Interaction of vortex rings with multiple permeable screens

Musta, Mustafa N.; Krueger, Paul S.
November 2014
Physics of Fluids;2014, Vol. 26 Issue 11, p1
Academic Journal
Interaction of a vortex ring impinging on multiple permeable screens orthogonal to the ring axis was studied to experimentally investigate the persistence and decay of vortical structures inside the screen array using digital particle image velocimetry in a refractive index matched environment. The permeable screens had porosities (open area ratios) of 83.8%, 69.0%, and 55.7% and were held by a transparent frame that allowed the screen spacing to be changed. Vortex rings were generated using a piston-cylinder mechanism at nominal jet Reynolds numbers of 1000, 2000, and 3000 with piston stroke length-to-diameter ratios of 2 and 3. The interaction of vortex rings with the porous medium showed a strong dependence of the overall flow evolution on the screen porosity, with a central flow being preserved and vortex ring-like structures (with smaller diameter than the primary vortex ring) being generated near the centerline. Due to the large rod size used in the screens, immediate reformation of the transmitted vortex ring with size comparable to the primary ring (as has been observed with thin screens) was not observed in most cases. Since the screens have lower complexity and high open area ratios, centerline vortex ring-like flow structures formed with comparable size to the screen pore size and penetrated through the screens. In the case of low porosity screens (55.7%) with large screen spacing, reemergence of large scale (large separation), weak vortical structures/pairs (analogous to a transmitted vortex ring) was observed downstream of the first screen. Additional smaller scale vortical structures were generated by the interaction of the vortex ring with subsequent screens. The size distribution of the generated vortical structures were shown to be strongly affected by porosity, with smaller vortical structures playing a stronger role as porosity decreased. Finally, porosity significantly affected the decay of total energy, but the effect of screen spacing decreased as porosity decreased.


Related Articles

  • Vortex formation of a finite-span synthetic jet: High Reynolds numbers. Buren, Tyler Van; Whalen, Edward; Amitay, Michael // Physics of Fluids;Jan2014, Vol. 26 Issue 1, p1 

    The formation and evolution of flow structures of a high-speed, finite-span synthetic jet issued into a quiescent flow were investigated experimentally using Stereoscopic Particle Image Velocimetry for jet peak velocities up to 150 m/s. The effect of high jet Reynolds number (Re? = 1150, 3450,...

  • Response of unconfined vortex breakdown to axial pulsing. Khalil, Sammy; Hourigan, Kerry; Thompson, Mark C. // Physics of Fluids;Mar2006, Vol. 18 Issue 3, p038102 

    The response of unconfined swirling jets undergoing vortex breakdown to axial pulsing is explored experimentally. In particular, the combination of particle visualization and particle image velocimetry has enabled the effect of axial pulsing on the development of shear-layer flow structures and...

  • Flow field topology of submerged jets with fractal generated turbulence. Cafiero, Gioacchino; Discetti, Stefano; Astarita, Tommaso // Physics of Fluids;2015, Vol. 27 Issue 11, p1 

    Fractal grids (FGs) have been recently an object of numerous investigations due to the interesting capability of generating turbulence at multiple scales, thus paving the way to tune mixing and scalar transport. The flow field topology of a turbulent air jet equipped with a square FG is...

  • Secondary flow structures due to interaction between a finite-span synthetic jet and a 3-D cross flow. Elimelech, Yossef; Vasile, Joseph; Amitay, Michael // Physics of Fluids;Sep2011, Vol. 23 Issue 9, p094104 

    An experimental investigation was performed to study the formation of secondary flow structures due to the interaction of a finite-span synthetic jet with a three-dimensional boundary layer over a finite and swept-back wing configuration (cross-sectional profile of the NACA 4421, aspect ratio of...

  • Experimental study of the formation and scaling of a round synthetic jet. Shuster, Jennifer M.; Smith, Douglas R. // Physics of Fluids;Apr2007, Vol. 19 Issue 4, p045109 

    The flow field from a piston-cylinder synthetic jet actuator was investigated in detail over a range of dimensionless stroke values, L°/D°, and Reynolds numbers, ReU°. In each of the test flows examined, only one of these dimensionless groups was varied. The flow fields were examined...

  • Near-exit flow physics of a moderately overpressured jet. Saffaraval, Farhad; Solovitz, Stephen A. // Physics of Fluids;Aug2012, Vol. 24 Issue 8, p086101 

    The developing region of high-speed jets is studied using particle image velocimetry methods. Ensemble-averaged and fluctuating velocity profiles were measured at a range of exit pressures, from a subsonic pressure-balanced case to an overpressured condition 3.2 times atmospheric. When...

  • Pre-switching bifurcation of a slender jet. Audier, P.; Sciamarella, D.; Artana, G. // Physics of Fluids;2016, Vol. 28 Issue 1, p1 

    In this work, we study the near-field of the jet flow exiting a slot-model with aspect ratio 7.5:1. The core of the slender jet separates into two streams which subsequently merge recomposing a single core jet. Axis switching occurs downstream following self-similarity rules. In order to unveil...

  • Jet flow characteristics of sinusoidal wavy nozzles. Lee, Sang-Joon; Kim, Hak-Lim; Lee, Jin-Pyung; Rajagopalan, Sundara // Journal of Mechanical Science & Technology;Dec2012, Vol. 26 Issue 12, p4007 

    The flow characteristics of jets issued from a sinusoidal nozzle with in-phase and 180° out-of-phase exit configurations were investigated using PIV (particle image velocimetry) and flow visualization techniques. The experiments were carried out at a Reynolds number of about 6300 based on the...

  • Experimental study of highly turbulent isothermal opposed-jet flows. Coppola, Gianfilippo; Gomez, Alessandro // Physics of Fluids;Oct2010, Vol. 22 Issue 10, p105101 

    Opposed-jet flows have been shown to provide a valuable means to study a variety of combustion problems, but have been limited to either laminar or modestly turbulent conditions. With the ultimate goal of developing a burner for laboratory flames reaching turbulence regimes of relevance to...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics