Simulation of Various Turrets at Subsonic and Transonic Flight Conditions Using OVERFLOW

Jelic, Renato; Sherer, Scott E.; Greendyke, Robert B.

doi:10.2514/1.c031844

Cited by 28 publications

(6 citation statements)

References 21 publications

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“…Also, it is a bit unusual how the correlation is not very strong for the separation line in any of the modes for the partial hemisphere, suggesting weak separation dynamics. These results also somewhat disagree with previous numerical studies where separation over a partial hemisphere was clearly evident [14,15], so additional studies are needed to resolve this issue. In the partial hemisphere mode 3, the unsteady separation line is a little clearer extending from about Z=0.05 all the way to the edge of the turret at about Z=-0.1.…”

Section: Pod Analysiscontrasting

confidence: 99%

“…The analysis presented in this paper further studies the same data and the transition from the partial hemisphere to hemisphere geometry. Submerged hemispherical turrets have been studied both experimentally [12,13] and computationally in [14][15][16]. However, from the results of these studies it is not clear what causes the dramatic change in flow behavior.…”

Section: Introductionmentioning

confidence: 99%

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Modal analysis of pressure fields on and around turrets with different protrusions

Bukowski

Kalensky

Gordeyev

et al. 2022

Unconventional Imaging and Adaptive Optics 2022

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Wind tunnel experiments were conducted to measure the unsteady surface pressure field of a hemisphere-oncylinder turret in subsonic flow. These measurements were obtained using pressure transducers coupled with fast response pressure sensitive paint. The surface pressure field data resulting from Mach 0.5 flow (Re D ≈ 2 × 10 6 ) over three different turret protrusion distances were analyzed. Previously, dominant surface pressure modes on the turret were found using proper orthogonal decomposition. The results of which showed that greater turret protrusion into the freestream flow increased the prevalence of spanwise anti-symmetric surface pressure field fluctuations. These anti-symmetric pressure fluctuations are caused by anti-symmetrical vortex shedding. However, when a partially submerged hemispherical turret geometry is used, it was shown that this anti-symmetric mode was of much lower relative energy. This suggests that there is a transition in flow field phenomena as protrusion is changed from partially submerged to a full hemisphere configuration. Further investigation into this so-called "mode switching" is the emphasis of the work presented here. This research heavily relied on modal analysis to identify correlations between turret and wake surface pressure fields. The fluctuations in the surface pressure field around the partial hemisphere were found to be mostly dominated by the wake with little influence from fluidic structures on the turret itself. For the hemisphere and hemisphere-oncylinder configurations, both symmetric and anti-symmetric unsteady separation grew to be the largest influence and was coupled with the wake fluctuations.

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Section: Pod Analysiscontrasting

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modal analysis of pressure fields on and around turrets with different protrusions

Bukowski

Kalensky

Gordeyev

et al. 2022

Unconventional Imaging and Adaptive Optics 2022

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“…Morgan et al 20 also accomplished resolving the flow around the turret by the high-order Navier-Stokes flow solver, and the results indicated that the flat window introduced moderate flow separation over most of the aperture. Jelic et al 21 numerically simulated two typical turret geometries and the performance of the turrets for directed energy applications is inferred through the flow features, density and pressure fluctuations, and forces on the turrets. Mathew et al 22 investigated the aero-optical effects over a hemisphere cylindrical turret by using large eddy simulation (LES).…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of aero-optical effects around the turret based on delayed detached eddy simulation and unsteady Reynolds averaged Navier-Stokes

Tan,

2023

Proceedings of the Institution of Mechanical Engineers, Part G:

