Criteria

Text:
Affiliation:
Display:

Results

Viewing 1 to 30 of 49
2009-06-15
Technical Paper
2009-01-1893
C. D. Bannister, J. G. Hawley, H. M. Ali, C. J. Chuck, P. Price, A. J. Brown, W. Pickford
A number of studies have been carried out examining the impact of biodiesel blend ratio on vehicle performance and emissions, however there is relatively little data available on the interaction between blend ratio and reduced ambient temperatures over the New European Drive Cycle (NEDC). This study examines the effects of increasing the blend ratio of Rapeseed Methyl Ester (RME) on the NEDC fuel consumption and tailpipe emissions of a vehicle equipped with a 2.0 litre common rail diesel engine, tested on a chassis dynamometer at ambient temperatures of 25, 10 & −5°C. This study found that under low temperature ambient conditions increasing blend ratios had a significant detrimental effect on vehicle particulate emissions reversing the benefits observed at higher ambient temperatures. Blend ratio was found to have minimal impact on hydrocarbon emissions regardless of ambient temperature while carbon monoxide and NOx emissions were found to increase by up to 20% and 5.5% respectively.
2011-08-30
Technical Paper
2011-01-1873
Trevor J. Davies, Roger F. Cracknell, Bob Head, Kathryn Hobbs, Timothy Riley
The octane appetite of an SI engine can be expressed in terms of an Octane Index: OI = (1−K) RON + K MON where K is a constant for a given operating condition and depends only on the pressure and temperature variation in the engine (it is not a property of the fuel). Experimental measurements of K values can be costly and time consuming. This paper reports the development of a new K-value simulation method that can be applied to any spark ignition engine given basic engine data. Good agreement between simulation and experimental results suggests the method is reliable and can be applied to a wide range of engines.
2013-04-08
Technical Paper
2013-01-1760
Deepak Hari, Christian Brace, Christopher Vagg, Sam Akehurst, Lloyd Ash, Richard Strong
A large proportion of automotive engineering research is focused on the reduction of vehicle fuel consumption thereby reducing CO₂ emissions. One effective method is to use an electric motor in conjunction with the engine (hybrid electric vehicle). This paper details the development and performance characteristics of a low cost hybrid vehicle electric motor, originally developed for the retrofit hybrid vehicle market, although it is intended to be suitable for many applications. The motor is a low cost, scalable, high performance motor, primarily for automotive applications. The motor has been designed to make it stackable for higher power or torque requirements. The use of lightweight materials and innovative cooling designs are novel to this motor. Results obtained from extensive testing of the motor are detailed in the paper including the efficiency map, power and torque curves, continuous powers, etc.
2014-04-01
Journal Article
2014-01-1185
J.W.G. Turner, A. Popplewell, R. Patel, T.R. Johnson, N.J. Darnton, S. Richardson, S.W. Bredda, R.J. Tudor, C.I. Bithell, R. Jackson, S.M. Remmert, R.F. Cracknell, J.X. Fernandes, A.G.J. Lewis, S. Akehurst, C.J. Brace, C. Copeland, R. Martinez-Botas, A. Romagnoli, A.A. Burluka
The paper discusses the concept, design and final results from the ‘Ultra Boost for Economy’ collaborative project, which was part-funded by the Technology Strategy Board, the UK's innovation agency. The project comprised industry- and academia-wide expertise to demonstrate that it is possible to reduce engine capacity by 60% and still achieve the torque curve of a modern, large-capacity naturally-aspirated engine, while encompassing the attributes necessary to employ such a concept in premium vehicles. In addition to achieving the torque curve of the Jaguar Land Rover naturally-aspirated 5.0 litre V8 engine (which included generating 25 bar BMEP at 1000 rpm), the main project target was to show that such a downsized engine could, in itself, provide a major proportion of a route towards a 35% reduction in vehicle tailpipe CO2 on the New European Drive Cycle, together with some vehicle-based modifications and the assumption of stop-start technology being used instead of hybridization.
