Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
29
2
2002
Cryogenic Fuel Tanks Pressure Reduction a Low-G Fluid Mixing Experiment
11
Jihad M.
Albayyari
Associate Professor of Mechanical Engineering Technology Eastern Michigan University, 118 Sill Hall, Ypsilanti, MI 48197, USA
"Reduced-Fill Tank The Pressure Control Experiment (TPCE/RF)" is a space experiment developed to meet the need for a critical aspect of cryogenic fluid management technology: "control of storage tank pressures in the absence of gravity by forced-convection mixing". The experiment used Freon-113, at near saturation conditions and a constant 40 % fill level, to simulate the fluid dynamics and thermodynamics of cryogenic fluids in space applications. The objectives of TPCE/RF were: to characterize the fluid dynamics of an axial jet-induced mixing in low gravity, to evaluate the validity of empirical mixing models, and to provide data for use in developing and validating computational fluid dynamics model of mixing processes. TPCE/RF accomplished all of its objectives in the Space Shuttle flight in May 1996. The flow patterns observed generally agreed with a prior correlation derived from drop tower tests. Several existing mixing correlations were found to provide reasonable performance predictions. Low-energy mixing jets, dissipating on the order of 1 % of the kinetic energy of previous mixer designs, were found to be effective and reliable at reducing thermal non-uniformities. Those jets promote heat and mass active mixing, whether continuous or periodic. The mentioned factors offer increased reliability and predictability in space cryogenic systems and can be accomplished with no significant boiloff penalty caused by kinetic energy dissipation.
Heat Transfer in a Thin Liquid Film in the Presence of Electric Field for Non-Isothermal Interfacial Condition
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
Jorge E.
Gatica
Department of Chemical Engineering Cleveland State University Cleveland, OH 44115, USA
Bahman
Ghorashi
Department of Chemical & Biomedical Engineering, Cleveland State University, Cleveland, Ohio 44115-2425
Pijarn
In-Eure
Department of Chemical Engineering Cleveland State University Cleveland, OH 44115, USA
Larry W.
Byrd
Thermal Structures Branch, Air Vehicles Directorate, Air Force Research Laboratory, Wright Patterson Air Force Base, OH 45433, USA
Heat transfer enhancement in an evaporating thin liquid film using the electric field under non-isothermal interfacial condition is presented. A new mathematical model subjected to van der Waals attractive forces, the capillary pressure and the electric field is developed to describe the heat transfer enhancement in the evaporating thin liquid film. The effect of an electrostatic field on the curvature of the thin film, evaporative flux, pressure gradient distribution, heat flux, and heat transfer coefficient in the thin film is presented. The results show that the electric field can enhance heat transfer in the thin liquid film significantly. In addition, using electric fields on the evaporating film will be a way to expand the extended meniscus region to attain high heat transfer coefficients and high rates of heat flux.
Velocity Characteristics of Turbulent Natural Convection in Convergent-Plates Vertical Channels
21
Mohamed A.
Habib
Mechanical Engineering Department, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia
Syed-Ahmad M.
Said
Mechanical Engineering Department King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
S. A.
Ahmed
Mechanical Engineering Department King Fahd University of Petroleum and Minerals Dhahran 31261, Saudi Arabia
Velocity measurements of natural convection in symmetrically and asymmetrically heated convergent-plates vertical channels are presented. In the first case, symmetrical flow, the two channel plates were both kept at a constant temperature higher than the ambient. In the second case, asymmetrical flow, one plate was kept at a temperature higher than ambient temperature while the other plate was kept at a temperature lower than the ambient temperature. The velocity measurements were performed using a Laser Doppler Anemometer. In the case of symmetrical flow, the results indicate a zero velocity region located at the center of the channel close to its exit. In the case of asymmetrical flow, the results show that the flow accelerates by the hot side and decelerates by the cold plate. The results also indicate that cooling one of the two plates below ambient influences the flow pattern significantly and results in the formation of a large vortex at the center of the channel.
Computing of Viscous Fluid in a Backflow Preventer with an Oscillating Boundary
15
Tienfuan
Kerh
Department of Civil Engineering National Pingtung University of Science and Technology Pingtung 91207, Taiwan
In a cross connection control field, the backflow assemblies that consist of an independently operated spring loaded check valve is an important device to prevent contaminations from reverse flow. In this paper, the interaction of a viscous fluid with a backflow preventer is investigated by solving Navier-Stokes equations and equilibrium equation for both fluid and solid. Three mesh systems are computed and compared to check grid independence and to obtain more reliable numerical results. The variables including displacement, velocity, and acceleration are presented as a function of time to describe the moving solid element. Whereas, the velocity vectors, pressure surface distributions, and pressure loss coefficients versus time are shown to reveal the resulting flow fields. The computational results show that the solid element will return to its static equilibrium position due to the effect of spring force and the development of a relatively stronger eddy at the upper right part of a solid body. The moving behavior of the solid body may cause a damage of the entire solid system and decrease the flow rate after a long-time action. This may imply that a block system is a better choice than a thin plate system for this type of backflow preventer, as the former one is balanced by fluid force at a new position to provide maximum flow rate if necessary.
The Effect of Inhomogeneity of Elastic Layer Placed between Different Fluids on the Wave Propagation
10
Olga V.
Avramenko
Kirovograd State V. Vinnichenko Pedagogical University, Kirovograd
Igor T.
