Publications
227 results found
Bayley AE, Hardalupas Y, Taylor AMKP, 2012, Local curvature measurements of a lean, partially premixed swirl-stabilised flame, EXPERIMENTS IN FLUIDS, Vol: 52, Pages: 963-983, ISSN: 0723-4864
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- Citations: 28
Katsikadakos A, Hardalupas Y, Hunt P, 2012, Hydrogen Abstraction from n-Butanol by the Methyl Radical: High Level Ab Initio Abstraction Pathways and the Importance of Low Energy Rotational Conformers, Phys. Chem. Chem. Phys., Pages: ---
Siu YW, Taylor AMKP, 2011, Particle capture by turbulent recirculation zones measured using long-time Lagrangian particle tracking, EXPERIMENTS IN FLUIDS, Vol: 51, Pages: 95-121, ISSN: 0723-4864
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- Citations: 3
Hardalupas Y, Panoutsos CS, Taylor AMKP, 2010, Spatial resolution of a chemiluminescence sensor for local heat-release rate and equivalence ratio measurements in a model gas turbine combustor, EXPERIMENTS IN FLUIDS, Vol: 49, Pages: 883-909, ISSN: 0723-4864
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- Citations: 65
Aleiferis PG, Kolokotronis D, Hardalupas Y, et al., 2010, Experimental Investigation of Cavitation in Gasoline Injectors, SAE Technical Paper Series, ISSN: 0148-7191
Hardalupas Y, Sahu S, Taylor AMKP, et al., 2010, Simultaneous planar measurement of droplet velocity and size with gas phase velocities in a spray by combined ILIDS and PIV techniques, EXPERIMENTS IN FLUIDS, Vol: 49, Pages: 417-434, ISSN: 0723-4864
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- Citations: 89
Charalampous G, Hardalupas Y, Taylor AMKP, 2010, Numerical and experimental evaluation of the optical connectivity technique for measurement of liquid breakup length in atomizers, 48th AIAA Aerospace Sciences Meeting and Exhibit
Charalampous G, Hardalupas Y, Taylor AMKP, 2009, 3-Dimensional structure of the intact liquid jet core during coaxial air-blast atomisation, International Journal of Spray and Combustion Dynamics, Vol: 1, Pages: 389-415, ISSN: 1756-8277
Charalampous G, Hardalupas Y, Taylor AMKP, 2009, Novel Technique for Measurements of Continuous Liquid Jet Core in an Atomizer, AIAA Journal, Vol: 47, Pages: 2605-2615, ISSN: 0001-1452
Panoutsos CS, Hardalupas Y, Taylor AMKP, 2009, Numerical evaluation of equivalence ratio measurement using OH* and CH* chemiluminescence in premixed and non-premixed methane-air flames, COMBUSTION AND FLAME, Vol: 156, Pages: 273-291, ISSN: 0010-2180
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- Citations: 188
Hardalupas Y, Sahu S, Taylor AMKP, et al., 2009, Simultaneous planar droplet size and droplet and gas velocity measurements in a confined spray, 47th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition
A new approach for simultaneous planar measurement of droplet velocity and size with gas phase velocities is used based on a combination of the out-of-focus imaging technique 'Interferometric Laser Imaging Droplet Sizing' (ILIDS) for planar simultaneous droplet size and velocity measurements with the in-focus technique 'Particle Image Velocimetry' (PIV) for gas velocity measurements in the vicinity of individual droplets. The measurements are presented in a model co-flowing (0.017 m/s) unheated spray dryer (0.5 m diameter, ≈ 2 m high) with a single air-assist solid cone atomizer with a characteristic droplet diameter (SMD) of the order of 150-200μm at liquid feed rates of the order of 1.4-1.6 · 10-3 kg/s and air feed rate of the order of 0.12·10-3 kg/s. The particular measurement location was 500 mm downstream and at a 120 mm off-axial location in the spray, the size of the viewing area being 8 mm × 12 mm. The experimental method, the image processing algorithm and the method of calculation of spatially averaged correlation are briefly described. The main results include plots of mean droplet velocity based on three different representative size classes, with Stokes numbers much less than unity, the mean gas velocity, instantaneous droplet and gas velocities and the spatially averaged correlations. For both the droplets and gas, the mean velocities were found to be of the similar magnitude, ≈ 0.2 m/s, with similar, though not identical, in direction. The one-time spatial correlation coefficient between the axial component of droplet and gas velocities was found to be about 0.6 while that of the other correlations calculated from combinations of other velocity components between the droplet and gaseous phases was close to zero, as expected in this region of the flow. Copyright © 2009 by Y. Hardalupas.
