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Viewing 1 to 30 of 2614
2014-10-13
Technical Paper
2014-01-2856
Elias Sundström, Bernhard Semlitsch, Mihai Mihaescu
Abstract Numerical analysis methods are used to investigate the flow in a ported-shroud centrifugal compressor under different operating conditions, i.e. several mass flow rates at two different speed lines. A production turbocharger compressor is considered, which is widely used in the heavy automotive sector. Flow solutions obtained under steady-state and transient flow assumptions are compared with available experimental data. The steady-state Reynolds Averaged Navier-Stokes method is used to assess the overall time averaged flow and the global performance parameters. Additionally, the Large Eddy Simulation (LES) approach is employed to capture the transient flow features and the developed flow instabilities at low mass flow rates near the surge line. The aim of this study is to provide new insights on the flow instability phenomena in the compressor flow near surge. Comparison of flow solutions obtained for near-optimal efficiency and near-surge conditions are carried out.
2014-10-13
Technical Paper
2014-01-2558
Qiyou Deng, Richard Burke
Abstract Current turbocharger models are based on characteristic maps derived from experimental measurements taken under steady conditions on dedicated gas stand facility. Under these conditions heat transfer is ignored and consequently the predictive performances of the models are compromised, particularly under the part load and dynamic operating conditions that are representative of real powertrain operations. This paper proposes to apply a dynamic mathematical model that uses a polynomial structure, the Volterra Series, for the modelling of the turbocharger system. The model is calculated directly from measured performance data using an extended least squares regression. In this way, both compressor and turbine are modelled together based on data from dynamic experiments rather than steady flow data from a gas stand. The modelling approach has been applied to dynamic data taken from a physics based model, acting as a virtual test cell.
2014-10-13
Technical Paper
2014-01-2821
Jonathan Stewart, Roy Douglas, Alexandre Goguet, Cristina Elena Stere, Luke Blades
Abstract One of the most critical aspects in the development of a kinetic model for automotive applications is the method used to control the switch between limiting factors over the period of the chemical reaction, namely mass transfer and reaction kinetics. This balance becomes increasingly more critical with the automotive application with the gas composition and gas flow varying throughout the automotive cycles resulting in a large number of competing reactions, with a constantly changing space velocity. A methodology is presented that successfully switches the limitation between mass transfer and reaction kinetics. This method originally developed for the global kinetics model using the Langmuir Hinshelwood approach for kinetics is presented. The methodology presented is further expanded to the much more complex micro-kinetics approach taking into account various kinetic steps such as adsorption/desorption and surface reactions.
2014-10-01
Journal Article
2014-01-9051
Jun Ma, Hua Zhao, Paul Freeland, Martyn Hawley, Jun Xia
In order to optimize the 2-stroke uniflow engine performance on vehicle applications, numerical analysis has been introduced, 3D CFD model has been built for the optimization of intake charge organization. The scavenging process was investigated and the intake port design details were improved. Then the output data from 3D CFD calculation were applied to a 1D engine model to process the analysis on engine performance. The boost system optimization of the engine has been carried out also. Furthermore, a vehicle model was also set up to investigate the engine in-vehicle performance.
2014-04-01
Technical Paper
2014-01-0968
Mona Einolghozati, Mohammad Kankarani Farahani, Hamid Reza Lari, Abbas Bahri
Abstract Modern high-cycle fatigue criteria were implemented in structural wind turbine parts using finite element method. As a result of a test carried out for two fatigue criteria, it was concluded that the Dang Van hypothesis has more conservative results than S-N method. The complete algorithm of the fatigue calculation was illustrated by applying the proposed procedures to a wind turbine hub which is subjected to multi-axial, non-proportional and non-constant amplitude high-cycle loadings and then a structural optimization method is used to reduce the weight and moment of inertia of the wind turbine rotor. ANSYS Workbench and nCode design life are used in the structural and fatigue modeling of the hub.
