

Effect of Engine Speed on InCylinder Tumble Flows in a Motored Internal Combustion Engine  An Experimental Investigation Using Particle Image Velocimetry


Pages :
114


Authors :
B. Murali Krishna,
J. M. Mallikarjuna,
Nowadays, the stratified and direct injection spark ignition engines are becoming very popular because of their low
fuel consumption and exhaust emissions. But, the challenges to them are the formation and control of the charge
which is mainly dependent on the incylinder fluid flows. Today, an optical tool like particle image velocimetry (PIV)
is extensively used for the incylinder fluid flow measurements. This paper deals with the experimental investigations
of the incylinder fluid tumble flows in a motored internal combustion engine with a flat piston at different engine
speeds during intake and compression strokes using PIV. The twodimensional incylinder flow measurements and
analysis of tumble flows have been carried out in the combustion space on a vertical plane at the cylinder axis. To
analyze the fluid flows, ensemble average velocity vectors have been used. To characterize the tumble flow, tumble
ratio has been estimated. From the results, it is found that the tumble ratio mainly varies with crank angle positions.
At the end of compression stroke, maximum turbulent kinetic energy is more at higher engine speeds. Present study
will be very useful in understanding the effect of engine speeds on the incylinder fluid tumble flows under real
engine conditions.





Radiation and Mass Transfer Effects on Transient Free Convection Flow of a Dissipative Fluid past SemiInfinite Vertical Plate with Uniform Heat and Mass Flux


Pages :
1526


Authors :
B. Vasu,
V. Ramachandra Prasad,
N. Bhaskar Reddy,
Effect of radiation and mass transfer on the transient free convection flow of a dissipative past semiinfinite vertical
plate with uniform heat and mass flux is analyzed, by taking into account the effect of viscous dissipation. This type
of problems finds application in many technological and engineering fields such as plasma studies, petroleum
industries, MHD energy generators, cooling of nuclear reactors, the boundary layer control in aerodynamics, crystal
growth and furnace engineering. The Rosseland approximation is used to describe the radiative heat transfer in the
limit of the optically thick fluid. The nonlinear, coupled equations are solved using an implicit finite difference
scheme of CrankNicolson type. Transient temperature, concentration and velocity profiles, local and average skinfriction
coefficient, Nusselt number and Sherwood number are presented graphically and discussed. It is observed
that, when the radiation parameter increases the velocity and temperature decrease accompanied by simultaneous
reduction in both momentum and thermal boundary layers.





Fluid Devices by the Use of Electrohydrodynamic Effects of Water


Pages :
2733


Authors :
H. Sugiyama,
H. Ogura,
Y. Otsubo,
When the high DC electric fields are applied to distilled water through needle electrodes, the jet flow with velocities
up to 0.3 ms1 is generated in bulk from the negative to positive electrodes. The flow direction and velocity can be
modified by the design of electrodes and their arrangements. By controlling the flow patterns, new types of inkjet
devices and liquid motor are developed. In inkjet devices, a set of electrodes consisting of short tube and needle is
vertically placed in plastic tube and the distilled water so filled in the reservoir that the electrodes are completely
immersed. The application of high voltages causes the vertical flow to produce a water column with free surface. The
motor consists of vane wheel, cup, two sets of electrodes, and working fluid. For aqueous solutions of ethanol and
glycerin, the angular velocity of motor is measured as a function of viscosity and conductivity. The high performance
of motor is achieved by the solutions with viscosity of 0.85 ~ 1.7 m Pa·s and conductivity of 20 ~ 30 Sm1. The
EHD water jets have great potential in application to new fluid devices.





