Unsteady Motion in the Supersonic Flow over a Wall-Mounted Hemisphere

Kiriakos, Ramez M.; Rivero, Mario J.; Khamseh, Arastou Pournadali; DeMauro, Edward P.

doi:10.2514/1.j060644

Cited by 2 publications

(2 citation statements)

References 33 publications

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“…2014; Kiriakos et al. 2021). Large-eddy simulations (LES) and direct numerical simulations (DNS) have been applied widely in the above-mentioned studies.…”

Section: Introductionmentioning

confidence: 99%

“…There have been many studies performed on hemispherical roughness elements (Toy et al 1983;Tang & Jiang 2012;Citro et al 2015), especially within turbulent boundary layers (Savory & Toy 1986b;Manhart 1998;Tavakol & Yaghoubi 2010;Tavakol, Yaghoubi & Motlagh 2010;Guala et al 2012;Wood et al 2016;Cao & Tamura 2020;Li et al 2022). Previous investigations also include particle transport in hemispherical wakes (Prevel et al 2013;Gao et al 2021), hemisphere in pulsatile flows (Carr & Plesniak 2016;Carr et al 2020), and hemispherical wakes in the supersonic regime (Wang et al 2012;Mortazavi et al 2014;Kiriakos et al 2021). Large-eddy simulations (LES) and direct numerical simulations (DNS) have been applied widely in the above-mentioned studies.…”

Section: Introductionmentioning

confidence: 99%

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Tomographic PIV investigation on near-wake structures of a hemisphere immersed in a laminar boundary layer

Tu,

Wang,

Gao

et al. 2023

J. Fluid Mech.

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The near wake of a hemisphere immersed in a laminar boundary layer is studied utilizing time-resolved tomographic particle image velocimetry (TPIV). Focus is placed on the three-dimensional vortical structures and the formation details of hairpin vortices before the onset of transition. The three-dimensional instantaneous pressure field of the hemisphere wake is reconstructed for better understanding the flow mechanism. Experiments are carried out with Reynolds number $Re_{r}=1370$ , based on the hemisphere radius $R$ . Features of periodicity of the near wake are analysed using proper orthogonal decomposition and Fourier transformation. The velocity fluctuation in the wall-normal direction is shown to be crucial to the formation of hairpin vortices in the near wake. By investigating the transport of mass and vorticity, and the correlation between pressure and hairpin vortex strength, the formation mechanism is revealed clearly. Specifically, the main hairpin vortices (MHVs) are formed within the reaction of outer high-speed flow and near-wall flow. The formation of the head portion is followed by the leg portion formation. The shedding of the MHVs is highly correlated with the pressure, as well as the pressure gradient in the wall-normal direction. For the side hairpin vortices (SHVs), the leg portion is formed first, followed by the generation of the head portion thanks to induction of the re-oriented standing vortices. The generation of the SHVs can be regarded as the downstream bridging of the standing vortices, similar to the generation of hairpin vortices due to the connection of streamwise vortices in turbulent boundary layers.

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“…2014; Kiriakos et al. 2021). Large-eddy simulations (LES) and direct numerical simulations (DNS) have been applied widely in the above-mentioned studies.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tomographic PIV investigation on near-wake structures of a hemisphere immersed in a laminar boundary layer

Tu,

Wang,

Gao

et al. 2023

J. Fluid Mech.

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Scaling law of aero-optical steady-distortion for hemisphere-on-cylinder conformal-window turrets across the subsonic, transonic, and supersonic flows

Ren,

Yu,

Zhang

et al. 2024

Physics of Fluids

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Aero-optical steady-distortion reduces the far-field quality of the forward-looking laser beam of an airborne turret. It has a complex relation with the viewing angle of the laser beam and the flow around the turret at different flight speeds. In this paper, the aero-optical steady-distortion, including the fixed tip/tilt and steady-lensing wavefront, for a hemisphere-on-cylinder turret with a conformal window is analyzed at different freestream Mach numbers (Ma∞=0.3–1.7) and window angles. Computational fluid dynamics and particle-based ray-tracing methods are combined to simulate the steady-state flow over the turret and its aero-optical effect. The scaling laws of the fixed tip/tilt and steady-lensing wavefront for the forward-looking laser beam are summarized under these subsonic, transonic, and supersonic flows. The results show that the scaling factor Ma∞2 is only applicable to the wavefront distortion caused by low-velocity flows, while the relevant scaling factors Ma∞2/[1+(γ+1)Ma∞2(γ+1)/(γ−1)] and (γ−1)/(2γ)Ma∞γ/(γ−1) are effective across subsonic/transonic and supersonic flows. The fixed tip/tilt is discussed separately, and its scaling factor and scaling law differ from the steady-lensing wavefront. In addition, the fixed tip/tilt and steady-lensing wavefront within these flow regimes are only related to the viewing angle, not the elevation angle.

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Unsteady Motion in the Supersonic Flow over a Wall-Mounted Hemisphere

Cited by 2 publications

References 33 publications

Tomographic PIV investigation on near-wake structures of a hemisphere immersed in a laminar boundary layer

Tomographic PIV investigation on near-wake structures of a hemisphere immersed in a laminar boundary layer

Scaling law of aero-optical steady-distortion for hemisphere-on-cylinder conformal-window turrets across the subsonic, transonic, and supersonic flows

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