Abstract: An experimental investigation is carried out to
establish the performance characteristics of a compression ignition
engine while using cerium oxide nanoparticles as additive in neat
diesel and diesel-biodiesel blends. In the first phase of the
experiments, stability of neat diesel and diesel-biodiesel fuel blends
with the addition of cerium oxide nanoparticles is analyzed. After
series of experiments, it is found that the blends subjected to high
speed blending followed by ultrasonic bath stabilization improves the
stability. In the second phase, performance characteristics are studied
using the stable fuel blends in a single cylinder four stroke engine
coupled with an electrical dynamometer and a data acquisition
system. The cerium oxide acts as an oxygen donating catalyst and
provides oxygen for combustion. The activation energy of cerium
oxide acts to burn off carbon deposits within the engine cylinder at
the wall temperature and prevents the deposition of non-polar
compounds on the cylinder wall results reduction in HC emissions.
The tests revealed that cerium oxide nanoparticles can be used as
additive in diesel and diesel-biodiesel blends to improve complete
combustion of the fuel significantly.
Abstract: The effects of flame-holder position, the ratio of flame
holder diameter to combustion chamber diameter and injection angle
on fuel propulsive droplets sizing and effective mass fraction have
been studied by a cold flow. We named the mass of fuel vapor inside
the flammability limit as the effective mass fraction. An empty
cylinder as well as a flame-holder which are a simulator for duct
combustion has been considered. The airflow comes into the cylinder
from one side and injection operation will be done by four nozzles
which are located on the entrance of cylinder. To fulfill the
calculations a modified version of KIVA-3V code which is a
transient, three-dimensional, multiphase, multi component code for
the analysis of chemically reacting flows with sprays, is used.
Abstract: Boiling process is characterized by the rapid
formation of vapour bubbles at the solid–liquid interface (nucleate
boiling) with pre-existing vapour or gas pockets. Computational fluid
dynamics (CFD) is an important tool to study bubble dynamics. In
the present study, CFD simulation has been carried out to determine
the bubble detachment diameter and its terminal velocity. Volume of
fluid method is used to model the bubble and the surrounding by
solving single set of momentum equations and tracking the volume
fraction of each of the fluids throughout the domain. In the
simulation, bubble is generated by allowing water-vapour to enter a
cylinder filled with liquid water through an inlet at the bottom. After
the bubble is fully formed, the bubble detaches from the surface and
rises up during which the bubble accelerates due to the net balance
between buoyancy force and viscous drag. Finally when these forces
exactly balance each other, it attains a constant terminal velocity. The
bubble detachment diameter and the terminal velocity of the bubble
are captured by the monitor function provided in FLUENT. The
detachment diameter and the terminal velocity obtained are compared
with the established results based on the shape of the bubble. A good
agreement is obtained between the results obtained from simulation
and the equations in comparison with the established results.
Abstract: Heat transfer due to forced convection of copper water
based nanofluid has been predicted by Artificial Neural network
(ANN). The present nanofluid is formed by mixing copper
nanoparticles in water and the volume fractions are considered here
are 0% to 15% and the Reynolds number are kept constant at 100.
The back propagation algorithm is used to train the network. The
present ANN is trained by the input and output data which has been
obtained from the numerical simulation, performed in finite volume
based Computational Fluid Dynamics (CFD) commercial software
Ansys Fluent. The numerical simulation based results are compared
with the back propagation based ANN results. It is found that the
forced convection heat transfer of water based nanofluid can be
predicted correctly by ANN. It is also observed that the back
propagation ANN can predict the heat transfer characteristics of
nanofluid very quickly compared to standard CFD method.
Abstract: Purpose: The study aimed to assess the depressant or
antidepressant effects of several Nonsteroidal Anti-Inflammatory
Drugs (NSAIDs) in mice: the selective cyclooxygenase-2 (COX-2)
inhibitor meloxicam, and the non-selective COX-1 and COX-2
inhibitors lornoxicam, sodium metamizole, and ketorolac. The
current literature data regarding such effects of these agents are
scarce.
