scholarly journals Jump of azimuthal velocity in a creeping two-fluid swirling flow

2020 ◽  
Vol 1677 ◽  
pp. 012077
Author(s):  
B R Sharifullin ◽  
I V Naumov ◽  
A Yu Kravtsova ◽  
V N Shtern
Keyword(s):  
Swirling Flow ◽  
Azimuthal Velocity ◽  
Two Fluid

Feature Extraction From Time Resolved Reacting Flow Data Sets

2018 ◽  
Author(s):  
H. Ek ◽  
I. Chterev ◽  
N. Rock ◽  
B. Emerson ◽  
J. Seitzman ◽  
...  
Keyword(s):  
Swirling Flow ◽  
Azimuthal Velocity ◽  
Flow Fields ◽  
Swirl Flow ◽  
Reacting Flow ◽  
Data Sets ◽  
Time Resolved ◽  
Recirculating Flow ◽  
Flow Features ◽  
Dynamical Flow

This paper presents measurements of the simultaneous fuel distribution, flame position and flow velocity in a high pressure, liquid fueled combustor. Its objective is to develop methods to process, display and compare large quantities of instantaneous data with computations. However, time-averaged flow fields rarely represent the instantaneous, dynamical flow fields in combustion systems. It is therefore important to develop methods that can algorithmically extract dynamical flow features and be directly compared between measurements and computations. While a number of data-driven approaches have been previously presented in the literature, the purpose of this paper is to propose several approaches that are based on understanding of key physical features of the flow — for this reacting swirl flow, these include the annular jet, the swirling flow which may be precessing, the recirculating flow between the annular jets, and the helical flow structures in the shear layers. This paper demonstrates nonlinear averaging of axial and azimuthal velocity profiles, which provide insights into the structure of the recirculation zone and degree of flow precession. It also presents probability fields for the location of vortex cores that enables a convenient method for comparison of their trajectory and phasing with computations. Taken together, these methods illustrate the structure and relative locations of the annular fluid jet, recirculating flow zone, spray location, flame location, and trajectory of the helical vortices.

scholarly journals Prospects for observing the magnetorotational instability in the plasma Couette experiment

2015 ◽  
Vol 81 (4) ◽  
Author(s):  
K. Flanagan ◽  
M. Clark ◽  
C. Collins ◽  
C. M. Cooper ◽  
I. V. Khalzov ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Body Force ◽  
Protoplanetary Disks ◽  
Azimuthal Velocity ◽  
Relevant Parameter ◽  
Magnetorotational Instability ◽  
Plasma Parameters ◽  
Global Stability Analysis ◽  
Two Fluid ◽  
Ideal Plasma

Many astrophysical disks, such as protoplanetary disks, are in a regime where non-ideal, plasma-specific magnetohydrodynamic (MHD) effects can significantly influence the behaviour of the magnetorotational instability (MRI). The possibility of studying these effects in the plasma Couette experiment (PCX) is discussed. An incompressible, dissipative global stability analysis is developed to include plasma-specific two-fluid effects and neutral collisions, which are inherently absent in analyses of Taylor–Couette flows (TCFs) in liquid metal experiments. It is shown that with boundary driven flows, a ion-neutral collision drag body force significantly affects the azimuthal velocity profile, thus limiting the flows to regime where the MRI is not present. Electrically driven flow (EDF) is proposed as an alternative body force flow drive in which the MRI can destabilize at more easily achievable plasma parameters. Scenarios for reaching MRI relevant parameter space and necessary hardware upgrades are described.

