Author: Ronald J. Hugo
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
An Experimental Investigation of Vortex Breakdown in Multiphase Pipe Flow
Author: Ronald J. Hugo
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
An Experimental Investigation of the Vortex-breakdown Phenomenon
Author: Turgut Sarpkaya
Publisher:
ISBN:
Category : Vortex-motion
Languages : en
Pages : 66
Book Description
The results of an experimental investigation of the characteristics of stationary and travelling vortex breakdowns in swirling flow in a diverging cylindrical tube are presented and discussed. Basically, three types of vortex breakdown were observed, viz., double helix, spiral, and axisymmetric breakdown. The type and location of the stationary breakdowns were found to be dependent upon the Reynolds and circulation numbers of the flow. The breakdown bubble responded to gradual and abrupt changes in the upstream and downstream flow conditions in a manner analogous to the hydraulic jump in open-channel flow. The observations reported and the evidence presented revealed unmistakably that the vortex breakdown is a finite transition from a uniform state of swirling flow (supercritical) to one (subcritical) featuring a large standing wave, followed by standing wavelets, of finite amplitude. (Author).
Publisher:
ISBN:
Category : Vortex-motion
Languages : en
Pages : 66
Book Description
The results of an experimental investigation of the characteristics of stationary and travelling vortex breakdowns in swirling flow in a diverging cylindrical tube are presented and discussed. Basically, three types of vortex breakdown were observed, viz., double helix, spiral, and axisymmetric breakdown. The type and location of the stationary breakdowns were found to be dependent upon the Reynolds and circulation numbers of the flow. The breakdown bubble responded to gradual and abrupt changes in the upstream and downstream flow conditions in a manner analogous to the hydraulic jump in open-channel flow. The observations reported and the evidence presented revealed unmistakably that the vortex breakdown is a finite transition from a uniform state of swirling flow (supercritical) to one (subcritical) featuring a large standing wave, followed by standing wavelets, of finite amplitude. (Author).
Experimental Study of Vortex Breakdown in a Cylindrical, Swirling Flow
Author: José L. Stevens
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 142
Book Description
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 142
Book Description
An Experimental Investigation of Vortex Breakdown in Tubes at High Reynolds Numbers
Author: Francis G. Novak
Publisher:
ISBN: 9781423557371
Category :
Languages : en
Pages : 336
Book Description
This thesis deals with non-cavitating swirling flows with vortex breakdown in various tubes. Phenomenological and quantitative investigations were carried out at Reynolds numbers as high as 300,000. It was shown that a high Re(D) vortex transitions to its new state (breaks down) via a rapidly spinning spiral form, as demonstrated with 4,000 frame per second video, short exposure time (6 ns) imaging, and Digital Particle Image Velocimetry. Of the known types, the spiral emerges as the fundamental breakdown form and the axisymmetric bubble may now be regarded as a relatively low Re(D) occurrence that is bypassed at sufficiently high Re(D). Some new phenomena were observed at high Re(D): Extremely rapid spiral rotation (over 1,000 revolutions per second), core bifurcation, and changes in the sense of the spiral windings. Familiar features of breakdowns, such as the transition from a jet-like to wake-like axial velocity profile and the rapidly expanding vortex core, were observed in extensive time averaged velocity and turbulence results ascertained with Laser Doppler Velocimetry. However, a mean stagnation point and recirculation were absent in the highest Re(D) flow. The core meandering and stagnation point darting in the turbulent flow field were quantified and discussed in detail.
Publisher:
ISBN: 9781423557371
Category :
Languages : en
Pages : 336
Book Description
This thesis deals with non-cavitating swirling flows with vortex breakdown in various tubes. Phenomenological and quantitative investigations were carried out at Reynolds numbers as high as 300,000. It was shown that a high Re(D) vortex transitions to its new state (breaks down) via a rapidly spinning spiral form, as demonstrated with 4,000 frame per second video, short exposure time (6 ns) imaging, and Digital Particle Image Velocimetry. Of the known types, the spiral emerges as the fundamental breakdown form and the axisymmetric bubble may now be regarded as a relatively low Re(D) occurrence that is bypassed at sufficiently high Re(D). Some new phenomena were observed at high Re(D): Extremely rapid spiral rotation (over 1,000 revolutions per second), core bifurcation, and changes in the sense of the spiral windings. Familiar features of breakdowns, such as the transition from a jet-like to wake-like axial velocity profile and the rapidly expanding vortex core, were observed in extensive time averaged velocity and turbulence results ascertained with Laser Doppler Velocimetry. However, a mean stagnation point and recirculation were absent in the highest Re(D) flow. The core meandering and stagnation point darting in the turbulent flow field were quantified and discussed in detail.