Eastwood PG, Tufail K, Winstanley T, et al., 2009, Estimation of deviations in NO and soot emissions between steady-state and EUDC transient operation of a common-rail diesel engine, SAE Technical Papers, Vol: 2, Pages: 648-659, ISSN: 0148-7191
The study measured Mass Air Flow, (MAF), Manifold Absolute Pressure, (MAP), and emissions of NO and soot during fourteen transients of speed and load, representative of the Extra Urban Drive Cycle (EUDC). The tests were conducted on a typical passenger car/light-duty truck powertrain (a turbocharged common-rail diesel engine, of in-line 4-cylinder configuration). The objective was to compare NO and soot with corresponding steady-state emission results and propose an engine measurement methodology that will potentially quantify deviation (i.e. deterioration with respect to steady state optimum) in emissions of NO and soot during transients. Comparison between steady state, quasi-steady-states (defined later in the paper) and transients indicated that discrete quasi-steady-state engine operation, can be used for accurate prediction of transient emissions of NO and soot. Furthermore, quasi-steady-state engine characterisation quantified NO and soot deterioration that may occur due to MAF and MAP deviations from their optimised (steady-state) values. Therefore, the results from quasi-steady-state can be used to estimate deterioration in emissions during transients. These results are potentially of use in modelling with a view to assess component to engine compatibility during the engine development phase and minimise emissions deterioration (due to component ageing and production variability) during the life-time of engine. Copyright © 2009 SAE International.
Tufail K, Winstanley T, Karagiorgis S, et al., 2009, Characterisation of diesel engine transient pumping-loss and control methodology for transient specific fuel consumption (SFC), SAE Technical Papers, ISSN: 0148-7191
This study measures, during various transients of speed and load, in-cylinder-, intake-/exhaust- (manifold) pressures and engine torque. The tests were conducted on a typical high power-density, passenger car powertrain (common-rail diesel engine, of in-line 4-cylinder configuration equipped with a Variable Geometry Turbocharger). The objective was to quantify the deterioration (relative to a steady-steady condition) in transient Specific Fuel Consumption (SFC) that may occur during lagged-boost closed-loop control and thus propose an engine control strategy that minimises the transient SFC deterioration. The results, from transient characterisation and the analysis method applied in this study, indicate that transient SFC can deteriorate up to 30% (function of load transient) and is primarily caused by excessive engine pumping-loss. The results are used to create an empirical model to estimate SFC online and a control methodology is proposed that restricts turbocharger-vanes closure as a function of SFC deviation from the steady-state calibration, thus reducing pumping-loss during transients. Copyright © 2009 SAE International.
Eastwood P, Tufail K, Winstanley T, et al., 2009, A comparison between cylinder charge composition of common rail diesel engine, INTERNATIONAL JOURNAL OF VEHICLE DESIGN, Vol: 49, Pages: 150-167, ISSN: 0143-3369
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- Citations: 1
Panoutsos CS, Hardalupas Y, Taylor AMKP, 2008, Effect of preheating on the local equivalence ratio at a swirl-stabilised partially-premixed combustor, 46th AIAA Aerospace Sciences Meeting and Exhibit
The effect of combustion air preheating between 25°C and 400°C on the mean and fluctuating local equivalence ratio of the reacting mixture, the flame structure and the flame stability of a swirl-stabilised partiallypremixed combustor has been studied using a Chemiluminescence Sensor. The main findings are: • Air preheating was beneficial for the premixing of fuel and air, resulting to measured values of local equivalence ratio of the reacting mixture approximately equal to the overall stoichiometry for high air temperature. This observation was combined with lower standard deviation of fluctuations of local equivalence ratio, which confirmed the improved premixing. • As the temperature of the combustion air increased from 25°C to 400°C, the flame became shorter and moved upstream towards the quarl of the combustor, until it stabilised at the boundaries of the inner recirculation zone and attached to the quarl. This occurred because the Karlovitz stretch factor K decreased, due to the increase of the laminar burning velocity as a result of the increase of air temperature. • For operation with combustion air temperature of 25°C, the flame oscillated at low frequencies between being anchored to the quarl of the combustor and detached from it. This can be explained by the fluctuations of the Karlovitz stretch factor K due to the fluctuations of the local equivalence ratio of the incoming air/fuel mixture, which is partially premixed. Copyright © 2008 by Y. Hardalupas.
