Thermal stratification of turbulent air flows in a rectangular channel.

by Marcel Dick Mossel

Publisher: Technische Universiteit Delft in Delft

Written in English
Published: Pages: 241 Downloads: 869
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Edition Notes

Thesis (doctoral) - Technische Universiteit Delft, 1995.

The Physical Object
Number of Pages241
ID Numbers
Open LibraryOL21238831M

  Choi and Kang elaborated on a thermal model to construct the flow systematization and characterize the suitable cooling method for an air-cooled hybrid electric vehicle. Wang et al. [ 19, 20 ], Yang et al. [ 21 ] and Xu et al. [ 22 ] developed the optimization of battery alignment and air movement channel, correspondingly, to attain improved. and outlet air; m is the mass flow rate measured by orifice plate, (kg/sec); and Cp is a specific heat of air is determined as a function of average temperature (J/kg.K). Furthermore the total heat transferred to air by forced convection is equal to the rate at which thermal energy of the fluid increases for a gas. The flowing model of turbulent flow in rectangular channels in rolling and heaving motion is established. The effects of several turbulent models and parameters on the flow are analyzed. In rolling motion, the velocity profile in channel center is more averaged. The mixing coefficient can be strengthened significantly in rolling motion. Length Development • Transition to Turbulent Flow Flows in this book, Gad-el-Hak, , Janson et al., , Arkilic et al. , and Harley et al., ). Liquid Flows in Microchannels Table ) qualitatively to the thermal conductivity and the thermal diffusivity.

The Effect of Lateral Divergence on the Structure of a Turbulent Channel Flow and Its Heat Transfer. Preview Buy Chap95 € Vortex Street and Turbulent Wakes behind a Circular Cylinder Placed in a Rotating Rectangular Channel. Pages Koyama, H. S. (et al.) Book Title Turbulent Shear Flows 6. Turbulence in Open Channel Flows Book Review: A review of open channel turbulence, focusing especially on certain features stemming from the presence of the free surface and the bed of a river. Part one presents the statistical theory of turbulence; Part two addresses the coherent structures in open-channel flows and boundary layers. Surface Conductances as Affected by Air Velocity, Temperature and Character of Surface by F.B. Rowley, A.B. Algren, and J.L. Blackshaw is the source for Fig. Their test plate was inserted (flush with interior) into a m by m opening cut from one vertical side of a m by m rectangular duct over 7 m long. For example, air and water; both are fluids and if we consider them together then they can be seen as a stratified fluid system. Density variations in the atmosphere profoundly affect the motion of water and air. Wave phenomena in air flow over the mountains and occurrence of smog are the examples of stratification effect in the atmosphere.

Principal differences between heat transfer in laminar flow and that in turbulent flow. In discussing heat transfer to or from a fluid flowing through a straight circular tube, it is useful to distinguish between the axial or main flow direction, and the directions that lie in a plane perpendicular to the tube axis. Abstract. Soap film flows provide a very convenient laboratory model for studies of two-dimensional (2-D) hydrodynamics including turbulence. For a gravity-driven soap film channel with a grid of equally spaced cylinders inserted in the flow, we have measured the simultaneous velocity and thickness fields in the irregular flow downstream from the cylinders. K-IIR~YuKI Ozot3 et al. a, uy, b,, b, parameters in expression for grid Greek symbols location a thermal diffusivity [m2/s] cr, c2, ca, c,,, c, parameters in k-c model % eddy diffusivity for heat transfer [m2/s] E dimensionless time-averaged rate of B volumetric coefficient of expansion [K- ‘1 dissipation of turbulent energy E time-averaged rate of dissipation of.

Thermal stratification of turbulent air flows in a rectangular channel. by Marcel Dick Mossel Download PDF EPUB FB2

Download PDF: Sorry, we are unable to provide the full text but you may find it at the following location(s): (external link)Author: M.D. (author) Mossel. Thermal stratification of turbulent air flows in rectangular channels () Pagina-navigatie: Main; Save publication. Save as MODS; Export to Mendeley; Save as EndNoteAuthor: M.D.

