Navier-Stokes Simulation of UH-60A Rotor/Wake Interaction Using Adaptive Mesh Refinement

Speaker: Neal M. Chaderjian, Computational Physics Branch, NASA Advanced Supercomputing Division
May 18, 2017

Presentation

Abstract

Time-dependent Navier-Stokes simulations have been carried out with the OVERFLOW CFD code for a flexible UH-60A Blackhawk helicopter rotor in forward flight. Previous studies have shown that resolution of the vortex wake beyond engineering accuracy, ΔS=10% of the blade-tip chord, has little effect on the predicted rotor airloads. However, these cases had very little blade-wake interaction. The numerical results presented in this seminar have very strong blade-wake interaction, including blade vortex interaction (BVI), and dynamic stall with BVI. These are two common conditions that occur as modern helicopter designs strive to achieve greater flight speeds and payloads. The numerical simulations utilize high-order spatial accuracy and a hybrid RANS/LES turbulence model. A practical engineering guideline is sought by examining how rotor wake resolution affects the prediction of the rotor normal force, pitching moment, and chord force using adaptive mesh refinement (AMR). Moreover, BVI was found to trigger dynamic stall, a relatively unknown phenomenon. State-of-the-art time-dependent flow visualization is utilized to provide an improved understanding of the numerical and physical mechanisms involved with three-dimensional dynamic stall.

Biography

Neal Chaderjian received his B.S. degree (1978) in Aeronautical Engineering from Cal Poly, San Luis Obispo, and his M.S. (1979) and Ph.D. (1984) degrees in Aeronautical and Astronautical Sciences from Stanford University. He has been working at NASA Ames Research Center for 33 years, and his research interests include numerical methods and applications, unsteady viscous flow, numerical flow visualization, and CFD Rotorcraft aeromechanics. Neal is an AIAA Associate Fellow and a member of the American Helicopter Society. He is also the recipient of numerous awards including several NASA Group Achievement Awards, NASA Ames Honor Award, NASA ARMD Associate Administrator Award, NASA Exceptional Achievement Medal, and DOD Technical Achievement Award for Maneuvering Aerodynamics.

Seminar Participation

Attending In Person

For select seminars, you may wish to attend in-person if you are in the vicinity of NASA Ames Research Center. These AMS seminars are held in Building N258 in Room 127, just off the front lobby. Sessions available to attend in-person will be indicated in the announcement information. In-person participants without NASA badges will need a valid visitor badge (US citizenship or permanent residency is required) to enter the facility.

Join Us Online

To attend an AMS seminar, click on the Microsoft Teams link in the seminar description. You can connect through the desktop Teams App if you have it, or you can select "Watch on the Web Instead" to enter the meeting as a guest. Please ensure that you've muted your microphone in Teams before you select "Join Now" to enter the meeting lobby.