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Delayed Detached Eddy Simulation (DDES) and Unsteady Reynolds Averaged Navier-Stokes (URANS), based on the two-equation Shear Stress Transport (SST) model, are implemented to investigate the flow features and the aero-optical distortions around the turret. The Mach number is Ma = 0.4 and the Reynolds number is Re = 1.43 × 106. Instantaneous and time-averaged flow fields are presented to compare the ability of DDES and URANS in predicting the flow features. The instantaneous results show that DDES can resolve the abundant flow structures and more disordered density distributions than URANS. The time-averaged pressure coefficient and the density distribution of both methods are generally similar, but the time-averaged turbulent kinetic energy of URANS is far higher than that of DDES. The time-averaged pressure coefficient of DDES is closer to experimental data. In the windward view, typical surface flow features of DDES and URANS are similar. In the leeward view, there are remarkable differences of typical flow features between DDES and URANS. At the six angles of elevation, 60°, 76°, 90°, 103°, 120°, and 132°, the spatial-temporal wavefront distortions are calculated and discussed with the geometric ray-tracing method and the Zernike polynomial fitting, respectively. In spatial distribution, the wavefront distortions of DDES and URANS are slightly different from the experimental data. At the angles of 60°, 76°, 90°, and 103°, the tendencies of wavefront distortion of DDES at different tracing distances are the same with that of URANS, which is due to the same ability of two methods to resolve the density distributions in the attached flow region. However, the results of DDES agree well with the experimental results at the angles of 120° and 132°, which is bigger than the results of URANS. For temporal characteristics, the frequencies of wavefront distortions of DDES are obviously higher than that of URANS. The amplitudes of wavefront distortions by DDES are about 3 to 5 times higher than that by URANS. At the cases of two different FLHs at Ma = 0.4, the flow structures are totally similar, and the tendencies of wavefront distortion with θ are also similar. At the cases of three Mach number, the compression has a big influence on the wavefront distortion.

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“…The requirement for optical transport resolution proposed by Mani et al and Mathews et al [21,22] provides a basis for the large eddy simulation (LES) method. Further considering the effect of the wall, researchers [15,[23][24][25][26][27][28] are trying hybrid RANS/ LES methods such as detached eddy simulation (DES) and wall-modeled LES (WMLES) for the numerical simulation for the flow over laser turrets, shown as Table 1, but only with limited success at subsonic flow. However, the simulated statistical fluctuations differ from the experiments.…”

Section: Introductionmentioning

confidence: 99%

Shock Boundary Layer Interaction and Aero-Optical Effects in a Transonic Flow over Hemisphere-on-Cylinder Turrets

Ren

Yao

et al. 2022

International Journal of Aerospace Engineering

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Hemisphere-on-cylinder turrets are the main airborne optical platform structure. However, an unsteady shock boundary layer interaction (SBLI) would act on flow separation and turbulent wake, which causes serious aero-optical effects with high spatial and temporal frequency characteristics. In this paper, the SBLI phenomenon of a hemisphere-on-cylinder turret is recorded in a wind tunnel at Ma = 0.7 using shadowing and Mach-Zehnder interferometer measurements. Its wavefront distortion is measured using the Shack-Hartmann measurement. The detached eddy simulation (DES) based on SST k - ω turbulence model and ray-tracing methods are used to reproduce the transonic flow and optical aberration. Experiments and simulations suggest that the SBLI causes the flow to separate earlier relative to a subsonic flow over the turret. The time-averaged root-mean-square of optical path difference (OPD) over the beam aperture is 0.56 λ∼0.59 λ with λ as the wavelength, while the root-mean-square of the time-averaged OPD is about 0.45 λ. The local shock and wavefront distortion have dual peak frequencies at S t D = f D / U ∞ = 0.24 and 0.34, different from the single-peak-frequency phenomenon of a subsonic flow over turrets. Fast model decomposition of wavefront can be performed by proper orthogonal decomposition (POD) of its Zernike coefficients. The first two modes contain the shock’s reciprocating motion.

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Simulation of Various Turrets at Subsonic and Transonic Flight Conditions Using OVERFLOW

Cited by 28 publications

References 21 publications

Modal analysis of pressure fields on and around turrets with different protrusions

Modal analysis of pressure fields on and around turrets with different protrusions

Numerical investigation of aero-optical effects around the turret based on delayed detached eddy simulation and unsteady Reynolds averaged Navier-Stokes

Shock Boundary Layer Interaction and Aero-Optical Effects in a Transonic Flow over Hemisphere-on-Cylinder Turrets

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