Heat exchange in two-phase flow about a surface located in a rectangular channel

Similitude equations are obtained on the basis of the principle of superposition of separate effects to calculate heat exchange between surfaces with complexshaped cross sections located in a rectangular channel during their cooling by a two-phase flow.Notation T, q temperature and heat flux - T_w mean surface temperature - I, R current and electrical resistance - V volume of the material - , , anda heat-transfer coefficients, thermal conductivity, and linear expansion of the material - relative functions - =_m; ^* = _m ^{* *} _s ^* ; temperature factor - X relative weight content of liquid phase Indices w surface - f incoming flow - v volume - m two-phase flow - angle of attack - s shape of surface - * pertains to surface with swirl vanes Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 40, No. 5, pp. 780–786, May, 1980.     

Features of two-phase flow in a rectangular microchannel

A two-phase (liquid-gas) flow in a short horizontal slit channel of rectangular cross section with a height (thickness) of 200 μm has been experimentally studied using laser-induced fluorescence and schlieren photography methods, which allowed the pattern of flow in the channel to be monitored and its quantitative characteristics to be measured. It is established that a separate (stratified) flow regime can exist in the system. The two-phase flow in the given channel can exhibit features in the form of liquid drops and rivulets. A change in the height of the horizontal slit channel significantly influences the boundaries between different regimes.     

Fluctuation model of a nonequilibrium two-phase channel flow

An ill-posed Cauchy problem for a model of a nonequilibrium two-phase flow in the barotropic approximation is transformed into a well-posed problem by changing the type of the initial hyperbolic equations. Approximation of fluctuations of the phase velocities by a random delta-correlated process and averaging of the equations over its realizations generate a system of parabolic equations. Results of numerical integration of this system are compared with experiment and calculations by well-known models.Notation a velocity of propagation of acoustic perturbations - frozen velocity of sound - b dimensionless constant - h enthalpy - L tube length, scale of velocity fluctuations - p pressure - R complex - T temperature - t time - velocity - x coordinate - step of the difference scheme - fluctuating component of the velocity, delta-function - dimensionless variable - phase density - ² variance of the velocity - characteristic correlation time - volume phase concentration Institute of Engineering Thermophysics, Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 6, pp. 651–656, June, 1994.     

Instability of plane Couette flow of two-phase liquids

The stability of plane Couette flow of a disperse liquid (gaseous or liquid suspension) is investigated. It is shown that in contrast to the flow of a pure liquid (gas), above a certain threshold particle mass density, this flow begins to become unstable to infinitesimal perturbations. Pis’ma Zh. Tekh. Fiz. 24, 76–80 (March 12, 1998)     

The Green function for potential flow in a rectangular channel

The evaluation of the Green function is considered for the three-dimensional Laplace equation, in the interior of a rectangular channel subject to homogeneous Neumann conditions on the boundaries. To complement the Fourier eigenfunction expansion which is effective in the far-field, a near-field algorithm is developed based on the simpler Green function for a channel of infinite width, using images to account for the channel sides. Examples are given of numerical applications including the added mass of a sphere in a square channel, and the interaction force between a ship and an adjacent canal wall.     

Turbulent flow in a rectangular cavity in the wall of a two-dimensional channel

Results are presented of a theoretical and experimental investigation of flow of a turbulent incompressible liquid over a rectangular cavity of relative depth 1–3.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 46, No. 3, pp. 363–371, March, 1984.     

气液混输下侧流道泵内压力脉动特性研究

侧流道泵是一种新型超低比转速泵,因其具有小流量、高扬程、可自吸和气液混输等优点,近年来广泛应用于化工、汽车、医药工业和油气开采等领域.由于侧流道泵内部流动复杂、湍流强度极大,势必会产生较强的压力脉动,造成侧流道泵性能降低和运行不稳定,这种影响在气液混输时更为严重.基于MUSIG模型,对不同含气率下侧流道泵内部流动进行数...     

Experimental investigation of isothermal turbulent flow in a rectangular channel with blowing

The profiles of longitudinal averaged velocities in a rectangular channel with two-way uniform blowing are measured. A method is proposed for the calculation of the velocities based on the obtained empirical relations. The normal components of the velocity and the shear stresses in the flow are computed.Deceased.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 19, No. 3, pp. 406–411, September, 1970.     