Materials and methods: The study was carried out on NMRI mice
weighing 20-35 g, kept in a standard laboratory environment. The
study was approved by the Ethics Committee of the University of
Medicine and Pharmacy „Carol Davila”, Bucharest. The study agents
were injected intraperitoneally, 10 mL/kg body weight (bw) 1 hour
before the assessment of the locomotor activity by cage testing (n=10
mice/ group) and 2 hours before the forced swimming tests (n=15).
The study agents were dissolved in normal saline (meloxicam,
sodium metamizole), ethanol 11.8% v/v in normal saline (ketorolac),
or water (lornoxicam), respectively. Negative and positive control
agents were also given (amitryptilline in the forced swimming test).
The cage floor used in the locomotor activity assessment was divided
into 20 equal 10 cm squares. The forced swimming test involved
partial immersion of the mice in cylinders (15/9cm height/diameter)
filled with water (10 cm depth at 28C), where they were left for 6
minutes. The cage endpoint used in the locomotor activity assessment
was the number of treaded squares. Four endpoints were used in the
forced swimming test (immobility latency for the entire 6 minutes,
and immobility, swimming, and climbing scores for the final 4
minutes of the swimming session), recorded by an observer that was
„blinded” to the experimental design. The statistical analysis used the
Levene test for variance homogeneity, ANOVA and post-hoc
analysis as appropriate, Tukey or Tamhane tests.
Results: No statistically significant increase or decrease in the
number of treaded squares was seen in the locomotor activity
assessment of any mice group. In the forced swimming test,
amitryptilline showed an antidepressant effect in each experiment, at
the 10 mg/kg bw dosage. Sodium metamizole was depressant at 100
mg/kg bw (increased the immobility score, p=0.049, Tamhane test),
but not in lower dosages as well (25 and 50 mg/kg bw). Ketorolac
showed an antidepressant effect at the intermediate dosage of 5
mg/kg bw, but not so in the dosages of 2.5 and 10 mg/kg bw,
respectively (increased the swimming score, p=0.012, Tamhane test).
Meloxicam and lornoxicam did not alter the forced swimming
endpoints at any dosage level.
Discussion: 1) Certain NSAIDs caused changes in the forced
swimming patterns without interfering with locomotion. 2) Sodium
metamizole showed a depressant effect, whereas ketorolac proved
antidepressant. Conclusion: NSAID-induced mood changes are not
class effects of these agents and apparently are independent of the
type of inhibited cyclooxygenase (COX-1 or COX-2).
Disclosure: This paper was co-financed from the European Social
Fund, through the Sectorial Operational Programme Human Resources Development 2007-2013, project number POSDRU /159
/1.5 /S /138907 "Excellence in scientific interdisciplinary research,
doctoral and postdoctoral, in the economic, social and medical fields
-EXCELIS", coordinator The Bucharest University of Economic
Studies.
Abstract: In order to avoid self-collision of space manipulators
during operation process, a real-time detection method is proposed in
this paper. The manipulator is fitted into a cylinder-enveloping
surface, and then, a kind of detection algorithm of collision between
cylinders is analyzed. The collision model of space manipulator
self-links can be detected by using this algorithm in real-time detection
during the operation process. To ensure security of the operation, a
safety threshold is designed. The simulation and experiment results
verify the effectiveness of the proposed algorithm for a 7-DOF space
manipulator.
