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Technical Paper

A High Resolution 3D Complete Engine Heat Balance Model

2015-09-06
2015-24-2533
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.
Technical Paper

A Mild Hybrid SIDI Turbo Passenger Car Engine with Organic Rankine Cycle Waste Heat Recovery

2019-09-09
2019-24-0194
While striving for more fuel-efficient vehicles, all possible measures are considered to increase the efficiency of the combustion engine powertrain. 48V mild hybrid technology is one such measure, SIDI (Spark Ignited Direct Injection) engines with Miller technology are another, while recovering energy from the engine’s waste heat (WHR) is yet another option. In this paper, results will be published from an advanced engineering project at Volvo Cars including all of these components. An ethanol based Organic Rankine Cycle (ORC) WHR-system was successfully built around a 4-cylinder, 2.0 litre SIDI-engine, including 48V mild hybrid technology, with vehicle packaging considered. A dedicated control system was also developed for the ORC system including communication between it and the engine. The ORC system uses the engine exhaust as the heat source, for which a purpose-built evaporator was designed and built to fit in the vehicle tunnel.
Technical Paper

A Reference Architecture for Infotainment Systems

2006-10-16
2006-21-0013
Volvo Car Corporation has developed a Reference Architecture for PAG1 Infotainment Systems. A Reference Architecture is an architecture scoping over more than a single system, i.e. an architecture aimed for a family of systems. The Infotainment Reference Architecture has since 2001 been successfully applied for the PAG family which so far covers the infotainment systems of Volvo XC90, Volvo S40/V50, Jaguar XK, Aston Martin DB9 and the brand new Volvo S80. In 1999, the system design departments started up with the clear objective to develop a system solution aiming for the PAG infotainment system family. The work was carried out according to the established development process at Volvo Cars. A year later a discouraging design review was performed. The number of involved functions, the level of function interaction and the distribution of functionalities between ECUs resulted in a non-manageable system solution.
Technical Paper

A Semiconductor Gas Sensor Array for the Detection of Gas Emissions from Interior Trim Materials in Automobiles

1998-02-23
980995
The principles of an electronic nose are described briefly. It is shown how a sensor array in combination with pattern recognition software can be used for quality control and classification of car interior trim materials. Anomalies such as bad smelling leather and carpet are shown as outliers. The results are consistent with GC-MS TVOC measurements as well as with data from a human sensory panel. More needs to be done, however, regarding the sensor stability in particular before the sensor array can be used for routine classification of the trim materials.
Technical Paper

Accuracy in Flow Simulations of Climate Control - Part 2: The Passenger Compartment

1999-03-01
1999-01-1201
Computational fluid dynamics has been used to study the flow pattern in a Volvo S80 passenger compartment. The main purpose of this work is to secure a method for future use of CFD in developing climate control systems in cars. The effects of mesh resolution and mesh size were studied by varying the number of cells from 1 million to approximately 5 million. It was found that at least 2 million cells are needed to approach a mesh size independent solution. The other focus of this study was the outlet boundary conditions. Since a passenger compartment is not air tight, outlets were assumed to be around doors, through the floor, through the backseat, as well as the evacuation at the rear of the passenger compartment. It can be seen that the solution is only sensitive to drastic changes in the leakage.
Technical Paper

Accuracy in Flow Simulations of Climate Control-Part 1: The Air Distribution System

1999-03-01
1999-01-1200
Flow simulations of an air distribution system have been carried out using the CFD code FLUENT/UNS [1]. The purpose of this study is to validate this complex flow problem versus experimental data. Two modes of the climate system are investigated; the Ventilation mode and the Floor/Defroster mode. The complete geometrical model contains all ducts, central unit, heat exchangers, defroster and nozzles of the air distribution system. A high level of geometrical detailing in the mesh, consisting of 2.1 - 3.3 million cells, is used. The study shows that CFD has a potential to give reliable results, even for complex systems, like air distribution systems, if used in a controlled manner.
Technical Paper

Acoustic One-Dimensional Compressor Model for Integration in a Gas-Dynamic Code

2012-04-16
2012-01-0834
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™.
Technical Paper

An Investigation of the Coupling Between the Passenger Compartment and the Trunk in a Sedan

2007-05-15
2007-01-2356
The low frequency acoustic response of the passenger compartment (cavity) in sedans is considered with respect to the coupling between the cavity and the trunk. Both acoustic (via holes in the parcel shelf or behind the backrest of the rear seat), and structural (via the parcel shelf itself, or the panel of the backrest) mechanisms are investigated by both test and CAE. It is found that the peaks in acoustic response of the cavity at low frequencies are due to both acoustic and structural phenomena. However, the acoustic ones can be effectively blocked by proper design of the trim. Recommendations concerning modeling of acoustic effects in sedans are formulated.
Technical Paper

