Showing 359 results for Type of Study: Research
M. Eftekhar, A. Keshavarz, A. Ghasemian, J. Mahdavinia,
Volume 3, Issue 1 (3-2013)
Abstract
Running the industrial components at a proper temperature is always a big challenge for engineers. Internal
combustion engines are among these components in which temperature plays a big role in their
performance and emissions. With the development of new technology in the fields of ‘nano-materials’ and
‘nano-fluids’, it seems very promising to use this technology as a coolant in the internal combustion
engines. In this study, a nano-fluid (Al2O3-Water/Ethylene Glycol (EG)) is used as an engine coolant along
with an optimized heat exchanger to reduce the warm-up timing. The effect of nano-fluid concentration is
considered here by using their corresponding governing equations, such as momentum and energy. The
engine coolant thermal behavior calculation is carried out based on the lumped method. The obtained
results indicated that using different percentage of nano-fluid mixtures (by volume), such as Al2O3-
Water/EG as engine coolant enhances the heat transfer coefficient and reduces the warm-up timing which,
in turn, results in reduced emissions and fuel consumption.
S. K. Kamboj, M. N. Karimi,
Volume 3, Issue 2 (6-2013)
Abstract
Alcohols have been used as a fuel for engines since 19th century. Among the various alcohols, ethanol and
methanol are known as the most suited renewable, bio-based and ecofriendly fuel for spark-ignition (SI)
engines. The most attractive properties of ethanol and methanol as an SI engine fuel are that it can be
produced from renewable energy sources such as sugar, cane, cassava, many types of waste biomass
materials, corn and barley. In addition, ethanol has higher evaporation heat, octane number and
flammability temperature therefore it has positive influence on engine performance and reduces exhaust
emissions. In this study, the effects of unleaded iso-octane, unleaded iso-octane–ethanol blend (E10) and
isooctane-methanol blend (M10) on engine performance were investigated experimentally in a single
cylinder four-stroke spark-ignition engine. The tests were performed by varying the throttle position,
engine speed and loads. Three sets of observations were recorded at (1301 rpm, 16.8 Kg load), (1468 rpm,
15.8 Kg load) and (1544 rpm, 10 Kg load) for all tested fuels. The results of the engine test showed that IP,
IMEP, Volumetric efficiency and thermal efficiency was higher for the E10 fuel and BSFC was lower. In
general, most suited blend for SI engines has been specified as a blend of 10% ethanol. It was also observed
that better performance was recorded during second set of observation for all the tested fuels. It was also
found that ethanol–gasoline blends allow increasing compression ratio (CR) without knock occurrence.
M. Iranmanesh,
Volume 3, Issue 2 (6-2013)
Abstract
In this study, various percentage of DEE was added to the optimum selected ethanol-diesel blend (D-E10)
and optimized its blending ratio to overcome the poor ignition quality of ethanol when utilized in a single
cylinder DI diesel engine. Some physicochemical properties of test fuels such as heating value, viscosity,
and density and distillation profile were determined in accordance to the ASTM standards. The heating
value of the blends was reduced with addition of DEE. Front-end volatility of the blends was improved by
addition of DEE, which in turn improves the cold starting property. The uncertainty associated with
measurements was also measured. The data were analyzed statistically for 95% confidence level. The
results have shown that addition of biofuels, ethanol and diethyl ether, have improved the combustion and
emissions characteristics of the engine. Addition of ethanol and DEE improved smoke and NOx emissions
simultaneously. It was found the 8% DEE add to the D-E10 blend is the optimum combination based on the
performance and emission analysis with the exception of smoke opacity in which 15% DEE addition made
the lowest smoke opacity. At this optimum ratio the minimum peak heat release rate, the lowest NOx
emissions and the maximum BTE were occurred at full load condition. Meanwhile the lowest level of CO
and HC emissions were obtained at all the load conditions with the same blending ratio.
A. Ghaffari, A. Khodayari, F. Alimardani, H. Sadati,
Volume 3, Issue 2 (6-2013)
Abstract
Overtaking a slow lead vehicle is a complex maneuver because of the variety of overtaking conditions and
driver behavior. In this study, two novel prediction models for overtaking behavior are proposed. These
models are derived based on multi-input multi-output adaptive neuro-fuzzy inference system (MANFIS).