2014-04-01
Journal Article
2014-01-1196
Andrew Lewis, Sam Akehurst, James Turner, Rishin Patel, Andrew Popplewell
Increasingly stringent regulations and rising fuel costs require that automotive manufacturers reduce their fleet CO2 emissions. Gasoline engine downsizing is one such technology at the forefront of improvements in fuel economy. As engine downsizing becomes more aggressive, normal engine operating points are moving into higher load regions, typically requiring over-fuelling to maintain exhaust gas temperatures within component protection limits and retarded ignition timings in order to mitigate knock and pre-ignition events. These two mechanisms are counterproductive, since the retarded ignition timing delays combustion, in turn raising exhaust gas temperature. A key process being used to inhibit the occurrence of these knock and pre-ignition phenomena is cooled exhaust gas recirculation (EGR). Cooled EGR lowers temperatures during the combustion process, reducing the possibility of knock, and can thus reduce or eliminate the need for over-fuelling.
2014-04-01
Technical Paper
2014-01-1374
Huayin Tang, Richard Burke, Sam Akehurst, Chris Brace, Les Smith
Abstract Vehicle start-stop systems are becoming increasingly prevalent on internal combustion engine (ICE) because of the capability to reduce emissions and fuel consumption in a cost effective manner. Thus, the ICE undergoes far more starting events, therefore, the behaviour of ICE during start-up becomes critical. In order to simulate and optimise the engine start, Model in the Loop (MiL) simulation approach was selected. A proceduralised cranking test has been carried out on a 2.0-liter turbocharged, gasoline direct injection (GDI) engine to collect data. The engine behaviour in the first 15 seconds was split into eight different phases and studied. The engine controller and the combustion system were highly transient and interactive. Thus, a controller model that can set accurate boundary conditions is needed. The relevant control functions of throttle opening and spark timing have been implemented in Matlab/Simulink to simulate the behaviours of the controller.
2015-04-14
Technical Paper
2015-01-1279
Pengfei Lu, Chris Brace, Bo Hu
Abstract After years of study and improvement, turbochargers in passenger cars now generally have very high efficiency. This is advantageous, but on the other hand, due to their high efficiency, only a small portion of the exhaust energy is needed for compressing the intake air, which means further utilization of waste heat is restricted. From this point of view, a turbo-compounding arrangement has significant advantage over a turbocharger in converting exhaust energy as it is immune to the upper power demand limit of the compressor. However, with the power turbine being located in series with the main turbine, power losses are incurred due to the higher back pressure which increases the pumping losses. This paper evaluates the effectiveness that the turbo-compounding arrangement has on a 2.0 litres gasoline engine and seeks to draw a conclusion on whether the produced power is sufficient to offset the increased pumping work.
2015-04-14
Journal Article
2015-01-1282
J.W.G. Turner, A. Popplewell, D.J. Marshall, T.R. Johnson, L. Barker, J. King, J. Martin, A.G.J. Lewis, S. Akehurst, C.J. Brace, C.D. Copeland
Abstract The paper discusses investigations into improving the full-load and transient performance of the Ultraboost extreme downsizing engine by the application of the SuperGen variable-speed centrifugal supercharger. Since its output stage speed is decoupled from that of the crankshaft, SuperGen is potentially especially attractive in a compound pressure-charging system. Such systems typically comprise a turbocharger, which is used as the main charging device, compounded at lower charge mass flow rates by a supercharger used as a second boosting stage. Because of its variable drive ratio, SuperGen can be blended in and out continuously to provide seamless driveability, as opposed to the alternative of a clutched, single-drive-ratio positive-displacement device. In this respect its operation is very similar to that of an electrically-driven compressor, although it is voltage agnostic and can supply other hybrid functionality, too.
2015-04-14
Technical Paper
2015-01-0505
Miguel Angel Reyes Belmonte, Colin D. Copeland, Drummond Hislop, George Hopkins, Adrian Schmieder, Scott Bredda, Sam Akehurst
Abstract Pressure and temperature levels within a modern internal combustion engine cylinder have been pushing to the limits of traditional materials and design. These operative conditions are due to the stringent emission and fuel economy standards that are forcing automotive engineers to develop engines with much higher power densities. Thus, downsized, turbocharged engines are an important technology to meet the future demands on transport efficiency. It is well known that within downsized turbocharged gasoline engines, thermal management becomes a vital issue for durability and combustion stability. In order to contribute to the understanding of engine thermal management, a conjugate heat transfer analysis of a downsized gasoline piston engine has been performed. The intent was to study the design possibilities afforded by the use of the Selective Laser Melting (SLM) additive manufacturing process.
