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Viewing 1 to 30 of 1861
Technical Paper
2014-10-13
Yingyi Wen, Shunichi Oshima
There is a growing need to reduce torque losses in bearings that are used in automotive power transmissions and differentials for improving fuel economy. While great reductions in rolling and sliding torque are achieved, agitation torque becomes an important factor of the total torque losses in bearings, especially under sufficient lubricating conditions. So far, efforts on reducing agitation torque were taken most by means of conventional experimental trials. To improve the efficiency of development of low-torque bearings, oil flow simulation based on CFD can be considered a good solution. Aiming for speedy, low-cost development, a calculation program for predicting the amount of agitation torque and oil distribution tendency in rolling bearings has been developed using CFD analysis. To precisely simulate the air-oil two-phase flow whirling inside bearings, the author introduced a free-surface flow model using volume of fluid (VOF) method. Generally, since rolling bearings are axially symmetric, sector models (including an integral roller/ball) of bearings in vertical posture are preferred in order to reduce calculation cost.
Technical Paper
2014-10-13
Shui-chang Liu, Lifu Li, Zhengqi Gu
In vehicle cooling system, the essential components—radiators often interact with each other air-side flow field thereby the thermal performance. To calculate the radiators’ performance more accurately at lower time cost against the background of today’s highly competitive marketplace, based on the CFD tools, a radiator group performance prediction method of a engineering vehicle cooling system is presented in this study. During CFD simulation, the RNG k–ε turbulence model is applied and the adopted numerical methods is SIMPLE, the first upwind discrete method is used firstly to get steady flow field and the second upwind is used to reach convergence at last. Air-side flow field simulations of the radiators unit model are carried out firstly to obtain the radiators resistance and heat transfer characteristics, during which three near-wall treatments are applied respectively, and simulations result present that flow field obtained from simulation with enhanced wall treatment has the least separated flow and backflow, also pressure drop; then, the air flow and heat transfer in the whole air channel containing the radiator group are simulated to get the inlet and outlet water temperatures of radiator group, during which radiators’ are processed as porous media with heat resource distribution near to the actual condition; at last, the water temperatures obtained from simulations are compared with the test values and the temperatures according to the enhanced wall treatment has lowest relative error 6.3%, which can meet the accuracy requirement in engineering computation, so the performance calculated method proposed in this paper is effective.
Technical Paper
2014-10-13
Sophie Porter, Ahmad Kamal Mat Yamin, Svetlana Aleksandrova, Stephen Benjamin, Carol A. Roberts, Jonathan Saul
Flow maldistribution across automotive exhaust catalysts significantly affects their conversion efficiency. This study investigates the application of CFD in modelling flow in a 2D rig consisting of a catalyst monolith downstream of a wide-angled planar diffuser presented with steady flow. Two distinct approaches, porous medium and individual channels, are used to model monoliths of length 27mm and 100mm. Flow predictions are compared to particle image velocimetry (PIV) measurements made in the diffuser and hot wire anemometry (HWA) data taken downstream of the monolith. Upstream of the monolith, the two CFD approaches agree well for velocity profiles across the central jet. CFD predictions diverge outside of this area, with neither one markedly closer to PIV results. Modelling the monolith as a fluid region of individual channels is shown to improve the prediction of flow maldistribution downstream of the monolith when compared to the porous medium approach. The individual channels model also predicts height and placement of secondary peaks closer to those of HWA data.
Technical Paper
2014-10-13
Yufeng Li
Swirl ratio in the cylinder of a diesel engine is an important parameter for air/fuel mixing and combustion process. Swirling flow in the cylinder is formed when the intake air flows thought a helical or tangential port and inlet valve seats and then recognized by the wall of the cylinder. The swirling angular speed generated by the intake ports can be determined on a steady flow rig. The swirl ratio at the end of intake stroke in an operating engine is then estimated by equations which have already been established by Ricardo and AVL. However, the swirl ratio estimated by these existing equations is not the real value in the cylinder of an operating engine as the equations were deducted from three basic assumptions: a) volumetric efficiency of an engine is 100%; b) the pressure drop between the intake ports is constant during the engine operation; c) no burned gas residual is trapped in the cylinder. They are not true definitely. On the other hand, an accurate swirl ratio in the cylinder is essential during the engine development.