MIMO Modeling Approach for a Small Photovoltaic Reverse Osmosis Desalination System


Pages :
3541


Authors :
A. B. Chaaben,
R. Andoulsi,
A. Sellami,
R. Mhiri,
The most widely used desalination processes are based on membrane separation via reverse osmosis (RO) which has
become an important process for desalting seawater and cleaning brackish water. The use of these processes requires
an efficient control system. Consequently, it is necessary to establish a dynamic model of the system with
experimental validation. This paper deals with a new modelling approach of a small photovoltaic reverse osmosis
(PVRO) desalination unit. The proposed model considers the unit as a Multi Input Multi Output (MIMO) process.
The relations between the output variables and the input variables are given by the use of empirical transfer matrix. A
state model of the unit is also given. Some experimental results are presented to validate the proposed model. As
result, the obtained unit model can be easily used for a process control loop implementation in order to assure an
optimum operating condition and to reduce the water product cost.





PushPull Air Curtain Performances for VOCs Containment in an Industrial Process


Pages :
4350


Authors :
A. Aubert,
C. Solliec,
The aim of this study is to analyze the efficiency of a Volatile Organic Compounds (VOCs) containment system
using an air curtain (pushpull type) on a manual workstation. This work combines CFD numerical simulations of the
air curtain system and experimental studies on a real scale test bench. The point is to evaluate whether the actual
worker protection can be replaced by an air curtain system, without weakening human safety. The new system could
considerably reduce energetic consumption (ventilation, heating) and VOCs emissions into the atmosphere.
Experimental studies of the flow using a Particle Image Velocimetry anemometer (PIV) have been carried out to
validate the numerical model kinematics. The containment quality obtained by the model has been validated with
experimental concentration fields given by a gaseous analyzer using flame ionization (FID). Numerical simulation
provides an overview of the containment efficiency in the global area of the system. Thus, it is possible to evaluate
numerically, but accurately, the quality of the containment of the system. Moreover, an energetic study proves the
economic benefit of the pushpull system.





Simulation of Magnetohydrodynamic and Thermal Coupling in the Linear Induction MHD Pump


Pages :
5157


Authors :
F. Z. Kadid,
S. Drid,
R. Abdessemed,
This article is concerned with the study of a coupling between the stationary Maxwell equations, the transient state
Navier Stokes and thermal equations. The model developed computes the magnetic field using the finite element
method and calculates the velocity and the temperature using the finite volume method. The paper focuses on the
analysis of the flux density, the electromagnetic thrust, the electric power density, the velocity, the pressure and the
temperature in the channel of the MHD pump. Effect of the frequency is also presented.





Finite Difference Analysis of Radiative Free Convection Flow Past an Impulsively Started Vertical Plate with Variable Heat and Mass Flux


Pages :
5968


Authors :
V. R. Prasad,
N. Bhaskar Reddy,
R. Muthucumaraswamy,
B. Vasu,
A numerical solution of the unsteady radiative free convection flow of an incompressible viscous fluid past an
impulsively started vertical plate with variable heat and mass flux is presented here. This type of problem finds
application in many technological and engineering fields such as rocket propulsion systems, spacecraft reentry
aerothermodynamics, cosmical flight aerodynamics, plasma physics, glass production and furnace engineering. The
fluid is gray, absorbingemitting but nonscattering medium and the Rosseland approximation is used to describe the
radiative heat flux in the energy equation. The governing nonlinear, coupled equations are solved using an implicit
finite difference scheme. Numerical results for the velocity, temperature, concentration, the local and average skinfriction,
the Nusselt and Sherwood number are shown graphically, for different values of Prandtl number, Schmidt
number, thermal Grashof number, mass Grashof number, radiation parameter, heat flux exponent and the mass flux
exponent. It is observed that, when the radiation parameter increases, the velocity and temperature decrease in the
boundary layer. The local and average skinfriction increases with the increase in radiation parameter. For increasing
values of radiation parameter the local as well as average Nusselt number increases.





