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Correct simulations of rotating wheels are essential for accurate aerodynamic investigations of passenger vehicles. Therefore, modern automotive wind tunnels are equipped with five-belt moving ground systems with wheel drive units (WDUs) connected to the underfloor balance. The pressure distribution on the exposed areas of the WDU belts results in undesired lift forces being measured which must be considered to obtain accurate lift values for the vehicle. This work investigates the parasitic WDU lift for various configurations of a crossover SUV using numerical simulations that have been correlated to wind tunnel data. Several parameters were considered in the investigation, such as WDU size, WDU placement, tyre variants and vehicle configurations. The results show that the parasitic lift is more sensitive to the width than the length of the WDU. However, the belt length is also important to consider, especially if the wheel cannot be placed centred.

The potential of 48V Mild Hybrid is promising in meeting the present and future CO2 legislations. There are various system layouts for 48V hybrid system including P0, P1, P2. In this paper, P2 architecture is used to investigate the effects of water injection benefits in a mild hybrid system. Electrification of the conventional powertrain uses the benefits of an electric drive in the low load-low speed region where the conventional SI engine is least efficient and as the load demand increases the IC Engine is used in its more efficient operating region. Engine downsizing and forced induction trend is popular in the hybrid system architecture. However, the engine efficiency is limited by combustion knocking at higher loads thus ignition retard is used to avoid knocking and fuel enrichment becomes must to operate the engine at MBT (Maximum Brake Torque) timing; in turn neutralizing the benefits of fuel savings by electrification.

With progressing electrification of automotive powertrains and demands to meet increasingly stringent emission regulations, a combination of an electric motor and downsized turbocharged spark-ignited engine has been recognized as a viable solution. The SI engine must be optimized, and preferentially downsized, to reduce tailpipe CO2 and other emissions. However, drives to increase BMEP (Brake Mean Effective Pressure) and compression ratio/thermal efficiency increase propensities of knocking (auto-ignition of residual unburnt charge before the propagating flame reaches it) in downsized engines. Currently, knock is mitigated by retarding the ignition timing, but this has several limitations. Another option identified in the last decade (following trials of similar technology in aircraft combustion engines) is water injection, which suppresses knocking largely by reducing local in-cylinder mixture temperatures due to its latent heat of vaporization.

In two research programs, Volvo has investigated high performance turbocharged versions based on the new 3-litre inline six-cylinder naturally aspirated engine. Power and torque targets were 180 kW and 385 Nm respectively, with a wide usable torque range. The MEP-(Methanol Environment Performance)-project was linked to alternative fuel studies and focused on methanol (M85) and Flexible Fuel Vehicle-(FFV)-development. With alternative fuels, it is important to investigate not only the emissions and fuel efficiency, but also the performance potential, in particular when used in turbocharged engines. The MEP-engine could be reduced to 2.5 litre displacement, due to the good specific performance with M85 fuel. Higher charge pressures could be used compared to gasoline. An M85 turbocharged high performance engine must be designed for higher peak combustion pressures.

Each year Volvo Car Corporation invests about 10 per cent of its turnover in product development. One tenth of this amount is reserved for advanced research projects, or high risk projects. Volvo LCP (Light Component Project) 2000 is one of these projects and a preparation in technology and competence for the year 2000. In addition to broad theoretical know-how concerning new materials, alternative drive lines, new production methods, etc, the LCP study has resulted in four road-going experimental cars. The project which started in mid 1979 was presented to the public in October 1983 after a year's testing and evaluation of the car, its sub-systems and design solutions. This paper is a description of the project work. Another paper ‘Magnesium in the Volvo LCP 2000’, deals more specifically with the results of the LCP material studies.

Pre-chamber combustion (PCC) has re-emerged in recent last years as a potential solution to help to decarbonize the transport sector with its improved engine efficiency as well as providing lower emissions. Research into the combustion process inside the pre-chamber is still a challenge due to the high pressure and temperatures, the geometrical restrictions, and the short combustion durations. Some fundamental studies in constant volume combustion chambers (CVCC) at low and medium working pressures have shown the complexity of the process and the influence of high pressures on the turbulence levels. In this study, the pre-chamber combustion process was investigated by combustion visualization in an optically-accessible pre-chamber under engine relevant conditions and linked with the jet emergence inside the main chamber. The pre-chamber geometry has a narrow-throat. The total nozzle area is distributed in two six-hole rows of nozzle holes.