Technical Paper
2014-09-30
Haoting Wang, Tieping Lin, Xiayi Yuan, Qi Zhang
Three dimensional, steady state computational fluid dynamics (CFD) simulations of flow around a generic pickup truck are performed to optimize the aerodynamic performance of a pickup truck model. Detailed comparison between the data of the CFD model and the experiment are made. By using deformation techniques, surrogate models and optimization methods, the drag is reduced. Four design variables are used for deformation: the cabin height, bed height, ground clearance and bed length. The optimization is single objective: minimizing the drag coefficient. A response surface model is built to reduce the sampling points for optimization, and the simulation time is reduced accordingly. Results show that the design variables are not fully independent with each other, and by proper combinations of the variable change, the drag coefficient of the pickup truck model can be reduced effectively. In this study, the drag coefficient reduced about 9.7% through optimization algorithm. The results also show that the single tailgate itself is not always profitable for drag reduction.
Technical Paper
2014-09-30
Ashok Patidar, Shivdayal Prasad, Umashanker Gupta, Mohan Subbarao
In today's competitive world, vehicle with light weighting is the most focused area. Vehicle light weighting can be done either by using light weight materials or by reducing the size of the existing components. In present paper later approach of vehicle light weighting is followed. It will help in packaging and reduce weight will add benefit to FE too. Scope for light weighting is identified in exhaust system where muffler volume is optimized using CFD commercial tool FLUENT. The back pressure, exhaust gas temperature, sound noise level & sound quality are chosen as design verification targets. The muffler volume is reduced by 15% resultant system become 15% compact with 2% lighter weight. CFD results are well correlated with physical test results on both the existing and optimized design results. Detailed design guideline and simulation process of exhaust system is explained in this paper.
Technical Paper
2014-09-30
Michael S. Barton, David Corson, John Quigley, Babak Emami, Tanuj Kush
In this work, the multi-physics problem arising from fluid sloshing within a tanker truck undergoing acceleration is investigated through the use of bi-directional coupling between AcuSolve and MotionSolve. This application represents a challenging test case for simulation technology within the design of commercial vehicles. Computer aided engineering is playing a more predominant role in the design process for commercial and passenger vehicles. Better understanding the real time loading and responses on a vehicle during intended (or unintended) use can result in improved design and reduced cost over traditional assumptions. Sloshing of liquid within the cargo tank of a commercial tanker truck results in increased loading on the vehicle's suspension when undergoing different types of acceleration maneuvers. The change in loading can have a significant effect on the design of the vehicles suspension components and braking components. The ability to investigate the fully coupled behavior of the mechanical and fluid systems is a key technology to enable improved designs for these types of applications.
Technical Paper
2014-09-30
Marc Ratzel, Warren Dias
Multiple engineering disciplines are considered in the development process of modern vehicles. This includes disciplines such as aerodynamics and structural dynamics. Often, these disciplines are applied in isolation, that is, without the consideration of interactions between disciplines. But in order to accurately represent the physical environment in which these designs and vehicles operate, it becomes important to consider the interaction effects. Interaction effects can be considered by including the effects of the different disciplines in a sequential manner, such as, determining the aerodynamic loads with a computational fluid dynamics (CFD) solver and then using the computed forces as boundary conditions in a structural analysis solver to determine displacements and stresses. However, for certain applications where this sequential modeling approach is not representative, the multiple disciplines can be analyzed in a co-simulation environment. An example of this would be the fluttering of an automotive hood under driving conditions.
Technical Paper
2014-09-30
Shaoyun Sun, Yin-ping Chang, Xinyu Wang, Qiang Fu, Kelong Lu, Zuofeng Pan, Bo Li, Heinz Friz
A big challenge for the aerodynamic optimization of trucks is the limited availability of wind tunnels for testing full scale trucks. FAW wants to introduce a development process which is mainly based on CFD simulation in combination with some limited amount of wind tunnel testing. While accuracy and maturity of CFD simulation for truck aerodynamics has been demonstrated in recent years, a complete validation is still required before committing to a particular process. The CFD tools involved in this validation are Star CCM+ and PowerFLOW. Since there is currently no wind tunnel available in China for the testing of full scale trucks, a 70% scale model is built for testing in the Shanghai Automotive Wind Tunnel Center. Drag and surface pressures are measured for providing a good basis for comparison to the simulation results. The simulations are performed for the scale model geometry as well as for the full scale geometry of the fully detailed truck. As a completion of this validation study a test of the full scale truck with a shortened trailer in a suitable wind tunnel in Europe is planned as future work.
