Investigation of Flow Dynamics Over Turrets with Different Spanwise Aspect Ratios Using PSP

Lucca, Nicholas G. De; Gordeyev, Stanislav; Morrida, Jacob J.; Jumper, Eric J.

doi:10.2514/6.2018-2047

Cited by 5 publications

(6 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For these studies, the same turret with diameter D= 0.30 m (12 in) was used. This turret is a shell of the AAOL turret which has produced many foundational datasets and impactful results [17][18][19] in the aero-optics community. It is worth noting that the AAOL shell turret model used in the studies presented here is not a smooth hemisphere-on-cylinder, but rather has realistic surface features such as small gaps between the stationary turret shell and the rotating "donut" part, screw holes, etc.…”

Section: Methodsmentioning

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

View full text Add to dashboard Cite

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.

show abstract

Section: Methodsmentioning

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

View full text Add to dashboard Cite

show abstract

“…2; here, the x-axis is the vertical coordinate (referenced to the shear layer slip line location) normalized by the shear-layer vorticity thickness, y * = y−y0. 5 δw , where y 0.5 is vertical coordinate of the shear layer slip line and δ ω is the shear layer vorticity thickness described by…”

Section: Ansys Fluentmentioning

confidence: 99%

Experimental and computational investigation of laser beam propagation through a free shear layer

Wells,

Kalensky,

Rennie

et al. 2023

Unconventional Imaging, Sensing, and Adaptive Optics 2023

Self Cite

View full text Add to dashboard Cite

Experimental Shack–Hartmann Wavefront Sensor (SHWFS) measurements were collected and examined to further understand image-plane irradiance pattern behavior in the presence of potentially sharp thermodynamic gradients. An analysis of path-integrated phase and image-plane irradiance pattern spreading discovered regions within a weakly compressible shear layer where sharp gradients were previously not observed. This paper describes the analysis process and shows results which suggest that Shack-Hartmann wavefront sensors are not adequately resolving sharp thermodynamic gradients in aberrating flows.

show abstract

“…The protrusion of the turret into the freestream flow creates a complicated turbulence environment, which can degrade the performance of these optical systems. [1][2][3][4][5][6][7][8][9][10] The optical-turbulence environment, which is caused by aerodynamic turbulence, is colloquially referred to as aero optics. [11][12][13] Laser beam propagation through shear layers has been one aero-optical environment of particular interest.…”

Section: Introductionmentioning

confidence: 99%

“…The protrusion of the turret into the freestream flow creates a complicated turbulence environment, which can degrade the performance of these optical systems 1 – 10 The optical-turbulence environment, which is caused by aerodynamic turbulence, is colloquially referred to as aero optics 11 – 13 …”

Section: Introductionmentioning

confidence: 99%

“…In order to better understand the underlying physics associated with these aero-optical aberrations, extensive lab-based 2 – 5 , 7 , 8 , 14 – 21 and aircraft-based 6 , 22 – 30 testing has been conducted in recent years. Although many foundational aero-optical experiments and analyses have been conducted, there is still much to learn about the coupling of fluidic properties and optical aberrations.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental and computational investigation of Shack–Hartmann wavefront sensor measurements through a free shear layer

Wells,

Kalensky,

Rennie

et al. 2024

Opt. Eng.

View full text Add to dashboard Cite

Experimental Shack-Hartmann wavefront sensor (SHWFS) measurements were collected for a laser beam that propagated through a weakly compressible shear layer. Complementary computational fluid dynamics (CFD) was also conducted to match the experiment. The path-integrated CFD results were then applied to a SHWFS model such that the experimental and CFD results could be compared. Using both the experimental and CFD wavefront results, it was found that, although the CFD results slightly overestimated the resultant wavefront error, the CFD and experimental results revealed extremely similar wavefront topology. In order to further examine the aberrations imposed onto the laser beam in both datasets, the SHWFS image-plane irradiance patterns and circulation of phase gradients were studied. Similar to the overall wavefront topology, these data reduction approaches revealed similar phenomena in both the experimental and CFD-modeled results. Specifically, appreciable circulation and beam spread of the SHWFS image-plane irradiance patterns were exhibited throughout the shear layer's braid region. Both of these findings suggest that sharp phase gradients exist in the weakly compressible shear layer and both (1) the SHWFS resolution and (2) the continuous nature of the phase estimate obtained using SHWFS data in a least-squares reconstruction algorithm make these phase gradients challenging to resolve. The findings presented here inform efforts looking to experimentally or computationally study aero-optical environments.

show abstract

Investigation of Flow Dynamics Over Turrets with Different Spanwise Aspect Ratios Using PSP

Cited by 5 publications

References 15 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

Experimental and computational investigation of laser beam propagation through a free shear layer

Experimental and computational investigation of Shack–Hartmann wavefront sensor measurements through a free shear layer

Contact Info

Product

Resources

About