Destabilization of Laminar Wall Jet Flow and Relaminarization of the Turbulent Confined Jet Flow in Axially Rotating Circular Pipe

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Snehamoy Majumder ◽  
Dipankar Sanyal
Keyword(s):  
Swirling Flow ◽  
Numerical Study ◽  
Azimuthal Velocity ◽  
Jet Flow ◽  
Wall Jet ◽  
Local Velocity ◽  
Recirculation Bubble ◽  
Circular Duct ◽  
Streamline Curvature ◽  
Wall Jet Flow

Destabilization and relaminarization phenomena have been investigated in an axially rotating circular duct. Standard k-ε model with modification for streamline curvature has been used in the numerical study. The laminar and turbulent velocity distributions at inlet have been observed to become turbulent and laminar, respectively, toward the exit of the pipe. A local velocity profile with parabolic or nearly uniform variation has been considered as the characteristic of laminarlike or turbulent flow, respectively, and changeover of flow from former to the later variation or vice versa has been taken to characterize destabilization and relaminarization, respectively. The predicted azimuthal velocity component was found to be reasonably accurate near the wall and not so encouraging in the core region of the swirling flow. The recirculation bubble generated by a central jet flow at the wall has been observed to reduce in size due to rotation of the pipe confirming the relaminarization phenomenon, whereas with laminar wall jet waspredicted recirculation bubble growing with rotation rate manifesting the destabilization effects.

On the Oseen linearization of the swirling-flow boundary layer

1976 ◽  
Vol 75 (4) ◽  
pp. 777-790 ◽  
Author(s):  
K. K. Tam
Keyword(s):  
Boundary Layer ◽  
Comparison Theorem ◽  
Vertical Velocity ◽  
Swirling Flow ◽  
Upper And Lower Solutions ◽  
Azimuthal Velocity ◽  
Linear Solution ◽  
Flow Boundary

The modified Oseen linearization of the swirling-flow boundary layer of a mature hurricane is discussed. Upper and lower solutions for the radial and azimuthal velocity components are constructed in a subdomain by using a comparison theorem. It is shown that the error incurred in these velocity components by using the linear solution is no more than 30% in the subdomain. It is then inferred that the vertical velocity is also approximated to that order.

scholarly journals Multi-cellular pattern of a two-fluid swirling flow in a closed cylinder

2018 ◽  
Vol 1105 ◽  
pp. 012030 ◽  
Author(s):  
I V Naumov ◽  
V G Glavny ◽  
B R Sharifullin ◽  
V N Shtern
Keyword(s):  
Swirling Flow ◽  
Cellular Pattern ◽  
Two Fluid

scholarly journals Self-generation of cells in a two-fluid swirling flow

2018 ◽  
Author(s):  
Igor V. Naumov ◽  
Bulat R. Sharifullin ◽  
Vladimir N. Shtern
Keyword(s):  
Swirling Flow ◽  
Two Fluid

Formation of Multiple Vortices in a Confined Two-Fluid Swirling Flow

2021 ◽  
Vol 30 (4) ◽  
pp. 636-645
Author(s):  
L. Carrión ◽  
M. A. Herrada ◽  
V. Shtern
Keyword(s):  
Swirling Flow ◽  
Two Fluid

The modified Myers boundary condition for swirling flow

2018 ◽  
Vol 847 ◽  
pp. 868-906 ◽  
Author(s):  
James R. Mathews ◽  
Vianney Masson ◽  
Stéphane Moreau ◽  
Hélène Posson
Keyword(s):  
Boundary Layer ◽  
Boundary Condition ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Swirling Flow ◽  
Azimuthal Velocity ◽  
Inviscid Flow ◽  
Layer Model ◽  
Quadratic Error ◽  
The Time Domain

This paper gives a modified Myers boundary condition in swirling inviscid flow, which differs from the standard Myers boundary condition by assuming a small but non-zero boundary layer thickness. The new boundary condition is derived and is shown to have the correct quadratic error behaviour with boundary layer thickness and also to agree with previous results when the swirl is set to zero. The boundary condition is initially derived for swirling flow with constant azimuthal velocity, but easily extends to radially varying swirling flow, with terms depending on the boundary layer model. The modified Myers boundary condition is then given in the time domain rather than in the frequency domain. The effect of the boundary layer profile is then considered, and shown to be small compared to the boundary layer thickness. The boundary condition is then used to analyse the eigenmodes and Green’s function in a realistic flow. Modelling the thickness of the boundary layer properly is shown to be essential in order to get accurate results.