2014-04-01
Technical Paper
2014-01-1145
Joohan Kim, Gyujin Kim, Hoon Lee, Kyoungdoug Min
Abstract Direct-injection spark-ignition (DISI) engines are regarded as a promising technology for the reduction of fuel consumption and improvement of engine thermal efficiency. However, due to direct injection, the shortened fuel-air mixing duration leads to a spatial gradient of the equivalence ratio, and these locally rich regions cause the formation of particulate matter. In the current study, numerical investigations on pollutant formation in a DISI engine were performed using combined flamelet models for premixed and diffusion flames. The G-equation model for partially premixed combustion was improved by incorporating the laminar flamelet library. Gasoline fuel was represented as a ternary mixture of gasoline surrogate and its laminar flame speeds were obtained under a wide range of engine operating conditions.
2014-04-01
Technical Paper
2014-01-1902
Thomas Juergen Boehme, Markus Schori, Heiko Rabba, Matthias Schultalbers
Abstract Most energy management systems for hybrid electric vehicles still use rule-based energy management systems that rely on information stored in lookup tables, to define the current mode of operation and set-points for the low-level control laws. Because of the high number of parameters, the calibration of such energy managements can be a cumbersome task for the engineers. Mathematical tools are therefore inalienable to the calibration process. In this paper, it will be demonstrated, how the theory of hybrid optimal control can be used to calculate an initial parameter set for the energy management of charge-sustaining hybrids. The calculation procedure includes the solution of a hybrid optimal control problem to determine the controls for the optimal operation of the vehicle over a given cycle.
2014-04-01
Journal Article
2014-01-0590
Daniel Wood, Martin A. Passmore, Anna-Kristina Perry
The use of simulation tools by vehicle manufacturers to design, optimize and validate their vehicles is essential if they are to respond to the demands of their customers, to meet legislative requirements and deliver new vehicles ever more quickly. The use of such tools in the aerodynamics community is already widespread, but they remain some way from replacing physical testing completely. Further advances in simulation capabilities depend on the availability of high quality validation data so that simulation code developers can ensure that they are capturing the physics of the problems in all the important areas of the flow-field. This paper reports on an experimental program to generate such high quality validation data for a SAE 20 degree backlight angle notchback reference model.
2013-10-15
Technical Paper
2013-32-9081
Denis Neher, Maurice Kettner, Fino Scholl, Markus Klaissle, Danny Schwarz, Blanca Gimenez Olavarria
A large number of small size gas-fired cogeneration engines operate with homogenous lean air-fuel mixture. It allows for engine operation at high efficiency and low NOx emissions. As a result of the rising amount of installed cogeneration units, however, a tightening of the governmental emission limits regarding NOx is expected. While engine operation with further diluted mixture reduces NOx emissions, it also decreases engine efficiency. This leads to lower mean effective pressure, in particular for naturally aspirated engines. In order to improve the trade-off between engine efficiency, NOx emissions and mean effective pressure, numerical investigations of an alternative combustion process for a series small cogeneration engine were carried out. In a first step, Miller and Atkinson cycles were implemented by advanced or retarded inlet valve closing timings, respectively.
2013-09-17
Technical Paper
2013-01-2324
Vincent Goudreault
The take-off of a departing aircraft is subjected to varying forces, the largest of which are function of the speed of the aircraft itself: the thrust of a jet engine, the aerodynamic drag of the airframe are essentially polynomial function of the airspeed. First principle field performance determination has relied for the last half century on stepwise integration, a brute force approach that requires properly tuned integration steps, which has the benefit of being fairly reliable but with relatively low computational efficiency. An alternate, mathematically more formal approach would be to algebraically integrate an accelerative function combining all the forces in presence.
2012-10-02
Technical Paper
2012-36-0454
Edson Luciano Duque, Rodrigo Alves Augusto
The continuous research for better performance and reduction of fuel consumption demanded the development of analytical techniques to better understand the rattle mechanism, with complex non-linear models being widely used for simulation. In regards to the fuel, the “flexible” engines, which can work with any mixture of gasoline/ethanol, are already a reality in the Brazilian market. These flex-fueled vehicles present higher values of irregularity, creating a specific scenario for this market. Several models with static approach of the clutch damper can be found in the available literature with limited measured data, which makes life difficult to validate or correlate these models. For this reason, the analytical formulation of dynamic clutch dampers developed high importance for solving and/or reducing clearance-induced vibro-impact problems which leads to rattle noise.