2014-10-13
Journal Article
2014-01-2718
Sarah Remmert, Steven Campbell, Roger Cracknell, Andrea Schuetze, Andrew Lewis, Karl Giles, Sam Akehurst, James Turner, Andrew Popplewell, Rishin Patel
Market demand for high performance gasoline vehicles and increasingly strict government emissions regulations are driving the development of highly downsized, boosted direct injection engines. The in-cylinder temperatures and pressures of these emerging technologies tend to no longer adhere to the test conditions defining the RON and MON octane rating scales. This divergence between fuel knock rating methods and fuel performance in modern engines has previously led to the development of an engine and operating condition dependent scaling factor, K, which allows for extrapolation of RON and MON values. Downsized, boosted DISI engines have been generally shown to have negative K-values when knock limited, indicating a preference for fuels of higher sensitivity and challenging the relevance of a lower limit to the MON specification.
2014-10-13
Technical Paper
2014-01-2559
Christopher Bannister
Abstract When evaluating the performance of new boosting hardware, it is a challenge to isolate the heat transfer effects inherent within measured turbine and compressor efficiencies. This work documents the construction of a lumped mass turbocharger model in the MatLab Simulink environment capable of predicting turbine and compressor metal and gas outlet temperatures based on measured or simulated inlet conditions. A production turbocharger from a representative 2.2L common rail diesel engine was instrumented to enable accurate gas and wall temperature measurements to be recorded under a variety of engine operating conditions. Initially steady-state testing was undertaken across the engine speed and load range in order that empirical Reynolds-Nusselt heat transfer relationships could be derived and incorporated into the model. Steady state model predictions were validated against further experimental data.
2014-10-13
Technical Paper
2014-01-2558
Qiyou Deng, Richard Burke
Abstract Current turbocharger models are based on characteristic maps derived from experimental measurements taken under steady conditions on dedicated gas stand facility. Under these conditions heat transfer is ignored and consequently the predictive performances of the models are compromised, particularly under the part load and dynamic operating conditions that are representative of real powertrain operations. This paper proposes to apply a dynamic mathematical model that uses a polynomial structure, the Volterra Series, for the modelling of the turbocharger system. The model is calculated directly from measured performance data using an extended least squares regression. In this way, both compressor and turbine are modelled together based on data from dynamic experiments rather than steady flow data from a gas stand. The modelling approach has been applied to dynamic data taken from a physics based model, acting as a virtual test cell.
2014-10-13
Technical Paper
2014-01-2550
Bo Hu, Chris Brace, Sam Akehurst, Colin Copeland, J.W.G. Turner
Abstract The Divided Exhaust Period (DEP) concept is an approach which has been proved to significantly reduce the averaged back pressure of turbocharged engines whilst still improving its combustion phasing. The standard layout of the DEP system comprises of two separately-functioned exhaust valves with one valve feeding the blow-down pulse to the turbine whilst the other valve targeting the scavenging behaviour by bypassing the turbine. Via combining the characteristics of both turbocharged engines and naturally aspirated engines, this method can provide large BSFC improvement. The DEP concept has only been applied to single-stage turbocharged engines so far. However, it in its basic form is in no way restricted to a single-stage system. This paper, for the first time, will apply DEP concept to a regulated two-stage (R2S) downsized SI engine.
2014-10-13
Technical Paper
2014-01-2596
Bo Hu, Colin Copeland, Chris Brace, Sam Akehurst, Alessandro Romagnoli, Ricardo Martinez-Botas, J.W.G Turner
Abstract Engines equipped with pressure charging systems are more prone to knock partly due the increased intake temperature. Meanwhile, turbocharged engines when operating at high engine speeds and loads cannot fully utilize the exhaust energy as the wastegate is opened to prevent overboost. The turboexpansion concept thus is conceived to reduce the intake temperature by utilizing some otherwise unexploited exhaust energy. This concept can be applied to any turbocharged engines equipped with both a compressor and a turbine-like expander on the intake loop. The turbocharging system is designed to achieve maximum utilization of the exhaust energy, from which the intake charge is over-boosted. After the intercooler, the turbine-like expander expands the over-compressed intake charge to the required plenum pressure and reduces its temperature whilst recovering some energy through the connection to the crankshaft.
