Global Luminescent Oil-film Skin-Friction Meter Generalized to Three-Dimensional Geometry and Applied to FAITH Hill

Abstract

This paper further develops the global luminescent oil-film skin-friction meter by considering its application to a three dimensional axisymmetric wall-mounted bump subjected to subsonic turbulent boundary layer flow. The geometry gives rise to a necklace vortex and large scale separation on its lee side. An oil-film is only usable by the global luminescent oil-film skin-friction meter if it meets certain criteria. Most notably, it must be sufficiently thick to provide a good signal but not so thick that the relationship between luminescent intensity and oil-film thickness becomes nonlinear. Different regions on the model give rise to a usable oil-film at different times in an experiment. This paper proposes a technique for the selection of which solutions from a sequence of "snapshot solutions" taken during the run should be averaged for a particular region on the model. A relative skin-friction distribution resulting from the techniques proposed herein is presented for each of four sections of the model: One down the model's centerline, and three across the model in the spanwise direction. Nomenclature y = height of model H = total height of model ℎ = thickness of oil film r = radial distance from origin ( 1 , 2 , 3 ) = global coordinate system in object space ( ̅ 1 , ̅ 2 , ̅ 3 ) = coordinate system with 1-2 plane locally tangent to surface (̃1,̃2,̃3) = coordinate system with 1-2 plane parallel with image plane S = function describing surface of model in ( 1 , 2 , 3 ) coordinates ̃ = function describing surface of model in (̃1,̃2,̃3) coordinates t = time p = static pressure of external flow field = dynamic viscosity of oil-film = density of oil-film = -th component of gravity = -th component of skin-friction = change of coordinate matrix I = Intensity of luminescent oil-film = Intensity of the excitation light incident on the oil-film = coefficient proportional to quantum efficiency of luminescent molecules = skin-friction ̅ = equivelant skin-friction = Lagrange multiplier Downloaded by UNIVERSITY OF QUEENSLAND on October 8, 2015 | http://arc.aiaa.org |

Computations of the BeVERLI Hill Three-dimensional Separating Flow Model Validation Cases

“…Hill, which captures many features shared by applications involving three-dimensional flow separation. Similar studies involving flow over hills were conducted in the past by Simpson et al [11], Byun and Simpson [12], in the NASA Faith Hill experiments by Bell et al [13] and Husen et al [14], and more recently in another ongoing collaborative effort between the University of Washington and Boeing [15][16][17]. Other studies include two-dimensional hills with a range of shapes [18,19], axisymmetric aft body flows [20,21], and backward-facing ramps [22].…”

Feasibility of skin-friction field measurements in a transonic wind tunnel using a global luminescent oil film

“…In its original formulation, an optical-flow method was proposed to extract the skinfriction field from the oil-film images. Using GLOF, relative (normalized) skin-friction distributions were obtained for low-speed flows in Woodiga and Liu (2009); ; Husen et al (2014); Zhong et al (2015); and Liu (2019). A further GLOF image analysis method based on the linear least-squares (LLS) method was presented in , where it was applied to extract relative skinfriction fields in subsonic and supersonic flows.…”

A new formulation for delayed detached eddy simulation based on the Smagorinsky LES model

“…For the specified bulk velocity U b , the predicted Re τ values for Model 1 and Model 2 are Bell et al (2012) and Husen et al (2014).…”