Whole-field velocity measurements around an 
axisymmetric body with a Stratford–Smith 
pressure recovery

Hammache, Mustapha; Browand, F. K.; Blackwelder, Ron F.

doi:10.1017/s0022112002008479

Cited by 10 publications

(2 citation statements)

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“…The BOR geometry, shown in figure 1, was inspired by prior work on a body of revolution with an aft ramp designed to have a Stratford–Smith pressure distribution (that corresponds to a boundary layer constantly on the verge of separation) (Hammache et al. 2002). The BOR was chosen to have a characteristic length of m, with a fore body comprised of a semi-ellipsoid nose and a constant-diameter () cylindrical section, with a 0.8 mm square trip ring sandwiched at (the trip was approximately 35 % of the local boundary layer thickness estimate obtained from the Thwaites–Walz method (Schetz & Bowersox 2011)).…”

Section: Apparatus and Instrumentationmentioning

confidence: 99%

“…However, studies on axisymmetric boundary layers under streamwise pressure gradients are relatively limited, focusing mostly on the mean flow in the adverse pressure gradient (APG) region or nearly separating flows, and downstream wake (Dengel & Fernholz 1990; Hammache, Browand & Blackwelder 2002; Jimenez, Hultmark & Smits 2010; Kumar & Mahesh 2018 b ; Manovski et al. 2020).…”

Section: Introductionmentioning

confidence: 99%

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The structure of a highly decelerated axisymmetric turbulent boundary layer

et al. 2021

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Experiments were performed over a body of revolution at a length-based Reynolds number of 1.9 million. While the lateral curvature parameters are moderate ( $\delta /r_s < 2, r_s^+>500$ , where $\delta$ is the boundary layer thickness and r s is the radius of curvature), the pressure gradient is increasingly adverse ( $\beta _{C} \in [5 \text {--} 18]$ where $\beta_{C}$ is Clauser’s pressure gradient parameter), representative of vehicle-relevant conditions. The mean flow in the outer regions of this fully attached boundary layer displays some properties of a free-shear layer, with the mean-velocity and turbulence intensity profiles attaining self-similarity with the ‘embedded shear layer’ scaling (Schatzman & Thomas, J. Fluid Mech., vol. 815, 2017, pp. 592–642). Spectral analysis of the streamwise turbulence revealed that, as the mean flow decelerates, the large-scale motions energize across the boundary layer, growing proportionally with the boundary layer thickness. When scaled with the shear layer parameters, the distribution of the energy in the low-frequency region is approximately self-similar, emphasizing the role of the embedded shear layer in the large-scale motions. The correlation structure of the boundary layer is discussed at length to supply information towards the development of turbulence and aeroacoustic models. One major finding is that the estimation of integral turbulence length scales from single-point measurements, via Taylor's hypothesis, requires significant corrections to the convection velocity in the inner 50 % of the boundary layer. The apparent convection velocity (estimated from the ratio of integral length scale to the time scale), is approximately 40 % greater than the local mean velocity, suggesting the turbulence is convected much faster than previously thought. Closer to the wall even higher corrections are required.

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