Hardware-in-the-Loop (HiL) simulation is recognized as a reliable approach for testing and verification of the control systems of hybrid vehicles. To perform the HiL simulation, a real-time vehicle simulator is needed which can virtually... more
Hardware-in-the-Loop (HiL) simulation is recognized as a reliable approach for testing and verification of the control systems of hybrid vehicles. To perform the HiL simulation, a real-time vehicle simulator is needed which can virtually emulate the real vehicle in communication with the control unit. This paper presents the design and implementation of a low-cost single PC based HiL simulation platform for testing of the Central Control Unit (CCU) in a series hybrid electric bus. For HiL simulation purposes, the generation and flow of the signals should be the same as those of the real system. Therefore, based on the Controller Area Network (CAN) messages and dynamic behaviour of each component, a comprehensive real-time simulator is designed in LabVIEW environment. The designed simulator together with the control unit and the necessary interfaces makes a functional low-cost HiL test bench. Due to modular simulation, subsystems of the designed simulator can be replaced by the real prototypes and this in turn leads to a more flexible HiL simulation test bench. With this system, the user can act like a real driver and experience driving regimes which may happen in reality without being involved with difficulties of testing on an actual vehicle. The designed simulation model has been validated using real test results. Using the designed test bench, the results show that all control functions in the CCU can be tested and verified.
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Abstract Long charging time is one of the main disadvantages of lead–acid batteries. Although the higher charging voltage can shorten the charging time, it is limited in order to avoid thermal instability. In the present research, the... more
Abstract Long charging time is one of the main disadvantages of lead–acid batteries. Although the higher charging voltage can shorten the charging time, it is limited in order to avoid thermal instability. In the present research, the charging time has shortened using a higher charging voltage while the stability of the system has remained the same through thermal stability analysis. The method of linear stability analysis is applied to derive governing equations of perturbations. The set of derived equations are rearranged to obtain the desired form of the eigenvalue problem. The obtained eigenvalue problem is solved numerically, which has resulted in a neutral curve separating the stable zone from the unstable one, and the critical point. In addition, the effects of some geometrical parameters on the position of the neutral curve are investigated. All charging processes are simulated using the computational battery dynamic method. The results show that on the one hand, the stable zone increases by increasing the maximum dimensionless volume. On the other hand, the stable zone decreases by increasing the charging voltage. In conclusion, an eight percent reduction in the charging time is observed through increasing both of the charging voltage and the maximum dimensionless volume at the same time.
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Thermal management of lithium-ion battery pack in hybrid electric vehicles (HEVs) and electric vehicles (EVs) have become a research focus in recent years because performance, safety and life time of battery have significant dependency on... more
Thermal management of lithium-ion battery pack in hybrid electric vehicles (HEVs) and electric vehicles (EVs) have become a research focus in recent years because performance, safety and life time of battery have significant dependency on temperature distribution throughout the cell. As the first step in designing a reliable thermal strategy, heat generation of battery must be computed accurately. But the most effective physical properties involved in heat source may not be exactly known, possibly because of intrinsic variability which cannot be measured directly in practice. In any simulation process, some uncertainties appear whose understanding and quantification is critical to assess the differences between the numerical predictions and actual system behavior. For this purpose, these uncertainties must be quantified and propagated through energy equation and heat flux to roll up the uncertainties of interest in order to determine range of temperature distribution, and consequent...
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Dynamic Mode Decomposition (DMD) is a data-driven reduced order method, which is known for its power to capture the basic features of dynamical systems. In fluid dynamics, modal analysis of unsteady fluid flows over moving structures is... more
Dynamic Mode Decomposition (DMD) is a data-driven reduced order method, which is known for its power to capture the basic features of dynamical systems. In fluid dynamics, modal analysis of unsteady fluid flows over moving structures is significant in terms of state estimation and control. However, the underlying algorithm of the DMD requires a fixed spatial domain, which is an obstacle for applying the DMD on the numerically investigated problems using dynamic meshes. In this study, a hybrid method called Hybrid Dynamic Mode Decomposition (HDMD) is presented for analysis of unsteady fluid flows over moving structures based on the DMD and machine learning. According to the assessment of several data interpolation methods, the K-nearest neighbor algorithm is employed for the interpolation of the numerical data from dynamic meshes at each time step to a single stationary grid. Three different case studies (rotating cylinder, oscillating airfoil, and Savonius wind turbine) are assessed...
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Aim of this paper is to investigate mechanism of NO and soot reduction by using multiple injection as useful strategy for reducing DI diesel engines emissions. In this paper, we first studied the mechanism of NO and soot reduction by... more
Aim of this paper is to investigate mechanism of NO and soot reduction by using multiple injection as useful strategy for reducing DI diesel engines emissions. In this paper, we first studied the mechanism of NO and soot reduction by using double injection. Then after investigating different modes of injection, at last we introduce optimum mode of fuel injection for a DI diesel engine manufactured in our country. Experiments were induced at Motorsazan Tabriz to validate results of CFD simulation. Amount of fuel in each pulse and dwell time between injection pulses are essential parameters. Results showed that by using double injection soot and NO will reduce by 33% and 11% respectively.