03-3565 - 03-3612
Author:
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 562
Book Description
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 562
Book Description
Experimental Study of Vortex Breakdown in a Cylindrical, Swirling Flow
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723049668
Category :
Languages : en
Pages : 146
Book Description
The stability of a steady, vortical flow in a cylindrical container with one rotating endwall has been experimentally examined to gain insight into the process of vortex breakdowwn. The dynamics of the flow are governed by the Reynolds number (Re) and the aspect ratio of the cylinder. Re is given by Omega R(sup 2)/nu, where Omega is the speed of rotation of the endwall, R is the cylinder radius, and nu is the kinematic viscosity of the fluid filling the cylinder. The aspect ratio is H/R, where H is the height of the cylinder. Numerical simulation studies disagree whether or not the steady breakdown is stable beyond a critical Reynolds number, Re(sub c). Previous experimental researches have considered the steady and unsteady flows near Re(sub c), but have not explored the stability of the steady breakdown structures beyond this value. In this investigation, laser induced fluorescence was utilized to observe both steady and unsteady vortex breakdown at a fixed H/R of 2.5 with Re varying around Re(sub c). When the Re of a steady flow was slowly increased beyond Re(sub c), the breakdown structure remained steady even though unsteadiness was possible. In addition, a number of hysteresis events involving the oscillation periods of the unsteady flow were noted. The results show that both steady and unsteady vortex breakdown occur for a limited range of Re above Re(sub c). Also, with increasing Re, complex flow transformations take place that alter the period at which the unsteady flow oscillates. Stevens, J. L. and Celik, Z. Z. and Cantwell, B. J. and Lopez, J. M. Ames Research Center VORTEX BREAKDOWN; SWIRLING; FLOW STABILITY; STEADY FLOW; INTERNAL FLOW; REYNOLDS NUMBER; CYLINDRICAL BODIES; ASPECT RATIO; AXISYMMETRIC FLOW; FLOW VISUALIZATION; OSCILLATIONS; PERTURBATION; BUBBLES; UNSTEADY FLOW; VISCOSITY; LASER INDUCED FLUORESCENCE...
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723049668
Category :
Languages : en
Pages : 146
Book Description
The stability of a steady, vortical flow in a cylindrical container with one rotating endwall has been experimentally examined to gain insight into the process of vortex breakdowwn. The dynamics of the flow are governed by the Reynolds number (Re) and the aspect ratio of the cylinder. Re is given by Omega R(sup 2)/nu, where Omega is the speed of rotation of the endwall, R is the cylinder radius, and nu is the kinematic viscosity of the fluid filling the cylinder. The aspect ratio is H/R, where H is the height of the cylinder. Numerical simulation studies disagree whether or not the steady breakdown is stable beyond a critical Reynolds number, Re(sub c). Previous experimental researches have considered the steady and unsteady flows near Re(sub c), but have not explored the stability of the steady breakdown structures beyond this value. In this investigation, laser induced fluorescence was utilized to observe both steady and unsteady vortex breakdown at a fixed H/R of 2.5 with Re varying around Re(sub c). When the Re of a steady flow was slowly increased beyond Re(sub c), the breakdown structure remained steady even though unsteadiness was possible. In addition, a number of hysteresis events involving the oscillation periods of the unsteady flow were noted. The results show that both steady and unsteady vortex breakdown occur for a limited range of Re above Re(sub c). Also, with increasing Re, complex flow transformations take place that alter the period at which the unsteady flow oscillates. Stevens, J. L. and Celik, Z. Z. and Cantwell, B. J. and Lopez, J. M. Ames Research Center VORTEX BREAKDOWN; SWIRLING; FLOW STABILITY; STEADY FLOW; INTERNAL FLOW; REYNOLDS NUMBER; CYLINDRICAL BODIES; ASPECT RATIO; AXISYMMETRIC FLOW; FLOW VISUALIZATION; OSCILLATIONS; PERTURBATION; BUBBLES; UNSTEADY FLOW; VISCOSITY; LASER INDUCED FLUORESCENCE...
Theoretical and Experimental Investigation of Vortex Breakdown Final Technical Report 1 June 85
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
An Experimental Investigation of the Vortex Breakdown Phenomenon in a Diverging Tube
Author: Luis E. Rodrigues Castro
Publisher:
ISBN:
Category : Mechanical engineering
Languages : en
Pages : 0
Book Description
Publisher:
ISBN:
Category : Mechanical engineering
Languages : en
Pages : 0
Book Description
An Experimental Investigation of the Effect of Adverse Pressure Gradient on Vortex Breakdown
Author: Gale Edward Treiber
Publisher:
ISBN:
Category : Mechanical engineering
Languages : en
Pages : 74
Book Description
The results of an experimental investigation of the effect of adverse pressure gradient on the vortex breakdown phenomenon in a diverging tube are presented. Adverse pressure gradient was found to be as significant in determining the breakdown position as were the previously known parameters of Reynolds and circulation numbers. An approximate momentum analysis for predicting the vortex breakdown position was carried out which appears to hold promise as a breakdown predictor. (Modified author abstract).
Publisher:
ISBN:
Category : Mechanical engineering
Languages : en
Pages : 74
Book Description
The results of an experimental investigation of the effect of adverse pressure gradient on the vortex breakdown phenomenon in a diverging tube are presented. Adverse pressure gradient was found to be as significant in determining the breakdown position as were the previously known parameters of Reynolds and circulation numbers. An approximate momentum analysis for predicting the vortex breakdown position was carried out which appears to hold promise as a breakdown predictor. (Modified author abstract).
Experimental Study of Vortex Breakdown and Its Control in Swirling Flow
Author: Dina Fastovsky
Publisher:
ISBN:
Category :
Languages : en
Pages : 144
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 144
Book Description