An Experimental Study and a Numerical Simulation of the Turbulent Flow under the Vortex Finder of a Cyclone Separator


Pages :
6975


Authors :
K. Talbi,
Z. Nemouchi,
A. Donnot,
N. Belghar,
An experimental study and a numerical simulation are presented concerning the three dimensional turbulent flow of
air in a cyclone separator in the region underneath the vortex finder. The computations are carried out using the
Fluent CFD code. The turbulence effects on the mean flow are taken into account using the standard k model and
the standard Reynolds stress Model (RSM). The axial and tangential mean velocity components and the turbulence
intensities are measured using Laser Doppler Anemometry. The LDA system is mounted in such a way that radial
traverses at different angles of the cyclone cylindrical geometry and at different axial positions could be possible. The
obtained results show interesting phenomena such as the three dimensional nature of the flow behaviour, the
turbulence decay and its evolution towards an isotropic state in the quasifree vortex region as the flow proceeds
downstream in the cyclone. In the region underneath the vortex finder, the surface separating the descending and the
ascending streams (set of points where the axial velocity component is nil) is located approximately in the fictitious
prolongation of the vortex finder cylindrical wall. The existence of a quasiforced vortex in the central region of the
cyclone surrounded by a coaxial quasifree vortex is confirmed. The radial distance separating the central vortex and
the surrounding annular vortex, at a given angle and axial position, can be clearly defined as the distance from the
axis to the point of intersection between two characteristic straight lines: the first line representing, ln Ut vs ln r, of
slope +1, in the quasiforced vortex and the second line, ln Ut vs ln r, of slope 1, in the quasifree vortex, where Ut is
the tangential component of the mean velocity.





Influence of Falling Height on the Behavior of Skid Launching FreeFall Lifeboat in Regular Waves


Pages :
7788


Authors :
M. M. Karim,
K. S. Iqbal,
M. R. H. Khondoker,
S. M. H Rahman,
This paper numerically investigated the influence of falling height on the behavior of the skidlaunching freefall
lifeboat (FFLB) in regular waves. The boat has been treated as a rigid body when the differential equations of motion
for the four falling phases, i.e., sliding or ramp phase, rotation phase, freefall phase and water entry phase of the
lifeboat were solved in the time domain. The hydrodynamic characteristics of the lifeboat has been studied for
different falling heights such as H = 1.5m, 1.75m and 2.00m. Horizontal and vertical excursions and the rotation of
the axis of the boat have been computed at different time along with its horizontal and vertical velocities.
Hydrodynamic forces and accelerations at normal and axial directions have also been determined. At first the analysis
has been done in still water and then in regular wave with amplitude of 0.5m and a period of 2.0 sec. In all of the
cases, effects of regular wave are shown by comparing the results with those considering the falling of FFLB into
calm water.





Height Partition Effect on Combined Mixed Convection and Surface Radiation in a Vented Rectangular Cavity


Pages :
8996


Authors :
A. Bahlaoui,
A. Raji,
M. Hasnaoui,
C. Ouardi,
M. Naïmi,
T. Makayssi,
The present paper reports numerical results of mixed convection and surface radiation within a horizontal ventilated
cavity heated from below and provided with an adiabatic thin partition on the heated surface. Air, a radiatively
transparent medium, is considered to be the cooling fluid. The effect of the governing parameters, which are the
Reynolds number, 200 Re 5000, the relative height of the baffle, 0 Hb 0.75, and the emissivity of the walls, 0
1, on the fluid flow and heat transfer characteristics is studied in detail. The maximum and mean temperatures,
the ratio, QE/QL, of the heat quantities leaving the cavity through the exit, QE, and through the left vertical cold side,
QL, are also presented versus the above controlling parameters.





Confined NonNewtonian Fluid Flow and Heat and Mass Transfers Induced by both Thermal and Solutal Buoyancy Forces of Equal Intensities


Pages :
97106


Authors :
T. Makayssi,
M. Naïmi,
M. Lamsaadi,
M. Hasnaoui,
A. Raji,
A. Bahlaoui,
In this paper is reported an analytical and numerical study on doublediffusive natural convection in a nonNewtonian
powerlaw fluid confined in a shallow horizontal rectangular enclosure submitted to uniform heat and mass fluxes
along its short vertical sides, while the horizontal ones are insulated and impermeable. Here, the cases of aiding and
opposing thermal and solutal buoyancy forces of equal intensities are considered. In the first part of the work the full
governing equations are solved and the effects of the powerlaw behavior index, n, and the generalized thermal
Rayleigh number, RaT , are examined and analyzed. In the second part, an analytical solution, based on the parallel
flow approximation valid in the case of a shallow cavity, is proposed and an excellent agreement of results between
the two approaches is observed, which validates them mutually.





