Evaluation of Turbulence Modeling Effects on Ground Shear Stress and Tip Vortex Dynamics for the Dragonfly Rotor in Ground Effect
Keywords
titan rotorcraft, dragonfly mission, cfd, ground effect, rotorcraft aerodynamics, wall shear stress, tip vortex dynamics, turbulence modeling, reynolds stress model, k-omega sst, virtual disk method, blade-resolved simulation, rotor-surface interaction, titan atmosphere, dust mobilization, brownout risk, near-ground flow, hover performance, rotor wake interaction, vehicle loading, fuselage pressure fluctuations, planetary rotorcraft, wall jet, recirculation zone, unsteady aerodynamics, computational fluid dynamics, induced flow modeling, rotor performance prediction, extraterrestrial flight, aerospace mission design
Presenter Abstract
11th Conference of the International Society for Atmospheric Research using Remotely-piloted Aircraft 25–28 August 2026 at Embry-Riddle Aeronautical University, Daytona Beach, United States
Evaluation of Turbulence Modeling Effects on Ground Shear Stress and Tip Vortex Dynamics for the Dragonfly Rotor in Ground Effect
Michael Marques1, Jackson Asiatico1, Ralph Lorenz2, Michael Kinzel1
1Embry-Riddle Aeronautical University, Daytona Beach, FL, 32114, USA
2Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA
∗Corresponding email: goncalvm@erau.edu
NASA Dragonfly rotorcraft is designed to perform leap-frog flights across dune fields of Titan, requiring low-altitude operations during takeoff, landing, and hover. This study examines the aerodynamic behavior of the Dragonfly rotor near the surface under Titan atmospheric conditions using Computational Fluid Dynamics (CFD). Performance is evaluated in and out of ground effect (IGE and OGE), with emphasis on thrust, moments, vehicle loading, and terrain wall shear stress (WSS) as functions of normalized rotor height (h/D). High-fidelity blade-resolved simulations are compared with lower-order virtual disk simulations using multiple turbulence models to assess predictive accuracy. Particular attention is given to wall shear stress distributions on the ground, a key parameter for brownout and dust mobilization models, and to the influence of turbulence closure on near-ground flow fidelity. The blade-resolved approach captures tip vortex evolution and ground interaction, whereas the virtual disk method approximates induced flow through turbulence modeling. Comparisons among Reynolds Stress Models (RSM), k–ω SST, and other eddy-viscosity models reveal differences in vortex impingement and predicted shear stress magnitudes. Results indicate a delayed onset of ground effect in VADR configurations, with thrust increasing near h/D ≈ 0.6. Below this threshold, the flow becomes increasingly unsteady and produces larger pressure fluctuations on the fuselage. High-WSS regions develop within recirculating zones beneath the rotor disk, indicating elevated potential for dust mobilization during surface operations. These findings improve understanding of rotor-surface interactions on Titan and clarify the validity and limitations of virtual disk approaches for predicting near-ground aerodynamic behavior.
Presentations
Presented in Session 2: Platform Development II
Evaluation of Turbulence Modeling Effects on Ground Shear Stress and Tip Vortex Dynamics for the Dragonfly Rotor in Ground Effect
11th Conference of the International Society for Atmospheric Research using Remotely-piloted Aircraft 25–28 August 2026 at Embry-Riddle Aeronautical University, Daytona Beach, United States
Evaluation of Turbulence Modeling Effects on Ground Shear Stress and Tip Vortex Dynamics for the Dragonfly Rotor in Ground Effect
Michael Marques1, Jackson Asiatico1, Ralph Lorenz2, Michael Kinzel1
1Embry-Riddle Aeronautical University, Daytona Beach, FL, 32114, USA
2Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA
∗Corresponding email: goncalvm@erau.edu
NASA Dragonfly rotorcraft is designed to perform leap-frog flights across dune fields of Titan, requiring low-altitude operations during takeoff, landing, and hover. This study examines the aerodynamic behavior of the Dragonfly rotor near the surface under Titan atmospheric conditions using Computational Fluid Dynamics (CFD). Performance is evaluated in and out of ground effect (IGE and OGE), with emphasis on thrust, moments, vehicle loading, and terrain wall shear stress (WSS) as functions of normalized rotor height (h/D). High-fidelity blade-resolved simulations are compared with lower-order virtual disk simulations using multiple turbulence models to assess predictive accuracy. Particular attention is given to wall shear stress distributions on the ground, a key parameter for brownout and dust mobilization models, and to the influence of turbulence closure on near-ground flow fidelity. The blade-resolved approach captures tip vortex evolution and ground interaction, whereas the virtual disk method approximates induced flow through turbulence modeling. Comparisons among Reynolds Stress Models (RSM), k–ω SST, and other eddy-viscosity models reveal differences in vortex impingement and predicted shear stress magnitudes. Results indicate a delayed onset of ground effect in VADR configurations, with thrust increasing near h/D ≈ 0.6. Below this threshold, the flow becomes increasingly unsteady and produces larger pressure fluctuations on the fuselage. High-WSS regions develop within recirculating zones beneath the rotor disk, indicating elevated potential for dust mobilization during surface operations. These findings improve understanding of rotor-surface interactions on Titan and clarify the validity and limitations of virtual disk approaches for predicting near-ground aerodynamic behavior.
Presenter Biography (Optional)
Aerospace engineer specializing in fluid dynamics and aeroacoustics, currently a postdoctoral researcher at Embry-Riddle after completing a PhD there. Research spans supersonic jets, rotor performance, and acoustic modeling, with projects supported by ONR and NASA ULI, plus industry experience at Joby Aviation in rotor broadband noise prediction.