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Spray Characterization of Gasoline Direct Injection Sprays Under Fuel Injection Pressures up to 150 MPa with Different Nozzle Geometries

Volvo Cars-Arjan Helmantel
Chalmers University of Technology-Lucien Koopmans, Petter Dahlander
Published 2019-01-15 by SAE International in United States
Maximum fuel injection pressures for GDI engines is expected to increase due to positive effects on emissions and engine-efficiency. Current GDI injectors have maximum operating pressures of 35 MPa, but higher injection pressures have yielded promising reductions in particle number (PN) and improved combustion stability. However, the mechanisms responsible for these effects are poorly understood, and there have been few studies on fuel sprays formed at high injection pressures.This paper summarizes experimental studies on the properties of sprays formed at high injection pressures. The results of these experiments can be used as inputs for CFD simulations and studies on combustion behavior, emissions formation, and combustion system design. The experiments were conducted using an injection rate meter and optical methods in a constant volume spray chamber. Injection rate measurements were performed to determine the injectors’ flow characteristics. Spray imaging was performed using a high-speed video camera. Several spray properties such as the liquid spray penetration, spray plume angle, and the spray breakup point were determined as functions of the fuel injection pressure and injected fuel mass…
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Knock Phenomena under Very Lean Conditions in Gasoline Powered SI-Engines

SAE International Journal of Engines

Volvo Cars-Daniel Dahl
Chalmers University of Technology-Gerben Doornbos, Stina Hemdal, Ingemar Denbratt
  • Journal Article
  • 03-11-01-0003
Published 2018-03-13 by SAE International in United States
Homogeneous lean operation is a well-known strategy for enhancing the thermal efficiency of SI-engines. At higher load points the efficiency is often compromised by the need to suppress knock. Experiments were performed to determine the knock characteristics of SI engines using homogeneous lean operation at λ values of up to 1.8 with various hardware configurations that are commonly used to increase the lean limit. Changing λ altered the eigenfrequencies of the combustion chamber and the highest energy excitation mode. Increasing λ from 1.0 to 1.2 increased the knock tendency and led to an earlier knock onset. However, further increases in λ significantly reduced the knock tendency and retarded the knock onset. The knock signal energy increased for higher λ values and constant knock tendencies. The differences in knock characteristics between the various λ values became more pronounced upon raising the intake temperature from 40 °C to 90 °C. The trends in knock tendency and knock onset largely parallels that observed for engine out NOx emissions and thus the NOx concentration in the internal EGR. The increased knock…
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On the Effects of Wind Tunnel Floor Tangential Blowing on the Aerodynamic Forces of Passenger Vehicles

SAE International Journal of Passenger Cars - Mechanical Systems

Volvo Cars-Alexander Broniewicz, Christoffer Landström
Chalmers University of Technology-Emil Ljungskog, Simone Sebben
  • Journal Article
  • 2017-01-1518
Published 2017-03-28 by SAE International in United States
Many aerodynamic wind tunnels used for testing of ground vehicles have advanced ground simulation systems to account for the relative motion between the ground and the vehicle. One commonly used approach for ground simulation is a five belt system, where moving belts are used, often in conjunction with distributed suction and tangential blowing that reduces the displacement thickness of the boundary layer along the wind tunnel floor. This paper investigates the effects from aft-belt tangential blowing in the Volvo Cars Aerodynamic wind tunnel. First the uniformity of the boundary layer thickness downstream of the blowing slots is examined in the empty tunnel. This is followed by investigations of how the measured performance of different vehicle types in several configurations, typically tested in routine aerodynamic development work, depends on whether the tangential blowing system is active or not. Numerical simulations are also used to explain the flow field origin of the force differences measured in the wind tunnel. Results show that even though the displacement thickness behind the blowers varies along the width of the blowing…
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Vertical Occupant Loading in Car Crashes; Test Methods and Countermeasures

Volvo Cars-Lotta Jakobsson, Magnus Björklund, Anders Axelson
Published 2015-04-14 by SAE International in United States
Vertical loading can cause thoracic and lumbar spine injuries to a car occupant. Crashes potentially causing occupant vertical loads include; rollover events or free flying events when the car lands on its wheels, and run off road events when the car goes into the ditch and collides with an embankment. To date, there is no standardized test method evaluating this occupant loading mechanism. The aim of this study was to develop test methods addressing vertical occupant loading for car occupants and to evaluate countermeasures for reduction of such loads. Based on real world run off road crashes, representative test track methods were developed. These complete vehicle test track methods were used to provide input to a simplified and repeatable rig test method. The rig test method comprises a dummy positioned in a seat attached to a frame and exposed to a vertical acceleration. Vertical pelvis acceleration is monitored, as an indication of potential loads through the spine. Two different seat designs are compared. The modified seat concept includes a deformation element which is built into…
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Thermal and Chemical Deactivation of Three-Way Catalysts: Comparison of Road-, Fuel-Cut and SAI- Aged Catalysts

Volvo Cars-Anna Fathali
Volvo Car Corporation-Fredrik Wallin, Annika Kristoffersson, Mats Laurell
Published 2015-04-14 by SAE International in United States
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. These catalysts were then compared to three-way catalysts aged on an engine bench comparing two fuel-cut (FC) strategies, i.e. fuel-cut retardation (FCR) and fuel-cut acceleration (FCA) [1].For 40-hour aged samples, SAI aged had the highest…
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Collision Avoidance Systems - Advancements and Efficiency