Balancing Thermodynamic and Aerodynamic Attributes Through the Use of a Common CFD Model

2005-05-10
2005-01-2052
This paper describes how simultaneous numerical simulation of cooling performance and aerodynamic drag can be used to achieve attribute-balanced solutions. Traditionally at Volvo, evaluation of cooling performance and aerodynamics are done by separate teams using separate models and software. However, using this approach, any project changes can be evaluated in terms of their effect on cooling performance and drag from one single model. This enables the project to make decisions that are optimal in a more global perspective. If several proposals have similar levels of cooling performance, the proposal that yields the lowest overall drag can be chosen, thus reducing the fuel consumption of the vehicle. The first part of the paper discusses the prerequisites for the method in terms of boundary conditions, mesh and solution strategy. For the cooling performance part, the importance of high quality boundary conditions is reviewed.
Technical Paper

Battery Parameter Estimation from Recorded Fleet Data

2016-10-17
2016-01-2360
Existing battery parameter model structures are evaluated by estimating model parameters on real driving data applying standard system identification methods. Models are then evaluated on the test data in terms of goodness of fit and RMSE in voltage predictions. This is different from previous battery model evaluations where a common approach is to train parameters using standardized tests, e.g. hybrid pulse-power capability (HPPC), with predetermined charge and discharge sequences. Equivalent linear circuit models of different complexity were tested and evaluated in order to identify parameter dependencies at different state of charge levels and temperatures. Models are then used to create voltage output given a current, state of charge and temperature. The average accuracy of modelling the DC bus voltage provides a model goodness of fit average higher than 90% for a single RC circuit model.
Technical Paper

Body and Component Accuracy in Assembly Systems

1998-09-29
982269
To give the customer an immediate impression of quality several of criteria must be fulfilled such as styling, paint finish and fitting of outer panels/closures. Therefore, higher demands on geometrical quality e.g. stability for both exterior and interior are needed. The structural part of the car body is the key element for success. Beside the visual impression, lack of noise and vibrations during driving can convince a potential buyer to become an actual customer. To achieve this, car manufacturers have to draw up an overall strategy in combination with proper working methods to be able to guarantee a stable geometrical output throughout the entire development process and during series production over the lifetime of the vehicle. On a simultaneous engineering basis, the OEM, the system/component- and the process suppliers (for the industrial system from press shop to final assembly) have to adopt a common measurement strategy.
Technical Paper

CFD-Analysis of Cycle Averaged Heat Flux and Engine Cooling in an IC-Engine

2005-04-11
2005-01-0200
It is demonstrated that the cycle averaged heat flux on the hot gas side of the cylinders can be obtained using in-cylinder CFD-analysis. Together with the heat transfer coefficient obtained from the coolant jacket CFD-analysis, a complete set of boundary conditions are made available exclusively based on simulations. The engine metal temperatures could then be predicted using FEA and the results are compared to an extensive set of measured data. Also 1-D codes are used to provide cooling circuit boundary conditions and gas exchange boundary condition for the CFD-models. The predicted temperature distribution in the engine is desirable for accurate and reliable prediction of knock, durability problems, bore distortion and valve seat distortion.
Technical Paper

Challenges and Opportunities for the Transition to Highly Energy-Efficient Passenger Cars

2011-06-09
2011-37-0013
Maintaining the current ratio between certified and the customer-observed fuel consumption even with future required levels poses a considerable challenge. Increasing the efficiency of the driveline enables certified fuel consumption down to a feasible level in the order of 80 g CO₂/km using fossil fuels. Mainly affecting off-cycle fuel consumption, energy amounts used to create good interior climate as well as energy-consuming options and features threaten to further increase. Progressing urbanization will lead to decreasing average vehicle speeds and driving distances. Highly efficient powertrains come with decreased amounts of waste energy traditionally used for interior climate conditioning, thus making necessary a change of auxiliary systems.
Technical Paper

