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Viewing 1 to 30 of 105
2016-04-05
Technical Paper
2016-01-0250
Filip Nielsen, Åsa Uddheim, Jan-Olof Dalenbäck
In recent years fuel consumption of passenger vehicles has received increasing attention by customers, the automotive industry, regulatory agencies and academia. However, some areas which affect the fuel consumption have received relatively small interest. One of these neglected areas is the total energy used for vehicle interior climate which can have a large effect on real-world fuel consumption. Realistic combinations of energy saving ideas, features and systems was evaluated regarding the total energy used for vehicle interior climate using a 1D simulation model of the important systems. The 1D simulation model included sub models of the passenger compartment, the air-handling unit, the Air Conditioning (AC) system, engine and engine cooling system. A combination of different climates were used for evaluation to better represent real-world fuel conditions.
2016-04-05
Technical Paper
2016-01-0875
Ludvig Adlercreutz, Andreas Cronhjort, Johannes Andersen, Roy Ogink
With alternative fuels having moved more into market in light of their reduction of emissions of CO2 and other air pollutants, the spark ignited internal combustion engine design has only been affected to small extent. The development of combustion engines running on natural gas or Biogas have been focused to maintain driveability on gasoline, creating a multi fuel platform which does not fully utilise the alternative fuels’ potential. However, optimising these concepts on a fundamental level for gas operation shows a great potential to increase the level of utilisation and effectiveness of the engine and thereby meeting the emissions legislation. The project described in this paper has focused on optimising a combustion concept for methane combustion on a single cylinder research engine. The ICE’s efficiency at full load and the fuels characteristics, including its knock resistance, is of primary interest, together with part load performance and overall fuel consumption.
2016-04-05
Technical Paper
2016-01-1368
Hongwen Wu, Johan Brunberg, Mireia Altimira, Niclas Bratt, Henrik Nyberg, Andreas Cronhjort, Justinas Peciura
Due to the requirement of contemporary automotive engine bay downsizing, air filter box has to be packed in a limit space without losing pressure drop, load capacity and efficiency. Yet, the air mass flow measurement at filter box outlet is sensitive to the flow changing. For those two reasons, this paper has developed an industrial affordable model to count the dust load on filter elements and calculate flow behavior over the life time in the air filter box. The model use semi-empirical models which are carried out by fundamental researches of calculating flows over pleated filters. This work also introduces an experiment method to record dust pattern in order to correlate the simulation result.
2016-04-05
Technical Paper
2016-01-1629
Gaspar Luis Gil Gómez, Johannes Vestlund, Egbert Bakker, Christian Berger, Mikael Nybacka, Lars Drugge
Vehicle dynamics development relies heavily on subjective assessments (SA). This requires expert test-engineers to drive real vehicles and to evaluate the results. It is a resource-intense procedure with a strong need for increasing its efficiency, while demands on quality and complexity increase. Most research has concentrated on substituting physical with virtual testing, but despite the effort, SA remains the central method. Less attention has been given to provide better tools for the SA process itself. One promising approach is to introduce computer-tablets to aid data collection, which has proven to be useful in medical studies. A simple software solution can eliminate the need to transcribe data and generate more flexible and better maintainable questionnaires. Besides, tablets’ technical features envision promising enhancement of SA. This would also enable better correlations to objective metrics, a requirement to improve CAE evaluations.
2016-04-05
Technical Paper
2016-01-0935
Gerben Doornbos, Stina Hemdal, Daniel Dahl, Ingemar Denbratt
A passive selective catalyst reduction (SCR) system can be one of the aftertreatment systems for lean burn spark ignition (SI)-engines. This system is based on the interaction between the engine an ammonia formation catalyst (AFC) and an SCR catalyst. Under rich conditions the AFC forms ammonia which is stored in the SCR catalyst. Under lean conditions the SCR catalyst reduces the engine out NOx using the stored NH3. In this study a standard three way catalyst (TWC) and a Pd/Al2O3 catalyst were compared under engine conditions for their ammonia production and response time. Furthermore the relation between the engine operation and ammonia formation over the TWC was studied; regarding engine load point and engine settings.