2012-10-02
Technical Paper
2012-36-0362
M. E. Guzzo, J. E. M. Barros, R. Huebner, R. M. Valle
The focus of this study was to create a methodology to evaluate spray characteristics in a gasoline direct injection injector by means of an automatic process. Computational codes were used to get information about cone angle and breakup length based on images got from injection process. A mathematical function was created to locate the boundaries of the spray and the cone angle was studied as the angle of arcs situated within these boundaries. The centre of the arc was located on the orifice of the injector and a value of angle was associated with several distances from orifice. The breakup length was associated as a distance from the orifice of an arc formed by a group of pixels with the maximum standard deviation related to the values of these pixels. The velocity field was studied by the Particle Image Velocimetry technique. Three fluids were tested at this work: water, ethanol and gasoline.
2012-03-01
Book
W. Charles Paulsen
This is a book for people wanting to learn the language of Science, Technology, and Engineering, and is intended to complement traditional text books in Mathematics. It puts the fun back into mathematics by demystifying confusing symbols and terminology – Think of this book as your personal journey leading to an eventual understanding of calculus, using everyday language to introduce new concepts in small manageable steps. Extensive use of color diagrams, pictures, and graphs are used throughout the book. Microsoft Excel is introduced early to show how mathematics can be made visual. Excel’s hidden equation solving talents are revealed.
2011-11-01
Book
J. Gilbert Kaufman
Relational analysis, defined as quantitative analysis of the relationships of high- and low-temperature properties in relation to their room-temperature values, provides a useful technique for estimating the properties of similar metals and alloys for which limited or no data are available. This book demonstrates how to use relational analysis methodology to extrapolate and estimate properties of metallic alloys at high temperatures from lower temperature data, and for estimating the properties of alloys for which scant property data exists. Data tables and graphs are presented for a wide range of aluminum alloys. Also shown, is how to apply relational analysis to other alloy systems including steels, magnesium alloys, and titanium alloys.
2011-10-18
Journal Article
2011-01-2594
Hugo Pervier, Devaiah Nalianda, Ramon Espi, Vishal Sethi, Pericles Pilidis, David Zammit-Mangion, Jean-Michel Rogero, Ricardo Entz
The aviation sector has played a significant role in shaping the world into what it is today. The rapid growth of global economies and the corresponding sharp rise in the number of people now wanting to travel on business and for pleasure, has largely been responsible for the development of this industry. With a predicted rise in Revenue Passenger Kilometers (RPK) by over 150% in the next 20 years, the industry will correspondingly be a significant contributor to environmental emissions. Under such circumstances optimizing aircraft trajectories for lowered emissions will play a critical role amongst various other measures, in mitigating the probable environmental effects of increased air traffic. Aircraft trajectory optimization using evolutionary algorithms is a novel field and preliminary studies have indicated that a reduction in emissions is possible when set as objectives.
2011-10-18
Journal Article
2011-01-2616
Gabriella Caporaletti
The paper presents feasibility and effectiveness of an innovative algorithm for spacecraft attitude determination, based on the real time fusion of raw data measurements provided by APS cameras, less limited by metrological constraints than traditional cameras used for star detection, and MEMS gyros, characterized by low-mass, low-power and low recurrent costs. The basic concept and the followed S&T methodological approach is described, which includes the use of cameras and gyros, even if the above basic concept states that gyros measurement data are neither strictly necessary, nor are increasing the attitude measurement accuracy in steady state conditions. Indeed, the availability of the gyro measurement data significantly contributes to the robustness of the spacecraft attitude measurement system particularly in “lost in space” and in “occulted camera” conditions. High quality gyros are not required.