Technical Paper
2014-09-16
C. Mallika Parveen, Khyati Ajay Jain, Abhilash Saksena, Miller Kalamegam
Aviation industry has come a long way since the invention of aero-plane by Wright Brothers. The shape and face of the industry has changed drastically from the time of its inception. With this paper, we intend to give a new perspective to the modeling industry. We try to do so by studying the aerodynamics of birds of prey, the most aerodynamically efficient examples created by nature. In this paper we are publishing the results and inferences of CFD analysis on the 3D CAD models of three birds. The birds we selected are : Red Tailed Hawk, Peregrine Falcon and Golden Eagle. The reason for this selection were their remarkable cruising speeds which reiterate the fact that they are natural examples of very high aerodynamic efficiency. Through this analysis, we are also trying an entirely different approach to designing aircrafts.
Technical Paper
2014-09-16
Jay Wilhelm, Joseph Close
Differential wing opening of a Hybrid Projectile (HP), an aerial vehicle that is ballistically launched and then transforms into an Unmanned Aerial Vehicle (UAV), was investigated to determine the amount of roll and pitch produced by uneven deployment. During testing of a 60 mm HP prototype, it was noticed that the projectile began to slightly roll after the spring assisted switchblade mechanism was activated deploying the wings, which takes about 100 milliseconds. This roll was undesirable and may lead the projectile off-course. An analytical investigation was done to determine how the roll angle and rate would be affected by the projectile wings being deployed improperly. The improper wing deployment situations that were investigated were that both wings were deployed at the same time but only one of the two sides was locked into an angle of incidence and the other was if one side of the wing was deployed before the other. The roll characteristics when both wings were deployed but only one was locked into an angle of incidence resulted in a steady state roll rate of 4.5 degrees per second.
Technical Paper
2014-09-16
Joseph Dygert, Melissa Morris, Patrick Browning
The continued high global demand for passenger and freight air traffic, in spite of rising fuel costs and several tragic cases involving loss-of-control events, has resulted in researchers examining alternative technologies which would result in safer, more reliable, and superior performing aircraft. Aerodynamic flow control may be the most promising approach to this problem having already proven its ability to enable higher flow efficiency while simultaneously improving overall flow control. Recent research in the area of aerodynamic control is transitioning from traditional mechanical flow control devices to plasma actuators. Plasma actuators offer an inexpensive and energy efficient method of flow control. In addition, plasma actuator technology has the potential of being applied to a host of other aircraft performance parameters including applications in radar mitigation and in situ wing deicing. Dielectric Barrier Discharge (DBD), one of the most widely studied forms of plasma actuation, employs an electrohydrodynamic device which uses only an electric field and the respective Coulomb force for actuation.
Technical Paper
2014-05-10
Robert E Smith, Edward Lumsdaine
Since transient vehicle HVAC computational fluids (CFD) simulations take too long to solve in a production environment, the goal of this project is to automatically create a lumped-parameter flow network from a steady-state CFD that solves nearly instantaneously. The data mining algorithm k-means is implemented to automatically discover flow features and form the network (a reduced order model). The lumped-parameter network is implemented in the commercial thermal solver MuSES to then run as a fully transient simulation. Using this network a “localized heat transfer coefficient” is shown to be an improvement over existing techniques. Also, it was found that the use of the clustering created a new flow visualization technique. Finally, fixing clusters near equipment newly demonstrates a capability to track localized temperatures near specific objects (such as equipment in vehicles).
