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1.
N. V. Malai E. R. Shchukin A. A. Stukalov K. S. Ryazanov 《Journal of Applied Mechanics and Technical Physics》2008,49(1):58-63
The steady motion of a uniformly heated spherical aerosol particle in a viscous gaseous medium is analyzed in the Stokes approximation
under the condition that the mean temperature of the particle surface can be substantially different from the ambient temperature.
An analytical expression for the drag force and the velocity of gravity-induced motion of the uniformly heated spherical solid
particle is derived with allowance for temperature dependences of the gaseous medium density, viscosity, and thermal conductivity.
It is numerically demonstrated that heating of the particle surface has a significant effect on the drag and velocity of gravity-induced
motion.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 1, pp. 74–80, January–February, 2008. 相似文献
2.
The infrared thermography technique was used to study the thermal and hydrodynamic phenomena in intermittent two-phase air–water flow in horizontal and inclined tubes at atmospheric pressure. The study was aimed at elucidating the relationship between the hydrodynamic parameters and dryout phenomena. It focuses on the empirical evaluation of the wall temperature distribution in a uniformly heated pipe. The results reveal the existence of dryout phenomena in horizontal pipe flow only. The flow parameter based on the frequency, length and velocity of elongated bubble is presented for the prediction of dryout. 相似文献
3.
Steffen Faik Mikhail M. Basko Anna Tauschwitz Igor Iosilevskiy Joachim A. Maruhn 《High Energy Density Physics》2012,8(4):349-359
Remaining within the pure hydrodynamic approach, we formulate a self-consistent model for simulating the dynamic behavior of matter passing through metastable states in the two-phase liquid–vapor region of the phase diagram. The model is based on the local criterion of explosive boiling, derived by applying the theory of homogeneous bubble nucleation in superheated liquids. Practical application of the proposed model is illustrated with hydrodynamic simulations of a volumetrically uniformly heated planar layer of fused silica SiO2. Implications for experimentally measurable quantities are briefly discussed. A newly developed equation of state, based on the well known QEOS model and capable of handling homogeneous mixtures of elements, was used in the numerical simulations. 相似文献
4.
N. V. Malai K. S. Ryazanov E. R. Shchukin A. A. Stukalov 《Journal of Applied Mechanics and Technical Physics》2011,52(4):553-559
The flow around a heated spherical drop in a viscous non-isothermal gaseous medium with uniformly distributed constant-power
heat sources (sinks) acting inside is theoretically described in the Stokes approximation. It is assumed that the mean temperature
of the drop surface can differ substantially from the temperature of the ambient gaseous medium. An analytical expression
for the drag force and drift velocity in the gravity field is derived by solving hydrodynamic equations with allowance for
the temperature dependence of viscosity, thermal conductivity, and density of the gaseous medium. 相似文献
5.
A study is made of the radial motion of a vapor envelope surrounding an isolated spherical particle in an unbounded mass of liquid. It is assumed that the liquid is viscous and incompressible and that the temperature is distributed uniformly in the solid particle. A model of a calorifically perfect gas is used for the vapor phase. The same assumptions are made as in Rayleigh's formulation for the problem of the dynamics of a single bubble: that the process is spherically symmetric and that the pressure P2 (t) in the vapor phase is homogeneous. The justification for making these assumptions in problems of the dynamics of gas, vapor, and vaporgas bubbles is discussed in [1–5]. In this paper, the collapse of the vapor layer and the boiling of the liquid on the surface of the heated particle are not considered.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 154–157, July–August, 1985. 相似文献
6.
N. V. Malai 《Fluid Dynamics》2003,38(6):954-962
In the Stokes approximation, for small Reynolds and Péclet numbers, the motion of a heated rigid spherical particle in a viscous fluid, in which external sources maintain a small constant temperature gradient, is described theoretically. The hydrodynamic equations are solved using an exponential-power form of the temperature dependence of the viscosity. The possibility of observing thermophoresis in a fluid experimentally is discussed. 相似文献
7.
The objective of this study is to investigate experimentally the stratification phenomena of boiling two-phase flow in a uniformly heated horizontal channel. Two-phase flow stratification due to gravity effects, and consequently its thermal and hydrodynamic behavior, under steady state conditions, have been determined by measuring 16 top and 16 bottom wall temperatures. Six distinct wall temperature profiles are found, and the corresponding flow patterns are discussed. A dimensionless number has been formulated for the prediction of the occurrence of different flow patterns. 相似文献
8.