2016-04-05
Technical Paper
2016-01-1582
Dirk Wieser, Sabine Bonitz, Lennart Lofdahl, Alexander Broniewicz, Christian Nayeri, Christian Paschereit, Lars Larsson
In this experimental investigation the surface flow pattern is visualized on a full scale passenger car in the Volvo wind tunnel in Gothenburg. The entire rear end of a Volvo S60 was equipped with a large amount of tufts. The movement of the tufts is recorded by a single lens reflex camera which takes pictures continuously. A new and efficient tuft image processing algorithm has been developed to calculate the statistical behavior of the tuft orientation. This allows the extraction of the mean angle and the standard deviation for individual tufts. This information on the surface flow can be used to identify unsteady and steady flow phenomena such as separation and reattachment lines, flow direction, stagnation points, and regions with increased turbulence and footprints of vortices. The main advantages over other flow visualization methods such as oil paint is that experimental facilities are not soiled and that statistical data can be extracted.
2016-04-05
Technical Paper
2016-01-1606
Charalampos Kounenis, Sabine Bonitz, Emil Ljungskog, David Sims-Williams, Lennart Lofdahl, Alexander Broniewicz, Lars Larsson, Simone Sebben
The aerodynamic drag, and hence fuel consumption and CO2 production, of a road vehicle depends strongly on the rear end flow which is an area of complex three-dimensional flow structures. This paper seeks to provide improved insight into this flow region to better inform future drag reduction strategies. Using experimental and numerical techniques, two vehicle shapes have been studied; a 30% scale model of a Volvo S60 representing a 2008MY vehicle and a full scale 2010MY S60.First the surface topology of the rear end (rear window and boot lid) of both configurations is analysed, using paint to visualise the skin friction pattern. By means of critical points, the pattern is characterized and changes are identified studying the location and type of the occurring singularities. The flow field away from the surface is then analysed using PIV measurements for the scale model and CFD simulations for the full scale vehicle.
2016-04-05
Technical Paper
2016-01-0732
Jessica Dahlstrom, Oivind Andersson, Martin Tuner, Håkan Persson
Heat loss is one of the greatest energy losses in engines. More than half of the heat is lost to cooling media and exhaust losses, and they thus dominate the internal combustion engine energy balance. Complex processes affect heat loss to the cylinder walls, including gas motion, spray-wall interaction and turbulence levels. The aim of this work was to experimentally compare the heat transfer characteristics of a stepped-bowl piston geometry to a conventional re-entrant diesel bowl studied previously. The stepped-bowl geometry features a low surface-to-volume ratio compared to the re-entrant bow, which is considered beneficial for low heat losses. Speed, load, injection pressure, swirl level, EGR rate and air/fuel ratio (λ) were varied in a multi-cylinder light duty engine operated in conventional diesel combustion mode.
2016-04-05
Technical Paper
2016-01-0028
Ali Shahrokni, Peter Gergely, Jan Söderberg, Patrizio Pelliccione
In novel areas, such as Active Safety, new technologies, designs and methods are introduced at a rapid pace. To keep up with the new demands, and also requirements on Functional Safety imposed by ISO 26262, the support for the engineering methods, including tools and data management, needs to evolve as well. Generic and file-based data management tools like spreadsheet tools are popular in the industry due to their flexibility and legacy in the industry but provide poor control and traceability. At the other side of the spectrum, rigid and special-purpose tools provide structure and control of data but with limited ability to adapt to changes. As organizations become more agile, the need for flexible and agile data management increases; as products become more complex and developed in larger and more distributed teams, the need for more unified, controlled, consistent, and coherent data increases.
2016-04-05
Technical Paper
2016-01-1201
Rickard Arvidsson, Tomas McKelvey
The paper investigates a method to identify battery parameters for a Li-ION hybrid battery based on current and voltage measurements performed in a vehicle during one year of in use operation. This is different from previous work where a common approach is to use current pulse derating tests, HPPC, which uses predetermined amplitudes and frequencies of current pulses. An equivalent circuit linear model was used in order to identify parameter dependencies at different state of charge levels and temperatures. A method to handle a large subset of calculations and logfiles have also been evaluated where the goodness of fit for each parameter value is used as a weightening factor to determine the parameter value in order to create a grid range in temperature and state of charge for the analyzed data. Data have been measured at a sampling rate of 100 Hz.