Selezov
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Zhelyabov St., 8/4, Kyiv, 03680, MSP, Ukraine
Propagation of harmonic waves in the hydroelastic system consisting of in-homogeneous elastic layer placed between the two compressible fluids of different physical properties is investigated. Numerical analysis of the dispersion equation is carried out for phase velocities less than the greater sound velocity of two fluids. The dispersion equation has two real roots corresponding to quasisymmetric and quasiantisymmetric oscillations of the layer. The two limiting cases are considered: the layer between the two fluids of different properties and the inhomogeneous layer between the same fluids. The wave modes are presented for longitudinal and transverse displacements, shear and normal stresses in elastic layer. It is established from the analysis of wave modes that inhomogeneity of the layer can lead to a strong concentration of wave fields both in central part (inhomogeneity of the first type), and near boundaries of the layer (inhomogeneity of the second type).
On Evaluation of Frequencies and Associated Masses of a Fluid in a Rectangular Container with Partition Walls in the Cross Plane of Symmetry
12
D. A.
Galitsyn
Institute of Mathematics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
V. A.
Trotsenko
Institute of Mathematics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
The paper proposes a technique for determination of the hydrodynamic coefficients of the equations of motion of a solid body with a cavity shaped like a rectangular parallelepiped when the body is in a transverse motion. This technique is based on solving the basic boundary-value problems by the modified method of conjugation of solutions and takes into account the singularities in the first-order derivatives of the unknown functions at the partition walls' edges. The efficiency of the algorithm and several results of evaluation of the frequencies and associated masses of a liquid filling the cavity are analyzed.
Modal Modeling of Nonlinear Fluid Sloshing in Tanks with Non-Vertical Walls. Non-Conformal Mapping Technique
27
A. N.
Timokha
National Academy of Sciences of Ukraine, Institute of Mathematics, Tereschenkivska 3, 01601 Kiev, Ukraine
I. A.
Lukovsky
National Academy of Sciences of Ukraine, Institute of Mathematics, Tereschenkivska 3, 01601 Kiev, Ukraine
Nonlinear sloshing of an incompressible fluid with irrotational flow is analyzed. The fluid partly occupies a smooth tank with walls having lion-cylindrical shape. No overturning, breaking and shallow water; waves are assumed. Non-conformal mapping technique by Lukovsky (1975) is developed further. It assumes that tank's cavity can be transformed into an artificial cylindrical domain, where equation of free surface allows both normal form and modal representation of instantaneous surface shape. Admissible tensor transformations have due singularities in mapping the lower (upper) corners of the tank into artificial bottom (roof). It leads to degenerating spectral boundary problems on natural modes. The paper delivers the mathematical background for these aspectral problems and establishes the spectral and variational theorems. Natural modes in circular conical cavity are calculated by variational algorithm based on these theorems. It is Shown that the algorithm is robust and numerically efficient for calculating both lower and higher natural modes. Finally, the paper shows that the well-known infinite-dimensional modal systems by Lukovsky (derived for sloshing in cylindrical tank) keep invariant structure with respect to admissible tensor transformations (for translatory motions of the vehicle). This makes it possible to offer the simple derivation algorithm of nonlinear modal systems for the studied case. When using anzatz by Lukovsky we derive the five-dimensional modal system for nonlinear sloshing in circular conic tanks.
Visco-Diffusive Stage of Two-Dimensional Mixed Patch's Evolution in the Field of Internal Wave
18
O. G.
Stetsenko
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
Vladimir S.
Maderich
Institute of Problems of Mathematical Machines and Systems of National Academy of Sciences of Ukraine, Kyiv, Ukraine
P. V.
Lukyanov
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
Peculiarities of visco-difiusive stage of a two-dimensional mixed patch, when it spreads in the field of a monochrome internal Wave (IW), have been studied. A model has been plotted for the case of maximum effect of an IW on a patch when typical horizontal scale of the patch is much less than the wave length. Numerical computations have been done for a linear stratified fluid layer with finite thickness. It has been shown that the effect of an IW on evolution of mixed patches may be neglected with sufficient degree of accuracy.
Modes of the Lamb's Type in the Generalized Pochhammer-Chree Problem
13
S. V.
Novotny
Institute of Mechanics of the Lomonosov Moscow State University, Russia
Propagation of harmonic axisymmetrical waves in an infinite elastic cylinder is considered. Properties of the waves are studied for specific case of the inertial boundary conditions on the cylinder's surface, when the mechanical stresses on the surface are proportional to the accelerations. The dispersion properties of propagating and evanescent waves, which correspond to real and pure imaginary roots of the dispersion equations, are studied. Special attention is given to determining those frequencies, for which the phase velocity does not depend on the Poisson's ratio (the Lamb's modes). It is proved that there is only finite number of such modes for the case of inertially supported boundary, while in classical case of free cylinder's surface the infinite number of the Lamb's modes exist. The behaviour of the boundary problem solutions at change of the Poisson's ratio is studied.
On the Linearized Dynamic Equations of a Rotating Stratified Compressible Fluid
10
P. A.
Shestopal
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
N. V.
Saltanov
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
Representations of the generalized potentials in the theory of a rotating stratified compressible fluid are considered. Being undisturbed, the fluid is exponentially stratified along the axis z directed along the gravity force vector. Using the generalized potential as the base, the solution of the problem of the uniform helical flow past a sphere is obtained. When the helicity coefficient of the helical flow tends to zero, this solution is shown to transform to the traditional solution of the problem of a potential flow past a sphere. The influence of the helicity coefficient's variation on the flow patterns and pressure coefficient is analyzed.