Cfd Sensitivity Analysis of a Modern Civil Transport Near Buffet-Onset Conditions

by National Aeronautics and Space Administration

A computational fluid dynamics (CFD) sensitivity analysis is conducted for a modern civil transport at several conditions ranging from mostly attached flow to flow with substantial separation. Two different Navier-Stokes computer codes and four different turbulence models are utilized, and results are compared both to wind tunnel data at flight Reynolds number and flight data. In-depth CFD sensitivities to grid, code, spatial differencing method, aeroelastic shape, and turbulence model are described for conditions near buffet onset (a condition at which significant separation exists). In summary, given a grid of sufficient density for a given aeroelastic wing shape, the combined approximate error band in CFD at conditions near buffet onset due to code, spatial differencing method, and turbulence model is: 6% in lift, 7% in drag, and 16% in moment. The biggest two contributers to this uncertainty are turbulence model and code. Computed results agree well with wind tunnel surface pressure measurements both for an overspeed 'cruise' case as well as a case with small trailing edge separation. At and beyond buffet onset, computed results agree well over the inner half of the wing, but shock location is predicted too far aft at some of the outboard stations. Lift, drag, and moment curves are predicted in good agreement with experimental results from the wind tunnel.Rumsey, Christopher L. and Allison, Dennis O. and Biedron, Robert T. and Buning, Pieter G. and Gainer, Thomas G. and Morrison, Joseph H. and Rivers, S. Melissa and Mysko, Stephen J. and Witkowski, David P.Langley Research CenterBUFFETING; COMPUTATIONAL FLUID DYNAMICS; SENSITIVITY ANALYSIS; TURBULENCE MODELS; WIND TUNNEL TESTS; SEPARATED FLOW; FINITE DIFFERENCE THEORY; NAVIER-STOKES EQUATION; PRESSURE MEASUREMENT

64 pages, Paperback

Published May 29, 2018

About the author

The National Aeronautics and Space Administration (NASA) is an independent agency of the U.S. federal government responsible for the civil space program, aeronautics research, and space research.