Abstract: In this research numerical simulations are performed,
using the multi-relaxation-time lattice Boltzmann method, in the
range 3 ≤ β = w[d] ≤ 30 at Re = 100, 200 and 300, where β the
blockage ratio, w is the equispaced distance between centers of
cylinders, d is the diameter of the cylinder and Re is the Reynolds
number, respectively. Special attention is paid to the effect of the
equispaced distance between centers of cylinders. Visualization of
the vorticity contour visualization are presented for some simulation
showing the flow dynamics and patterns for blockage effect. Results
show that the drag and mean drag coefficients, and Strouhal number,
in general, decrease with the increase of β for fixed Re. It is found
that the decreasing rate of drag and mean drag coefficients and
Strouhal number is more distinct in the range 3 ≤ β ≤ 15. We found
that when β > 15, the blockage effect almost diminishes. Our results
further indicate that the drag and mean drag coefficients, peak value
of the lift coefficient, root-mean-square value of the lift and drag
coefficients and the ratio between lift and drag coefficients decrease
with the increase of Re. The results indicate that symmetry boundary
condition have more blockage effect as compared to periodic
boundary condition.
Abstract: The present work attempts to investigate the
combustion, performance and emission characteristics of an existing
single-cylinder four-stroke compression-ignition engine operated in
dual-fuel mode with hydrogen as an alternative fuel. Environmental
concerns and limited amount of petroleum fuels have caused interests
in the development of alternative fuels like hydrogen for internal
combustion (IC) engines. In this experimental investigation, a diesel
engine is made to run using hydrogen in dual fuel mode with diesel,
where hydrogen is introduced into the intake manifold using an LPGCNG
injector and pilot diesel is injected using diesel injectors. A
Timed Manifold Injection (TMI) system has been developed to vary
the injection strategies. The optimized timing for the injection of
hydrogen was 10^0 CA after top dead center (ATDC). From the study
it was observed that with increasing hydrogen rate, enhancement in
brake thermal efficiency (BTHE) of the engine has been observed
with reduction in brake specific energy consumption (BSEC).
Furthermore, Soot contents decrease with an increase in indicated
specific NOx emissions with the enhancement of hydrogen flow rate.
Abstract: In this study, a computational fluid dynamics (CFD)
model has been developed for studying the effect of surface
roughness profile on the EHL problem. The cylinders contact
geometry, meshing and calculation of the conservation of mass and
momentum equations are carried out using the commercial software
packages ICEMCFD and ANSYS Fluent. The user defined functions
(UDFs) for density, viscosity and elastic deformation of the cylinders
as the functions of pressure and temperature are defined for the CFD
model. Three different surface roughness profiles are created and
incorporated into the CFD model. It is found that the developed CFD
model can predict the characteristics of fluid flow and heat transfer in
the EHL problem, including the main parameters such as pressure
distribution, minimal film thickness, viscosity, and density changes.
The results obtained show that the pressure profile at the center of the
contact area directly relates to the roughness amplitude. A rough
surface with kurtosis value of more than 3 has greater influence over
the fluctuated shape of pressure distribution than in other cases.
Abstract: The main objective of aircraft aerodynamics is to
enhance the aerodynamic characteristics and maneuverability of the
aircraft. This enhancement includes the reduction in drag and stall
phenomenon. The airfoil which contains dimples will have
comparatively less drag than the plain airfoil. Introducing dimples on
the aircraft wing will create turbulence by creating vortices which
delays the boundary layer separation resulting in decrease of pressure
drag and also increase in the angle of stall. In addition, wake
reduction leads to reduction in acoustic emission. The overall
objective of this paper is to improve the aircraft maneuverability by
delaying the flow separation point at stall and thereby reducing the
drag by applying the dimple effect over the aircraft wing. This project
includes both computational and experimental analysis of dimple
effect on aircraft wing, using NACA 0018 airfoil. Dimple shapes of
Semi-sphere, hexagon, cylinder, square are selected for the analysis;
airfoil is tested under the inlet velocity of 30m/s and 60m/s at
different angle of attack (5˚, 10˚, 15˚, 20˚, and 25˚). This analysis
favors the dimple effect by increasing L/D ratio and thereby
providing the maximum aerodynamic efficiency, which provides the
enhanced performance for the aircraft.