2014-04-01
Journal Article
2014-01-1656
Bo Hu, Sam Akehurst, Chris Brace, Colin Copeland, James Turner
Fuel efficiency and torque performance are two major challenges for highly downsized turbocharged engines. However, the inherent characteristics of the turbocharged SI engine such as negative PMEP, knock sensitivity and poor transient performance significantly limit its maximum potential. Conventional ways of improving the problems above normally concentrate solely on the engine side or turbocharger side leaving the exhaust manifold in between ignored. This paper investigates this neglected area by highlighting a novel means of gas exchange process. Divided Exhaust Period (DEP) is an alternative way of accomplishing the gas exchange process in turbocharged engines. The DEP concept engine features two exhaust valves but with separated function. The blow-down valve acts like a traditional turbocharged exhaust valve to evacuate the first portion of the exhaust gas to the turbine.
1993-05-01
Technical Paper
931294
Allan L. Dickinson, Kevin A. Edge, D. Nigel Johnston
The design of quiet power steering vane pumps requires accurate experimental and analytical tools to assess fluidborne noise. Measurement of vane pump fluidborne noise-generating potential must minimize hydraulic circuit effects. The difficulties of distinguishing between pump and hydraulic circuit effects is discussed. A technique called the “secondary source” method for measuring positive displacement pump flow ripple is described. The technique allows evaluation of the pump discharge impedance and flow ripple based on the analysis of the wave propagation characteristics in a special test circuit. This test method is used to validate a computer model of the vane pump flow ripple at the rotating group discharge. The model computes the vane chamber pressure histories which are used to obtain net discharge flow ripple. Geometric definition is kept flexible in the model so that compression and leakage can be evaluated for any vane pump design.
1993-03-01
Technical Paper
930823
M.F. Mathieson, S.J. Charlton, D.N. Johnston, R. Horrocks, M. Watts
A new hydraulic cam follower with variable valve timing (VVT) properties is described. Experimental results show that the point of closure of the valve may be delayed as a linear function of engine speed without external control. No other parameter of the valve event is modified by the device. An obvious application is the control of intake valve timing for engines with a wide speed range, where the point of valve closure could be scheduled with engine speed in order to maximise the trapped mass, hence improving the torque curve at low and high speeds. The device is considered for application to the Ford 2.5 litre DI diesel engine, where it may be used to retard inlet valve closure from close to bottom dead centre (BDC) at cranking speed to 50-60 deg after BDC at rated speed.
1993-04-01
Technical Paper
931097
N. J. A. Thorne, S. J. Charlton, S. A. MacGregor, A. R. Hughes
The last decade has seen a rapid increase within industry of the use of computational fluid dynamics (CFD) to assist in the design and development phase of product manufacture. There have recently evolved many new commercial CFD codes, both general and problem specific, but little validation data is available with which the engineer may assess the code's ability to simulate accurately a given flow problem. Much doubt prevails about current methods of turbulence modelling yet without comparison with experimental data few firm conclusions may be drawn. The work described in this paper is an investigation into the highly turbulent air flow through a vehicle intercooler duct. The general purpose CFD code STAR CD was used to obtain a computational prediction of the flow field. These results were correlated with experimental values of velocity and turbulence levels obtained using a single component laser Doppler anemometry system.
1993-04-01
Technical Paper
931178
N. D. Vaughan, D. G. Tilley, P. E. Pomeroy
Abstract The authors describe the early stages of a programme to investigate the wear sensitivity of spool valves to abrasive contaminant in the fluid flow. Wear mechanisms in valves and aspects of test rig design are discussed. Methods of assessing wear are considered, both during and after completion of a test. Preliminary results are presented to highlight the difference between these methods and illustrate the changes in geometry that take place during the wear test.
