An Unexpected Journey in Rotorcraft CFD

Speaker: Neal Chaderjian, Fundamental Modeling and Simulation Branch, NASA Ames Research Center
February 24, 2015

Presentation

Abstract

Rotorcraft perform many useful civil and military functions by virtue of their ability to take off and land vertically. Consequently, a significant amount of design effort is directed at a rotorcraft’s hover performance. These rotor flow fields consist of complex vortical wakes that are challenging to accurately predict with computational fluid dynamics (CFD). Unlike fixed-wing applications, a rotor blade can encounter the tip vortices of preceding blades. This interaction can strongly affect the vehicle performance, acoustics, and structural vibrations. The situation is further complicated by rotor blade flexibility, requiring a computational structural dynamics (CSD) analysis. Rotorcraft simulations are therefore inherently unsteady and multidisciplinary, combining CFD, CSD, and a flight trim algorithm that determines the blade motions. This talk will highlight the numerical and physical mechanisms involved in the accurate prediction of hover and forward-flight performance and flow fields using the time-dependent Navier-Stokes equations. Examples will draw upon results presented over the past four years and discussed in greater depth, drawing upon lessons learned from hundreds of CFD simulations.

Biography

Chaderjian received his B.S. in Aeronautical Engineering at Cal Poly, San Luis Obispo (1978) and M.S and Ph.D. degrees in Aeronautical and Astronautical Sciences at Stanford University (1984). He has been working at NASA Ames Research Center for 31 years as a research scientist. His research focuses on numerical methods and applications, unsteady viscous flow, numerical flow visualization, and CFD rotorcraft aeromechanics. He is an AIAA Associate Fellow and a member of the American Helicopter Society. He has won several NASA Group Achievement Awards, NASA Ames Honor Award, NASA Exceptional Achievement Medal, and a DOD Technical Achievement Award for Maneuvering Aerodynamics.

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