The effects of EGR on diesel combustion were visually examined in a single-cylinder heavy duty research engine with a low compression ratio, low swirl, a CR fuel injection system and an eight-orifice nozzle. Optical access was primarily obtained through the cylinder head. The effects of EGR were found to be significant. NOx emissions were reduced from over 500 ppm at 0% EGR to 5 ppm at 55% EGR. At higher levels of EGR (approximately 35% or more) there was a loss in efficiency. Constant fuel masses were injected. Results from the optical measurements and global emission data were compared in order to obtain a better understanding of the spray behaviour and mixing process. Optical measurements provide fundamental insights by visualizing air motion and combustion behaviour. The NOx reductions observed might be explained by reductions in oxygen concentration associated with the increases in EGR.

The wavelet transform is used in the analysis of the cylinder pressure trace and the ionic current trace of a knocking, single-cylinder, spark ignition engine. Using the wavelet transform offers a significant reduction of mathematical operations when compared with traditional filtering techniques based on the Fourier transform. It is shown that conventional knock analysis in terms of average energy in the time domain (AETD), corresponding to the signal's energy content, and maximum amplitude in the time domain (MATD), corresponding to the maximum amplitude of the bandpass filtered signal, can be applied to both the reconstructed filtered cylinder pressure and the wavelet coefficients. The use of the filter coefficients makes possible a significant additional reduction in calculation effort in comparison with filters based on the windowed Fourier transform.

Crash-test-data on local longitudinal and shear stiffness of the vehicle front is needed to estimate impact severity from car deformation in offset or pole impacts, and to predict vehicle acceleration and compartment intrusion in car-to-car crashes. Repeated full frontal crash-tests were carried out with a load-cell barrier to determine the local longitudinal stiffness with increasing crush. Repeated off-set tests were run to determine shear stiffness. Two single high-speed tests (full frontal and offset) were carried out and compared to the repeated tests to determine the rate sensitivity of the front structure. Four repetitions at 33.4 km/h provided equivalent energy absorption to a single 66.7 km/h test, when rebound was considered. Power-train inertial effects were estimated from highspeed tests with and without power-train. Speed effects averaged 2% per [m/s] for crush up to power-train impact, and post-crash measurements were a reasonable estimate of front-structure stiffness.

A system for stratifying recycled exhaust gas (EGR) to substantially increase dilution tolerance has been applied to a port injected four-valve gasoline engine. This system, known as Combustion Control through Vortex Stratification (CCVS), has shown greatly improved fuel consumption at a stoichiometric air/fuel ratio. Both burnrate (10-90% burn angle) and HC emissions are almost completely insensitive to EGR up to best economy EGR rate. Cycle to cycle combustion variation is also excellent with a coefficient of variation of IMEP of less than 2% at best economy EGR rate. This paper describes a research programme aimed at gaining a better understanding of the in-cylinder processes in this combustion system.

The need for a more complete understanding of the flow behavior in aerodynamic wind tunnels has increased as they have become vital tools not only for vehicle development, but also for vehicle certification. One important aspect of the behavior is the empty test section flow, which in a conventional tunnel should be as uniform as possible. In order to assess the uniformity and ensure consistent behavior over time, accurate measurements need to be performed regularly. Furthermore, the uncertainties and errors of the measurements need to be minimized in order to resolve small non-uniformities. In this work, the quantification of the measurement uncertainties from the full measurement chain of the new flow uniformity measurement rig for the Volvo Cars aerodynamic wind tunnel is presented. The simulation based method used to account for flow interference of the probe mount is also discussed.

Soot particle size, particle concentration and volume fraction were measured by laser based methods in optically dense, highly turbulent combusting diesel sprays under engine-like conditions. Experiments were done in the Chalmers High Pressure, High Temperature spray rig under isobaric conditions and combusting commercial diesel fuel. Laser Induced Incandescence (LII), Elastic Scattering and Light Extinction were combined quasi-simultaneously to quantify particle characteristics spatially resolved in the middle plane of a combusting spray at two instants after the start of combustion. The influence that fuel injection pressure, gas temperature and gas pressure exert on particle size, particle concentration and volume fraction were studied. Probability density functions of particle size and two-dimensional images of particle diameter, particle concentration and volume fraction concerning instantaneous single-shot cases and average measurements are presented.

A Turbulent Flame Speed Closure Model is modified and implemented into the FIRE code for use in 3D computations of combustion in an SI-engine. The modifications are done to account for mixture inhomogeneity, and mixture compression through the dependency of local equivalence ratio, pressure and temperature on the chemical time scale and a global reaction time scale. The model is also subjected to further evaluation against experimental data, covering different mixture and turbulence conditions. The combustion process in a 4-valve pentroof combustion chamber is simulated and heat release rates and spatial flame distribution are evaluated against experimental data. The computations show good agreement with the experiments. The model has proven to be a robust and time effective simulation tool with good predictive ability.