1997-05-19
Technical Paper
971791
N.A.F Campbell, D.G. Tilley, S.A. MacGregor, L. Wong
Precision cooling has a number of advantages over the conventional cooling of combustion engines. It is primarily used to prevent component failures and is generally intended to create an even distribution of temperature within the cylinder head and block. This leads to lower thermal stresses and higher component durability. Precision cooling in the form of forced convection and nucleate boiling can be used to greater effect than that of traditional precision cooling concentrating on forced convection only. This paper describes the analytical and experimental precision cooling strategy that has been used to investigate nucleate and transition boiling. Analytical details of the models are described and preliminary experimental data is provided for comparison. The major finding indicates that the diameter of the internal cooling passage is one of the significant factors that influences the critical heat flux.
1997-05-19
Technical Paper
971802
J. A. Sidders, D. G. Tilley
This paper presents a lumped parameter method for whole circuit simulation of vehicle cooling systems using the Bathfp simulation environment. The dynamic performance of a 1.8 litre internal combustion engine cooling system is examined. The simulation is compared with experimental data from a test rig incorporating a non-running engine with external heat source and a good correspondence is achieved. The background to the modelling approach is described. It is shown that simulating cooling systems with Bathfp offers the designer the flexibility to assess component sensitivity and changes in system configuration which will aid the process of cooling system optimisation.
1992-09-01
Technical Paper
921734
Changyou Chen, Ali Veshagh, F. J. Wallace
A comprehensive general purpose engine simulation model has been successfully developed. This paper reports on an investigation undertaken to compare the accuracy and computational efficiency of four alternative methods for modelling the gas flow and performance in internal combustion engines. The comparison is based on the filling-and-emptying method, the acoustic method, the Lax-Wendroff two-stage difference method and the Harten-Lax-Leer upstream method, using a unified treatment for the boundary conditions. The filling-and-emptying method is the quickest method among these four methods, giving performance predictions with reasonably good accuracy, and is suitable for simulating engines using not highly tuned gas exchange systems. Based on the linearized Euler equations, the acoustic method is capable of describing time-varying pressure distributions along a pipe.
1996-08-01
Technical Paper
961823
S. P. Tomlinson, C. R. Burrows
In traditional liquid cooled internal combustion engine systems, the coolant temperature is controlled by a thermostat which governs the coolant flow rate to the radiator. The thermostat is effectively a directional control valve in which the spool displacement is used to direct flow to the radiator. The coolant temperature is primarily a function of four parameters, namely radiator and thermostat characteristics, coolant flow rate and ambient temperature. By employing closed-loop feedback, the coolant temperature can be controlled according to environmental conditions. To achieve this goal the overall system must be correctly designed. That is the issue discussed in this paper. The increasing use of simulation for both circuit and component analysis in the automtive industry has come about due to the requirement for acceptable transient as well as steady state system performance.
1996-08-01
Technical Paper
961854
Iain B. James, Nicholas D. Vaughan
Problems inherent in pressure control circuits are manifest in many common applications such as those of cushion control, and bumpless transfer between displacement and pressure control. Often, solutions involve complex electrical feedback systems to achieve the required performance characteristics. However, in many cases, a thorough understanding of the plant and control circuit should enable fulfilment of these requirements using a simple and inexpensive open-loop system. In this case the plant is an automotive CVT (Continuously Variable Transmission) which has particular performance requirements. Constraints applied by the plant characteristics dictate that large flows be catered for with a low pressure increase and also that specific frequency response features are attained.
1996-08-01
Technical Paper
961797
N. D. Vaughan, M. Gübeli, C. R. Burrows
As part of a larger programme of work on the integrated control of engine and transmissions a study has been made of the control aspects of the transmission with a detailed investigation of the hydraulic circuit. The requirements of the broader programme necessitated an electrical input for the transmission control and a test bed version was successfully modified with electro-hydraulic valves. Attention to detail in the design of the hydraulic circuit and the control of operating pressure can bring significant benefits to the transmission efficiency with consequent beneficial effects on fuel economy. This paper investigates several aspects of the components used and their effect on efficiency, in particular pump sizing. This investigation is illustrated with results from a computer simulation of the system. Possible improvements through a modified control strategy for the belt pressure are also proposed with steady state results obtained experimentally from the test bed transmission.
