Studies of Flow Topology around Hemisphere at Transonic Speeds Using Time-Resolved Oil Flow Visualization

Gordeyev, Stanislav; Vorobiev, Alexander; Jumper, Eric J.; Gogineni, Sivaram; Wittich, Donald J.

doi:10.2514/6.2016-1459

Cited by 18 publications

(7 citation statements)

References 13 publications

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“…Additionally, at this Strouhal number, there are no shock-related motions present. Assuming that these small structures are inside the interface region between the upcoming flow and the recirculating region downstream of the hemisphere, the recirculation region appears to be smaller for M = 0.55, see Figure 16, bottom, than for M = 0.65, see Figure 16, top; similar conclusions were made using the oil-based surface flow visualization studies around the hemisphere [15]. The higher order modes also show a weakness of DMD: local shot noise begins to corrupt the modes.…”

Section: B Dmd Resultssupporting

confidence: 55%

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Modal Analysis of the Surface Pressure Field Around a Hemispherical Turret using Pressure Sensitive Paint

Lucca

Gordeyev

Morrida

et al. 2018

2018 AIAA Aerospace Sciences Meeting

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Fast-response Pressure Sensitive Paint (PSP) measurements were performed on hemispherical models at transonic flow speeds. Both Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) were used to analyze the spatially and temporally resolved data. POD was used to isolate the dominant behavior in the data and isolate the dominant frequencies by looking at the temporal coefficient spectra. DMD was then used to further investigate specific frequencies. At St = 0.15-0.2, previously investigated "wake breathing" and "wake shifting" modes were found. These modes represent large spanwise symmetric and antisymmetric structures, respectively. Further, at St = 1 and St = 2, DMD showed that the wake of the turret was dominated by smaller convecting structures. The DMD modes were used to estimate the convective velocity in the wake, which was found to be relatively constant across various Strouhal Numbers.

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Section: B Dmd Resultssupporting

confidence: 55%

“…To predict these shock properties, the flow dynamics must be better understood. Optical and pressure measurements in both flight and tunnel tests indicate that there is a coupling between the shock and wake motion [13,14,15,16,17].…”

Section: Introductionmentioning

confidence: 99%

Modal Analysis of the Surface Pressure Field Around a Hemispherical Turret using Pressure Sensitive Paint

Lucca

Gordeyev

Morrida

et al. 2018

2018 AIAA Aerospace Sciences Meeting

Self Cite

View full text Add to dashboard Cite

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“…The second and the third modes are symmetric in the spanwise direction. Most of the pressure variations in these first modes are near or upstream of the separation line, which is approximately located at x/R = 0.2 [18]. Overall, these POD modes are very similar to the POD modes, observed on a hemisphere-on-cylinder turret for M = 0.4 [3].…”

Section: IVsupporting

confidence: 67%

“…The necklace vortex is present as a thin line in front of the hemisphere and the "footprint" of the turbulent wake is seen downstream of the hemisphere, between x/R = 1 -3. In [18] the topology of the wake was studied using oil-flow visualization technique and the approximate extent of the recirculation region downstream of the hemisphere is also plotted in Figure 4 as a dotted line. The region of the increased pressure fluctuations approximately coincides with the boundary of the recirculation region.…”

Section: IVmentioning

confidence: 99%

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Conditional Studies of the Wake Dynamics of Hemispherical Turret Using PSP

Gordeyev

Lucca

Morrida

et al. 2018

2018 AIAA Aerospace Sciences Meeting

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Fast-response Pressure-Sensitive Paint (PSP) was used to study the wake response of the hemispherical turret at different subsonic and transonic Mach numbers to different pressure patterns on the hemisphere itself. POD technique was used to extract dominant spatial modes and the corresponding temporal coefficients of the unsteady pressure field on the hemisphere. The unsteady pressure distributions in the wake for different conditional events, such as large positive or negative temporal coefficients for different hemisphere-only POD modes, were computed and analyzed. It was found that the wake has the two main dynamic modes, the "switching" and "breathing" ones. The wake dynamics was found to be coupled with the instantaneous location of the separation line on the hemisphere. In the range of tested Mach numbers, the presence of the unsteady shock on the hemisphere did not have any significant effect of the wake dynamics.

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Advanced surface oil flow visualization technique applied to complex transonic flows for the verification of viscous effects in CFD

Mielke

Klatt

Leopold

et al. 2022

J Vis

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Studies of Flow Topology around Hemisphere at Transonic Speeds Using Time-Resolved Oil Flow Visualization

Cited by 18 publications

References 13 publications

Modal Analysis of the Surface Pressure Field Around a Hemispherical Turret using Pressure Sensitive Paint

Modal Analysis of the Surface Pressure Field Around a Hemispherical Turret using Pressure Sensitive Paint

Conditional Studies of the Wake Dynamics of Hemispherical Turret Using PSP

Advanced surface oil flow visualization technique applied to complex transonic flows for the verification of viscous effects in CFD

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