The problem of rotation of a rigid spheroidal particle about its axis of revolution in a viscous fluid is studied analytically and numerically in the steady limit of negligible Reynolds number. The fluid is allowed to slip at the surface of the particle. The general solution for the fluid velocity in prolate and oblate spheroidal coordinates can be expressed in an infinite-series form of separation of variables. The slip boundary condition on the surface of the rotating particle is applied to this general solution to determine the unknown coefficients of the leading orders, which can be numerical results obtained from a boundary collocation method or explicit formulas derived analytically. The torque exerted on the spheroidal particle by the fluid is evaluated for various values of the slip parameter and aspect ratio of the particle. The agreement between our hydrodynamic torque results and the available analytical solutions in the limiting cases is good. It is found that the torque exerted on the rotating spheroid normalized by that on a sphere with radius equal to the equatorial radius of the spheroid increases monotonically with an increase in the axial-to-radial aspect ratio for a no-slip or finite-slip spheroid and vanishes for a perfectly slip spheroid. For a spheroid with a specified aspect ratio, the torque is a monotonically decreasing function of the slip capability of the particle. 相似文献
9.
The temperature field and flow patterns of a liquid film flowing over a vertical uniformly heated surface have been experimentally investigated. Our experiments show that this film flow is sensitive to the heating conditions. When the film is cooled by the substrate, its surface area increases, and when it is heated its surface area decreases. The analysis attributed the changing properties of the flow to lateral Marangoni effect, i.e. to surface tension gradient transverse to the flow. The influence of the viscosity variations on the non-isothermal liquid film flow was also considered and compared with that of the surface tension variations. It was shown that the contraction or extension of the films was mainly caused by the lateral surface tension gradient that might be determined by the viscosity variations. 相似文献
10.
A combined analytical and numerical study of the Stokes flow caused by a rigid spheroidal particle translating along its axis of revolution in a viscous fluid is presented. The fluid is allowed to slip at the surface of the particle. The general solution for the stream function in prolate and oblate spheroidal coordinates can be expressed in an infinite-series form of semi-separation of variables. The slip boundary condition incorporating the shear stress at the particle surface is applied to this general solution to determine its unknown coefficients of the leading orders. The solution of these coefficients can be either numerical results obtained from a boundary-collocation method or explicit formulas derived analytically. The drag force exerted on the spheroidal particle by the fluid is evaluated with good convergence behavior for various values of the slip parameter and aspect ratio of the particle. The agreement between our hydrodynamic drag results and the relevant numerical solutions obtained previously using a singularity method is excellent. Although the drag force acting on the translating spheroid normalized by that on a corresponding sphere with equal equatorial radius increases monotonically with an increase in the axial-to-radial aspect ratio for a no-slip spheroid, it decreases monotonically as this aspect ratio increases for a perfect-slip spheroid. The normalized drag force exerted on a spheroid with a given surface slip coefficient in between the no-slip and perfect-slip limits is not a monotonic function of its aspect ratio. For a spheroid with a fixed aspect ratio, its drag force is a monotonically decreasing function of the slip coefficient of the particle. 相似文献
11.
The homogeneous nucleation limit is investigated in pure liquid subject to intense uniform heating at constant pressure. The
energy equation is solved in conjunction with a new non-equilibrium vapor formation model in order to predict the maximum
attainable liquid superheat as a function of the heating rate. It is shown that for uniformly heated liquids, conditions related
to the local temperature in a critical vapor embryo and to the local heat consumption for vapor generation on the homogeneous
fluctuation centers, must be satisfied simultaneously in order to initiate explosive boiling. The effect of heating rate on
the maximum attainable superheat temperature could be as high as 10 K. 相似文献
12.
An expression for the drag force on a spheroidal hydrosol particle is obtained for arbitrary temperature differences between the particle surface and the far region and with account for the temperature dependence of the viscosity represented in the form of an exponential-power series. 相似文献
13.
Problems similar to those considered in [1, 2] are studied, namely, slow flow over a uniformly heated (or cooled) spherical particle and flow past a weakly nonuniformly heated sphere in the absence of external body forces and with allowance for thermal stresses in the gas. The use of an improved method of numerical solution [3] has made it possible to advance into the region of large temperature differences. A new effect is found: allowance for the thermal stresses in the case of flow around a strongly heated sphere leads to the appearance of a suction force instead of a drag. In the case of flow around a nonuniformly heated sphere the influence of thermal stresses is unimportant. The problems are considered for two temperature dependences of the transport coefficients.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 170–175, October–December, 1981. 相似文献
14.