1996-08-01
Technical Paper
961795
S. P. Hampson, P. K. Chawdhry, C. R. Burrows
Developing controllers for hydraulic servos is difficult due to the inherent uncertainty and nonlinear characteristics of the system. Systems are classed as uncertain when they are subject to unknown parameter variations or disturbances, or when there is incomplete knowledge of the system model, all of which are common in hydraulic servo systems. However, unlike conventional control techniques, the use of modern control methods means that system uncertainty can be considered at the controller design stage, and consequently robust controllers can be developed. In this paper the robust control of hydraulic servo systems is considered, and sources of uncertainty typical in hydraulic drives are discussed. The effect of ignoring these uncertainties is demonstrated by simulation experiments of a hydraulic servo, comparing conventional control techniques to the modern approach of H∞ optimal control. The implementation of modern controllers is also discussed.
1998-09-14
Technical Paper
982023
B. L. Jones, D. N. Johnston, D. K. Longmore
Noise emitted from the pump can be a major influence on the overall noise created by a power steering system. Dynamic simulation can aid the designer by showing the effect of the pump geometry and oil properties on noise before the prototype has been built. This paper discusses a simulation of suction port flow ripple in a power steering vane pump, which is validated against experimental data. Results show that the mean pressure in the delivery line affects the amplitude of suction port flow ripple. Internal leakage in the pump was found to have little effect on suction port flow ripple. The level of high-frequency flow ripple from the suction port was found to be comparable with or greater than that from the delivery port. The simulation is used to recommend the addition of relief grooves to reduce the high-frequency flow ripple.
2007-01-23
Technical Paper
2007-01-0018
William J. Dunne, Christian J. Brace, Andrew Stodart
This paper describes the development and automated calibration of a compact analytically based model of the wall-wetting phenomenon of modern port fuel-injected (PFI) spark-ignition (SI) gasoline engines. The wall-wetting model, based on the physics of forced convection with phase change, is to be used in an automated model-based calibration program. The first stage of work was to develop a model of the wall-wetting phenomenon in Matlab. The model was then calibrated using experimental data collected from a 1.8-litre turbocharged I4 engine coupled to a dynamic 200kW AC dynamometer. The calibration was accomplished by adopting a two stage optimization approach. Firstly, a design of experiments (DoE) approach was used to establish the effect of the principal model parameters on a set of metrics that characterized the magnitude and duration of the measured lambda deviation during a transient.
2005-04-11
Technical Paper
2005-01-1262
Peter E. Pfeffer, D. Nigel Johnston, Matija Sokola, Manfred Harrer
The reduction of fuel consumption in vehicles remains an important target in vehicle development to meet the carbon dioxide emission reduction target. One of the significant consumers of energy in a vehicle is the hydraulic power-assisted steering system (HPS) powered by the engine belt drive. To reduce the energy consumption an electric motor can be used to drive the pump (electro-hydraulic power steering or EHPS). In this work a simulation model was developed and validated to model the energy consumption of the whole steering system. This includes an advanced friction model for the steering rack, a physically modeled steering valve, the hydraulic pump and the electric motor with the control unit. The model is used to investigate the influence of various parameters on the energy consumption for different road situations. The results identified the important parameters influencing the power consumption and showed the potential to reduce the power consumption of the system.
2008-04-14
Journal Article
2008-01-0391
C. D. Bannister, C. J. Brace, G. D. Lock, J. Taylor, T. Brooks, N. Fraser
This paper describes the characterisation of heat transfer in a series of 11 test sections designed to represent a range of configurations seen in production exhaust systems, which is part of a larger activity aimed at the accurate modeling of heat transfer and subsequent catalyst light off in production exhaust systems comprised of similar geometries. These sections include variations in wall thickness, diameter, bend angle and radius. For each section a range of transient and steady state tests were performed on a dynamic test cell using a port injected gasoline engine. In each case a correlation between observed Reynolds number (Re) and Nusselt number (Nu) was developed. A model of the system was implemented in Matlab/Simulink in which each pipe element was split into 25 sub-elements by dividing the pipe into five both axially and radially. The modeling approach was validated using the experimental data.
Viewing 1 to 30 of 49

Filter

  • Range:
    to:
  • Year: