Unsteady Shock Motion in a Transonic Flow over a Wall-Mounted Hemisphere

Beresh, Steven J.; Henfling, John F.; Spillers, Russell Wayne; Pruett, Brian Owen Matthew

doi:10.2514/1.j055040

Cited by 23 publications

(8 citation statements)

References 27 publications

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“…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

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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: 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

View full text Add to dashboard Cite

show abstract

“…Due to the presence of shock and shock-related separation at the surface of a turret, the flow over it under transonic free stream conditions is quite complex. To study the detailed regime of the transonic flow field over a turret, much experimental and numerical work has been performed (Coirier et al 2014;Vorobiev et al 2014;Beresh et al 2016;De Lucca et al 2018;Kamel et al 2019;Weston and Sherer 2019). Vorobiev et al (2014) studied the relationship between shock and relevant separation in a two-dimensional cylindrical turret in wind tunnel experiments.…”

Section: Introductionmentioning

confidence: 99%

“…Active flow control, unlike passive flow control, involving additional energy brought into the flow field, is also effective for the control of the features of flow Gregory 2015a,b, 2018;Joshi and Bhattacharya 2019; Bhattacharya and Gregory 2020; Bhattacharya and Ahmed 2020) and OPD reduction (Tian et al 2020). Beresh et al (2016) studied shock motion and related flow fields in the wake of a hemispherical turret using wind tunnel experiments. The shock locations of the 3D turret were different than those of the 2D cylindrical turret.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of the Influences of the Features of Transonic Flow over a Hemispherical Turret on Beam Wavefront Distortions

2023

JAFM

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Complex features of transonic flow over a turret make it challenging to use passive flow control to reduce aero-optical effects. In this study, the influence of different flow features on wavefront distortions is numerically investigated through improved delayed detached eddy simulation coupled with a modified sub-grid scale. The proper orthogonal decomposition (POD) method is used to study the spatiotemporal characteristics of the flow features. The flow field changes in the wake along with the motion of the shock. Two features, namely, lateral shift (dominant in modes 1 and 2) and wall-normal fluctuation (dominant in modes 3 and 4) of the wake, are the most dominant in the flow field. All beams share the common feature of transmitting the flow field, in which a large component of optical path difference (OPD) appears at St=0.35, indicating the high impact of wall-normal fluctuation on the distortion of the wavefront. After the different POD modes, which contain 30% of the mode energy, are removed, all beams transmitted through different reconstructed fields show very different features for OPD. The flow features that do not exhibit higher-order modes from modes 21 to 92 affect the OPD slightly, as the OPD components in the low-St region are almost unchanged. With the removal of modes from 3 to 32, wavefront distortions are considerably reduced, particularly at St=0.35. The wavefront distortions are most reduced after the lower order modes from 1 to 20 are removed, as the components of OPD in the low-St region are dramatically reduced. The significant relations between OPD and the flow features reveal that controlling the dominant flow features has significant potential for reducing aero-optical effects.

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“…Optical and pressure measurements in both flight and tunnel tests indicate that at transonic speeds there is a coupling between the shock and the wake motion [16][17][18][19][20]. Recent advances in fast-response Pressure Sensitive Paint (PSP) allows studying a full spatio-temporal pressure field on and around the turret.…”

Section: Introductionmentioning

confidence: 99%

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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Unsteady Shock Motion in a Transonic Flow over a Wall-Mounted Hemisphere

Cited by 23 publications

References 27 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

Numerical Investigation of the Influences of the Features of Transonic Flow over a Hemispherical Turret on Beam Wavefront Distortions

Conditional Studies of the Wake Dynamics of Hemispherical Turret Using PSP

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