Sensitivity of an asymmetric 3D diffuser to vortex-generator induced inlet condition perturbations

Grundmann, Sven; Sayles, Emily L.; Elkins, Christopher J.; Eaton, John K.

doi:10.1007/s00348-011-1205-0

Cited by 12 publications

(4 citation statements)

References 14 publications

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“…Schatzman & Thomas (2010) observed that DBD-VGs could be just as effective as co-flow actuators in a similar configuration. Grundmann, Sayles & Eaton (2011) and Grundmann et al (2012) found a significant improvement with DBD-VGs for controlling the separation bubble in a three-dimensional diffuser, where the effect was very similar to vane-type VGs with height h/δ ≈ 0.3-0.6. In addition, these actuators have recently been demonstrated to produce streamwise vortices in relatively high-speed turbulent flow (Wicks et al 2012).…”

Section: Dielectric-barrier-discharge Vortex Generatorsmentioning

confidence: 83%

On the formation of streamwise vortices by plasma vortex generators

Jukes

Choi

2013

J. Fluid Mech.

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The streamwise vortices generated by dielectric-barrier-discharge plasma actuators in the laminar boundary layer were investigated using particle image velocimetry to understand the vortex-formation mechanisms. The plasma vortex generator was oriented along the primary flow direction to produce a body force in the spanwise direction. This created a spanwise-directed wall jet which interacted with the oncoming boundary layer to form a coherent streamwise vortex. It was found that the streamwise vortices were formed by the twisting and folding of the spanwise vorticity in the oncoming boundary layer into the outer shear layer of the spanwise wall jet, which added its own vorticity to increase the circulation along the actuator length. This is similar to the delta-shaped, vane-type vortex generator, except that the circulation was enhanced by the addition of the vorticity in the plasma jet. It was also observed that the plasma vortex was formed close to the wall with an enhanced wall-ward entrainment, which created strong downwash above the actuator.

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Section: Dielectric-barrier-discharge Vortex Generatorsmentioning

confidence: 83%

On the formation of streamwise vortices by plasma vortex generators

Jukes

Choi

2013

J. Fluid Mech.

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“…Most of these quantities can be extracted from MR data (Elkins and Alley, 2007). For example, three-dimensional, three-component (3D3C) MRV data was obtained from an internal flow through a ribbed cooling channel of a turbine blade , or flow through an open-celled foam structure (Onstad et al, 2011) or from flow through an asymmetric 3D diffuser (Grundmann et al, 2011).…”

Section: Magnetic Resonance Imagingmentioning

confidence: 99%

Progress in on-going experimental and computational fluid dynamic investigations within a CANDU fuel channel

Piro

Wassermann

Grundmann

et al. 2016

Nuclear Engineering and Design

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“…Cherry et al (2010) later investigated the flow field and performance of an annular diffuser consisting of two different inlets, one had a fully developed flow while the other inlet was a wake induced by a row of struts. Cherry et al's experiment (2008) laid the groundwork for Grundmann et al's investigation which induced a different inlet secondary current using a plasma actuator and observed a significant difference in the mean flow-separation size and location which led to an improvement of the pressure recovery of 13-17% (Grundmann et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Flow Separation Dynamics in Three-Dimensional Asymmetric Diffusers

Hajaali

Stoesser

2021

Flow Turbulence Combust

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The mean and instantaneous flow separation of two different three-dimensional asymmetric diffusers is analysed using the data of large-eddy simulations. The geometry of both diffusers under investigation is based on the experimental configuration of Cherry et al. (Int J Heat Fluid Flow 29(3):803–811, 2008). The two diffusers feature similar area ratios of $$\mathrm{AR}=4.8$$ AR = 4.8 and $$\mathrm{AR}=4.5$$ AR = 4.5 while exhibiting differing asymmetric expansion ratios of $$\mathrm{AER}=4.5$$ AER = 4.5 or $$\mathrm{AER}=2.0$$ AER = 2.0 , respectively. The Reynolds number based on the averaged inlet velocity and height of the inlet duct is approximately $${\textit{Re}}=10{,}000$$ Re = 10 , 000 . The time-averaged flow in both diffusers in terms of streamwise velocity profiles or the size and location of the mean backflow region are validated using experimental data. In general good agreement of simulated results with the experimental data is found. Further quantification of the flow separation behaviour and unsteadiness using the backflow coefficient reveals the volume portion in which the instantaneous reversal flow evolves. This new approach investigates the cumulative fractional volume occupied by the instantaneous backflow throughout the simulation, a power density spectra analysis of their time series reveals the periodicity of the growth and reduction phases of the flow separation within the diffusers. The dominating turbulent events responsible for the formation of the energy-containing motions including ejection and sweep are examined using the quadrant analysis at various locations. Finally, isourfaces of the Q-criterion visualise the instantaneous flow and the origin and fate of coherent structures in both diffusers.

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Sensitivity of an asymmetric 3D diffuser to vortex-generator induced inlet condition perturbations

Cited by 12 publications

References 14 publications

On the formation of streamwise vortices by plasma vortex generators

On the formation of streamwise vortices by plasma vortex generators

Progress in on-going experimental and computational fluid dynamic investigations within a CANDU fuel channel

Flow Separation Dynamics in Three-Dimensional Asymmetric Diffusers

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