Mossel. The main objective of this study is to experimentally investigate the turbulent thermal mixing structures of a co-current steam-water stratified flow in a horizontal rectangular channel by visualizing the liquid motion, which causes a mixing and stratification of hot and cold-water by exchanging the mass, momentum, and energy at the gas-liquid interface.

Benzenine et al. [33] studied by numerical simulation the turbulent air flow in a rectangular channel equipped with two waved baffles sequentially arranged in the bottom and top of the channel.

The stable thermal stratification can cause a destruction of the turbulence. This results in the relaminarization of the flow in the upper Thermal stratification of turbulent air flows in a rectangular channel.

book of the cavity and may significantly affect the. rectangular channel with roughened surfaces. A.S. Yadav, J.L. Bhagoria [1] A numerical investigation on the heat transfer and fluid flow characteristics of fully developed turbulent flow in a rectangular duct having repeated transverse square sectioned rib roughness on the absorber plate has been carried out.

The effect of different inlet conditions of air in a rectangular channel on convection heat transfer: Turbulence flow Experimental Thermal and Fluid Science, Vol. 33, No. 1 Friction and forced convective heat transfer in a sintered porous channel with obstacle blocks.

equation for a channel with rectangular cross section and then for a channel with arbitrary (but unvarying) cross section. To generalize Equation to a rectangular channel, take the flow width to be b (Figure ) and write the force balance for a free body that fills the channel, from wall to wall, in a segment of length L along the flow.

A synthetic-turbulence and temperature-fluctuation-generation method is developed and embedded in large-eddy simulations to investigate the effects of weak stable stratification (i.e. Richardson number \(Ri\le 1\)) on turbulence and dispersion following a simulated rural-to-urban modelling approach is validated by comparing predictions of mean velocity, turbulent.

Basics of Turbulent Flow Whether a flow is laminar or turbulent depends of the relative importance of fluid friction (viscosity) and flow inertia. The ratio of inertial to viscous forces is the Reynolds number. Given the characteristic velocity scale, U, and length scale, L, for a system, the Reynolds.

Flow in a rectangular channel is characterized by the presence of corners and the free surface. Thus, the flow structure in any developing turbulent flow in channels is different from that in circular.

turbulent flows and it is this factor which determines considerable interest in this phenomenon [9]. The flow through a straight duct of rectangular cross-section has important similarities in common with both straight circular pipe flow and plane channel flow (well-known canonical flows).

The decay of grid-generated turbulence in the presence of strong thermal stratification is studied in a continuously stratified, open-loop wind stratified turbulence in a continuously stratified air flow. In this work, we use a new In a turbulent flow, the local r.m.s. displacement of fluid particles.

The studies demonstrated that due to unilateral heating, the regulation of microribs on heat transfer and thermal cracking is nonuniform in the channel, relating to local turbulence intensity and fluid properties.

Particularly, the thermal cracking of fuel responses more slowly than turbulence. As the applications, channel flow and cavity flow are simulated. Reynolds number is and all the other properties are the same as water at 20 °C.

Velocity at the free stream is set to be From the result of channel flow analysis, the velocity profile at the exit is the same as analytical solution, U(y) = ×U 0 ×y(−y).

And. Gandhi et al. [15] have performed experiments to study thermal stratification phenomenon inside a rectangular tank ( m 3) fitted with a centrally heated tube.

The large temperature gradient prevails in the vicinity of heat source (Fig. ) and it becomes weak with an increase in the radial distance. validity evaluation of turbulent flux modeling in standard k-ε model within and above urban canyon under various conditions of thermal stratification using les.

Journal of Environmental Engineering (Transactions of AIJ), Vol. 82, Issue. p. To study the thermal behavior inside scramjet cooling channels at different aspect ratios, a three-dimensional model of fuel flow in terms of the fuel real properties is built and validated through experiments.