Abstract: An analysis is carried out to investigate the effect of
magnetic field and heat source on the steady boundary layer flow and
heat transfer of a Casson nanofluid over a vertical cylinder stretching
exponentially along its radial direction. Using a similarity
transformation, the governing mathematical equations, with the
boundary conditions are reduced to a system of coupled, non –linear
ordinary differential equations. The resulting system is solved
numerically by the fourth order Runge – Kutta scheme with shooting
technique. The influence of various physical parameters such as
Reynolds number, Prandtl number, magnetic field, Brownian motion
parameter, thermophoresis parameter, Lewis number and the natural
convection parameter are presented graphically and discussed for non
– dimensional velocity, temperature and nanoparticle volume
fraction. Numerical data for the skin – friction coefficient, local
Nusselt number and the local Sherwood number have been tabulated
for various parametric conditions. It is found that the local Nusselt
number is a decreasing function of Brownian motion parameter Nb
and the thermophoresis parameter Nt.
Abstract: In this report we have discussed the theoretical aspects
of the flow transformation, occurring through a series of bifurcations.
The parameters and their continuous diversion, the intermittent bursts
in the transition zone, variation of velocity and pressure with time,
effect of roughness in turbulent zone, and changes in friction factor
and head loss coefficient as a function of Reynolds number for a
transverse flow across a cylinder have been discussed. An analysis of
the variation in the wake length with Reynolds number was done in
FORTRAN.
Abstract: In this study the instability problem of a modified
Taylor-Couette flow between two vertical coaxial cylinders of radius
R1, R2 is considered. The modification is based on the wavy shape of
the inner cylinder surface, where inner cylinders with different
surface amplitude and wavelength are used. The study aims to
discover the effect of the inner surface geometry on the instability
phenomenon that undergoes Taylor-Couette flow. The study reveals
that the transition processes depends strongly on the amplitude and
wavelength of the inner cylinder surface and resulting in flow
instabilities that are strongly different from that encountered in the
case of the classical Taylor-Couette flow.
Abstract: The in-cylinder flow and mixture formations are
significant in view of today’s increasing concern on environmental
issues and stringent emission regulations. In this paper, the numerical
simulations of a SI engine at different engine speeds (2000-5000
rpm) at fixed intake flow pressure of 1 bar are studied using the AVL
FIRE software. The simulation results show that when the engine
speed at fixed intake flow pressure is increased, the volumetric
efficiency of the engine decreases. This is due to a richer fuel
conditions near the engine cylinder wall when engine speed is
increased. Significant effects of impingement are also noted on the
upper and side walls of the engine cylinder. These variations in
mixture formation before ignition could affect the thermodynamics
efficiency and specific fuel consumption that would lead to a reduced
engine performance.
Abstract: Quality control helps industries in improvements of its
product quality and productivity. Statistical Process Control (SPC) is
one of the tools to control the quality of products that turning practice
in bringing a department of industrial engineering process under
control. In this research, the process control of a turning
manufactured at workshops machines. The varying measurements
have been recorded for a number of samples of a rice polished
cylinder obtained from a number of trials with the turning practice.
SPC technique has been adopted by the process is finally brought
under control and process capability is improved.
Abstract: This paper is devoted to the study of a viscous
incompressible flow around a circular cylinder performing harmonic
oscillations, especially the steady streaming phenomenon. The
research methodology is based on the asymptotic explanation method
combined with the computational bifurcation analysis. The research
approach develops Schlichting and Wang decomposition method.
Present studies allow to identify several regimes of the secondary
streaming with different flow structures. The results of the research
are in good agreement with experimental and numerical simulation
data.
Abstract: The global demand for continuous and eco-friendly
renewable energy as alternative to fossils fuels is large and ever
growing in nowadays. This paper will focus on capability of Vortex
Induced Vibration (VIV) phenomenon in generating alternative
energy for offshore platform application. In order to maximize the
potential of energy generation, the effects of lock in phenomenon and
different geometries of cylinder were studied in this project. VIV is
the motion induced on bluff body which creates alternating lift forces
perpendicular to fluid flow. Normally, VIV is unwanted in order to
prevent mechanical failure of the vibrating structures. But in this
project, instead of eliminating these vibrations, VIV will be exploited
to transform these vibrations into a valuable resource of energy.