They are validated at microscopic level and are able to simulate and predict the future behavior of the
overtaking vehicle in real traffic flow. In these models, the kinematic features of Driver-Vehicle-Units
(DVUs) such as distance, velocity, and acceleration are used. Unlike the previous models, where some
variables of the two involved vehicles are considered to be constant, in this paper, instantaneous values of
the variables are considered. The first model predicts the future value of the longitudinal acceleration and
the movement angle of the overtaking vehicle. The other model predicts the overtaking trajectory for the
overtaking vehicle. The second model is designed for two different vehicle classes: motorcycles and autos.
Also, the result of the trajectory prediction model is compared with the result of other models. This
comparison provides a better chance to analyze the performance of this model. Using the field data, the
outputs of the MANFIS models are validated and compared with the real traffic dataset. The simulation
results show that these two MANFIS models have a very close compatibility with the field data and reflect
the situation of the traffic flow in a more realistic way. These models can be used for all types of drivers
and vehicles and also in other roads and are not limited to certain types of situations. The proposed models
can be employed in ITS applications and the like.
B. Jafari, D. Domiri Ganji,
Volume 3, Issue 2 (6-2013)
Abstract
Air pollution is one of the major issues about the diesel engines in todays' world. It is a special concern in
those areas that have difficulty meeting health-based outdoor air quality standards. Natural gas has low
emission and resource abundance and also conventional compression ignition engine can be easily
converted to a dual fuel mode to use natural gas as main fuel and diesel as pilot injection. The main object
of this work is to investigate the effect of number of injector nozzle hole on the combustion and exhaust
emission in a gas engine ignited with diesel fuel. We use one and three-dimensional simulation in parallel
way in order to analyze the performance and combustion process of a dual fuel engine. The experimental
results have also reported and compared with the simulated data.
S. Jafarmadar, M. Khanbabazadeh,
Volume 3, Issue 2 (6-2013)
Abstract
In the present work, multidimensional modeling of open-cycle process of OM355 engine was developed.
Calculations for computational mesh were carried out. The results of the model were validated by
experimentally measured in-cylinder pressure and the good agreement between calculations and
measurements approved the trustworthy of numerical code. Results included pressure, temperature,
emission and Rate of heat release diagrams were represented for the full cycle. Furthermore local flow field
velocity vectors were indicated. The results show the importance of open-cycle simulations in automotive
researches.
A. Fazli,
Volume 3, Issue 2 (6-2013)
Abstract
In this paper, the optimum shape of Tailor-Welded Blanks (TWB) is investigated. The optimization is
performed for two different case studies. The first example is deep drawing of a TWB with dissimilar
materials and uniform thicknesses and the next example is deep drawing of a TWB with similar materials
and non-uniform thicknesses. The effect of blank optimization on the weld line movement is investigated.
Also the effect of weld line location on the blank optimization and weld line movement is examined.
A. Khalkhali, V. Agha Hosseinali Shirazi, M. Mohseni Kabir,
Volume 3, Issue 2 (6-2013)
Abstract
One of the most important structural components of engine compartment assembly in a car body is the Srail. S-rails has significant role in absorbing energy during crash events and therefore it is designed for efficient behavior in such conditions. Driving the peak crushing force of the S-rails is one of the important objectives in the design process of such structures. Peak crushing force is exactly the force applied to the downstream components and then will be transferred to the cabin of vehicle. In this paper, closed form solution is performed to drive the peak crushing force of the S-rails. Results of such analytical model finally are compared with the results of finite element simulation. Good agreement between such results shows the accuracy of the proposed analytical model.
M. Baghaeian, A. A. Akbari,
Volume 3, Issue 3 (9-2013)
Abstract
In this paper, the enhancement of vehicle stability and handling is investigated by control of the active
geometry suspension system (AGS). This system could be changed through control of suspension mounting
point’s position in the perpendicular direction to wishbone therefore the dynamic is alternative and
characteristics need to change. For this purpose, suitable controller needs to change mounting point’s
position in limit area. Adaptive fuzzy control able to adjust stability and handling characteristics in all
conditions. Also, simple controller such as proportional-integral-derivative (PID) versus adaptive fuzzy
have been used that submit intelligent controllers. The three of freedom model (3DOF) in vehicle handling
is validated with MATLAB and CarSim software. The results show that the steady state response of the
adaptive fuzzy controller has been closed to desired yaw and roll angle has been enhanced about %20. In
cases of lateral velocity and side slip angle have the same condition that it shows the stability has been
improved. The control effort of PID needs to change very high that this response is not good physically,
while control effort in adaptive fuzzy is less than 50 mm.