Ahmad J Rusumdar A. Abuthalib Vaka Murali Mohan C. Srinivasa Kumar V. Sujatha P. Rajendra Prasad 《Experimental Thermal and Fluid Science》2009,33(5):791-796
The hydrodynamics and energy consumption have been studied in a cold flow, bubbling and turbulent, pressurized gas–liquid–solid three-phase fluidized bed (0.15 m ID × 1 m height) with concurrent gas–liquid up flow is proposed with the intention of increasing the gas hold up. The hydrodynamic behaviour is described and characterised by some specific gas and liquid velocities. Particles are easily fluidized and can be uniformly distributed over the whole height of the column. The effect of parameters like liquid flow rate, gas flow rate, particle loading, particle size, and solid density on gas hold up and effect of gas flow rate, solid density and particle size on solid hold up, energy consumption and minimum fluidization velocity has been studied. At the elevated pressures a superior method for better prediction of minimum fluidization velocity and terminal settling velocities has been adopted. The results have been interpreted with Bernoulli’s theorem and Richardson–Zaki equation. Based on the assumption of the gas and liquid as a pretend fluid, a simplification has been made to predict the particle terminal settling velocities. The Richardson–Zaki parameter n′ was compared with Renzo’s results. A correlation has been proposed with the experimental results for the three-phase fluidization. 相似文献
15.
T. Aihara K. Yamamoto K. Narusawa T. Haraguchi M. Ukaku A. Lasek F. Feuillebois 《Heat and Mass Transfer》1997,33(1-2):109-120
Heat transfer characteristics of a turbulent, dilute air-solids suspension flow in thermally developing/developed regions
were experimentally studied, using a uniformly heated, horizontal 54.5 mm-ID pipe and 43-μm-diameter glass beads. The local
heat transfer was measured at 27 locations from the inlet to 120-dia downstream of the heated section over a range of Reynolds
numbers 3×104−1.2×105 and solids loading ratio 0–3, and the fully developed profiles of air velocity/temperature and particle mass flux were measured
at a location 140-dia downstream of the heated section using specially designed probes, inserted into the suspension flow.
The effects of the Reynolds number, solids loading ratio, and azimuthal/longitudinal locations on the heat transfer characteristics
and their interactions are discussed through comparison of the present results with the data obtained by other investigators.
Received on 14 October 1996 相似文献
16.
S. G. Cherkasov 《Fluid Dynamics》1982,17(4):610-612
A study is made of the unsteady heating of a viscoplastic liquid in the space between two infinite vertical plates when one is thermally insulated and a constant, uniformly distributed heat flux is supplied to the other after a certain initial time. It is assumed that at the initial time the liquid is uniformly heated.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 148–150, July–August, 1982. 相似文献
17.
Yanpeng Li Bofeng Bai 《中国颗粒学报》2006,4(5):220-228
1. Introduction The mechanisms of impact and rebound of solid parti- cles in particulate flow systems are of interest over a wide range of application areas such as fluidized beds, pneu- matic transport, filtration processes, erosion and pollution control of suspended particles. In many cases, the colli- sions of particles against themselves and against walls may affect the properties of the mixture. Efforts have been made to describe the fundamental mechanics of particle collisions. The conta… 相似文献
18.
Meccanica - In the present study, the two-phase gas–liquid convective heat transfer is numerically studied inside uniformly heated wavy micro-tubes in the Taylor flow regime. Both Newtonian... 相似文献
19.
S. A. Savkov A. A. Yushkevich 《Journal of Applied Mechanics and Technical Physics》2002,43(5):718-723
The problem of heat flow from a uniformly heated spherical particle in a diatomic gas is considered. The paper reports results of numerical calculations for an analog of the Bhatnagar–Gross–Krook model of the collision integral under for purely diffuse reflection of the gas molecules from the surface. 相似文献
20.
The results of buckling tests on circular cylinders heated uniformly along axial strips are presented and discussed. Calculations of critical temperature based upon the small-deflection theory for thin circular cylindrical shells are included and a comparison is made between theoretical and experimental results. Cylinders heated along axial strips of given widths have a theoretically predicted behaivor which corresponds reasonably well to the behavior obtained by experiment. Curves are included showing the variation of critical temperature with respect to heated axial-strip width. 相似文献