Circulation control in magnetohydrodynamic rotating flows

2017 ◽  
Vol 829 ◽  
pp. 328-344 ◽  
Author(s):  
V. D. Borisevich ◽  
E. P. Potanin ◽  
J. Whichello
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Exact Analytical Solution ◽  
External Rotation ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Rotating Cylinder ◽  
Rotating Disc ◽  
Angular Velocities ◽  
Energy Equations

A model of a laminar viscous conducting flow, near a dielectric disc in a uniform magnetic field and in the presence of external rotation, is considered, where there is a uniform suction and an axial temperature gradient between the flow and the disc’s surface. It is assumed that the parameters of the suction or the magnetohydrodynamic (MHD) interaction are such that the nonlinear inertial terms, related to the circulation flow, are negligible in the differential equations of the MHD boundary layer on a rotating disc. Analysis of the motion and energy equations, taking the dependence of density on temperature into account, is carried out using the Dorodnitsyn transformation. The exact analytical solution for the boundary layer and heat transfer equations is obtained and analysed, neglecting the viscous and Joule dissipation. The dependence of the flow characteristics in the boundary layer on the rate of suction and the magnetic field induction is studied. It is shown that the direction of the radial flow in the boundary layer on a disc can be changed, not only by variation of the ratio between the angular velocities in the external flow and the boundary layer, but also by changing the ratio of the temperatures in these two flows, as well as by varying the hydrodynamic Prandtl number. The approximate calculation of a three-dimensional flow in a rotating cylinder with a braking disc (or lid) is carried out, demonstrating that a magnetic field slows the circulation velocity in a rotating cylinder.

scholarly journals Numerical Study of Bleed Slot Flow Characteristics Using Magneto-Aerodynamics

2021 ◽  
Author(s):  
Szym on Buhajczuk
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
High Speed ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Past Research ◽  
Charge Generation ◽  
High Speed Engine ◽  
Displacement Thickness ◽  
Sonic Flow

A numerical study into magneto-aerodynamic bleed control systems has been undertaken with the intent of improving the shock swallowing ability of high speed engine intakes. Past research has shown that bleed slots effectively remove sufficient mass flow of air from the system to permit shocks to be swallowed. A magnetic field's influence on a charged boundary layer creates a possibility of sealing a bleed slot when not needed. 2D bleed slots were modeled using structured grids for use with the FLUENT CFD solver. User defined functions were written to simulate charge generation and magnetic field forces. Solutions revealed that bleed slot angles, free stream Mach numbers, pressure ratios, boundary layer displacement thickness, field strength and field position all affect how the system performs. Results have shown that a properly positioned magnetic field can reduce sonic flow coefficients up to 88%, thus justifying further research and investment in wind tunnel experiments.

Flow Characteristics in a Three-Dimensional Rectangular Channel With a Pair of Ribs Placed Symmetrically at the Channel Walls

2000 ◽  
Author(s):  
M. Singh ◽  
P. K. Panigrahi ◽  
G. Biswas
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Numerical Study ◽  
Rectangular Channel ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Complex Flow ◽  
Energy Equations

Abstract A numerical study of rib augmented cooling of turbine blades is reported in this paper. The time-dependent velocity field around a pair of symmetrically placed ribs on the walls of a three-dimensional rectangular channel was studied by use of a modified version of Marker-And-Cell algorithm to solve the unsteady incompressible Navier-Stokes and energy equations. The flow structures are presented with the help of instantaneous velocity vector and vorticity fields, FFT and time averaged and rms values of components of velocity. The spanwise averaged Nusselt number is found to increase at the locations of reattachment. The numerical results are compared with available numerical and experimental results. The presence of ribs leads to complex flow fields with regions of flow separation before and after the ribs. Each interruption in the flow field due to the surface mounted rib enables the velocity distribution to be more homogeneous and a new boundary layer starts developing downstream of the rib. The heat transfer is primarily enhanced due to the decrease in the thermal resistance owing to the thinner boundary layers on the interrupted surfaces. Another reason for heat transfer enhancement can be attributed to the mixing induced by large-scale structures present downstream of the separation point.

scholarly journals Three-Dimensional Magnetic Fluid Boundary Layer Flow Over a Linearly Stretching Sheet

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
E. E. Tzirtzilakis ◽  
N. G. Kafoussias
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Magnetic Fluid ◽  
Boundary Layer Flow ◽  
Stretching Sheet ◽  
Numerical Technique ◽  
Three Dimensional ◽  
Magnetic Interaction ◽  
Layer Flow ◽  
The Magnetic Field

The three-dimensional laminar and steady boundary layer flow of an electrically nonconducting and incompressible magnetic fluid, with low Curie temperature and moderate saturation magnetization, over an elastic stretching sheet, is numerically studied. The fluid is subject to the magnetic field generated by an infinitely long, straight wire, carrying an electric current. The magnetic fluid far from the surface is at rest and at temperature greater of that of the sheet. It is also assumed that the magnetization of the fluid varies with the magnetic field strength H and the temperature T. The numerical solution of the coupled and nonlinear system of ordinary differential equations, resulting after the introduction of appropriate nondimensional variables, with its boundary conditions, describing the problem under consideration, is obtained by an efficient numerical technique based on the common finite difference method. Numerical calculations are carried out for the case of a representative water-based magnetic fluid and for specific values of the dimensionless parameters entering into the problem, and the obtained results are presented graphically for these values of the parameters. The analysis of these results showed that there is an interaction between the motions of the fluid, which are induced by the stretching surface and by the action of the magnetic field, and the flow field is noticeably affected by the variations in the magnetic interaction parameter β. The important results of the present analysis are summarized in Sec. 6.

scholarly journals MHD Stagnation Point Flow of Nanofluid on a Plate with Anisotropic Slip

Symmetry ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 132 ◽  
Author(s):  
Muhammad Sadiq
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Stagnation Point ◽  
Three Dimensional ◽  
Stagnation Point Flow ◽  
Three Dimensional Flow ◽  
Moving Plate ◽  
Physical Quantities ◽  
The Magnetic Field ◽  
Momentum Boundary Layer

In this article, an axisymmetric three-dimensional stagnation point flow of a nanofluid on a moving plate with different slip constants in two orthogonal directions in the presence of uniform magnetic field has been considered. The magnetic field is considered along the axis of the stagnation point flow. The governing Naiver–Stokes equation, along with the equations of nanofluid for three-dimensional flow, are modified using similarity transform, and reduced nonlinear coupled ordinary differential equations are solved numerically. It is observed that magnetic field M and slip parameter λ 1 increase the velocity and decrease the boundary layer thickness near the stagnation point. Also, a thermal boundary layer is achieved earlier than the momentum boundary layer, with the increase in thermophoresis parameter N t and Brownian motion parameter N b . Important physical quantities, such as skin friction, and Nusselt and Sherwood numbers, are also computed and discussed through graphs and tables.

scholarly journals Three-Dimensional Radiative Flow of Hybrid Nanofluid Past a Shrinking Plate with Suction

2021 ◽  
Vol 85 (1) ◽  
pp. 54-70
Author(s):  
Nur Syahirah Wahid ◽  
Norihan Md Arifin ◽  
Najiyah Safwa Khashi’ie ◽  
Rusya Iryanti Yahaya ◽  
Ioan Pop ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Fluid Motion ◽  
Three Dimensional ◽  
Boundary Layer Separation ◽  
Hybrid Nanofluid ◽  
Volumetric Concentration ◽  
Similarity Transformations ◽  
The Stability ◽  
Energy Equations ◽  
Shrinking Surface

Hybrid nanofluid has been widely used in various heat transfer applications especially as the heat exchanger due to the great thermal conductivity compared to the conventional fluid. However, numerous investigations should still be carried out to properly understand its properties. Hence, in this study, a three-dimensional radiative flow of hybrid Cu-Al2O3/water nanofluid past a permeable shrinking plate is numerically analyzed. The boundary layer including the energy equations are reduced to a system of ordinary differential equations using the similarity transformations and are then solved numerically by using the bvp4c solver in MATLAB. The application of suction through the permeable plate is necessary in aiding the fluid motion past the shrinking surface. Dual solutions are also observable, hence the stability analysis is conducted to mathematically validate the real solution. The enhancement of copper volumetric concentration in the hybrid nanofluid is capable in decelerating the boundary layer separation.