Taylor AMKP, 2008, Science review of internal combustion engines, ENERGY POLICY, Vol: 36, Pages: 4657-4667, ISSN: 0301-4215
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- Citations: 128
Alelferis PG, Charalambides AG, Hardalupas Y, et al., 2008, The Effect of Axial Charge Stratification and Exhaust Gases on Combustion Development in a Homogeneous Charge Compression Ignition Engine, Proceedings of IMechE, Part D, Journal of Automobile Engineering, Vol: 222, Pages: 2171-2183, ISSN: 0020-3483
Eastwood P, Hardalupas Y, Morris T, et al., 2008, The effect of multiple fuel-injections on emissions of NOx and smoke with partially-premixed diesel combustion in a common-rail diesel engine, Institution of Mechanical Engineers: Combustion Engines and Fuels Group - Internal Combustion Engines: Performance, Fuel Economy and Emissions, Pages: 285-301
The aim of this study is to quantify, using partially-premixed combustion, the effect of fuel-injection schedules on the NOx-smoke trade-off. Steady-state tests were conducted, between 1200 - 2000rpm and 3bar BMEP with conventional (two-injections) and partially-premixed combustion (three-, four- and five-injections). Compared with conventional combustion, partially-premixed achieved up to 61% reduction in NOx, for similar smoke. However, four-injections, compared with three- and five-injections, gave the lowest NOx-smoke trade-off and 19.5% increase in Specific Fuel Consumption (SFC) compared with conventional combustion. The most effective fuel distribution was achieved when high quantities were injected earlier and smaller ones later i.e. closer to TDC. The last fuel-injection quantity made the greatest contribution to combustion noise. The general level of three-injection partially-premixed combustion noise, compared with conventional at 2000rpm and 2bar BMEP, was more spectrally uniform with frequency. © Ford Motor Company Ltd, 2007.
Aleiferis PG, Hardalupas Y, Kolokotronis D, et al., 2007, Investigation of the Internal Flow Field of a Diesel Model Injector Using Particle Image Velocimetry and CFD, SAE Technical Papers
Eastwood IM, Al Jafari M, Bergstrom ET, et al., 2007, The use of microfluidics to combat fuel crime (Catching Mr Big with the Small), Pages: 621-623
Taxation on fuels is an incentive for crime syndicates to set up smuggling and laundering groups that extract billions of dollars from the global economy every year. This crime falls into three categories, adulteration, grade swapping and tax evasion e.g. smuggling. In order to combat these crimes Authentix has developed and installed advanced microfluidic systems to test the fuel. Our system allows efficient marker testing in-field and we have demonstrated consistent extractions under a variety of conditions. Although microfluidics drives the technical engine of the testing program, our multi-million dollar success in these areas is also related to our ability to bring about legal enforcement. This is done through wide-scale testing and control programs.