Radiation and Mass Transfer Effects on MHD Free Convective Dissipative Fluid in the Presence of Heat Source/Sink


Pages :
107113


Authors :
S. Suneetha,
N. Bhaskar Reddy,
V. Ramachandra Prasad,
Thermal radiation effects on MHD flow past an impulsively started vertical plate in the presence of heat source/sink
is investigated, by taking into account the heat due to viscous dissipation. The governing boundary layer equations of
the flow field are solved by an implicit finite difference method of CrankNicholson type. A parametric study is
performed to illustrate the influence of radiation parameter, magnetic parameter, Grashof number, Prandtl number,
Eckert number on the velocity, temperature and concentration profiles. Also, the local and average skinfriction,
Nusselt number and Sherwood number are presented graphically. The numerical results reveal that the radiation
induces a rise in both the velocity and temperature, and a decrease in the concentration. Also with an increase in the
heat absorption/generation parameter the velocity increases whereas the temperature decreases. The model finds
applications in solar energy collection systems, geophysics and astrophysics, aero space and also in the design of high
temperature chemical process systems.





Effect of External Constraints of Magnetic Field and Velocity Shear on the Propagation of Internal Waves in a Chiral Fluid


Pages :
115120


Authors :
N. Rudraiah,
M. L. Sudheer,
G. K. Suresh,
The propagation of internal electromagnetic waves in an inviscid chiral fluid in the presence of the external constraint
of transverse magnetic field is investigated. These waves are shown to be generated due to the stabilizing nature of
the distribution of charge density. It is shown that the effect of the external constraint of magnetic field in a chiral
fluid is analogous to the effect of viscosity in ordinary fluids. The wave equation, derived from the conservation of
mass and momentum together with Maxwell’s equations and suitable auxiliary equations for chiral materials, reveals
the existence of a critical level (i.e., resonance level) at which the Doppler shifted frequency d = 0, i.e., at the point
where the basic fluid velocity matches with the phase velocity of the wave. The solution of this wave equation is
obtained near and away from the critical levels from which the attenuation of waves is predicted using momentum
flux. This is verified using group velocity approach.





The Fire Simulation in a Road Tunnel


Pages :
121128


Authors :
M. J. Jafari,
A. Karimi,
A. E. Usachov,
H. Kanani Moghaddam,
Fire behaviour, especially its interaction with ventilation system in tunnels, is still a challenging issue for road tunnel
designers .This paper presents the results of a study investigating the influence of a road tunnel ventilation system, on
conventional fires. For this purpose, a 25 MW fire corresponding to a conventional fire in a road tunnel was
simulated using 2D numerical modelling, for transient viscous multicomponent gas at low Mach numbers to study
smoke and heat propagation within a road tunnel under fire .Complete NavierStocks and Reynolds equations were
solved using developed algorithm of numerical modelling .The results from a series of calculations were compared
with results of experimental researches to examine the accuracy and stability of the calculations .The comparisons
showed that the algorithm provided a good description of physical processes in selected class of flow. It was also
concluded that calculation accuracy is not lower than those obtained from established simulation software programs .
The stability and good convergence of the algorithm was confirmed by separate calculations with different grid
patterns for the tunnel under consideration .The results revealed that the temperature at tunnel wall may rise up to
900oC. The concentration of smoke may also increase up to 95 %with a burning truck .Results were applied to assess
the ventilation system designed for a new long road tunnel in case of fire .The results from the study along with other
information were applied to assess the designed ventilation system and to establish the suitable fire fighting and
rescue plan .