A self-similar solution of dissipative MHD for a jet in the boundary-layer approximation

1995 ◽  
Vol 53 (1) ◽  
pp. 49-62
Author(s):  
Alejandro G. Gonález ◽  
Martin Heyn
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Analytical Solution ◽  
Exact Analytical Solution ◽  
Viscous Drag ◽  
Integrals Of Motion ◽  
Boundary Layer Approximation ◽  
Initial Stage ◽  
Self Similar Solution ◽  
Self Similar

A solution of dissipative nonlinear MHD taking account of the balance between viscous drag, the Lorentz force, resistive diffusion and inertia in a boundary- layer approximation is presented. It is a steady solution corresponding to a jet in a conducting fluid with viscosity. The problem is solved using a self-similar variable. An exact analytical solution is possible. The integrals of motion are obtained and their physical meaning is explained. The behaviour of the solutions is described. The entrainment of the jet is observed in some examples after an initial stage dominated by magnetic fields. These solutions are an extension of Bickley's jet for a case with magnetic field and resistivity.

A nonlinear, asymptotic investigation of the stationary modes of instability of the three-dimensional boundary layer on a rotating disc

1987 ◽  
Vol 413 (1845) ◽  
pp. 497-513 ◽  
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Nonlinear Effects ◽  
Finite Amplitude ◽  
Neutral Stability ◽  
Lower Branch ◽  
Rotating Disc ◽  
Dimensional Boundary ◽  
High Reynolds ◽  
Set Up

There exist two types of stationary instability of the flow over a rotating disc corresponding to the upper, inviscid mode and the lower-branch mode, which has a triple-deck structure, of the neutral stability curve. The linear problem has been investigated by P. Hall ( Proc. R. Soc. Lond. A 406, 93-106 (1986)) and the asymptotic structure of the wavenumber and orientation of these modes has been obtained. Here, a nonlinear investigation of high Reynolds number, stationary instabilities in the three-dimensional boundary layer on a rotating disc is given for the lower branch mode. By considering nonlinear effects and following the framework set up by Hall, asymptotic solutions are obtained that enable the finite amplitude growth of a disturbance close to the neutral location to be described.

scholarly journals The Effect of Inlet Boundary Layer Thickness on the Flow Within an Annular S-Shaped Duct

1998 ◽  
Author(s):  
Toyotaka Sonoda ◽  
Toshiyuki Arima ◽  
Mineyasu Oana
Keyword(s):  
Boundary Layer ◽  
Flow Pattern ◽  
Pressure Loss ◽  
Total Pressure ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Vortex Pair ◽  
Separated Flow ◽  
Total Pressure Loss ◽  
Centrifugal Impeller

Experimental and numerical investigations were carried out to gain a better understanding of the flow characteristics within an annular S-shaped duct, including the effect of the inlet boundary layer (IBL) on the flow. A duct with six struts and the same geometry as that used to connect compressor spools on our experimental small two-spool turbofan engine was investigated. A curved downstream annular passage with a similar meridional flow path geometry to that of the centrifugal compressor has been fitted at the exit of S-shaped duct. Two types of the IBL (i.e. thin and thick IBL) were used. Results showed that large differences of flow pattern were observed at the S-Shaped duct exit between two types of the IBL, though the value of “net” total pressure loss has not been remarkably changed. According to “overall” total pressure loss, which includes the IBL loss, the total pressure loss was greatly increased near the hub as compared to that for a thin one. For the thick IBL, a vortex pair related to the hub-side horseshoe vortex and the separated flow found at the strut trailing edge has been clearly captured in the form of the total pressure loss contours and secondary flow vectors, experimentally and numerically. The high-pressure loss regions on either side of the strut wake near the hub may act on a downstream compressor as a large inlet distortion, and strongly affect the downstream compressor performance. There is a much-distorted three-dimensional flow pattern at the exit of S-Shaped duct. This means that the aerodynamic sensitivity of S-Shaped duct to the IBL thickness is very high. Therefore, sufficient carefulness is needed to design not only downstream aerodynamic component (for example centrifugal impeller) but also upstream aerodynamic component (LPC OGV).

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