Black J, Eastwood PG, Tufail K, et al., 2007, The effect of VGT vane control on pumping losses during full-load transient operation of a common-rail diesel engine, SAE Technical Papers, Vol: 2007-September, ISSN: 0148-7191
This study measures transient torque, smoke opacity and pumping-losses derived from in-cylinder pressure, as a function of Variable Geometry Turbocharger (VGT) vane position (derived through Engine Control Unit, ECU). Tests were conducted using a typical passenger car/light duty truck application turbo-charged common-rail diesel engine, of 14 configuration. The aim was to seek potential improvements in engine pumping-losses (and thus fuel economy) during full-load transients and at low engine speeds, due to opening of VGT vanes. The objective was to record engine performance (e.g. engine transient-torque, smoke opacity, fuel-demand, engine pressure-ratio etc.), under full-load operation, and at engine speeds of 900-1600 rpm. The effects of "slow" and "fast" transient manoeuvres were established (in a transient test facility) by performing four different acceleration rates (i.e. 2s, 5s, 10s and 20s). The potential reduction in Pumping Mean Effective Pressure (PMEP), due to reduction in engine pressure-ratio by VGT vane opening, and the corresponding gain in transient torque (and hence improvements in Specific Fuel Consumption, SFC) were to be analysed during full-load transients. Analysis of the results at four engine speeds during the said transients (1000, 1100, 1200 and 1400 rpm), shows that, by opening VGT vanes from fully-closed position (and therefore reducing exhaust back-pressure), PMEPs are reduced. However, by varying the VGT vanes only, two observations are made, specific to regions where boost-lag is present: 1) the reduction in PMEP causes degradation in boost pressure and therefore results in the production of excessive smoke opacity. Therefore, the benefit of reducing transient PMEP is lost as transient torque demand is only achieved by vane closure (producing more boost-pressure, to restrict excessive smoke opacity); and 2) lower engine pressure-ratio reduces PMEP at no extra penalty of excessive smoke opacity. However, the transie
Eastwood PG, Morris T, Tufail K, et al., 2007, The effects of fuel-injection schedules on emissions of NO<inf>x</inf> and smoke in a diesel engine during partial-premix combustion, SAE Technical Papers, Vol: 2007-September, ISSN: 0148-7191
Our aim was to quantify, through engine calibration, benefits in emissions of NOx and smoke, and effects on Specific Fuel Consumption (SFC) and noise, whilst operating with partial-premix combustion. Tests were conducted using a current passenger car diesel engine in series production; thus highlighting limitations in contemporary engine hardware. By scheduling three fuel injections - hereafter designated early (90-62obTDC), middle (49-31obTDC) and late (39-15obTDC) - we sought to quantify the effect of injection timing (with constant fuel-demand) on engine performance. These results were then compared to those obtained with the same engine running under conventional diesel combustion. All tests were conducted at a desired steady-state operating point of 2000 rpm and 3 bar BMEP. The timing of the three injection events had different effects on combustion, as follows. With timing of the early injection, emissions of NOx and smoke were least affected. With middle injection, fuel mass delivered and emissions of NOx were more sensitive to the chosen timing than with the early and late injections. This plausibly relates to interactions between rail-pressure fluctuations and the timing of the injection event. With the timing of the late injection, measured fuel mass was unaffected (due to lack of rail-pressure interactions), but emissions of smoke were modified significantly. This could be explained by the interaction of the late-arriving liquid "slug" of fuel in the main combustion event i.e., insufficient opportunity was furnished for much evaporation or premixing to occur. Optimum partial premix (at the above operating point) reduced emissions of NOx, compared with the conventional-combustion baseline, by 60%, for similar levels of smoke emissions. However, an increase of 27% in SFC was observed, together with a noticeable increase in combustion noise (60% based on cylinder-pressure rise rate), plausibly due to the higher percentage of premix burn.