M. H. Shojaeefard, M. Tahani, M. M. Etghani, M. Akbari,
Volume 3, Issue 3 (9-2013)
Abstract
Cooled exhaust gas recirculation is emerging as a promising technology to address the increasing demand for fuel economy without compromising performance in turbocharged spark injection engines. The objectives of this study are to quantify the increase in knock resistance and to decrease the enrichment and emission at high load. For this purpose four stroke turbo charged Spark Ignition engine (EF7-TC) including its different systems such as inlet and exhaust manifold, exhaust pipe and engine geometry are modeled using GT Power Software. As predicted, using cooled EGR at high load enabled operation at lambda near to one with the same serial engine performances, which offers substantial advantages Such As BSFC reduction (up to 14%), and emission reduction (CO, NOx).
M. Bostanian, S. M. Barakati, B. Najjari, D. Mohebi Kalhori,
Volume 3, Issue 3 (9-2013)
Abstract
Hybrid Electric Vehicles (HEVs) are driven by two energy convertors, i.e., an Internal Combustion (IC) engine and an electric machine. To make powertrain of HEV as efficient as possible, proper management of the energy elements is essential. This task is completed by HEV controller, which splits power between the IC engine and Electric Motor (EM). In this paper, a Genetic-Fuzzy control strategy is employed to control the powertrain. Genetic-Fuzzy algorithm is a method in which parameters of a Fuzzy Logic Controller (FLC) are tuned by Genetic algorithm. The main target of control is to minimize two competing objectives, consisting of energy cost and emissions, simultaneously. In addition, a new method to consider variations of Battery State of Charge (SOC) in the optimization algorithm is proposed. The controller performances are verified over Urban Dinamometer Driving Cycle (UDDS) and New Europian Driving Cycle (NEDC). The results demonstrate the effectiveness of the proposed method in reducing energy cost and emissions without sacrificing vehicle performance.
A. R. Noorpoor,
Volume 3, Issue 3 (9-2013)
Abstract
Oil pump in diesel engine has significant effect on energy consumption and environment pollution. In this
paper, the modeling and simulation of a gear oil pump used in a diesel engine and its fluid flow analysis by
a solver has been explained. Also the optimization and redesign of it has been discussed and then the
outcomes have been compared with the experimental and previous results. The type of this oil pump is
external gear pump with involute tooth profile, so we need to use the gears with the minimum number of
tooth to optimize the pump performance and getting the optimum displacement volume rate of it. While the
engaged gears of the pump rotating together, the intersection between them changes in time. So their
boundaries should be considered as movable. The strategy used here consist in using dynamic meshes,
dividing a tooth rotating cycle into a certain number of time steps and investigating the flow and getting the
results for each time steps.
B. Soleimani, M. M. Jalili,
Volume 3, Issue 3 (9-2013)
Abstract
Wheel/rail contact simulation is one of the most complicated problems in the modeling of railway vehicles.
The wheel/rail interaction plays a unique role in rail vehicle dynamics. In this paper, the dynamic response
of the wheel on irregular rail track is analyzed with analytical approach using the method of Multiple
Scales (MMS). The Hertzian contact theory is used to obtain the relationship between normal contact force
and the displacement of the mass center of the wheel. Analytical approach is expanded for performance of
train’s wheel travelling on the rail. To validate the method presented in this paper, responses of the model
using MMS method are compared with the results obtained from the Runge–Kutta numerical solution.
Finally effects of the wheelset preload on response frequency have been studied.
A. Jafari, Sh. Azadi, M. Samadian,
Volume 3, Issue 3 (9-2013)
Abstract
The directional response and roll stability characteristics of a partly filled tractor semi-trailer vehicle, with
cylindrical tank, are investigated in various maneuvers. The dynamic interaction of liquid cargo with the
tractor semi-trailer vehicle is also evaluated by integrating a dynamic slosh model of the partly filled tank
with five-degrees-of-freedom of a tractor semi-trailer tank model. The dynamic fluid slosh within the tank
is modeled using three-dimensional Navier-Stokes equations, coupled with volume-of-fluid equations and
analysed using the FLUENT software. The coupled tank-vehicle model is subsequently analysed to
determine the roll stability characteristics for different maneuvers. The results showed the interaction of
fluid slosh with vehicle's dynamic. Another findings of this investigation also revealed that the roll stability
of a tractor semi-trailer tank carrying liquid was highly affected by fluid sloshing and caused degradation of
roll stability in comparison with vehicle carrying rigid cargo.