2015-12-01
Journal Article
2015-01-9116
Filip Nielsen, Sam Gullman, Fredrik Wallin, Åsa Uddheim, Jan-Olof Dalenbäck
Abstract In recent years fuel consumption of passenger vehicles has received increasing attention by customers, the automotive industry, regulatory agencies and academia. However, some areas which affect the fuel consumption have received relatively small interest. One of these areas is the total energy used for vehicle interior climate which can have a large effect on real-world fuel consumption. Although there are several methods described in the literature for analyzing fuel consumption for parts of the climate control system, especially the Air-Condition (AC) system, the total fuel consumption including the vehicle interior climate has often been ignored, both in complete vehicle testing and simulation. The purpose of this research was to develop a model that predicts the total energy use for the vehicle interior climate.
2015-09-06
Technical Paper
2015-24-2533
Mirko Bovo, Joop Somhorst
The focus on engine thermal management is rapidly increasing due to the significant effect of heat losses on fuel consumption, engine performance and emissions. This work presents a time resolved, high resolution 3D engine heat balance model, including all relevant components. Notably, the model calculates the conjugated heat transfer between the solid engine components, the coolant and the oil. Both coolant and oil circuits are simultaneously resolved with a CFD solver in the same finite volume model as the entire engine solid parts. The model includes external convection and radiation. The necessary boundary conditions of the thermodynamic cycle (gas side) are mapped from a calibrated 1D gas exchange model of the same engine. The boundary conditions for the coolant and at the oil circuits are estimated with 1D models of the systems. The model is calibrated and verified with measurement data from the same engine as modeled.
2015-06-15
Technical Paper
2015-01-2266
Andrzej Pietrzyk
Abstract Several of the exterior noise sources existing around a vehicle can cause airborne noise issues at relatively low frequencies. SEA, traditionally used for airborne sound issues is not suitable for the frequency range of interest. Finite Element analysis has been used. Handling of the non-reflecting condition on the outer boundary of the exterior cavity is an issue. Recently, advances have been made in several commercially available codes, which made the analysis practical. Including the poro-elastic material model for foam-based carpets is also becoming practically possible. The purpose of the current study is to investigate the practical applications of those new developments against test data, and to estimate the feasibility of using these procedures in the vehicle development projects. Measurements were carried out in a new semi-anechoic chamber at Volvo Cars.
2015-06-15
Technical Paper
2015-01-2367
David Lennström, Arne Nykänen
Abstract When it comes to the acoustic properties of electric cars, the powertrain noise differs dramatically compared to traditional vehicles with internal combustion engines. The low frequency firing orders, mechanical and combustion noise are exchanged with a more high frequency whining signature due to electromagnetic forces and gear meshing, lower in level but subject to annoyance. Previous studies have highlighted these differences and also investigated relevant perception criteria in terms of psycho-acoustic metrics. However, investigations of differences between different kinds of electric and hybrid electric cars are still rare. The purpose of this paper was to present the distribution of tonal components in today's hybrid/electric vehicles. More specifically, the number of prominent orders, their maximum levels and frequency separation were analyzed for the most critical driving conditions. The study is based upon measurements made on 13 electrified cars on the market.
2015-06-15
Journal Article
2015-01-2285
Arne Nykänen, David Lennström, Roger Johnsson
Abstract Subjects who are well aware of what to judge commonly yield more consistent results in laboratory listening tests. This awareness may be raised by explicit instructions and training. However, too explicit instructions or use of only trained subjects may direct experiment results in an undesired way. An alternative is to give fairly open instructions to untrained subjects, but give the subjects a chance to get familiar with the product and context by, for example, riding a representative car under representative driving conditions before entering the laboratory. In this study, sound quality assessments of interior sounds of cars made by two groups were compared. In one group subjects were exposed to the same driving conditions that were later assessed in a laboratory listening test by taking them on a ride in one of the cars to be assessed, just before entering the laboratory. In the other group subjects made the laboratory assessments without prior car riding.