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Background. In order to reduce the mortality risk of aneurysm rupture, a timely diagnosis and treatment are vital. There are different reasons for aneurysm, such as hypertension, arteriosclerosis, and heredity. An efficient and... more
Background. In order to reduce the mortality risk of aneurysm rupture, a timely diagnosis and treatment are vital. There are different reasons for aneurysm, such as hypertension, arteriosclerosis, and heredity. An efficient and cost-effective method to study the generation, development, and rupture of aneurysm and also analysis of treatment methods can accelerate progress. The Computational Fluid Dynamics is a well-known tool to simulate various phenomena. A reliable virtual modeling in biology depends on our knowledge about variety of characteristics, that is, biological features, structural properties, and flow conditions. Objective. Because of the vast research about the related subjects, an organized review is required. The aim of current review article is classification of the required foundations for a reliable virtual modeling of cerebral aneurysm, especially in the Circle of Willis.
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The present study aims to provide a modified model for analysing the longitudinal dynamics of ground vehicles. Bearing in mind that an inevitable tire slip occurs under the transmission of driving torque to the drive wheels, the pure... more
The present study aims to provide a modified model for analysing the longitudinal dynamics of ground vehicles. Bearing in mind that an inevitable tire slip occurs under the transmission of driving torque to the drive wheels, the pure rolling assumption employed in many previous works is modified in this research. This paves the way through the development of a more realistic simulation framework with promising performance when used in vehicle and powertrain related topics. The modified equation of motion is an explicit function of tire slip ratio, and as a result, by rewriting the power balance equation, a dissipation term due to tire slip appears, which is consistent with the outcome of the recent contributions. Simulation results indicate a significant difference between the modified and simplified models in the case of a relatively high tractive force. Moreover, tire slip loss is obviously large in such a case, so that its neglect would lead to a noticeable inaccuracy in the resp...
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The present study aims to investigate the effect of hydrogen enrichment of the methane jet fuel on the formation of pollutants and greenhouse gases and exergy efficiency of a burner working on flameless MILD combustion mode for different... more
The present study aims to investigate the effect of hydrogen enrichment of the methane jet fuel on the formation of pollutants and greenhouse gases and exergy efficiency of a burner working on flameless MILD combustion mode for different amounts of oxygen present in the hot air co-flow stream using computational fluid dynamics coupled with detailed chemistry. OpenFOAM v. 3.0 is employed for the simulations. The results indicate considerable the pivotal role of the amount of hydrogen present in the fuel stream. It is also evident that hydrogen enrichment could be considered as a promising strategy for further increasing the exergy efficiency of burners working in MILD combustion mode.
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In the present study, the effects of Organic Rankine Cycle (ORC) and turbo-compound (T/C) system integration on a heavy-duty diesel engine (HDDE) is investigated. An inline six-cylinder turbocharged 11.5 liter compression ignition (CI)... more
In the present study, the effects of Organic Rankine Cycle (ORC) and turbo-compound (T/C) system integration on a heavy-duty diesel engine (HDDE) is investigated. An inline six-cylinder turbocharged 11.5 liter compression ignition (CI) engine employing two waste heat recovery (WHR) strategies is modelled, simulated, and analyzed through a 1-D engine code called GT-Power. The WHR systems are evaluated by their ability to utilize the exhaust excess energy at the downstream of the primary turbocharger turbine, resulting in brake specific fuel consumption (BSFC) reduction. This excess energy is dependent on the mass flow rate and the temperature of engine exhaust gas. However, this energy varies with engine operational conditions, such as speed, load, etc. Therefore, the investigation is carried out at six engine major operating conditions consisting engine idling, minimum BFSC, part load, maximum torque, maximum power, and maximum exhaust flow rate. The results for the ORC and T/C syst...
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The trade-off between the fuel consumption and drag coefficient makes the investigations of drag reduction of utmost importance. In this paper, the rear-end shape optimization of Ahmed body is performed. Before changing the geometry, to... more
The trade-off between the fuel consumption and drag coefficient makes the investigations of drag reduction of utmost importance. In this paper, the rear-end shape optimization of Ahmed body is performed. Before changing the geometry, to identify the suitable simulation method and validate it, the standard Ahmed body is simulated using k − ω shear stress transport (SST) and k-epsilon turbulence models. The slant angle, rear box angle, and rear box length as variables were optimized simultaneously. Optimizations conducted by genetic algorithm (GA) and particle swarm optimization (PSO) methods indicate a 26.3% decrease in the drag coefficient. To ensure the validity of the results, a numerical-experimental study is conducted on the optimized model. Thereafter, the velocity profiles and flow structure in the boundary layers of the original geometry were compared to those of the optimized geometry at different sections. The results indicate that there are points where the velocity profile in the boundary layer can exceed the free stream velocity and return to it again, an overlooked observation in the previous studies. In addition to the streamlines, to better understand the formation of three-dimensional vortexes, the Q-criterion factor is computed and illustrated.
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The calibration process of the internal combustion engine becomes more costly and time-consuming than ever due to complexity of the engines and stringent emission regulations. The accurate and fast calibration of the engine requires a lot... more
The calibration process of the internal combustion engine becomes more costly and time-consuming than ever due to complexity of the engines and stringent emission regulations. The accurate and fast calibration of the engine requires a lot of performance tests which demands time, cost, and expert manpower as well as test facilities that must be taken into considerations. This process needs a large number of test points which should be examined to get an optimum map of the engine. Although some works have been done on reducing test time for the engine calibration, still the process timing remains one of the challenges for the automotive industry. The present study aims to decrease the calibration cost and time by employing the proper orthogonal decomposition (POD) method. The POD-based reduced order model is applied to reduce the number of experimental engine tests to regenerate the entire calibration table by using only a few operating points accurately. The low, mid-range and high R...
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Lithium-ion batteries (LIBs) have drawn attention in research due to their broad range of applications. In this regard, researchers are working on the degradation phenomena of these batteries so that manufacturers can produce less... more
Lithium-ion batteries (LIBs) have drawn attention in research due to their broad range of applications. In this regard, researchers are working on the degradation phenomena of these batteries so that manufacturers can produce less expensive and more reliable batteries than they used to do. Among the aging phenomena, the Solid Electrolyte Interphase (SEI) layer is the most important one and causes the cell to capacity fade and internal resistance raise. In this paper, a stochastic approach, based on the sparse Jacobi polynomial chaos expansion, was utilized to investigate the effect of the uncertainty sources on the lithium-ion battery aging. Furthermore, the importance of each uncertainty source is calculated by using Sobol indices. Capacity fade and resistance raise obtained at the end of the Constant Current-Constant Voltage (CC-CV) charging. The results indicate that the importance of the open circuit potential of positive electrode and end of charge voltage (EOCV) on capacity fa...
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Two-stroke cycle engines have always been prominent due to their distinctive advantage incorporating high power-to-weight ratio, however the drawbacks are poor combustion efficiency, fuel short-circuiting and excessive emission of uHC and... more
Two-stroke cycle engines have always been prominent due to their distinctive advantage incorporating high power-to-weight ratio, however the drawbacks are poor combustion efficiency, fuel short-circuiting and excessive emission of uHC and CO. These problems are apparent at low-load and speed regions and are the major obstacle to their global acceptance. The deficiencies can be addressed by increasing the in-cylinder average charge temperature employing Exhaust Gas Recirculation (EGR). An experimental study is conducted to investigate the influence of utilizing EGR techniques, including Internal and External EGR, on combustion misfiring occurrence, combustion stability and exhaust emissions using a single cylinder two-stroke SI engine at idling, low and mid-load conditions. From the results, it is observed since the average in-cylinder charge temperature is increased, due to utilizing EGRs, engine’s low and mid-load irregular combustions (misfire) and exhaust emissions are remarkably...
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Fluid-structure interaction (FSI) problems in microchannels play prominent roles in many engineering applications. The present study is an effort towards the simulation of flow in microchannel considering FSI. Top boundary of the... more
Fluid-structure interaction (FSI) problems in microchannels play prominent roles in many engineering applications. The present study is an effort towards the simulation of flow in microchannel considering FSI. Top boundary of the microchannel is assumed to be rigid and the bottom boundary, which is modeled as a Bernoulli-Euler beam, is simulated by size-dependent beam elements for finite element method (FEM) based on a modified couple stress theory. The lattice Boltzmann method (LBM) using D2Q13 LB model is coupled to the FEM in order to solve fluid part of FSI problem. In the present study, the governing equations are non-dimensionalized and the set of dimensionless groups is exhibited to show their effects on micro-beam displacement. The numerical results show that the displacements of the micro-beam predicted by the size-dependent beam element are smaller than those by the classical beam element.
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ABSTRACT
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ABSTRACT
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The construction of single structured grids for complex geome- tries is not always possible and it can be a high time consuming part in Com- putation Fluid Dynamics (CFD). The governing equations for computations of supersonic flows are... more
The construction of single structured grids for complex geome- tries is not always possible and it can be a high time consuming part in Com- putation Fluid Dynamics (CFD). The governing equations for computations of supersonic flows are nonlinear and, in general, do not admit an analyti- cal solution. Thus, numerical techniques are indispensable for obtaining the full-scale solution of