A. Mirmohammadi, F. Ommi,
Volume 3, Issue 3 (9-2013)
Abstract
The purpose of present paper is simulation a direct injection stratified charge natural gas engine. The
KIVA-3V code was used for gaseous fuel injection simulation. Compression and expansion stroke of
engine cycle is simulated using KIVA-3V code. In cylinder fuel equivalence ratio distribution criterion is
used for studying mesh independency. The results show that 550000 cells number is sufficient. The
amount of NO emission in the end of closed cycle simulation was found equal 674.875 ppm and In cylinder
pressure versus engine crank angle degree was simulated that maximum value found in 366 oCA that equal
to 27.3222 bar.
B. Sakhaei, M. Durali,
Volume 3, Issue 4 (12-2013)
Abstract
By new advancements in vehicle manufacturing vehicle quality evaluation and assurance has become a
more critical issue. In present work, the vibration transfer path analysis and vibration path ranking of a car
interior has been performed. The method is similar to classical multilevel TPA methods but has distinct
differences. The method is named VIVS which stands for Vehicle Interior Vibration Simulation.
Performance of some tests like chassis dyno test, virtual mass function test and body transfer function test
are required in this approach. The accelerations on both sides of the engine mounts are measured on chassis
dyno by which the virtual mass and body transfer functions are measured at engine mounts. Using the
concept of multilevel TPA, the vibration share from each path is calculated. The overall vibration
magnitude at target point is calculated by summing the shares. Path ranking can be done by having the
share of each path from overall vibration magnitude. Using this method on a sample vehicle, some
modification has been proposed to decrease the vibration at target point, and the side effect of the
modifications on the powertrain dynamic behavior has been evaluated. The proposed method needs less
analysis time than classical TPA methods and its ability in optimization of vibration magnitude at target
points is proven.
E. Masoumi Khalil Abad, A. Ghazanfari, R. Hashemi,
Volume 3, Issue 4 (12-2013)
Abstract
In this study, an extended stress-based forming limit diagram (FLD) for prediction of necking based on the
Marciniak and Kucznski (M-K) model is represented and applied in tube hydroforming. The bulge forming
of a straight tube is simulated by finite element method and verified with published experimental data. This
adaptive simulation technique is based on the ability to detect the onset and growth of defects (e.g., bursting
and wrinkling) and to promptly readjust the loading paths. Thus, a suitable load path is determined by
applying Adaptive Simulation Method in ANSYS Parametric Design Language (APDL).
M. Esfahanian, A. Mahmoodian, M. Amiri, M. Masih Tehrani, H. Nehzati, M. Hejabi, A. Manteghi,
Volume 3, Issue 4 (12-2013)
Abstract
In the present study, a model of a large Lithium Polymer (Li-Po) battery for use in the simulation of Hybrid
Electric Vehicles (HEVs) is developed. To attain this goal, an Equivalent Circuit (EC) consisting of a series
resistor and two RC parallel networks is considered. The accuracy and the response time of the model for
use in an HEV simulator are studied. The battery parameters identification and model validation tests are
performed in low current with a good accuracy. Similar test process is implemented in high current for
another cell and the simulation is verified with experimental results. The validation tests confirm the
accuracy of the model for use in HEV simulator. Finally, the battery model is used to model a Vehicle, Fuel
and Environment Research Institute (VFERI) hybrid electric city bus using ADVISOR software and its
compatibility with other components of the vehicle simulator are demonstrated in a drive cycle test.
S. Pramanik,
Volume 3, Issue 4 (12-2013)
Abstract
Kinematic synthesis of a trailing six-member mechanism has been carried out to achieve five precision
points of an automotive steering mechanism. The inner wheel can be rotated up to forty five degrees with
fair accuracy. Results show that the divergent end behavior of Ackermann Steering Mechanism has been
overcome by the present mechanism. The work is similar to earlier work by the present author. But the
present mechanism is a trailing mechanism instead of a leading one. This helps to eliminate the spur gears
used earlier to bring the mechanism on the rear side of the front axle.
A. Amini, M. Mirzaei, R. Khoshbakhti Saray,
Volume 3, Issue 4 (12-2013)
Abstract
In spark ignition (SI) engines, the accurate control of air fuel ratio (AFR) in the stoichiometric value is
required to reduce emission and fuel consumption. The wide operating range, the inherent nonlinearities
and the modeling uncertainties of the engine system are the main difficulties arising in the design of AFR
controller. In this paper, an optimization-based nonlinear control law is analytically developed for the
injected fuel mass flow using the prediction of air fuel ratio response from a mean value engine model. The
controller accuracy is more increased without chattering by appending the integral feedback technique to
the design method. The simulation studies are carried out by applying severe changes in the throttle body
angle to evaluate the performance of the proposed controller with and without integral feedback. The
results show that the proposed controller is more effective than the conventional sliding mode controller in
regulating the AFR without chattering.