Approximate method for calculating turbulent two-phase flow in a channel with permeable walls

Based on a model of a double-velocity and two-temperature medium the authors constructed a system of equations that describes plane or axisymmetric turbulent flow of a gas suspension in a channel with permeable walls. The system of equations of motion and heat transfer reduces to a system of ordinary differential equations, whose integration is much less difficult than solution of the initial system. The authors obtained the distribution of the velocity and local characteristics of turbulence in the channel with injection with allowance for the inverse effect of a condensed phase.     

Instability of Poiseuille flow of two immiscible liquids with different viscosities in a channel

We study the stability of plane Poiseuille flow of two immiscible liquids of different viscosities and equal densities. The problem is like one considered by C. S. Yih who found that flow in two layers of equal thickness was always unstable. We find regions of stability when there are three layers with one of the fluids centrally located. We view our contribution as a study of selection of stable steady flow from a nonunique continuum of Poiseuille flows all of which satisfy the steady Navier-Stokes and which differ from another in the number and thickness of layers of different viscosity. Experiments have shown that there is a tendency for the less viscous fluid to encapsulate the more viscous one. This arrangement of components, with the more viscous fluid in the center of the channel maximizes the mass flux for a fixed pressure gradient. A linear stability analysis of centrally located configuration to long waves is carried out by the analytic methods introduced by Yih [1]. The stability results depend on the viscosity and volume ratio in a fairly complicated way. The flow with the high viscosity fluid centrally located is always stable. Centrally located layers of less viscous fluid, called fingering flows, are always unstable.     

Hydrodynamic characteristics of a horizontal channel with the motion of a two-phase helium flow

Experimental data is presented on the pressure drop in the motion of a two-phase helium flow in a horizontal pipe under adiabatic conditions and with a supply of heat.     

Calculation of the parameters of a two-phase mixture flow in a channel of variable cross section

The case of steady-state one-dimensional flow in a channel of variable cross section is examined for a two-phase gas-solids mixture. Equations relating the parameters of a gas-dust mixture and the dimensionless gas velocity are derived on the assumption that the velocities and temperatures of the two phases are equal. A formula is obtained for the coefficient of polytropy with allowance for flow friction against the channel walls.     

Turbulent biomagnetic fluid flow in a rectangular channel under the action of a localized magnetic field

The fundamental problem of the turbulent flow of a biomagnetic fluid (blood) between two parallel plates under the action of a localized magnetic field is studied. The blood is considered to be an electrically conducting, incompressible and Newtonian fluid and its flow is steady, two-dimensional and turbulent. The turbulent flow is described by the Reynolds averaged Navier–Stokes (RANS) equations. For the numerical solution of the problem under consideration, which is described by a coupled and non-linear system of PDEs, with appropriate boundary conditions, the stream function–vorticity formulation is used. For the eddy-kinematic viscosity, the low Reynolds number k–ε turbulence model is adopted. The solution of the problem, for different values of the dimensionless parameter entering into it, is obtained by developing and applying an efficient numerical technique based on finite differences scheme. Results concerning the velocity and temperature field, skin friction and rate of heat transfer, indicate that the presence of the localized magnetic field, appreciable influences the turbulent flow field. A comparison is also made with the corresponding laminar flow, indicating that the influence of the magnetic field decreases in the presence of turbulence.     

Instability of a viscoelastic flow

The kinematic characteristics of the unstable (fluctuating) flow of a 1% solution of polyacrylamide in plane channels have been studied. The profiles of the time-average velocities, the rms velocity fluctuations, and the fluctuation probabilities were found on a computer.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 25, No. 6, pp. 1106–1111, December, 1973.     

Energy losses in a two-phase flow at interaction of solid particles with the wall of a vertical channel

Experimental and calculated data on the interaction of solid particles with the wall of a conveying pipe are presented.State Research and Design Institute of Chemical Technologies, Severodonetsk, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 3, pp. 333–338, September, 1992.     

Temperature distribution in laminar flow of an incompressible fluid in a rectangular channel allowing for energy dissipation

Expressions have been obtained for the temperature distribution over the section and heat flux through the channel wall in the presence of energy dissipation for the case of laminar flow of a liquid in an Infinitely long channel of rectangular section with constant wall temperature.     

Instabilities of two-phase flows in short rectangular microchannels

Two-phase (liquid-gas) flows in a short horizontal slit channel of rectangular cross section with heights (thicknesses) from 100 to 500 μm have been experimentally studied using the laser-induced fluorescence and schlieren photography methods. It is established that the formation of various two-phase flow regimes and the transitions between different regimes are determined by instabilities of the liquid-gas flow in the side parts of a channel. In a 100-μm-thick channel, a frontal instability has been observed during the liquid-gas interaction in the region of liquid output from the nozzle.