Showing 353 results for Type of Study: Research
M. H. Askari, S. M. Hoseinalipour, S. A. Jazayeri, M. Baghsheikhi,
Volume 1, Issue 2 (6-2011)
Abstract
The HCCI combustion process is initiated due to auto-ignition of fuel/air mixture which is dominated by chemical kinetics and therefore fuel composition has a significant effect on engine operation and a detailed reaction mechanism is essential to analysis HCCI combustion. A single zone-model permits to have a detailed chemical kinetics modeling for practical fuels. In this study a single-zone thermodynamic model with detail chemical mechanism is developed to investigate the effect of hydrogen addition to natural gas in a homogeneous charge compression ignition combustion and to analyze the performance and emissions of the HCCI engine. The effect of five different percentage of hydrogen added to natural gas ranging from 0 to 40 on HCCI combustion is investigated in this study. The results indicate that by increasing hydrogen portion in intake mixture, start of combustion advances and maximum temperature increase, but increasing in maximum pressure is negligible. Carbon’s included emissions such as Co, Co2 and unburned hydrocarbons decreases by increasing of hydrogen, and also, specific fuel consumption decreases. The result shows that hydrogen improves combustion characteristics of natural gas in an HCCI engine and leads to better performance and less emissions.
T. Feyzi, M. Esfahanian, R. Tikani, S. Ziaei Rad,
Volume 1, Issue 2 (6-2011)
Abstract
M. H. Shojaeefard, I. Sohrabiasl, E. Sarshari,
Volume 1, Issue 2 (6-2011)
Abstract
Intake system design as well as inlet ports and valves configuration is of paramount importance in the optimal performance of internal combustion engines. In the present study, the effect of inlet ports design is investigated on OM-457LA diesel engine by using a CFD analysis and the AVL-Fire code as well. A thermodynamic model of the whole engine equipped with a turbocharger and an intercooler is used to obtain the initial and boundary conditions of the inlet and outlet ports of the engine cylinder which are necessary for performing the three dimensional CFD analysis. The intake stroke as well as the compression and power strokes are included in this three dimensional CFD model. As a mean of validation the performance of the engine model with the base configuration of the inlet ports is compared to the experimental data. Two new alternative configurations for the inlet ports are then investigated with respect to the turbulence levels of the in-cylinder flow and the combustion characteristics as well. Finally it is demonstrated that applying the new configurations results in circa 75% reduction in nitric oxide formation besides increase of 32% in the in-cylinder flow swirl.
A.h. Kakaee, M. Pishgooie,
Volume 1, Issue 2 (6-2011)
Abstract
S. Sanaye, M. Dehghandokht,
Volume 1, Issue 3 (5-2011)
Abstract
Thermal modeling of an automotive cabin was performed in this paper to predict the inside cabin air temperature. To implement this task, thermal and ventilation loads were estimated and the mass and energy balance conservation equations for dry air and water vapor with considering a new parameter (air circulation ratio) as well as the balance equations of internal components of a cabin were derived and solved simultaneously. The performance of the proposed thermal modeling of a cabin was compared with the data collected from hot room experimental tests. These tests were run for various design parameters such as evaporating cooling load and cabin size (air volume inside cabin). The comparison of experimental and numerical results showed a good agreement.
Parametric analysis with three parameters namely, vehicle speed, number of passengers, and A/C air mass flow rate was performed to investigate the effects of these parameters on cabin air temperature.
M. Abbasi, R. Kazemi, A. Ghafari Nazari,
Volume 1, Issue 3 (5-2011)
Abstract
Parametric design optimization of an automotive body crashworthiness improvement is presented. The thicknesses of parts are employed as design variables for optimization whose objective is to increase the maximum deceleration value of the vehicle center of gravity during an impact. Using the Taguchi method, this study analyzes the optimum conditions for design objectives and the impact factors and their optimal levels are obtained by a range analysis of the experiment results. A full frontal impact is implemented for the crashworthiness simulation in the nonlinear dynamic code, LS-DYNA. The controllable factors used in this study consist of the six inside foreheads structural parts, while design parameters are relevant thicknesses. The most interestingly the maximum deceleration of the vehicle center of gravity is reduced by 20% during a full frontal impact while several parts experience mass reduction.
D. Younesian, A.a. Jafari, R. Serajian,
Volume 1, Issue 3 (5-2011)
Abstract
Nonlinear hunting speeds of railway vehicles running on a tangent track are analytically obtained using Hopf bifurcation theory in this paper. The railway vehicle model consists of nonlinear primary yaw dampers, nonlinear flange contact stiffness as well as the clearance between the wheel flange and rail tread. Linear and nonlinear critical speeds are obtained using Bogoliubov method. A comprehensive parametric study is then carried out and effects of different parameters like the magnitudes of lateral clearance, damping values, wheel radius, bogie mass, lateral stiffness and the track gauge on linear and nonlinear hunting speeds are investigated.
A. Gharehgahani, M. Mirsalim, A. Jazayeri,
Volume 1, Issue 3 (5-2011)
Abstract
A newly developed heavy duty diesel engine in dual fuel mode of operation has been studied in detail. The main fuel would be natural gas and diesel oil as pilot injection. The importance and effects of mixture preparation and formation through ports, valves and in cylinder flow field with different swirl ratio and tumble on diesel combustion phenomena is an accepted feature which has been studied using a developed CFD model together with a KIVA3-V2 code. This analysis is capable to investigate engine geometry, valves lift, and valves timing turbo charging, and its effects on dynamic flow field with variable dual fuel ratio on power and emission levels output. This complete open cycle study of a dual fuel engine has been carried out originally and for the first time and by considering complete grid consisted of four moving valves, two intake ports, two exhaust ports, and the port runners. It is found that important complex flow structures are developed during the intake stroke. While many of these structures decay during the compression stroke, swirl and tumble can survive. The effect of increased swirl ratio at the end of the compression stroke for the D87 engine with a piston bowl is clearly observed in this study. This is important for aiding in good fuel spray atomization. The formation, development, and break-up of tumble flow are seen, contributing to an increase in turbulent kinetic energy at the end of the compression stroke. The complete engine flow field, i.e. the inlet jet, and formation of swirl in the intake ports, is also clearly shown in the study. Results of these simulations assist in the improved understanding of the intake process and its influence on mixture formation and flow field in a dual fuel engine.
M. Manteghi, B. Abdi, A.a. Tofigh,
Volume 1, Issue 3 (5-2011)
Abstract
This article aims at strategic vision to technology and suggests a strategic planning for this purpose. The main emphasis in this article is on strategic report compilation in the framework of strategic vision and covers issues such as identification of strategic planning dimensions and strategic vision levels, technology priority setting, environment monitoring, focus on costumer needs, methods of strategic vision compilation and future research methods. This article also concentrates on R&D strategies in a separate section. Furthermore, a separate section is dedicated to strategic vision in automotive industry and issues are discussed related to Iran Khodro Co. strategic visions. At the end, a model is presented for strategic vision compilation.
M. Bidarvatan, M. Shahbakhti, S.a. Jazayeri,
Volume 1, Issue 3 (5-2011)
Abstract
Homogenous Charge Compression Ignition (HCCI) engines hold promise of high fuel efficiency and low emission levels for future green vehicles. But in contrast to gasoline and diesel engines, HCCI engines suffer from lack of having direct means to initiate combustion. A combustion timing controller with robust tracking performance is the key requirement to leverage HCCI application in production vehicles. In this paper, a two-state control-oriented model is developed to predict HCCI combustion timing for a range of engine operation. The experimental validation of the model confirms the accuracy of the model for HCCI control applications. An optimal integral state feedback controller is designed to control the combustion timing by modulating the ratio of two fuels. Optimization methods are used in order to determine the controller’s parameters. The results demonstrate the designed controller can reach optimal combustion timing within about two engine cycles, while showing good robustness to physical disturbances.
M. Salehpour, A. Jamali, N. Nariman-Zadeh,
Volume 1, Issue 4 (12-2011)
Abstract
In this paper, multi-objective uniform-diversity genetic algorithm (MUGA) with a diversity preserving mechanism called the ε-elimination algorithm is used for Pareto optimization of 5-degree of freedom vehicle vibration model considering the five conflicting functions simultaneously. The important conflicting objective functions that have been considered in this work are, namely, vertical acceleration of seat, vertical velocity of forward tire, vertical velocity of rear tire, relative displacement between sprung mass and forward tire and relative displacement between sprung mass and rear tire. Further, different pairs of these objective functions have also been selected for 2-objective optimization processes. The comparison of the obtained results with those in literature demonstrates the superiority of the results of this work. It is shown that the results of 5-objective optimization include those of 2-objective optimization and, therefore, provide more choices for optimal design of vehicle vibration model.
S. Babazadeh Shayan, S. M. Seyedpour, F. Ommi, S. H. Moosavy, M. Alizadeh,
Volume 1, Issue 4 (12-2011)
Abstract
E. Mohammadi, M. A. Moghadam,
Volume 1, Issue 4 (12-2011)
Abstract
F. Javid, E. Esmailzadeh, D. Younesian,
Volume 1, Issue 4 (12-2011)
Abstract
M. R. Ayatollahi, F. Mohammadi, H. R. Chamani,
Volume 1, Issue 4 (12-2011)
Abstract
P. Hosseini-Tehrani, S. Pirmohammad,
Volume 1, Issue 4 (12-2011)
Abstract
M. Durali, M. Sadedel,
Volume 1, Issue 4 (12-2011)
Abstract
N. Tavassoli, A. Darvizeh, M. Darvizeh,
Volume 2, Issue 1 (1-2012)
Abstract
Car body lightening and crashworthiness are two important objectives of car design. Due to their excellent performance, composite materials are extensively used in the car industries. In addition, reducing the weight of vehicle is effective in decreasing the fuel consumption. Hat shape energy absorber is used in car’s doors for side impact protection.
The aim of these numerical models and experimental tests is to unveil some important fact about using composite materials in hat shape energy absorber and also show the effect of orientation angles on the amount of energy absorption. The effects of different orientation angles on crushing behavior of hat shape structure are presented.
M. H. Shojaeefard, R. Talebitooti, M. Amirpour Molla, R. Ahmadi,
Volume 2, Issue 1 (1-2012)
Abstract
S. Javan, S. V. Hosseini, S. Sh. Alaviyoun,
Volume 2, Issue 1 (1-2012)
Abstract
Temperature is one of the effective parameters in erosion of spark plug electrodes. In this research, temperature of
spark plug was measured in engine's different operation conditions with two types of fuels: compressed natural gas and
gasoline. Test results showed that, temperature of center electrode is lower than ground electrode and maximum
difference between them is 110ºC that occurs at 2500 rpm and full load conditions. Maximum temperature of spark
plug occurs with CNG under full load conditions and 6380 rpm. In these conditions, ground electrode’s temperature
reaches to 960ºC which is very prone to pre-ignition. On the other hand, center electrode’s temperature is 195ºC higher
than the same condition with gasoline as a fuel which cause more electrode erosion rate. This temperature rise lead to
cold type spark plug selection because of its better heat transfer. Spark plug erosion was studied after endurance tests
with CNG as a fuel. Electrodes have non uniform wear patterns and consequently gap growth is not uniform. The
average gap growth for two sets of spark plugs after two similar 200 hr endurance tests is 49.6%