Technical Paper
2014-04-01
Yinhong Liu, Dazhong Lao, Yixiong Liu, Ce Yang, Mingxu Qi
Abstract Variable nozzle turbine (VNT) adjusts the openings of its nozzles to insure the required flow at throat area, which broadens the operating range of the turbine, and improves the matching relationship between the turbocharger and the engine. But the changes of nozzle openings have significant influence on the flow field structure of downstream radial turbine. To evaluate this effect, the leakage flow through nozzle clearance in various nozzle openings were simulated by unsteady computational fluid dynamic (CFD). Meanwhile, the interaction between nozzle clearance leakage flow and nozzle wake were investigated to reveal its effects on aerodynamic losses and forced responses for downstream rotor. The results showed that the changes of nozzle openings not only affect the interaction between nozzle leakage flows and wake significantly, but also affect aerodynamic performance of the rotor and the blade forced response. With the decreases of nozzle openings, the nozzle leakage flow increases and the interaction between nozzle leakage flow and wake enhances.
Technical Paper
2014-04-01
Daniela Siano, Luigi Teodosio, Vincenzo De Bellis, Fabio Bozza
Abstract The present paper reports 1D and 3D CFD analyses of the air-filter box of a turbocharged VVA engine, aiming to predict and improve the gas-dynamic noise emissions through a partial re-design of the device. First of all, the gas-dynamic noise at the intake mouth is measured during a dedicated experimental campaign. The developed 1D and 3D models are then validated at full load operation, based on experimental data. In particular, 1D model provides a preliminary evaluation of the radiated noise and simultaneously gives reliable boundary conditions for the unsteady 3D CFD simulations. The latter indeed allow to better take into account the geometrical details of the air-filter and guarantee a more accurate gas-dynamic noise prediction. 3D CFD analyses put in evidence that sound emission mainly occur within a frequency range of 350 to 450 Hz. Starting from the above result, the original air-box design is modified through the installation of a single Helmholtz resonator, taking into account layout constraints and the influence on engine performance, as well.
Technical Paper
2014-04-01
Xiao Hu, Scott Stanton
Abstract Due to growing interest in hybrid and electric vehicles, li-ion battery modeling is receiving a lot of attention from designers and researchers. This paper presents a complete model for a li-ion battery pack. It starts from the Newman electrochemistry model to create the battery performance curves. Such information is then used for cell level battery equivalent circuit model (ECM) parameter identification. 28 cell ECMs are connected to create the module ECM. Four module ECMs are connected through a busbar model to create the pack ECM. The busbar model is a reduced order model (ROM) extracted from electromagnetic finite element analysis (FEA) results, taking into account the parasitic effects. Battery thermal performance is simulated first by computational fluid dynamics (CFD). Then, a thermal linear and time-invariant (LTI) ROM is created out of CFD solution. The thermal LTI ROM is then two-way coupled with the battery pack ECM to form a complete battery pack model. Thanks to the ROM technology, such a battery pack model can finish a complete charge discharge cycle within seconds of simulation time.
Technical Paper
2014-04-01
Kamalesh Bhambare, Junya Fukuyama, Jaehoon Han, Kosuke Masuzawa, Akihiro Iwanaga, Steven Patterson
Abstract The climate inside a vehicle cabin is affected by the performance of the vehicle HVAC system, the thermal characteristics of the vehicle structure and the components, as well as the external environmental conditions. Due to the complex interactions among these various factors, the flow field and the temperature distribution can be very complicated. The need for a fully three-dimensional transient analysis is increasing in order to provide sufficiently detailed information that can be used to improve the vehicle design. In this study, a numerical simulation methodology to predict the local climate conditions in a passenger vehicle cabin is presented. The convective heat transfer from both the exterior and the interior of the cabin were calculated by three dimensional CFD simulations using a Lattice-Boltzmann method based flow solver. The conduction and the radiation effects including the solar loading were solved using a finite-difference based radiation-conduction thermal solver.