Volvo Cars-Mikael Ljung Aust, Lotta Jakobsson, Magdalena Lindman, Erik Coelingh
Published 2015-04-14 by SAE International in United States
This paper first discusses the advancement and challenges in the areas of developing Collision Avoidance Systems, or CAS. CAS have been on the market for a decade, and their development has been rapid. Starting with forward collision warning with brake support, targeting vehicles moving in the same direction in front of the car, CAS now cover pedestrians and cyclists in front of the car as well as vehicles standing still and even some situations of approaching vehicles in crossings. This development up to date is described and discussed according to the challenge areas of detection, decision strategy and intervention strategy.Next, the paper discusses assessment of system effects on driving safety. Numerous studies have tried to predict the effect of various CAS, and the real world effect of these systems has been shown to be significant. For example, for a standard equipped low-speed CAS, independent studies have found real world benefits in terms of reduction of the rate of rear-end frontal impacts as well as claim frequency rates.Based on these discussions, several conclusions are drawn. First,…
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The Influence of the Acoustic Transfer Functions on the Estimated Interior Noise from an Electric Rear Axle Drive

SAE International Journal of Passenger Cars - Mechanical Systems

Volvo Cars-David Lennström
Luleå University of Technology-Roger Johnsson, Anders Agren, Arne Nykänen
  • Journal Article
  • 2014-01-9124
Published 2014-05-09 by SAE International in United States
In the vehicle development process, targets are defined to fulfill customers' expectations on acoustic comfort. The interior complete vehicle acoustic targets can be cascaded down to system and component targets, e.g. insulation properties and source strengths. The acoustic transfer functions (ATFs) from components radiating airborne noise play a central role for the interior sound pressure levels. For hybrid vehicles fitted with an electric traction motor, the contribution of high frequency tonal components radiated from the motor housing needs to be controlled. The interior sound pressure due to an airborne motor order can be estimated by surface velocities and ATFs. This study addresses the ATFs measured from a large number of positions located around an electric rear axle drive (ERAD) and their influence on estimated interior noise. First, the magnitude variation between the individual ATFs and how it clearly can be visualized was presented. Displaying all ATFs in a color map revealed the magnitude at each geometrical location of the respective microphone. Secondly, the influence of the ATF's spatial resolution on estimated interior sound pressure was…
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Extracting Situations with Uneasy Driving in NDS-Data

Volvo Cars-Tobias Karlsson, Magdalena Lindman, Jordanka Kovaceva, Bo Svanberg, Henrik Wiberg, Lotta Jakobsson
Published 2014-04-01 by SAE International in United States
Different types of driver workload are suggested to impact driving performance. Operating a vehicle in a situation where the driver feel uneasy is one example of driver workload. In this study, passenger car driving data collected with Naturalistic Driving Study (NDS) data acquisition equipment was analyzed, aiming to identify situations corresponding to a high driver's subjective rating of ‘unease’. Data from an experimental study with subjects driving a passenger car in normal traffic was used. Situations were rated by the subjects according to experienced ‘unease’, and the Controller Area Network (CAN) data from the vehicle was used to describe the driving conditions and identify driving patterns corresponding to the situations rated as ‘uneasy’. These driving patterns were matched with the data in a NDS database and the method was validated using video data.Two data mining approaches were applied. The first was based on an ensemble classifier on general variables derived from the CAN-data to predict the subjective rating of segments of the data. The second used hierarchical clustering with a distance metric based on the…
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Addressing Run Off Road Safety

SAE International Journal of Passenger Cars - Mechanical Systems

Volvo Cars-Lotta Jakobsson, Magdalena Lindman, Anders Axelson, Bengt Lokensgard, Mats Petersson, Bo Svanberg, Jordanka Kovaceva
  • Journal Article
  • 2014-01-0554
Published 2014-04-01 by SAE International in United States
Run off road events are frequent and can result in severe consequences. The reasons for leaving the road are numerous and the sequence the car is exerted to differs in most events. The objective of this study is to identify different situations and mechanisms both in respect to accident avoidance and occupant protection and to present test methods addressing the different identified mechanisms of run off road occupant safety.Mechanisms and influencing factors are identified using statistical and in-depth crash data as well as driving data. There are a number of reasons for leaving the road; driver fatigue, driver distraction and inadequate speed in relation to the traffic situation to mention a few. An outline of principle test methods for evaluating technology assisting the driver to stay on the road is presented in relation to the identified situations and mechanisms.Crash test methods for some typical run off road scenarios are suggested. Important occupant protection aspects concern mainly occupant retention as well as vertical loading through the seat. System test methods complement the whole vehicle tests, simulating…
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Fuel-Cut Based Rapid Aging of Commercial Three Way Catalysts - Influence of Fuel-Cut Frequency, Duration and Temperature on Catalyst Activity

Anna Fathali
Volvo Cars-Mats Laurell
Published 2013-09-08 by SAE International in United States
In order to quantify fuel-cut aging effects on commercial bimetallic Pd/Rh three-way catalysts (TWCs), supported on cerium-zirconium promoted alumina, full-size automotive catalysts were exposed to accelerated fuel-cut aging on an engine test bench, with a variation in temperature, fuel-cut frequency and fuel-cut duration. After aging, samples of the catalysts were tested in a laboratory environment for Light-off temperature (T50), Specific surface area (BET), Dispersion of noble metals and changes in the oxidation state of Pd and Rh.The catalytic tests showed clear deactivation of the aged samples and influence on the TWC's properties. The light off temperature and noble metal dispersion were found to be a clear function of oxygen exposure to the catalysts, i.e. fuel-cut frequency and duration, while the specific surface area was found to be a function of fuel-cut frequency. No changes in oxidation states of Pd and Rh could be detected. The variation in temperature had the lowest influence on the TWC properties among the varied parameters.
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