Begell House Inc.
Heat Transfer Research
HTR
1064-2285
45
2
2014
TOMOGRAPHIC TECHNIQUES OF MULTISCALE COHERENT STRUCTURES RECONSTRUCTION IN TURBULENT FLOWS. 1. LARGE SCALES RECONSTRUCTION
97-118
10.1615/HeatTransRes.v45.i2.10
Nikita A.
Fomin
Laboratory of Physical-Chemical Hydrodynamics, Department of Physics and Chemistry of Nonequilibrium Media, A. V. Luikov Heat and Mass Transfer Institute, National Academy of Sciences of Belarus, Minsk, Belarus
O. V.
Meleeva
A. V. Luikov Heat and Mass Transfer Institute, National Academy of Sciences of Belarus, 15 P. Brovka Str, Minsk, 220072, Belarus
turbulent flows
tomography
Radon transform
speckle photography
Abel transform
ray tracing
General techniques of tomographic reconstruction of three-dimensional structures in turbulent flows are described. Numerical simulation of the process of reconstruction of the local parameters of 3D flows from the data of limited-projection integral measurements with the use of the integral Radon transform is carried out. Errors of such a reconstruction are calculated and their analysis is given. It is shown that at the number of projections not exceeding four, the reconstruction of only relatively simple flows with a comparatively small asymmetry is possible. The integral relations used in analyzing various images of flows with allowance for the symmetry of the structures under study are presented. The differences in the Abel transform for laminar and turbulent flows are shown. The current possibilities of digital laser speckle photography for the analysis of speckled images of turbulent flows using the integral Erbeck−Merzkirch transforms are considered briefly. It is shown that these transforms can be used to advantage also in the analysis of nanostructures in various microflows, for example, in production of nanoconcrete, dissolution of carbon nanomaterials in paint coatings, and so on.
NATURAL CONVECTION FLOW PAST AN OSCILLATING PLATE WITH NEWTONIAN HEATING
119-135
10.1615/HeatTransRes.2013006385
Abid
Hussanan
Shenzhen University
Muhammad Imran
Anwar
Department of Mathematical Sciences, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia; Department of Mathematics, Faculty of Science, University of Sargodha UOS, Sargodha, Punjab, Pakistan
Farhad
Ali
City University of Science and Information Technology, Peshawar
Ilyas
Khan
Ton Duc Thang University
Sharidan
Shafie
Department of Mathematical Sciences, Faculty of Science, Universiti Teknologi Malaysia
81310 UTM Johor Bahru, Johor, Malaysia
natural convection
oscillating plate
Newtonian heating
exact solutions
An exact analysis of unsteady natural convection flow of viscous fluid past an oscillating plate with Newtonian heating is presented. The mathematical model with radiation effect in the energy equation is reduced to a system of linear partial differential equations. These equations are solved exactly using the Laplace transform technique. Expressions for the velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions. As a special case, these solutions can be reduced to similar solutions in the existing literature. The skin friction and Nusselt number are evaluated analytically as well as numerically in a tabular form. Numerical results for velocity and temperature are shown graphically for various parameters of interest and the physics of the problem is well explored.
EXPERIMENTAL STUDY OF MINIATURE RADIALLY ROTATING HEAT PIPES WITH WATER AS THE WORKING FLUID
137-144
10.1615/HeatTransRes.2013005702
Yiding
Cao
Department of Mechanical and Materials Engineering, Florida International University,
Miami, Florida 33174
Brian
Reding
Department of Mechanical and Materials Engineering, Florida International University, Miami, Florida 33174, USA
Jian
Ling
Department of Mechanical and Materials Engineering, Florida International University, Miami, Florida 33174, USA
rotating heat pipe
heat transfer limitations
gas turbine cooling
In this study, three copper−water rotating heat pipes having inner diameters of 1.5, 2, and 3 mm, respectively, are fabricated and tested. The effectiveness of the copper−water heat pipe is first validated by comparing its performance with that of a copper cylinder having the same outer diameter. The heat pipes are then tested to prove their reliability, high effective thermal conductance, and critical working limitation. The experimental data show that the critical limitation may be reached when the inner diameter of the heat pipe is below 1.5 mm and under the condition of a low rotational speed. The tests of these water heat pipes could also explore potential applications of radially rotating heat pipes in disks and/or blades of a high-pressure compressor.