Technical Paper
2014-04-01
Benjamin Lawler, Joshua Lacey, Nicolas Dronniou, Jeremie Dernotte, John Dec, Orgun Guralp, Paul Najt, Zoran Filipi
Abstract Refinements were made to a post-processing technique, termed the Thermal Stratification Analysis (TSA), that couples the mass fraction burned data to ignition timing predictions from the autoignition integral to calculate an apparent temperature distribution from an experimental HCCI data point. Specifically, the analysis is expanded to include all of the mass in the cylinder by fitting the unburned mass with an exponential function, characteristic of the wall-affected region. The analysis-derived temperature distributions are then validated in two ways. First, the output data from CFD simulations are processed with the Thermal Stratification Analysis and the calculated temperature distributions are compared to the known CFD distributions. The results show very good agreement between the calculated TSA and known CFD distributions, except at the leading (hottest) edge where the CFD distributions exhibit a discrete step change and the calculated TSA distributions show a smooth progression.
Technical Paper
2014-04-01
Kar Mun Pang, Mehdi Jangi, Xue-Song Bai, Jesper Schramm
Abstract In this reported work, 2-dimsensional computational fluid dynamics studies of n-heptane combustion and soot formation processes in the Sandia constant-volume vessel are carried out. The key interest here is to elucidate how the chemical kinetics affects the combustion and soot formation events. Numerical computation is performed using OpenFOAM and chemistry coordinate mapping (CCM) approach is used to expedite the calculation. Three n-heptane kinetic mechanisms with different chemistry sizes and comprehensiveness in oxidation pathways and soot precursor formation are adopted. The three examined chemical models use acetylene (C2H2), benzene ring (A1) and pyrene (A4) as soot precursor. They are henceforth addressed as nhepC2H2, nhepA1 and nhepA4, respectively for brevity. Here, a multistep soot model is coupled with the spray combustion solver to simulate the soot formation/oxidation processes. Comparison of the results shows that the simulated ignition delay times and liftoff lengths have good agreements with the experimental measurements across wide range of operating conditions when the nhepC2H2 model is implemented.
Technical Paper
2014-04-01
Stefano Fontanesi, Stefano Paltrinieri, Giuseppe Cantore
Abstract The paper critically discusses Large-Eddy Simulation (LES) potential to investigate cycle-to-cycle variability (CCV) in internal combustion engines. Particularly, the full load/peak power engine speed operation of a high-performance turbocharged GDI unit, for which ample cycle-to-cycle fluctuations were observed during experimental investigations at the engine test bed, is analyzed through a multi-cycle approach covering 25 subsequent engine cycles. In order to assess the applicability of LES within the research and development industrial practice, a modeling framework with a limited impact on the computational cost of the simulations is set up, with particular reference to the extent of the computational domain, the computational grid size, the choice of boundary conditions and numerical sub-models [1, 2, 3]. In order to evaluate the applicability of the adopted approach to the resolution of an adequate portion of the overall turbulent energy spectrum, different grid metrics are at first introduced, based on criteria available in literature [4, 5].
Technical Paper
2014-04-01
Lei Zhou, Kai Hong Luo, Shi-jin Shuai, Ming Jia
Abstract Unlike RANS method, LES method needs more time and much more grids to accurately simulate the spray process. In KIVA, spray process was modeled by Lagrangain-drop and Eulerian-fluid method. The coarse grid can cause errors in predicting the droplet-gas relative velocity, so for reducing grid dependency due to the relative velocity effects, an improved spray model based on a gas-jet theory is used in this work and in order to validate the model seven different size grids were used. In this work, the local dense grid was used to reduce the computation cost and obtain accurate results that also were compared with entire dense grid. Another method to improve computation efficiency is the MUSCL (Monotone Upstream-centered Schemes for Conservation Laws) differencing scheme that was implemented into KIVA3V-LES code to calculate the momentum convective term and reduce numerical errors. At last, Combustion is simulated using parallel algorithm for realistic chemistry mechanism that is also added into KIVA3V-LES code and named KIVALES-Chemistry-Parallel in this study.
Technical Paper
2014-04-01
Andrea Montorfano, Federico Piscaglia, Angelo Onorati
Abstract The dynamics and evolution of turbulent structures inside an engine-like geometry are investigated by means of Large Eddy Simulation. A simplified configuration consisting of a flat-top cylinder head with a fixed, axis-centered valve and low-speed piston has been simulated by the finite volume CFD code OpenFOAM®; the standard version of the software has been extended to include the compressible WALE subgrid-scale model, models for the generation of synthetic turbulence, some improvements to the mesh motion strategy and algorithms for LES data post-processing. In order to study both the initial transient and the quasi- steady operating conditions, ten complete engine cycles have been simulated. Phase and spatial averages have been performed over cycles three to ten in order to extract first and second moment of velocity; these quantities have then been used to validate the numerical procedure by comparison against experimental data. Complex unsteady features of turbulent fields like laminar-to-turbulent transition and tumble vortexes evolution have been studied either by time-resolved analysis and Proper Orthogonal Decomposition (POD).
