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Modelling Pressure Losses in Gasoline Particulate Filters in High Flow Regimes and Temperatures

Coventry University-M. Prantoni, S. Aleksandrova, H. Medina, J. Saul, S. Benjamin
Jaguar Land Rover-O. Garcia Afonso
  • Technical Paper
  • 2019-01-2330
Published 2019-12-19 by SAE International in United States
This study presents a one-dimensional model for the prediction of the pressure loss across a wall-flow gasoline particulate filter (GPF). The model is an extension of the earlier models of Bissett [1] and Konstandopoulos and Johnson [2] to the turbulent flow regime, which may occur at high flow rates and temperatures characteristic of gasoline engine exhaust. A strength of the proposed model is that only one parameter (wall permeability) needs to be calibrated. An experimental study of flow losses for cold and hot flow is presented, and a good agreement is demonstrated. Unlike zero-dimensional models, this model provides information about the flow along the channels and thus can be extended for studies of soot and ash accumulation, heat transfer and reaction kinetics.
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A New Take on Porous Medium Approach for Modelling Monoliths and Other Multiple Channel Devices

Coventry University-Gianluca Padula, Jonathan Saul, Svetlana Aleksandrova, Humberto Medina, Stephen Benjamin
  • Technical Paper
  • 2019-24-0049
Published 2019-09-09 by SAE International in United States
The porous medium approach is widely used to represent high-resistance devices, such as catalysts, filters or heat exchangers. Because of its computational efficiency, it is invaluable when flow losses need to be predicted on a system level. One drawback of using the porous medium approach is the loss of detailed information downstream of the device. Correct evaluation of the turbulence downstream affects the calculation of the related properties, e.g. heat and mass transfer.The novel approach proposed in the current study is based on a modified distribution of the resistance across the porous medium, which allows to account for the single jets developing in the small channels, showing an improved prediction of the turbulence at the exit of the device, while keeping the low computational demand of the porous medium approach.The benefits and limitations of the current approach are discussed and presented by comparing the results with different numerical approaches and experiments. The flexibility of the proposed approach in terms of describing the device geometry is demonstrated via an optimisation study where the size of the…
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An Investigation of Aerodynamic Characteristics of Three Bluff Bodies in Close Longitudinal Proximity

Coventry University-Geoffrey Le Good, Peter Boardman, Max Resnick, Brian Clough
Published 2019-04-02 by SAE International in United States
The potential benefit for passenger cars when travelling in a ‘platoon’ formation results from the total aerodynamic drag reduction which may result from the interaction of bluff bodies in close-proximity. In the 1980s this was considered as an opportunity to alleviate congestion and also for fuel-saving in response to the oil crises of the 1970s. Early interest was limited by the availability of suitable systems to control vehicle spacing. However, recent developments in communication and control technologies intended for connected and autonomous driving applications has provided the potential for ‘platooning’ to be incorporated within future traffic management systems. The study described in this paper uses a systematic approach to changes in vehicle shape in order to identify the sensitivity of the benefits of platooning to vehicle style. The Windsor bluff-body model with its’ interchangeable rear-end geometry was chosen as the test subject because of its similarity to the approximate proportions of typical mid-sized European passenger cars. Three small-scale models were manufactured so as to be accommodated in-line within the working section of the Coventry University
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An Examination of Comfort and Sensation for Manual and Automatic Controls of the Vehicle HVAC System

Coventry University-Alexandra Galina Petre, James Brusey, Ross Wilkins
Published 2019-01-15 by SAE International in United States
The fast-changing and asymmetrical nature of the cabin environment challenges climate control systems in maintaining occupant comfort. This article examines the relationship between the control that occupants have over the heating, ventilation, and air conditioning (HVAC) system and their perceived comfort within the surrounding thermal environment. Three test cases using automatic control (20°C, 22°C, 24°C) and one in manual mode were evaluated via driving trials under normal road conditions in the United Kingdom during winter. In these trials, car cabin occupants felt more comfortable when using manual control than automatic (Fisher’s test, p = 2.2 × 10−16). Occupants felt neutral thermal sensations at head and foot level when using manual control. At chest level, occupants felt thermally neutral for both automatic and manual controls. This research highlights the need for further exploration of the interaction of the cabin occupants with their HVAC systems and the impact it has on their comfort perception.
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Development of semi-active suspension for Formula SAE vehicle

Coventry University-Georgios Chrysakis
Universidade Federal de Pernambuco-Marcos Gabriel Diodato dos Santos, Ramiro Britto Willmersdorf, Luiz Otávio Ferrão Teixeira Alves
Published 2018-09-03 by SAE International in United States
The design of passive suspension systems is being improved since the early days of the automotive industry in order to obtain the best tradeoff between ride comfort and handling. In this context, passenger cars tend to prioritise ride comfort whilst racing cars tend to focus on handling. On the other hand, Formula SAE is a series of undergraduate competitions in which the students design, build and compete with small, formula-style, mono-seated vehicles. As part of the competition events, the vehicle experiences tight corners and short-length slaloms. The minimum turning diameter and the shortest length of slalom period conducted by Formula SAE prototypes are 9 m and 7.6 m, respectively. Therefore, high controllability of vehicle dynamic behaviour is required in order to enhance the cornering speed, this is achievable by working on the dampers to optimise the rates of load transfer in cornering. This paper describes the development of semiactive control algorithms to optimise the handling performance of a Formula SAE vehicle by reducing the non-suspended mass displacements and tyre load variations, which are meant to…
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Effects on the Aerodynamic Characteristics of Vehicles in Longitudinal Proximity Due to Changes in Style