Abstract: The use of biodiesel in conventional diesel engines results in substantial reduction of unburned hydrocarbon, carbon monoxide and particulate matters. The performance, emission and combustion characteristics of a single cylinder four stroke variable compression ratio engine when fueled with Karanja (Pongamia) methyl ester and its 10-50 % blends with diesel (on a volume basis) are investigated and compared with standard diesel. The suitability of karanja methyl ester as a biofuel has been established in this study. The useful brake power obtained is similar to diesel fuel for all loads. Experiment has been conducted at a fixed engine speed of 1500 rpm, variable load and at compression ratios of 17.5:1 and 18.5:1. The impact of compression ratio on fuel consumption, combustion pressures and exhaust gas emissions has been investigated and presented. Optimum compression ratio which gives best performance has been identified. The results indicate longer ignition delay, maximum rate of pressure rise, lower heat release rate and higher mass fraction burnt at higher compression ratio for pongamia oil methyl ester when compared to that of diesel. The brake thermal efficiency for pongamia oil methyl ester blends and diesel has been calculated and the blend B20 is found to give maximum thermal efficiency. The blends when used as fuel results in reduction of carbon monoxide, hydrocarbon and increase in nitrogen oxides emissions. PME as an oxygenated fuel generated more complete combustion, which means increased torque and power. This is also supported with higher thermal efficiencies of the PME blends. NOx is slightly increased due to the higher combustion temperature and the presence of fuel oxygen with the blend at full load. PME as a new Biodiesel and its blends can be used in diesel engines without any engine modification.
Abstract: This numerical study aims to develop a coupled,
passive and active control strategy of the flow around a cylinder of
diameter D, and Re=4000. The strategy consists to put a cylindrical
rod in front of a deforming cylinder. The quasi- elliptical deformation
of cylinder follow a sinusoidal law in order to reduce the drag force.
To analyze the evolution of unsteady vortices, the Large Eddy
Simulation approach is used in this 2D simulation, carried out using
ANSYS – Fluent. The movement of deformation is reproduced using
an internal subroutine, introduced in the form of a User Defined
Function UDF. Two diameters of the rod were tested for a rod placed
at a distance L = 3 ×d, with an amplitudes of deformation A = 5%, A
= 25% and A = 50% of the cylinder diameter, the frequency of
deformation take the values fd = 1fn, 5fn and 8fn, which fn
represents the naturel vortex shedding frequency. The results show
substantial changes in the flow behavior and for a rod of 6mm (1%
D) with amplitude A = 25%, and with a 2fn frequency, drag
reduction of 60% was recorded.
Abstract: The aim of present study is to control the unsteady flow structure downstream of a circular cylinder by use of attached permeable plates. Particle image velocimetry (PIV) technique and dye visualization experiments were performed in deep water and the flow characteristics were evaluated by means of time-averaged streamlines, Reynolds Shear Stress and Turbulent Kinetic Energy concentrations. The permeable plate was made of a chrome-nickel screen having a porosity value of β=0.6 and it was attached on the cylinder surface along its midspan. Five different angles were given to the plate (θ=0o, 15o, 30o, 45o, 60o) with respect to the centerline of the cylinder in order to examine its effect on the flow control. It was shown that the permeable plate is effective on elongating the vortex formation length and reducing the fluctuations in the wake region. Compared to the plain cylinder, the reductions in the values of maximum Reynolds shear stress and Turbulent Kinetic Energy were evaluated as 72.5% and 66%, respectively for the plate angles of θ=45oand 60o which were also found to be suggested for applications concerning the vortex shedding and consequent Vortex-Induced Vibrations.