Technical Paper
2014-04-01
Helgi Skuli Fridriksson, Martin Tuner, Oivind Andersson, Bengt Sunden, Hakan Persson, Mattias Ljungqvist
Abstract Heat transfer losses are one of the largest loss contributions in a modern internal combustion engine. The aim of this study is to evaluate the contribution of the piston bowl type and swirl ratio to heat losses and performance. A commercial CFD tool is used to carry out simulations of four different piston bowl geometries, at three engine loads with two different swirl ratios at each load point. One of the geometries is used as a reference point, where CFD results are validated with engine test data. All other bowl geometries are scaled to the same compression ratio and make use of the same fuel injection, with a variation in the spray target between cases. The results show that the baseline case, which is of a conventional diesel bowl shape, provides the best emission performance, while a more open, tapered, lip-less combustion bowl is the most thermodynamically efficient. The results also show that the response of the flow field, due to swirl variations, is not the same for all piston configurations and, therefore, the effects of swirl on heat transfer are not the same for all piston geometries.
Technical Paper
2014-04-01
Karl Georg Stapf, Sandeep Menon, David Schmidt, Michael Rieß, Marc Sens
Abstract Mesh generation is frequently one of the most labor-intensive aspects of in-cylinder engine simulation with computational fluid dynamics (CFD). This expense makes parameter studies, such like engine geometry, valve timing or injection timing, a particularly challenging endeavor. The present paper introduces a CFD approach for the simulation of the in-cylinder processes of an internal combustion engine that minimizes user-required meshing effort and can handle almost unlimited boundary motion. The adaptation is fully automated and avoids the use of target meshes and global solution remapping. The intention of the approach is to use CFD for numerous parameter variations involving combustion system variabilities. Therefore, an open source base is chosen to avoid limitations of individual simulations due to a finite number of commercial licenses. The approach is used here for the simulation of a modern direct injection spark igniton (DISI) engine. It enables a fast setup process for individual simulations and does not require a manual remeshing if geometric boundary conditions are changed.
Technical Paper
2014-04-01
Tommaso Lucchini, Marco Fiocco, Roberto Torelli, Gianluca D'Errico
The definition of a robust methodology to perform a full-cycle CFD simulation of IC engines requires as first step the availability of a reliable grid generation tool, which does not only have to guarantee a high quality mesh but also has to prove to be efficient in terms of required time. In this work the authors discuss a novel approach entirely based on the OpenFOAM technology, in which the available 3D grid generator was employed to automatically create meshes containing hexahedra and split-hexahedra from triangulated surface geometries in Stereolithography (STL) format. The possibility to introduce local refinements and boundary layers makes this tool suitable for IC engine simulations. Grids are sequentially generated at target crank angles which are automatically determined depending on user specified settings such as maximum mesh validity interval and quality parameters like non-orthogonality, skewness and aspect ratio. This ensures high quality grids for the entire cycle and requires a very reduced amount of user time.
Technical Paper
2014-04-01
Benjamin Reveille, Nicolas Gillet, Julien Bohbot, Olivier Laget
Abstract An automatic mesh generation process for a body fitted 3D CFD code is presented in this paper along with the methodology to guarantee the mesh quality. This tool named OMEGA (Optimized MEsh Generation Automation) uses a direct coupling procedure between the IFP-C3D solver and a hybrid mesher Centaur. Thanks to this automatic procedure, the engineering time needed for body fitted 3D CFD simulation in internal combustion engines is drastically reduced from a few weeks to a few hours. Valve and piston motion laws are just given as input files and geometries and meshes are automatically moved and generated. Unlike other procedures, this automatic mesh generation does not use an intermediate geometry discretization (STL file, tetrahedral surface mesh) but directly the original CAD that has been modified thanks to the geometry motion functionalities integrated into the mesher. All the meshes generated by the tool discretize precisely the surface geometry (nodes are projected on the correct CAD surfaces) to guarantee a correct flow prediction around intake valves and piston.
