Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
40
6
2013
Accretion of the Efficiency of a Forward-Curved Centrifugal Fan by Modification of the Rotor Geometry: Computational and Experimental Study
469-481
10.1615/InterJFluidMechRes.v40.i6.10
Javad
Alinejad
Center of Excellence on Modeling and Control Systems (CEMCS) and Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad 91775-1111, Iran
Nader
Montazerin
Department of Mechanical Engineering, Amirkabir University of Technology Tehran, Iran
Sina
Samarbakhsh
Department of Mechanical Engineering, Amirkabir University of Technology Tehran, Iran
The present publication shows complex characteristics of the flow both in cylindrical and conical frustum-shaped rotor. The comparison of the results presented
a great dependence of the rotor shape and the fan efficiency. The targeted topic in this particular study is the design optimization of a centrifugal fan in central
heating and air-conditioning systems and in numerous other applications. In order to improve efficiency of a centrifugal fan and uniform flow field in outlet,
the current study optimizes the shape of rotor using two different geometries:
cylindrical and conical frustum-shaped. Numerical simulation was performed
by a 3D turbulence, incompressible flow analysis. Reynolds-averaged Navier − Stokes equations with the standard k−ε turbulence model have been discretized
by the finite volume method. The overall experiments were conducted in a standard
ISO 5801:1997 test chamber apparatus. To obtain the occurring flow patterns
inside the test section from the experimental data, the optical measurement technique
laser Doppler anemometry (LDA) is applied in the analysis and they were used to validate the CFD simulations. It was found that, a conical frustum-shaped rotor with the optimal cone angle can cause a higher efficiency and performance
than a cylindrical design under similar conditions such as, equal head coefficient.
Slip Effects on the Parametric Space and the Solution for Boundary Layer Flow of Casson Fluid over a Porous Stretching/Shrinking Sheet
482-493
10.1615/InterJFluidMechRes.v40.i6.20
Krishnendu
Bhattacharyya
Institute of Science, Banaras Hindu University
Kuppalapalle
Vajravelu
Department of Mathematics, University of Central Florida, Orlando, Florida 32816-1364,
USA
Tasawar
Hayat
Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000, Pakistan; Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science,
King Abdulaziz University, P.O. Box 80257, Jeddah 21589, Saudi Arabia
This investigation reports slip effects on the boundary-layer flow of a Casson
fluid over a porous stretching/shrinking sheet. A self-similar ODE is first obtained
for the governing PDEs and then the obtained ODE with appropriate boundary
conditions is solved analytically. The effects of all the physical parameters on
flow field are presented through figures and a table. It is found that there is a
pronounced effect of slip on flow characteristics. Moreover, a unique solution
exists for stretching sheet problem; whereas dual solutions exist for shrinking
sheet case. Furthermore, feasible solution domains for physical parameters are
obtained and discussed.
Oil-Water Two-Phase Flow Redistribution in Horizontal and Near Horizontal Pipelines
494-511
10.1615/InterJFluidMechRes.v40.i6.30
Mohamed A.
Habib
Mechanical Engineering Department, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia
Rached
Ben-Mansour
Mechanical Engineering Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
Wael
Ahmed
Abdullah M.
Al-Otaibi
Saudi Aramco Oil Company Dhahran, Saudi Arabia
Abdelsalam
Al-Sarkhi
King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia
Zuhair
Gasem
Department of Mechanical Engineering, King Fahd University of Petroleum & Minerals Dhahran, Saudi Arabia
This paper presents a study to numerically investigate the effect of the operational and design parameters on the oil-water two-phase flow re-distribution in horizontal and near horizontal pipeline and their effect on pipe internal corrosion. The present simulations were carried out for pipe diameters of 100 mm, 154 mm, and 202 mm and for Reynolds numbers range from 6.37×103 to 1.59×105. The
typical oil production conditions in Saudi Arabian Oil Company (Saudi Aramco) are used in the present study. These conditions cover a mixture of Arabian oil,
whose density and viscosity range from 830 kg/m3 to 998.2 kg/m3 and from 2 cP to 30 cP respectively, with water cuts of 20, 30 and 50 %. Effect of pipe inclinations of 15° up and 15° down are also investigated. The numerical results
showed good agreement with available experiments and models at different inlet mixture velocities and water cuts. The results emphasize the strong effect of inlet
mixture velocity, oil physical properties, and pipe inclination on the water holdup and the flow patterns and consequently on the corrosion rate.
