Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
31
3
2004
Heat Transfer in an Evaporating Extended Meniscus in Capillary Tubes Utilizing Binary Fluid Mixtures
12
Rama Subba Reddy
Gorla
Department of Mechanical Engineering, Cleveland State University, Cleveland, OH, 44115 USA; Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA; Department of Mechanical & Civil Engineering, Purdue University Northwest, Westville, IN 46391, USA
Larry W.
Byrd
Thermal Structures Branch, Air Vehicles Directorate, Air Force Research Laboratory, Wright Patterson Air Force Base, OH 45433, USA
The deformation of a thin liquid film in the presence of a binary fluid with higher surface tension under varying temperature distributions is considered. Lubrication theory and the interfacial thermocapillary stress condition were used to yield a differential equation for the film thickness. The evaporative mass flow rate, heat flux and heat transfer coefficient were evaluated for various concentrations of the binary fluid mixture. The heat transfer rate increases as the concentration of the driver fluid in the binary mixture reaches a value of 9 %. After reaching this value of concentration, the heat transfer rate was observed to decrease.
Natural Convection of Liquid Metals in an Inclined Enclosure in the Presence of a Magnetic Field
23
Ali F.
Al-Mudhaf
Manufacturing Engineering Department, The Public Authority for Applied Education and Training, P. O. Box 42325, Shuweikh, 70654 Kuwait
Ali J.
Chamkha
Department of Mechanical Engineering, Prince Sultan Endowment for Energy and
Environment, Prince Mohammad Bin Fahd University, Al-Khobar 31952, Kingdom of Saudi
Arabia; RAK Research and Innovation Center, American University of Ras Al Khaimah, United Arab Emirates, 10021
The problem of steady, laminar, natural convective flow of electrically-conducting liquid metals such as gallium and germanium in an inclined rectangular enclosure in the presence of a uniform magnetic field is considered. Transverse gradient of heat is applied on two opposing walls of the inclined enclosure while the other two walls are adiabatic. A magnetic field is applied normal to the non-insulated walls. The problem is formulated in terms of the vorticity - stream function procedure. A numerical solution based on the finite-difference method is obtained. Representative results illustrating the effects of the enclosure inclination angle and the Hartmann number for two different Rayleigh numbers on the contour maps of the streamlines and temperature as well as the profiles of velocity components and temperature at mid-section of the enclosure are reported. In addition, results for the average Nusselt number are presented and discussed for various parametric conditions.
Sound Generation by a Limited Region of Disturbed Flow in a Rigid Channel of Circular Cross-Section. A General Theory
11
A. O.
Borisyuk
Institute of Hydromechanics of the National Academy of Sciences of Ukraine, Zhelyabov Str., 8/4, 03680, Kyiv-180, MSP, Ukraine
A general theory of sound generation by a limited region of disturbed flow in an infinite straight rigid-walled channel of circular cross-section is developed, and the quantitative relationships between the characteristics of the sound field generated and the parameters of the channel and flow are established. A disturbed flow is modeled by distributed quadrupole and dipole sources (which characteristics are assumed to be known), and the cases of uniform and non-uniform source distribution are considered. It is shown that the sound energy does not decrease as the distance from the sources increases, and it is equal to a sum of energies of the acoustic modes of the channel. The acoustic mode energy consists of three parts herewith. The first part is the energy generated by the volume quadrupoles, the second part results from the surface dipoles, and the third part is due to interaction of the quadrupoles and dipoles. An order of magnitude analysis of these parts is carried out for different values of the flow Mach number, and the corresponding simplified expressions for the acoustic power are obtained.
Microphone Based Sensor for Recording the Respiratory Sounds
12
I. Yu.
Goncharova
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
Physical and mathematical models of sensors for recording the respiratory sounds with the use of electret microphones have been developed. Corresponding boundary problems with and without the compensating tube have been solved in the exact statement. Influence of dimensions of the air chamber and compensating tube on the efficiency of such sensors has been investigated. When solving the problems the losses caused by viscous friction in narrow compensating tube were taken into account. Ways for optimization of geometrical parameters of such systems have been outlined.
Performance Analysis of Acoustic Receiving Devices Functioning in a Car Cabin Based on Computer Modeling of a Sound Field
7
A. Ya.
Kalyuzhny
Scientific and Production Enterprise "Delta", Kyiv, Ukraine
A. A.
Kovtonyuk
Scientific and Production Enterprise "Delta", Kyiv, Ukraine
V. B.
Galanenko
State Research and Production Enterprise "Delta", Kyiv, Ukraine
A model for speech and noise sound fields in a car cabin is proposed. The model takes into account a complicated geometry of the cabin, frequency dependence of sound absorption on its surfaces and spatial correlation of distributed noises. The sound field computation is based on the wave approach for the range of low frequencies (below 1000 Hz) and on the ray approximation for higher frequencies. The software is developed, which provides simulation of speech and noise fields in the cabin during the car motion. This software may be utilized as an simulator of the sound field for the development of speech coding and recognition devices intended for car cabins. To check the model adequacy the spectra of simulated noise of the engine and results of natural measurements are compared. The effectiveness of microphone arrays as speech enhancement tools is investigated on the base of the developed model for different signal processing algorithms and noise conditions.
Algebraic Models of Turbulent Viscosity and Heat Transfer in Analysis of Near-Wall Turbulent Flows
15
M.
Lunis
Kyiv International University of Civil Aviation, Kyiv, Ukraine
V. I.
Mamchuk
Kyiv International University of Civil Aviation, Kyiv, Ukraine
V. T.
Movchan
Kyiv International University of Civil Aviation, Kyiv, Ukraine
Eugene Alexeyevich
Shkvar
Higher and Computational Mathematics Chair, National Aviation University 1 Cosmonaut Komarovave., 03058, Kiev, Ukraine
L. A.
Romanyuk
Kyiv International University of Civil Aviation, Kyiv, Ukraine
This paper presents developed and tested algebraic models of turbulent viscosity and thermal conductivity coefficients. The models have been developed in the form of one formula valid across the whole boundary layer. The empirical coefficients and parameters for accounting the action of several physical factors being modified, the models are generalized to applications in the analysis of a large class of near-wall turbulent flows. The approximate analytical and numerical solutions of velocity and temperature distributions, skin-friction and heat transfer coefficients, that have been obtained with the models, are compared in the report with experimental and computed data of several authors.
Kinematics of Flow in a Dead End Part of a Vortex Chamber
8
V. N.
Turick
Institute of Hydromechanics of National Academy, of Sciences of Ukraine, Kyiv, Ukraine
R. A.
Makarenko
National Engineering University of Ukraine "KPI", Kyiv, Ukraine
The paper presents results of an experimental study of an averaged flow in the dead end part of a cylindrical chamber with tangential supply of immersed air jet. The flow is shown to consist of large-scale vortical structures "embedded" in one another. Empirical relationships are suggested, describing the geometry of the main peripheral spiral flow and a distribution of axial projections of the average velocity in its characteristic areas.
On a Self-Similar Solution of Flow Equations for Viscous Liquid
5
A. M.
Palti
E. O. Paton Electric Welding Institute, National Academy of Sciences of Ukraine, Kyiv, Ukraine
An analytical solution of the problem of an immersed incompressible viscous fluid jet in self-similar approximation is obtained in the paper. The proposed solution, unlike known ones, describes a jet with a paraxial back flow expanding along a cone.