Gas density field imaging in shock dominated flows using planar laser scattering

Pickles, Joshua D.; Mettu, Balachandra R.; Subbareddy, Pramod K.; Narayanaswamy, Venkateswaran

doi:10.1007/s00348-018-2562-8

Cited by 10 publications

(1 citation statement)

References 40 publications

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“…In a recent effort, Pickles et al. (2018) demonstrated a methodology to convert the PLS signal to gas density by accounting for the physical processes the particulates undergo in shock dominated flows. Higher temperatures such as within the boundary layer or downstream of strong shocks allow the condensed water to vaporise and drastically reduce the laser scattering in these regions lending these regions to be visualised with very high fidelity.…”

Section: Experimental Set-upmentioning

confidence: 99%

Investigation of shock dynamics in an axisymmetric inlet/isolator with attached boundary layers

Leonard

Narayanaswamy

2020

J. Fluid Mech.

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Section: Experimental Set-upmentioning

confidence: 99%

Investigation of shock dynamics in an axisymmetric inlet/isolator with attached boundary layers

Leonard

Narayanaswamy

2020

J. Fluid Mech.

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On the mean structure of sharp-fin-induced shock wave/turbulent boundary layer interactions over a cylindrical surface

et al. 2019

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Interactions between an oblique shock wave generated by a sharp fin placed on a cylindrical surface and the incoming boundary layer are investigated to unravel the mean features of the resulting shock/boundary layer interaction (SBLI) unit. This fin-on-cylinder SBLI unit has several unique features caused by the three-dimensional (3-D) relief offered by the cylindrical surface that noticeably alter the shock structure. Complementary experimental and computational studies are made to delineate both the surface and off-body flow features of the fin-on-cylinder SBLI unit and to obtain a detailed understanding of the mechanisms that dictate the mean flow and wall pressure features of the SBLI unit. Results show that the fin-on-cylinder SBLI exhibits substantial deviation from quasi-conical symmetry that is observed in planar fin SBLI. Furthermore, the separated flow growth rate appears to decrease with downstream distance and the separation size is consistently smaller than the planar fin SBLI with the same inflow and fin configurations. The causes for the observed diminution of the separated flow and its downstream growth rate were investigated in the light of changes caused by the cylinder curvature on the inviscid as well as separation shock. It was found that the inviscid shock gets progressively weakened in the region close to the triple point with downstream distance due to the 3-D relief effect from cylinder curvature. This weakening of the inviscid shock feeds into the separation shock, which is also independently impacted by the 3-D relief, to result in the observed modifications in the fin-on-cylinder SBLI unit.

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Dual separation control and drag mitigation in high speed flows using viscoelastic materials

Walz

Narayanaswamy

2023

Physics of Fluids

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Boundary layer separation and friction drag form the key delimiting phenomena that subvert the aerial platforms from achieving greater efficiency and accessing wider operation envelope. Both these phenomena are significantly amplified in supersonic platforms due to the interactions between shock waves with the boundary layer that develops over the vehicle surface and within the engines. The present work demonstrates a new paradigm that leverages the native or programmable material properties of the aerostructures to engender simultaneous reduction of the separation scales and mitigation of skin friction drag. As a first step towards realizing this paradigm, the present work makes maiden demonstration of simultaneous skin friction drag mitigation in a Mach 2.5 boundary layer and control of shock induced boundary layer separation, both using viscoelastic implants placed under the flow. It is experimentally demonstrated that the appropriately chosen viscoelastic materials can simultaneously reduce the skin friction coefficient at the measurement location by 11% and mitigate the size of a large-scale separated flow by up to 28%. The reported performance matches the current generation flow effectors in both separation scale and skin friction mitigation. The present study opens a new application space for soft/programmable materials in high speed aerial vehicles.

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Gas density field imaging in shock dominated flows using planar laser scattering

Cited by 10 publications

References 40 publications

Investigation of shock dynamics in an axisymmetric inlet/isolator with attached boundary layers

Investigation of shock dynamics in an axisymmetric inlet/isolator with attached boundary layers

On the mean structure of sharp-fin-induced shock wave/turbulent boundary layer interactions over a cylindrical surface

Dual separation control and drag mitigation in high speed flows using viscoelastic materials

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