2011-10-06
Technical Paper
2011-28-0112
Park Jooil
In most popular steering angle sensor, the calculation method for steer angle is that the angular positions of two smaller sized angle measurement gear wheels, being coupled to the steering hub on the steering column, are measured. The two angle measurement gear wheels differ from each other by more one gear tooth, each gear wheel bearing magnetic pole pairs. With these two angle values, it is possible to determine the steering angle of the steering wheel as soon as the power up without non volatile memory. There are many calculation methods to solve absolute angle. This paper introduces the easy and optimal method to calculate the steer angle among the many approach.
2011-08-30
Technical Paper
2011-01-1941
Kiyoshi Kawasaki, Koji Yamane, Tatsuro Ikawa
This study derives regression equations for predicting the cetane number of biodiesel fuels based on chemical analysis data. For conducting the regression analysis, 34 fuel samples with a wide variety of ignition qualities were made by mixing five kinds of biodiesels and five kinds of fatty acid methyl ester (FAME) reagents. The relationship between the cetane number, measured in a constant-volume combustion chamber, and fuel properties such as iodine value, saponification number, and boiling point, was investigated. Based on the results, four regression equations were proposed and their accuracies were compared. The results show that the regression equation based on fuel composition gives a cetane number with high accuracy, whereas it can be only be approximately predicted from the iodine value.
2011-06-13
Technical Paper
2011-38-0005
Jason Mickey, Eric Loth, Colin Bidwell
A new technique is proposed for computing particle concentrations and fluxes with Lagrangian trajectories. This method calculates particle concentrations based on the volume of a parcel element, or cloud, at the flux plane compared against the initial volume and is referred to as the Lagrangian Parcel Volume (LPV) method. This method combines the steady-state accuracy of area-based methods with the unsteady capabilities of bin-based methods. The LPV method results for one-dimensional (1D) unsteady flows and linear two-dimensional (2D) steady flows show that a quadrilateral element shape composed of a single parcel (with four edge particles) is capable of accurately predicting particle concentrations. However, nonlinear 2D flows can lead to concave or crossed quadrilaterals which produce significant numerical errors.
2011-06-13
Technical Paper
2011-38-0004
Peng Ke, Xinxin Wang
Lagrangian approach has been widely adopted in the droplet impingement analysis for aircraft icing simulation. Some improvements were proposed, including: 1) The heat and mass transfer consideration in droplet dynamics; 2) More efficient droplet localization method, which could and facilitated to find the initial cell in Eulerian grid; 3) New computation method of impingement efficiency, which uses the cover ratio to transform the impingement efficiency of arbitrary impinged region to that of the cell element of body surface and avoids the iterative computation to find the trajectories reaching the corner of the panel or cell element. A numerical solver was built and integrated with the capabilities to deal with super-cooled large droplet (SLD) conditions by considering the splashing and bouncing of SLD. The computational results were validated with the experiment data, which shown good agreements in the impingement limitations and tendency.
2011-06-13
Technical Paper
2011-38-0022
Marco Fossati, Rooh-ul-Amin Khurram, Wagdi G. Habashi
The irregular shapes that glaze ice may grow into while accreting over the surface of an aircraft represent a major difficulty in the numerical simulation of long periods of in-flight icing. In the framework of Arbitrary Lagrangian-Eulerian (ALE) formulations, a mesh movement scheme is presented, in which frame and elasticity analogies are loosely coupled. The resulting deformed mesh preserves the quality of elements, especially in the near-wall region, where accurate prediction of heat flux and shear stresses are required. The proposed scheme handles mesh movement in a computationally efficient manner by localizing the mesh deformation. Numerical results of ice shapes and the corresponding aerodynamic coefficients are compared with the experimental results.
