one example being the shallow waters adjacent to the Gulf Stream. The proposed system will consist of a high lift/drag rigid wing that executes periodic cycles. Each cycle will consist of a high-tension cross-current spool-out phase, followed by a low-tension spool-in phase. The use of multiple control tethers and/or on-board control surfaces will make it possible to achieve and control this desired periodic motion in a manner that is robust to fluctuations and uncertainties (e.g., ocean current speed/direction, etc.). It has been demonstrated that properly controlled periodic motions can lead more than an order of magnitude increase in net energy production over equivalently-sized stationary devices, or equivalently, the same amount of power as a stationary system using an order of magnitude less material. The proposed research will focus on two candidate kite-based system configurations: (i) A system where the electric motors/generators and power electronics are housed on a floating platform out of the water and (ii) a system where they are housed at the seabed, in shallower waters.

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Aerodynamic Forces on Slender Body in Supersonic Cavity

Air Force Research Laboratory (AFRL)(7/09/16 - 9/30/19)

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Aerodynamic Forces on Slender Body in Supersonic Cavity

Sponsor: Air Force Research Laboratory (AFRL)

Start Date: 7/09/16

End Date: 9/30/19

Abstract

The purpose of this project is to investigate the magnitude of lift and pitching moment variation during an unsteady vs. the quasi-steady translation of a slender body from a cavity through a vortex-shear layer into supersonic flow. Mean- and time-varying, as well as frequency content of the normal force and pitching moment will be recorded. To correlate the forces on the store, simultaneous flowfield information, as well as surface pressure data will be obtained. The future application is to investigate whether timed-release of stores from cavities offer a benefit in a more accurate prediction of safe trajectory from the air vehicle.

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