FREE CONVECTION IN RECTANGULAR ENCLOSURES CONTAINING NANOFLUID WITH NANOPARTICLES OF VARIOUS DIAMETERS
145-169
10.1615/HeatTransRes.2013004029
Saeid
Jani
Department of Mechanical Engineering, Golpayegan University of Technology, Golpayegan, Iran
Mostafa
Mahmoodi
Department of Mechanical Engineering, Amirkabir University of Technology, Tehran 15875-4413,
Iran; Department of Mechanical Engineering, University of Kashan, Kashan 87317-53153, Iran
Meysam
Amini
Energy Technologies Research Division, Research Institute of Petroleum Industry (RIPI), Tehran, Iran
Mohammad
Akbari
Department of Mechanical Engineering, Semnan University, Semnan, Iran
numerical simulation
finite volume method
nanofluid
heat transfer enhancement
Free convection heat transfer in rectangular enclosures filled with Al2O3−water nanofluid is investigated numerically, and the effects of suspended nanoparticles of different diameters are considered. The governing equations in terms of primitive variables are discretized numerically using the finite volume method and SIMPLER algorithm. The results were obtained for width range of the Rayleigh number, nanoparticles volume fraction and aspect ratio of cavity. Also nanoparticles with two different diameters, namely 36 nm and 47 nm have been chosen. The obtained results showed that for the square enclosure utilizing the suspended nanoparticles with both considered diameters the rate of heat transfer increased only at Ra = 103 that conduction dominated the heat transfer process, while at other Rayleigh numbers, a deterioration on average Nusselt number was observed.
EFFECT OF SECOND-ORDER VELOCITY SLIP AND TEMPERATURE JUMP CONDITIONS ON ROTATING DISK FLOW IN THE CASE OF BLOWING AND SUCTION WITH ENTROPY GENERATION
171-198
10.1615/HeatTransRes.2013006717
Aytac
Arikoglu
Faculty of Aeronautics and Astronautics, Aeronautical Engineering Department, Istanbul Technical University, Maslak, TR-34469, Istanbul, Turkey
G.
Komurgoz
Faculty of Electrical and Electronic Engineering, Electrical Engineering Department, Istanbul Technical University, Maslak, TR-34469, Istanbul, Turkey
Ahmet Yasar
Gunes
Faculty of Aeronautics and Astronautics, Aeronautical Engineering Department, Istanbul Technical University, Maslak, TR-34469, Istanbul, Turkey
Ibrahim
Ozkol
Faculty of Aeronautics and Astronautics, Aeronautical Engineering Department, Istanbul Technical University, Maslak, TR-34469, Istanbul, Turkey
rotating disk flow
temperature jump
velocity slip
second-order
entropy generation
blowing
suction
In this work, the rotating disk flow problem is studied with suction and blowing on the surface by considering entropy generation. To give differences in applications of boundary conditions, second-order velocity slip and temperature jump conditions on the thermal and flow field are implemented for the first time. Governing equations related to boundary conditions are derived and solved by using a semianalytical numerical technique, the differential transform method, which is capable of carrying a solution set as an integrable and differentiable form. The common property observed in the presented figures is that the effects of both slip factor and jump factor reduce the magnitude of entropy generation. Additionally, using the second-order slip and jump boundary conditions further reduces entropy generation. Minimum entropy generation gives the maximum available work for this type fluidic system. In other words, the efficiency of the system increases with slip and jump. First- and second-order slip and jump boundary conditions were applied separately and shown their sole effects. Differences in applying first-and second-order slip and jump boundary conditions are depicted. As a consequence, using the second-order boundary conditions reduces the total entropy generation, which directly affects the efficiency calculation of the thermal system. This is vital for the design calculation of energy consumption.