Progress toward CFD for full flight envelope

Abstract

The value of computational fluid dynamics, CFD, delivered to date has mainly been related to its application to high-speed cruise design. To increase its applicability CFD must apply to the full flight envelope frequently characterised by large regions of separated flows. These flows are encountered by transport aircraft at low speed with deployed high lift devices, at their structural design loads conditions, or subjected to in-flight upsets that expose them to speed and/or angle-of-attack conditions outside the envelope of normal flight conditions to name a few. Such flows can only be characterised by the Navier-Stokes equations. This paper will report the progress toward CFD for full flight envelope. The CFD methods in use at Boeing will be described. Examples presented will address high-lift, loads and stability and control concerns including Reynolds scaling from wind tunnel to flight, vortex generator simulation, spoiler and horizontal tail effectiveness. In general, results shown are in ‘good enough’ agreement with experimental data. Deficiencies and the need for further algorithm and process improvement are noted. The need for automation to enable the large scale use of CFD will also be discussed.

Enabling the environmentally clean air transportation of the future: a vision of computational fluid dynamics in 2030

“…(ii) Physical modelling Advances in the physical modelling of turbulence for separated flows, transition and combustion are critically needed to achieve the desired state of CFD in 2030 [8,[12][13][14][15][16][17]. For the advancement of turbulent flow simulation, three separate tracks for research are proposed: RANS-based turbulence treatments; hybrid RANS/LES approaches where the entire boundary layer is resolved with RANS-based models, and the outer flow is resolved with LES models; and LES, including both wall-modelled (WMLES) and wall-resolved (WRLES).…”

Computational Methods for Stability and Control (COMSAC): The Time Has Come

“…Reynolds number scaling effects on elevator control authority at a low Mach number are presented in figure 32, and detailed by Tinoco 29 . CFD results show good correlation with experimental trends and a general increase in control authority with increasing Reynolds number out to flight conditions.…”

Reduced-order models for aerodynamic applications, loads and MDO

“…For unconventional aircraft, where little or no engineering experience is available, up to 10 million computations may be required. The use of high-fidelity computational fluid dynamics (CFD) in this context is at the horizon [1], but still too costly and time consuming to provide all the required aerodynamic data [57], i.e., steady and unsteady pressure and shear stress distributions on the aircraft surface, at any point within this envelope [65]. This motivates procedures and techniques aimed at reducing the computational cost and complexity of high-fidelity simulations in order to provide accurate but fast computations of, e.g., the aerodynamic loads and aircraft performance [34].…”