Development of Swirling Flow in a Rod Bundle Subchannel

2002 ◽  
Vol 124 (3) ◽  
pp. 747-755 ◽  
Author(s):  
Heather L. McClusky ◽  
Mary V. Holloway ◽  
Donald E. Beasley ◽  
Michael E. Conner
Keyword(s):  
Angular Momentum ◽  
Swirling Flow ◽  
Axial Direction ◽  
Azimuthal Velocity ◽  
Lateral Velocity ◽  
Full Field ◽  
Rod Bundle ◽  
Image Velocimetry ◽  
Oseen Vortex ◽  
Support Grid

Experimental measurements of the axial development of swirling flow in a rod bundle subchannel are presented. Swirling flow was introduced in the subchannel from a split vane pair located on the downstream edge of the support grid. Particle image velocimetry using an optical borescope yielded full-field lateral velocity data. Lateral flow fields and axial vorticity fields at axial locations ranging from 4.2 to 25.5 hydraulic diameters downstream of the support grid were examined for a Reynolds number of 2.8×104. The lateral velocity fields show that the swirling flow was initially centered in the subchannel. As the flow developed in the axial direction, the swirling flow migrated away from the center of the subchannel. Radial distributions of azimuthal velocity and circulation are presented relative to the centroid of vorticity, and are compared to that of a Lamb-Oseen vortex. The angular momentum decreased as the flow developed in the axial direction. The spatial decay rate of the angular momentum is compared to that of decaying, swirling flow in a pipe.

scholarly journals Quasi-cylindrical approximation to the swirling flow in an atomizer chamber

2014 ◽  
Vol 758 ◽  
pp. 603-620
Author(s):  
F. J. Higuera ◽  
A. Pereña
Keyword(s):  
Boundary Layers ◽  
Flow Rate ◽  
Swirling Flow ◽  
Radial Pressure ◽  
Azimuthal Velocity ◽  
Liquid Sheet ◽  
Ekman Pumping ◽  
Air Core ◽  
Swirl Atomizer ◽  
Exit Orifice

AbstractA quasi-cylindrical approximation is used to analyse the axisymmetric swirling flow of a liquid with a hollow air core in the chamber of a pressure swirl atomizer. The liquid is injected into the chamber with an azimuthal velocity component through a number of slots at the periphery of one end of the chamber, and flows out as an annular sheet through a central orifice at the other end, following a conical convergence of the chamber wall. An effective inlet condition is used to model the effects of the slots and the boundary layer that develops at the nearby endwall of the chamber. An analysis is presented of the structure of the liquid sheet at the end of the exit orifice, where the flow becomes critical in the sense that upstream propagation of long-wave perturbations ceases to be possible. This analysis leads to a boundary condition at the end of the orifice that is an extension of the condition of maximum flux used with irrotational models of the flow. As is well known, the radial pressure gradient induced by the swirling flow in the bulk of the chamber causes the overpressure that drives the liquid towards the exit orifice, and also leads to Ekman pumping in the boundary layers of reduced azimuthal velocity at the convergent wall of the chamber and at the wall opposite to the exit orifice. The numerical results confirm the important role played by the boundary layers. They make the thickness of the liquid sheet at the end of the orifice larger than predicted by irrotational models, and at the same time tend to decrease the overpressure required to pass a given flow rate through the chamber, because the large axial velocity in the boundary layers takes care of part of the flow rate. The thickness of the boundary layers increases when the atomizer constant (the inverse of a swirl number, proportional to the flow rate scaled with the radius of the exit orifice and the circulation around the air core) decreases. A minimum value of this parameter is found below which the layer of reduced azimuthal velocity around the air core prevents the pressure from increasing and steadily driving the flow through the exit orifice. The effects of other parameters not accounted for by irrotational models are also analysed in terms of their influence on the boundary layers.

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