2015-04-14
Technical Paper
2015-01-1000
Anna Fathali, Fredrik Wallin, Annika Kristoffersson, Mats Laurell
Abstract The objective of this study was to investigate which of the artificial aging cycles available in the automotive industry that causes major deactivation of three-way catalysts (TWCs) and can be used to obtain an aged catalyst similar to the road aged converter (160 000km). Standard bench cycle (SBC) aging with secondary air injection (SAI) covered aging with various mass flows - a flow from three cylinders into one catalyst system and a flow from three cylinders into two parallel connected catalysts. For rapid catalyst bench aging, secondary air injection is a very efficient tool to create exotherms. Furthermore, the effect on catalytic activity of SAI aging with poisons from oil and fuel dopants (P, Ca, Zn) was investigated. The catalysts were thoroughly characterized in light-off and oxygen storage capacity measurements, emission conversion as a function of lambda and load variation was determined.
2015-04-14
Technical Paper
2015-01-1500
Marcus Ljungberg, Mikael Nybacka, Gaspar Gil Gómez, Diomidis Katzourakis
Abstract The automotive industry strives to develop high quality vehicles in a short period of time that satisfy the consumer needs and stand out in the competition. Full exploitation of simulation and Computer-Aided Engineering (CAE) tools can enable quick evaluation of different vehicle concepts and setups without the need of building physical prototypes. Addressing the aforementioned statements this paper presents a method for optimising the Electric Power-Assisted Steering (EPAS) ECU parameters employing solely CAE. The objective of the optimisation is to achieve a desired steering response. The developed process is tested on three specific steering metrics (friction feel, torque build-up and torque deadband) for two function parameters (basic steering torque and active return) of the EPAS. The optimisation method enabled all metrics to fall successfully within the target range.
2015-04-14
Technical Paper
2015-01-1545
Lennert Sterken, Simone Sebben, Lennart Lofdahl, Tim Walker, Thies Wölken
Abstract Previous research on both small-scale and full-scale vehicles shows that base extensions are an effective method to increase the base pressure, enhancing pressure recovery and reducing the wake size. These extensions decrease drag at zero yaw, but show an even larger improvement at small yaw angles. In this paper, rear extensions are investigated on an SUV in the Volvo Cars Aerodynamic Wind Tunnel with focus on the wake flow and on the unsteady behavior of the surface pressures near the base perimeter. To increase the effect of the extensions on the wake flow, the investigated configurations have a closed upper- and lower grille (closed-cooling) and the underbody has been smoothed with additional panels. This paper aims to analyze differences in flow characteristics on the wake of an SUV at 0° and 2.5° yaw, caused by different sets of extensions attached to the base perimeter. Extensions with several lengths are investigated with and without a kick.
2015-04-14
Journal Article
2015-01-1529
Sabine Bonitz, Lars Larsson, Lennart Lofdahl, Alexander Broniewicz
Abstract The phenomenon of three-dimensional flow separation is and has been in the focus of many researchers. An improved understanding of the physics and the driving forces is desired to be able to improve numerical simulations and to minimize aerodynamic drag over bluff bodies. To investigate the sources of separation one wants to understand what happens at the surface when the flow starts to detach and the upwelling of the streamlines becomes strong. This observation of a flow leaving the surface could be captured by investigating the limiting streamlines and surface parameters as pressure, vorticity or the shear stress. In this paper, numerical methods are used to investigate the surface pressure and flow patterns on a sedan passenger vehicle. Observed limiting streamlines are compared to the pressure distribution and their correlation is shown. For this investigation the region behind the antenna and behind the wheel arch, are pointed out and studied in detail.
2014-11-01
Journal Article
2014-01-9129
Filip Nielsen, Åsa Uddheim, Jan-Olof Dalenbäck
Abstract Fuel consumption of vehicles has received increased attention in recent years; however one neglected area that can have a large effect on this is the energy usage for the interior climate. This study aims to investigate the energy usage for the interior climate for different conditions by measurements on a complete vehicle. Twelve different NEDC tests in different temperatures and thermal states of the vehicle were completed in a climatic wind tunnel. Furthermore one temperature sweep from 43° to −18°C was also performed. The measurements focused on the heat flow of the air, from its sources, to its sink, i.e. compartment. In addition the electrical and mechanical loads of the climate system were included. The different sources of heating and cooling were, for the tested powertrain, waste heat from the engine, a fuel operated heater, heat pickup of the air, evaporator cooling and cooling from recirculation.