The whole cooling channel is divided into noncracking and cracking zones, and only the noncracking zone is studied in this paper.

Direct numerical simulations of the fully developed horizontal channel flow under unstable density stratification were carried out to investigate interactive shear and buoyancy effects on the turbulent momentum and heat transport.

As the Grashof number is increased, buoyant thermal plumes are. Turbulence Channel Flow. MEB/3/GI 29 From High-Re to Low-Re k-e Grid Turbulent kinetic energy Wall boundary condition dk/dy=0 + + k=0 Wall clustering y=30 y~1 Re τ = MEB/3/GI 30 Velocity and k profiles Low-Re k-ε model.

This monograph details recent achievements in turbulence theory, experiments and computations relevant to heat and mass transfer. Containing over 90 papers presented at the International Syposium on Turbulence, Heat and Mass Transfer, held in Lisbon, Portugal inthis book covers topics from turbulence structure to computation of complex flows.

A thermocline (also known as the thermal layer or the metalimnion in lakes) is a thin but distinct layer in a large body of fluid (e.g. water, as in an ocean or lake; or air, e.g. an atmosphere) in which temperature changes more drastically with depth than it does in the layers above or the ocean, the thermocline divides the upper mixed layer from the calm deep water below.

Kim and P. Moin, “ Transport of passive scalars in a turbulent channel flow,” in Turbulent Shear Flows (Springer, ), pp. 85– Google Scholar Crossref   A numerical investigation of turbulent flows through an artificially roughened solar air heater.

Numer. Heat Transf. Part A Appl. 65 (7), – () CrossRef Google Scholar. Figure Variation heat transfer coefficient for turbulent flow (Re=) in circular micro channel for water and its nanofluid 37 Figure Variation wall temperature for laminar flow (Re =) in circular micro channel for water and its nanofluid 39 Figure Variation wall temperature for turbulent flow (Re =).

For weak thermal driving the flow remains turbulent and reaches the equilibrated state after ~50 h. When thermal driving is strong, the stratification damps the turbulence for long periods of time between episodic turbulent events.

These intermittent cases do not reach equilibrated state in 50 h and must be continued for long periods of time. Analysis of the Zone of Flow Establishment for Buoyant Turbulent Jets in Cross ' Flow LatifM. Jiji and Joseph Hoch Calculation of Three-Dimensional Heated Surface Jets /.

McGuirk and W. Rodi Influence of Buoyancy on Dispersion in Open Channel-Flow Jost Grimm-Strele and William W. Sayre Vertical Buoyant Air Jets P. Oosthuizen Menu. Ansys cfx pipe flow tutorial. Experiments were conducted in a range of fully developed turbulent flows of mercury in a rectangular duct in the presence of a transverse magnetic field.

Friction coefficients expressing the effect of the magnetic field on the flow were derived, covering the Reynolds number range from x 10/sup 4/ to x 10/ sup 5/ and the Hartmann number.

Flow stratification suppresses turbulence mixing and, as a result, the mean flow (in plus units) increases as a function of flow stratification. This is still the case here. Thermal stratification affects the wall region z > CL more than the wall layer, where C is a O() constant.

Hence, both the velocity and the temperature profiles collapse. Heat transfer experiments were conducted to investigate the thermal performance of air cooling through mini-channel heat sink with various configurations.

Two types of channels have been used, one has a rectangular cross section area of 5 × 18 mm2 and the other is triangular with dimension of 5 × 9 mm2. Four channels of each configuration have been etched on copper block of 40 mm width,30 mm.Peavy recommends the following relationship for turbulent flow over smooth flat plates at low air velocities (V air node within the attic space and ignores thermal stratification of attic air.

The insulation surface temperature is significantly over-predicted in the upper graph.Stably stratified turbulent flows are common in the ocean and the atmosphere. Buoyancy forces in these flows tend to damp the vertical components of turbulence, altering the decay of turbulence.

These studies encompassed experimental measurements of turbulence in airflow which had varying levels of thermal stratification.