Experimental Study on Vortex Motion
512-519
10.1615/InterJFluidMechRes.v40.i6.40
P.
Sinha
Department of Aerospace and Applied Mechanics, Bengal Engineering and Science University Shibpur, Howrah-711103, West Bengal, India Howrah, West Bengal, India
K.
Sarkar
Department of Aerospace and Applied Mechanics, Bengal Engineering and Science University Shibpur, Howrah-711103, West Bengal, India Howrah, West Bengal, India
B.
Pandey
Department of Aerospace and Applied Mechanics, Bengal Engineering and Science University Shibpur, Howrah-711103, West Bengal, India Howrah, West Bengal, India
Nityananda
Nandi
Department of Aerospace and Applied Mechanics, Bengal Engineering and Science University Shibpur, Howrah-711103, West Bengal, India Howrah, West Bengal, India
The present paper makes an effort to visualize the flow patterns and other
characteristics of both forced and free vortex motion by an experimental method.
Works of both experimental and numerical have been conducted to understand
the various features of vortex motion and its effects on drag, etc. Here colored
die has been used to understand the profiles and an arrow shaped strip marks the
difference between irrotational and rotational flow. In the forced vortex motion it
has been observed that the parabolic profile remains invariant with the rpm of the
paddle and the height of the lowest point of the profile decreases with the increase
in paddle speed. In the free vortex motion, it is observed that the hyperbolic
profile does not change with the change in flow rate. In this case, suction is
created towards the centre where as in the case of forced vortex no such suction
arises. With the reduction in the size of the orifice diameter, the profile becomes
less steep for free vortex. In this case the velocity profile in the core region is
straight; as the radius increases the profile becomes rectangular hyperbola where
as in the case of forced vortex the velocity profile maintains its linear nature for
the entire range of radii.
Influence of Viscosity on Drag in Presence of Polymer Solutions in Gravity Driven Flow Systemy
520-529
10.1615/InterJFluidMechRes.v40.i6.50
P. Srinvasa
Rao
Andhra Pradesh Pollution Control Board, Regional Office Vizianagaram-535002, Andhra Pradesh, India
Chirravuri
Subbarao
Department of Chemical Engineering, MVGR College of Engineering, Chintalavalasa,
Vizianagaram-535005, Andhra Pradesh
G. M. J.
Raju
Department of Chemical Engineering, AU College of Engineering, Andhra University Visakhapatnam-530003, Andhra Pradesh, India
V. S. R. K.
Prasad
Anil Neerukonda Institute of Technology & Sciences (ANITS)
Mathematical equation for efflux time is developed during gravity draining of a Newtonian liquid from a large spherical tank through an exit pipe under laminar
flow conditions in the exit pipe. This equation gives the maximum time required for draining the contents of spherical storage vessel. The model is verified with
the experimental data for water as well as for different viscosities of Glycerin solutions and found to be in good agreement with a maximum deviation of 14.8 %
and an average deviation of 9 %. Experiments are also performed with mixed solutions containing aqueous polymer solutions and Glycerin. The polymers used
in this study are Polythene Oxide (PEO) and Polyacryl Amide (PAM). Drag reduction takes place only in presence of polymer solutions. However, in case of
polymer solutions mixed with Glycerin, in stead of drag reduction, drag enhancement takes place. The possible reasons for drag enhancement are also discussed.