2014-06-30
Journal Article
2014-01-2060
Raimo Kabral, Lin Du, Mats Åbom, Magnus Knutsson
Abstract Current trends for IC-engines are driving the development of more efficient engines with higher specific power. This is true for both light and heavy duty vehicles and has led to an increased use of super-charging. The super-charging can be both in the form of a single or multi-stage turbo-charger driven by exhaust gases, or via a directly driven compressor. In both cases a possible noise problem can be a strong Blade Passing Frequency (BPF) typically in the kHz range and above the plane wave range. In this paper a novel type of compact dissipative silencer developed especially to handle this type of problem is described and optimized. The silencer is based on a combination of a micro-perforated (MPP) tube backed by a locally reacting cavity. The combined impedance of micro-perforate and cavity is chosen to match the theoretical optimum known as the Cremer impedance at the mid-frequency in the frequency range of interest.
2013-04-08
Technical Paper
2013-01-0759
Lotta Jakobsson, Graeme McInally, Anders Axelson, Magdalena Lindman, Anders Kling, Thomas Broberg, Mikael Fermér, Linus Wågström
Frontal Severe Partial Overlap Collisions (SPOC) also called small overlap crashes pose special challenges with respect to structural design as well as occupant protection. In the early 1990s, the SPOC test method was developed addressing 20-40% overlap against a fixed rigid barrier with initial velocities up to 65 km/h. The knowledge gained has been used in the design of Volvo vehicles since then. Important design principles include front side members orientated along the wheel envelopes together with a strong support structure utilizing a space frame principle with beams loaded mainly in tension and compression. This novel setup was first introduced in the 850-model in 1991 and has been refined and patented (2001) in later Volvo front structures. Among the design principles are multiple front side members on each side, helping energy absorption efficiency and robustness.
2013-04-08
Technical Paper
2013-01-0464
Lennert Sterken, Simone Sebben, Tim Walker, Lennart Lofdahl
With the increase in fuel prices and the increasingly strict environmental legislations regarding CO₂ emissions, reduction of the total energy consumption of our society becomes more important. Passenger vehicles are partly responsible for this consumption due to their strong presence in the daily life of most people. Therefore reducing the impact of cars on the environment can assist in decreasing the overall energy consumption. Even though several fields have an impact on a passenger car's performance, this paper will focus on the aerodynamic part and more specifically, the wake behind a vehicle. By definition a car is a bluff body on which the air resistance is for the most part driven by pressure drag. This is caused by the wake these bodies create. Therefore analyzing the wake characteristics behind a vehicle is crucial if one would like to reduce drag.
2013-04-08
Journal Article
2013-01-0953
Alexey Vdovin, Sabine Bonitz, Christoffer Landstrom, Lennart Lofdahl
Passenger car fuel consumption is a constant concern for automotive companies and the contribution to fuel consumption from aerodynamics is well known. Several studies have been published on the aerodynamics of wheels. One area of wheel aerodynamics discussed in some of these earlier works is the so-called ventilation resistance. This study investigates ventilation resistance on a number of 17 inch rims, in the Volvo Cars Aerodynamic Wind Tunnel. The ventilation resistance was measured using a custom-built suspension with a tractive force measurement system installed in the Wheel Drive Units (WDUs). The study aims at identifying wheel design factors that have significant effect on the ventilation resistance for the investigated wheel size. The results show that it was possible to measure similar power requirements to rotate the wheels as was found in previous works.
2013-04-08
Journal Article
2013-01-0955
Teddy Hobeika, Simone Sebben, Christoffer Landstrom
It is well known that wheels are responsible for a significant amount of the total aerodynamic drag of passenger vehicles. Tyres, and mostly rims, have been the subject of research in the automotive industry for the past years, but their effect and interaction with each other and with the car exterior is still not completely understood. This paper focuses on the use of CFD to study the effects of tyre geometry (tyre profile and tyre tread) on road vehicle aerodynamics. Whenever possible, results of the numerical computations are compared with experiments. More than sixty configurations were simulated. These simulations combined different tyre profiles, treads, rim designs and spoke orientation on two car types: a sedan and a sports wagon. Two tyre geometries were obtained directly from the tyre manufacturer, while a third geometry was obtained from our database and represents a generic tyre which covers different profiles of a given tyre size.