A positive trend to more frequent use of child restraint systems (CRS) in Sweden, during the last 20 years, is shown in this report. During the same period, the overall injury risk, for different age groups of child occupants, has decreased substantially. This indicates the high effectiveness of the child restraint systems. Children need car occupant safety systems specially designed for their size. This paper clearly states the need for child safety systems and discusses benefits and drawbacks with regard to different restraints, ages and injuries. The analysis points out, that when a crash occurs, the maximum effect of a child restraint system is not reached, if the child is not using the correct system for their size. There is even a tendency that the injury risk increases when children switch from one restraint system to another, i.e. are at the youngest ages for which the specific restraint is recommended. The background data used, is based on Volvo's traffic accident research.

Due to stricter emission regulations and more environmental awareness, the powertrain systems are moving toward higher fuel efficiency and lower emissions. In response to these pressing needs, new technologies have been designed and implemented by manufacturers. As a result of increasing complexity of the powertrain systems, their control and optimization become more and more challenging. Virtual powertrain calibration, also known as model-based calibration, has been introduced to transfer a part of test bench testing into a virtual environment, and hence considerably reduce time and cost of product development process while increasing the product quality. Nevertheless, virtual calibration has not yet reached its full potential in industrial applications. Volvo Penta has recently developed a virtual test cell named VIRTEC, which is used in an ongoing pilot project to meet the Stage V emission standards.

The interaction between a combusting diesel spray and a wall was studied by measuring the spray flame temperature time and spatially resolved. The influence of injection sequences, injection pressure and gas conditions on the heat transfer between the combusting spray and the wall was investigated by measuring the flame temperature during the complete injection event. The flame temperature was measured by an emission based optical method and determined by comparing the relative emission intensities from the soot in the flame at two wavelength intervals. The measurements were done by employing a monochromatic and non intensified high speed camera, an array of mirrors, interference filters and a beam splitter. The studies were carried out in the Chalmers High Pressure High Temperature (HP/HT) spray rig at conditions similar to those prevailing in a direct injected diesel engine prior to the injection of fuel.

Thermodynamic power cycles have been shown to provide an excellent method for waste heat recovery (WHR) in internal combustion engines. By capturing and reusing heat that would otherwise be lost to the environment, the efficiency of engines can be increased. This study evaluates the maximum power output of different cycles used for WHR in a heavy duty Diesel engine with a focus on working fluid selection. Typically, only high temperature heat sources are evaluated for WHR in engines, whereas this study also considers the potential of WHR from the coolant. To recover the heat, four types of power cycles were evaluated: the organic Rankine cycle (ORC), transcritical Rankine cycle, trilateral flash cycle, and organic flash cycle. This paper allows for a direct comparison of these cycles by simulating all cycles using the same boundary conditions and working fluids.

During 1990, the Volvo Car Corporation will Introduce a new In-line six-cylinder engine featuring three litre displacement, twin overhead camshafts and 24 valves, designated the B6304F. The engine has been designed and adapted for Volvo's top-of-the-line model 960, and it has been developed to meet the market's high demands on comfort, performance, reliability, economy and environmental friendliness. The engine has been designed and manufactured with the help of advanced CAE technology. The engine structure consists of five basic aluminium parts. This construction contributes to the low engine weight of 182 kg including auxiliary units, oil and wiring. The engine's gas flow has been optimized with the help of data simulation and laser measurement technology so as to ensure efficient utilization of energy. Fuel injection and ignition timing are regulated and controlled by an advanced electronic control system, the Bosch Motronic 1.8.

The airbag simulation program DRACR has been revised to include belt routines. The amended program is used to indicate optimal choice of parameters for a driver supplementary airbag system. As a validation, results from sled tests are given and compared with the computer runs. A good agreement is found for the values of the most essential protection criteria such as chest g's and HIC's. The model has proven to be useful in the engineering process of an airbag restraint system. The interrelationship between important input variables is easily studied. Further validation of the model by other teams is encouraged

In 1981 Volvo launched the 2.1L turbocharged engine for the 240 model. Since then, the market interest for turbocharged engines has increased rapidly and along with this the demand for more efficient engines. The use of intercooler and micro-computer controlled fuel- and ignition systems in passenger car applications made it possible to develop a second generation of turbocharged engines with the capability to meet these demands. This paper describes the 2.3L turbocharged engine and its development for the US-version of the 1984 760 model.