Two-Dye Laser-Induced Fluorescence Measurements and Numerical Study of Scalar Transport in Planar, Microfluidic Mixers
530-544
10.1615/InterJFluidMechRes.v40.i6.60
Mohamed
Hassoun
KACST-Intel Consortium Center of Excellence in Nano-Manufacturing Applications Riyadh, Kingdom of Saudi Arabia; IMEC, VZW Leuven, Belgium; Institute of Graduate Studies and Research, Alexandria University Alexandria, Egypt
Benjamin
Jones
IMEC, VZW Leuven, Belgium
Moataz
Soliman
Institute of Graduate Studies and Research, Alexandria University Alexandria, Egypt
Maaike Op
de Beeck
IMEC, VZW Leuven, Belgium
A novel method of characterizing a micromixer is proposed. The method is based on two-dye, ratiometric laser-induced fluorescence measurements using a confocal microscope. A fluorescent tracer is added to one of the two inlet fluid
streams of the micromixer while a second fluorescent dye is added to both inlet fluid streams to serve as a reference. The emission intensity of the fluorescence
tracer was normalized by the reference fluorescent signal. Using this technique an accurate, spatially-resolved, quantitative measurement of the tracer concentration
field can be obtained. This method was used successfully to quantify the
mixing performance of three different micromixer designs: a straight channel, a
curved, meandering channel, and a square-wave channel. Computational fluid
dynamics (CFD) simulations were also conducted for the straight and curved, meandering micromixers. The CFD results were in good agreement with experimental
data. At a Reynolds number of 22.5, the square-wave microchannels yield the best mixing performance with a higher mixing efficiency for a fixed channel length. Curved microchannels showed better mixing performance than straight microchannels at this same Reynolds number. The numerical and experimental results underscore the importance of spatially-resolved measurements in the depth-wise direction since even relatively simple, planar mixer designs can produce complex three-dimensional flow fields.
Transient Mixed Convection Coupled with Surface Radiation inside a Square Cavity with Different Configurations − A Critical Study
545-563
10.1615/InterJFluidMechRes.v40.i6.70
Sikata
Samantaray
Siksha 'O' Anusandhan University, ITER, BBSR-751030, ODISHA, INDIA
Swarup Kumar
Mahapatra
Indian Institute of Technology Bhubaneswar
Sofen K.
Jena
Department of Flows and Materials Simulation, Fraunhofer Institute for Industrial Mathematics (ITWM), Kaiserslautern, Germany, D-67663; Department of Mechanical Engineering, Jadavpur University, Kolkata, India-700032
Amitava
Sarkar
Department of Mechanical Engineering, Jadavpur University, Kolkata, India-700032
The conjugate heat transfer within differentially heated enclosure in presence of surface radiation is a complex phenomenon, which has become a research
topic because of its practical relevance. The flow and heat transfer depends on the orientation of source of buoyancy and shear force. Buoyancy driven flow depends on the terminal temperature difference between the walls and its orientation. Similarly, the shear driven flow depends on the wall movement and its direction.
The interaction between the shear induced flow with the buoyancy induced flow caused due to different orientation of differential heating of walls in presence of surface radiation is studied in the present article. The governing equations of mass, momentum and energy are solved using modified MAC method. The unsteady flow and heat transfer characteristics significantly vary with the magnitude
of velocity and the direction of wall movement. The relative importance of different influencing parameters such as Rayleigh number (Ra), emissivity (ε) and Richardson number (Ri) has been analyzed in the present study. It is noticed that direction of wall movement and Rayleigh number affect both steady and unsteady flow patterns and heat transport processes in the cavity. Presence of surface radiation significantly changes the flow structures in case of vertical wall movement compared to horizontal wall movement for bottom heated cavity. Period of transience for shear dominated regimes (Ri << 1) is less compared to buoyancy dominated regimes (Ri >> 1). This study finds its application in industrial convection ovens and uninterrupted-flow in bakery systems, in food processing industries.