2011-05-17
Technical Paper
2011-39-7201
Thank-Son Dao, Aden Seaman, John McPhee, Koichi Shigematsu
The recent increase in oil prices and environmental concerns have attracted various research efforts on hybrid electric vehicles (HEVs) which provide promising alternatives to conventional engine-powered vehicles with better fuel economy and fewer emissions. To speed up the design and prototyping processes of new HEVs, a method that automatically generates mathematics equations governing the vehicle system response in an optimized symbolic form is desirable. To achieve this goal, we employed MapleSimTM, a new physical modeling tool developed by Maplesoft Inc., to develop the multi-domain model of a series-HEV, utilizing the symbolic computing algorithms of Maple software package to generate an optimized set of governing equations. The HEV model consists of a mean-value internal combustion engine (ICE), a chemistry-based Ni-MH battery pack, and a multibody vehicle model. Simulations are then used to demonstrate the performance of the developed HEV system.
2011-05-17
Technical Paper
2011-01-1660
Ienkaran Arasaratnam, Saeid Habibi, Christopher Kelly, Tony J. Fountaine, Jimi Tjong
Advanced engine test methods incorporate several different sensing and signal processing techniques for identifying and locating manufacturing or assembly defects of an engine. A successful engine test method therefore, requires advanced signal processing techniques. This paper introduces a novel signal processing technique to successfully detect a faulty internal combustion engine in a quantitative manner. Accelerometers are mounted on the cylinder head and lug surfaces while vibration signals are recorded during engine operation. Using the engine's cam angular position, the vibration signals are transformed from the time domain to the crank-angle domain. At the heart of the transformation lies interpolation. In this paper, linear, cubic spline and sinc interpolation methods are demonstrated for reconstructing vibration signals in the crank-angle domain.
2011-04-12
Technical Paper
2011-01-1345
Thomas A. Timbario, Thomas J. Timbario, Melissa J. Laffen, Mark F. Ruth
Currently, several cost-per-mile calculators exist that can provide estimates of acquisition and operating costs for consumers and fleets. However, these calculators are limited in their ability to determine the difference in cost per mile for consumer versus fleet ownership, to calculate the costs beyond one ownership period, to show the sensitivity of the cost per mile to the annual vehicle miles traveled (VMT), and to estimate future increases in operating and ownership costs. Oftentimes, these tools apply a constant percentage increase over the time period of vehicle operation, or in some cases, no increase in direct costs at all over time. A more accurate cost-per-mile calculator has been developed that allows the user to analyze these costs for both consumers and fleets. Operating costs included in the calculation tool include fuel, maintenance, tires, and repairs; ownership costs include insurance, registration, taxes and fees, depreciation, financing, and tax credits.
2011-04-12
Technical Paper
2011-01-0411
H Pandarinath, J Sureshkumar, Ramalingam Sivanantham, S Prabhakar, S R Nagendiran
Vacuum pumps are predominantly used in diesel engines of passenger cars and trucks for generating vacuum in servo brake applications. With the emission norms getting stringent, there is a need for vacuum signal for EGR actuation, turbo-charger waste gate actuation and other servo applications. These multi-functional applications of vacuum pumps and the functional criticality in application like braking system demand an effective and reliable performance. In gasoline engines, the vacuum generated in the intake manifold is tapped for braking. The recent technology of gasoline direct injection compels the use of vacuum pump in gasoline engines also due to scarce vacuum in intake manifold. The performance of the vacuum pump is highly dependent on the opening and closing of the check valve sub-system, which is positioned between the vacuum reservoir and the pump at the suction side.
2011-04-12
Technical Paper
2011-01-0447
Arkadeb Ghosal, Paolo Giusto, Prakash Peranandam, Purnendu Sinha, Haibo Zeng
Recent trends in the automotive industry show growing demands for the introduction of new in-vehicle features (e.g., smart-phone integration, adaptive cruise control, etc.) at increasing rates and with reduced time-to-market. New technological developments (e.g., in-vehicle Ethernet, multi-core technologies, AUTOSAR standardized software architectures, smart video and radar sensors, etc.) provide opportunities as well as challenges to automotive designers for introducing and implementing new features at lower costs, and with increased safety and security. As a result, the design of Electrical/Electronic (E/E) architectures is becoming increasingly challenging as several hardware resources are needed. In our earlier work, we have provided top-level definitions for three relevant metrics that can be used to evaluate E/E architecture alternatives in the early stages of the design process: flexibility, scalability and expandability.
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