2012-09-10
Technical Paper
2012-01-1572
Fredrik B. Ekstrom, Joop Somhorst
Passenger cars equipped with diesel engines will meet challenging emission legislation for the coming decade, with introduction of Euro6 and Euro7, which comprises reduced NOX emissions and possibly new driving cycles including off-cycle limits. The technology measures to meet these legislative limits comprise a broad spectrum of engine and aftertreatment, i.e., engine measures such as improved fuel injection with respect to mass and timing, improved exhaust gas recirculation, improved warm-up and reduced friction, as well as aftertreatment measures such as selective catalytic reduction and lean NOX trap in combination with diesel particulate filter, and the thereby associated engine control. The resulting technology matrix is therefore large, and calls for a multidisciplinary simulation approach for appropriate selection and optimization of technology and control with the objectives and constraints of emissions, fuel consumption, performance and cost.
2012-06-13
Technical Paper
2012-01-1559
Sabry Allam, Magnus Knutsson, Hans Boden
Automotive turbo compressors generate high frequency noise in the air intake system. This sound generation is of importance for the perceived sound quality of luxury cars and may need to be controlled by the use of silencers. The silencers usually contain resonators with slits, perforates and cavities. The purpose of the present work is to develop acoustic models for these resonators where relevant effects such as the effect of a realistic mean flow on losses and 3D effects are considered. An experimental campaign has been performed where the two-port matrices and transmission loss of sample resonators have been measured without flow and for two different mean flow speeds. Models for two resonators have been developed using 1D linear acoustic theory and a FEM code (COMSOL Multi-physics). For some resonators a separate linear 1D Matlab code has also been developed.
2012-04-16
Technical Paper
2012-01-0355
Markus Grahn, Krister Johansson, Christian Vartia, Tomas McKelvey
The development and implementation of a new structure for data-driven models for NOX and soot emissions is described. The model structure is a linear regression model, where physically relevant input signals are used as regressors, and all the regression parameters are defined as grid-maps in the engine speed/injected fuel domain. The method of using grid-maps in the engine speed/injected fuel domain for all the regression parameters enables the models to be valid for changes in physical parameters that affect the emissions, without having to include these parameters as input signals to the models. This is possible for parameters that are dependent only on the engine speed and the amount of injected fuel. This means that models can handle changes for different parameters in the complete working range of the engine, without having to include all signals that actually effect the emissions into the models.
2012-04-16
Technical Paper
2012-01-0834
Antonio Torregrosa, Francisco Arnau, Pedro Piqueras, Miguel Reyes-Belmonte, Magnus Knutsson, Johan Lennblad
An acoustic one-dimensional compressor model has been developed. This model is based on compressor map information and it is able to predict how the pressure waves are transmitted and reflected by the compressor. This is later on necessary to predict radiated noise at the intake orifice. The fluid-dynamic behavior of the compressor has been reproduced by simplifying the real geometry in zero-dimensional and one-dimensional elements with acoustic purposes. These elements are responsible for attenuating or reflecting the pressure pulses generated by the engine. In order to compensate the effect of these elements in the mean flow variables, the model uses a corrected compressor map. Despite of the fact that the compressor model was developed originally as a part of the OpenWAM™ software, it can be exported to other commercial wave action models. An example is provided of exporting the described model to GT-Power™.
2012-04-16
Journal Article
2012-01-0169
Christoffer Landstrom, Linda Josefsson, Tim Walker, Lennart Lofdahl
Targets for reducing emissions and improving energy efficiency present the automotive industry with many challenges. Passenger cars are by far the most common means of personal transport in the developed part of the world, and energy consumption related to personal transportation is predicted to increase significantly in the coming decades. Improved aerodynamic performance of passenger cars will be one of many important areas which will occupy engineers and researchers for the foreseeable future. The significance of wheels and wheel housings is well known today, but the relative importance of the different components has still not been fully investigated. A number of investigations highlighting the importance of proper ground simulation have been published, and recently a number of studies on improved aerodynamic design of the wheel have been presented as well. This study is an investigation of aerodynamic influences of different tires.
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