Technical Paper
2014-04-01
Daniela Anna Misul, Mirko Baratta, Hamed Kheshtinejad
Abstract Sustainable mobility has become a major issue for internal combustion engines and has led to increasing research efforts in the field of alternative fuels, such as bio-fuel, CNG and hydrogen addition, as well as into engine design and control optimization. To that end, a thorough control of the air-to-fuel ratio appears to be mandatory in SI engine in order to meet the even more stringent thresholds set by the current regulations. The accuracy of the air/fuel mixture highly depends on the injection system dynamic behavior and to its coupling to the engine fluid-dynamic. Thus, a sound investigation into the mixing process can only be achieved provided that a proper analysis of the injection rail and of the injectors is carried out. The present paper carries out a numerical investigation into the fluid dynamic behavior of a commercial CNG injection system by means of a 0D-1D code. The model has been validated by comparing the experimental readings to the numerical outputs in terms of injection system pressure profiles versus time.
Technical Paper
2014-04-01
Jonathan Harrison, Rodrigo Aihara, Mojtaba Eshraghi, Irina Dmitrieva
Abstract Variable displacement vane pumps are becoming more popular for engine oil circuits due to their fuel savings over traditional fixed displacement pumps. As a result, engineers need to analyze these pumps to ensure the pump design meets the demands of the oil circuit while having good friction characteristics and avoiding issues like high pressure amplitude and resonance. By employing 1D flow simulation to these pumps, the user can analyze the most important issues surrounding vane pumps at a fraction of the time as 3D CFD. This paper showcases the prediction of several major performance quantities of a variable displacement vane pump including flow rate, pressure rise, and friction torque vs. engine speed and temperature. The simulation results show good correlation to measurement data. In addition, the pressure pulsation at several locations including in the vane chamber and at the outlet is compared directly with 3D CFD for a different pump. Furthermore, the effect of aerated oil on pump performance is also shown.
Technical Paper
2014-04-01
Karthikeyan N, Anish Gokhale, Narendra Bansode
Abstract The Continuous Variable Transmission (CVT) in scooters is used to transmit the power from the engine to the wheels. The CVT transmission consists of a drive pulley and a driven pulley connected to each other through a belt. The centrifugal clutch is attached to the rear pulley which transmits the power to the wheel. The engagement and disengagement of the clutch generates heat and friction heat is generated between the belt and pulley, thereby requiring continuous external cooling for its safe operation. A centrifugal fan is employed for cooling of the CVT belt. Since the cooling fan takes air from atmosphere, there is always a possibility of dust from the atmosphere entering the system, which might cause wear of pulley and belt, thereby decreasing the performance of the transmission system. The objective of the work is to analyze the dust ingress pattern in to CVT housing. The work aims at simulating the possible conditions for dust entry into the CVT housing for a complete scooter and the study of different design proposals to minimize the dust entry without compromising the cooling requirement of CVT.
Technical Paper
2014-04-01
Tetsuhiro Kawamura, Atsushi Ogawa
Abstract The change in the aerodynamic lift force (henceforth CL) by heave motion is discussed in this paper in order to clarify the effect of aerodynamic characteristics on the vehicle dynamic performance. We considered that phenomenon in actual car running at 160km/h and 1Hz heave frequency. Using a towing tank to change its water from the air to the working fluid to more easily observe this phenomenon. That makes possible to observe the same phenomenon with reduced velocity and small models under same Strouhal number condition. This method can be reducing vehicle speed to 3m/s (1/15 actual) and frequency to 0.2Hz (1/5 actual) in case using 40% scaled model. The results of these tests showed that unsteady CL is proportional to heave motion. These results showed the proportional relationship between unsteady CL and heave motion. The formularization of unsteady CL made it possible to introduce shape coefficients to vehicle dynamics simulations as functions of heave velocity. This makes it possible to consider the effect of unsteady CL on dynamic performance at the initial stages of the development process.
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