Comparison Between CFD and PIV Measurements in a Passenger Compartment

2000-03-06
2000-01-0977
Numerical simulations of the flow inside a passenger compartment are compared with experimental data obtained from velocity field measurements using Particle Image Velocimetry (PIV). Comparisons are made in the front part of the passenger compartment with the air-distribution system operated in a ventilation mode. The sensitivty of the CFD-model to the boundary conditions was investigated and two different turbulence models were tested. Computations and experiments resulted in similar results for the overall flow field, however, rather large differences were found in the vertical spreading of the jet from the dashboard nozzle. The width of the jet was lower in the measurements than in the simulations. This difference is believed to be caused by the high diffusivity obtained when using a k-epsilon model in combination with an unstructured grid.
Technical Paper

Conceptual Design of Distributed by-Wire Systems

2002-03-04
2002-01-0271
A design method for ultra-dependable control-by-wire systems is presented here. With a top-down approach, exploiting the system's intrinsic redundancy combined with a scalable software redundancy, it is possible to meet dependability requirements cost-effectively. The method starts with the system's functions, which are broken down to the basic elements; task, sensor or actuator. A task graph shows the basic elements interrelationships. Sensor and actuator nodes form a non-redundant hardware architecture. The functional task-graph gives input when allocating software on the node architecture. Tasks are allocated to achieve low inter-node communication and transient fault tolerance using scalable software redundancy. Hardware is added to meet the dependability requirements. Finally, the method describes fault handling and bus scheduling. The proposed method has been used in two cases; a fly-by-wire aircraft and a drive-by-wire car.
Technical Paper

Demonstration of Two-Dimensional Temperature Characterization of Valves and Transparent Piston in a GDI Optical Engine

2004-03-08
2004-01-0609
Thermographic phosphors thermometry was used to measure engine valves and transparent piston temperatures in two dimensions as well point wise of a running, optically accessible, gasoline direct injection engine. The engine, fueled with isooctane, was operated in continuous and skip-fire mode at 1200 and 2000 rpm. A calibration of the phosphorescence lifetime and spectral properties against temperature allowed temperature measurements between 25 and 600°C. Results from the measurements show the potential of the technique for two-dimensional mapping of engine walls, valves and piston temperatures inside the cylinder.
Technical Paper

Development and Validation of Coolant Temperature and Cooling Air Flow CFD Simulations at Volvo Cars

2004-03-08
2004-01-0051
This paper describes the development of a robust and accurate method to model one-phase heat exchangers in complete vehicle air flow simulations along with a comprehensive comparison of EFD and CFD results. The comparison shows that the inlet radiator coolant temperatures obtained with CFD were within ±4°C of the experimental data with a trend in the differences being dependent on the car speed. The relative differences in cooling air mass flow rates increase with increasing car speed, with CFD values generally higher than EFD. From the investigation, the conclusion is that the methodology and modeling technique presented offer an accurate tool for concept and system solutions on the front end design, cooling package and fan. Care must be taken in order to provide the best possible boundary conditions paying particular attention to the heat losses in the engine, performance data for the radiator and fan characteristics.
Technical Paper

Development of a Model Scale Heat Exchanger for Wind Tunnel Models of Road Vehicles

2008-04-14
2008-01-0097
During the development of the aerodynamic properties of fore coming road vehicles down scaled models are often used in the initial phase. However, if scale models are to be utilised even further in the aerodynamic development they have to include geometrical representatives of most of the components found in the real vehicle. As the cooling package is one of the biggest single generators of aerodynamic drag the heat exchangers are essential to include in a wind tunnel model. However, due mainly to limitations in manufacturing techniques it is complicated to make a down scaled heat exchanger and instead functional dummy heat exchangers have to be developed for scaled wind tunnel models. In this work a Computational Fluid Dynamics (CFD) code has been used to show that it is important that the simplified heat exchanger model has to be of comparable size to that of the full scale unit.
Technical Paper

Digital Human Models' Appearance Impact on Observers' Ergonomic Assessment

2005-06-14
2005-01-2722
The objective of this paper is to investigate whether different appearance modes of the digital human models (DHM or manikins) affect the observers when judging a working posture. A case where the manikin is manually assembling a battery in the boot with help of a lifting device is used in the experiment. 16 different pictures were created and presented for the subjects. All pictures have the same background, but include a unique posture and manikin appearance combination. Four postures and four manikin appearances were used. The subjects were asked to rank the pictures after ergonomic assessment based on posture of the manikin. Subjects taking part in the study were either manufacturing engineering managers, simulation engineers or ergonomists. Results show that the different appearance modes affect the ergonomic judgment. A more realistic looking manikin is rated higher than the very same posture visualized with a less natural appearance.
Technical Paper

Electric Power Assist Steering System Parameterization and Optimisation Employing Computer-Aided Engineering

2015-04-14
2015-01-1500
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.
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