Coventry University-Geoff Le Good, Max Resnick, Peter Boardman, Brian Clough
Published 2018-05-30 by SAE International in United States
The potential benefit for vehicles travelling in ‘platoon’ formations arises from a reduction in total aerodynamic drag which can result from the interaction of bluff bodies in close-proximity. During the 1980s this was considered as an opportunity to alleviate congestion and also for fuel-saving in response to the fuel crises of the 1970s. Early interest was limited partly due to the level of available control technology. But recent developments in vehicle-to-vehicle communication systems and autonomous driving technologies have provided the potential for platooning to be incorporated within future traffic management systems prompting renewed interest. For the investigation described in this paper, a new passenger car model was designed as the basis for determining the effectiveness of future low-drag styles in platoon formations. Small-scale models were tested in the Coventry University Wind Tunnel in platoons of up to 5 vehicles. It was found that, for the ‘streamlined’ profile, drag penalties occurred for all vehicles in the platoon configurations compared to a single model of this style when tested alone. Thus the current process within the automotive…
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Modelling of a Coupled Catalyst and Particulate Filter for Gasoline Direct Injection Engines

Coventry University-Remus Cirstea, Essam F. Abo-Serie, Christophe Bastien, Hua Guo
Published 2018-04-03 by SAE International in United States
There has been extensive research in the development of Gasoline Direct Injection ‘GDI’ engine exhaust systems with the aim of reducing engine-out emissions and meeting legislation requirements. Depending on the room available for packaging the exhaust system, the engine may be equipped with a single catalyst or two catalysts one close to the engine and another one located further downstream. With the strict particulate matter emission regulations of GDI engine, the engine has to be equipped with a Gasoline Particulate Filter ‘GPF’ in addition to the Closed Coupled Catalyst ‘CCC’. The common practice is to have the GPF further downstream the catalyst. In this paper, an assessment method is carried for a new design of a hot end exhaust system. The new design brings the GPF closer to ‘CCC’ to be packed in the same enclosure. The gas flow velocity and pressure distributions inside the exhaust system are identified using CFD for a uniform exhaust gas flow inlet conditions. The system also has been investigated considering a typical inlet exhaust gas flow conditions from a…
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The Effect of Swirl on the Flow Uniformity in Automotive Exhaust Catalysts

Coventry University-Ijhar H. Rusli, Svetlana Aleksandrova, Humberto Medina, Stephen F. Benjamin
Published 2017-10-08 by SAE International in United States
In aftertreatment system design, flow uniformity is of paramount importance as it affects aftertreatment device conversion efficiency and durability. The major trend of downsizing engines using turbochargers means the effect of the turbine residual swirl on the flow needs to be considered. In this paper, this effect has been investigated experimentally and numerically. A swirling flow rig with a moving-block swirl generator was used to generate swirling flow in a sudden expansion diffuser with a wash-coated diesel oxidation catalyst (DOC) downstream. Hot-wire anemometry (HWA) was used to measure the axial and tangential velocities of the swirling flow upstream of the diffuser expansion and the axial velocity downstream the monolith. With no swirl, the flow in the catalyst monolith is highly non-uniform with maximum velocities near the diffuser axis. At high swirl levels, the flow is also highly nonuniform with the highest velocities near the diffuser wall. An intermediate swirl level exists where the flow is most uniform. To gain further insight into the mechanisms controlling flow redistribution, numerical simulations have been performed using the commercial…
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A Model-Based Approach for Investigating Tire-Pavement Friction Threshold Values

Coventry University-Emmanuel Bolarinwa
NEVS-Mustafa Ali Arat
Published 2017-03-28 by SAE International in United States
Most ground vehicles related accidents occur when the friction demand to perform a maneuver with a certain vehicle and tires exceeds the coefficient of friction of the pavement surface. As generally known, the forces and moments acting on the vehicle body are mainly generated at the tire-road surface interface. The common characteristics of tire forces on any surface include a linear region where the forces vary linearly with respect to the relative slip values; and a nonlinear region where the forces saturate and may even start decreasing. The experience of most of the daily drivers on the roads is limited within this linear region where the dynamic behavior of the vehicle remains proportional to the driver’s inputs. Therefore, an unexpected change in tire or surface characteristics (due to a change in surface friction, large driver inputs, etc.) may easily cause the driver to panic and/or to lose his/her ability to maintain a stable vehicle. These types of instabilities underline the importance of monitoring the corresponding tire and pavement attributes for improved vehicle performance and controls.…
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PICASSOS – Practical Applications of Automated Formal Methods to Safety Related Automotive Systems

Coventry University-Olivier Haas
D-RisQ Ltd.-Nick Tudor
Published 2017-03-28 by SAE International in United States
PICASSOS was a UK government funded programme to improve the ability of automotive supply chains to develop complex software-intensive systems with high safety assurance and at an acceptable cost. This was executed by a consortium of three universities and five companies including an automotive OEM and suppliers. Three major elements of the PICASSOS project were: use of automated model based verification technology utilising formal methods; application of this technology in the context of ISO 26262; and evaluation to measure the impact of this approach to inform key management decisions on the costs, benefits and risks of applying this technology on live projects. The project spanned system level design and software development. This was achieved by using a unified model based process incorporating SysML at the system level and using Simulink and Stateflow auto-coded into C at the software level. An ISO 26262 compliant development process based on those already used by the commercial partners was used as a baseline, and a modified process using formal methods was developed. Tools that are commercially available were used…
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