Aleiferis PG, Charalambides AG, Hardalupas Y, et al., 2007, Axial Fuel Stratification of a Homogeneous Charge Compression Ignition (HCCI) Engine, International Journal of Vehicle Design, Vol: 44, Pages: 41-61, ISSN: 1741-5314
Black J, Eastwood PG, Tufail K, et al., 2007, Diesel engine transient control and emissions response during a European extra-urban drive cycle (EUDC), SAE Technical Papers, ISSN: 0148-7191
Deviations between steady-state and transient NOx emissions, due to limitations in current air-path control strategies were identified during transient operation. Three different engine and vehicle installations were operated under transient conditions i.e., the European Extra-Urban Drive Cycle (EUDC), in an emission rolls and powertrain testing facility. Air-path control factors and emissions were then identified by first, running a powertrain on the EUDC; second, selecting various operating points on this cycle (according either to speed-fuel or speed-torque); and third, running the same powertrain at these operating points in steady state. EUDC test results show that Mass Air Flow (MAF) and Manifold Ambient Pressure (MAP), as determined from steady-state optimisation, are achievable, during transient operation, by employing alternative air-path control parameters, relative to steady-state e.g. Exhaust Gas Recirculation, EGR (valve lift) and Variable Nozzle Turbocharger, VNT (vane position) - accommodating, that is, transient air-path lags. However, the strategy thus employed, during transient operation, also varies levels of EGR; and, therefore, may cause transient NOx emissions to deviate from those of optimized steady-states. Comparison between European EUDC test results and corresponding steady-state operation (i.e. operation at the same engine speed with either same torque or same fuel consumption), demonstrated parity in NOx emissions. Hence, provided no transient delays in MAP and MAF are realized, transient emissions of NOx, at any instant during a EUDC, are approximately those emitted under steady-state operation. Detailed steady-state results show that MAF demand may not be the most appropriate set-point with which to control EGR levels during transient operation. It is proposed that a control system based on accurate prediction of the percentage of EGR as set point may provide superior robustness. Copyright © 2007 Society of Automotive Engineers of
Black J, Eastwood PG, Tufail K, et al., 2007, Inter-correlations between smoke opacity, Legal Particulate Sampling (LPS) and TEOM, during transient operation of a diesel engine, SAE Technical Papers, ISSN: 0148-7191
The Particulate Matter (PM) emissions from a diesel passenger car were measured using three units concurrently: a commercially-available opacimeter (Celesco), a Tapered Element Oscillating Microbalance (TEOM) and a Legal Particulate Sampling (LPS) unit consisting of dilution tunnel with Constant Volume Sampling (CVS). The opacimeter provides a time resolved measurement for the visible component of the Particulate Matter (PM); the TEOM does the same for particulate mass. The motivation was to determine whether the opacimeter or TEOM could be used to suggest the likely result with CVS during transient engine operation. This would be accomplished more conveniently by empirical correlations, but with the advantage, that temporal variations during transients are then available. Forty-seven tests were conducted on a 4-cylinder 1.8l Turbo-Diesel Common-Rail Injection (TDCi) engine, operated under transient conditions according to the European Extra-Urban Drive Cycle (0-70kph EUDC). A linear relationship was found to exist between the CVS and the opacimeter, with the latter signal integrated with respect to time throughout the EUDC. The highest transient smoke emissions were consistently associated with the highest scheduled transient Exhaust Gas Recirculation (EGR) demands. The TEOM was unable to capture the fastest transient features in the emission behaviour; the opacimeter was better able to pin-point the operating conditions responsible for these events. It should, however, be noted that the transient maneuvers in the EUDC are quite gentle: real-world duty cycles contain harsher accelerations for which further correlations may be required. Copyright © 2007 Society of Automotive Engineers of Japan, Inc.
Charalampous G, Hardalupas Y, Taylor AMKP, 2007, A novel technique for measurements of the intact liquid jet core in a coaxial air-blast atomizer, 45th AIAA Aerospace Sciences Meeting and Exhibit
Taylor A, 2006, The new fuel thing, Fortune, Vol: 154, Pages: 22-23, ISSN: 0015-8259
Taylor A, 2006, The new fuel thing, Fortune, Vol: 154, Pages: 47-48, ISSN: 0015-8259
Matsuura K, Zarogoulidis K, Hardalupas Y, et al., 2006, Simultaneous planar measurement of size and three-component velocity of droplets in an aero-engine airblast fuel spray by stereoscopic interferometric laser imaging technique, 10th International Conference on Liquid Atomization and Spray Systems, ICLASS 2006
A new technique is proposed to simultaneously measure the size and three-component velocity of droplets, which is the extension of the interferometric laser imaging technique to the stereoscopic configuration. The optical compression concept is also utilized to avoid droplet image overlap for the application to the relatively dense region of sprays. The applicability of the technique is successfully demonstrated by using a practical aero-engine airblast fuel spray field. The results are compared with those by the phase Doppler anemometry to evaluate the performance. The results by the two techniques show good agreement. The influence of the air pressure drop through the nozzle is also studied by the present technique and the results are reasonable and consistent with those from literatures. Some important characteristics of the complicated counter-swirling airblast spray field is clearly revealed, taking advantage of the present technique, such as the droplet motions influenced by the air flow in the recirculation zone and in the attenuated circumferential counter-swirl shear-layer structure, not only by the mean velocity values, but also by the various correlations among droplet properties.
Aleiferis PG, Charalambides AG, Hardalupas Y, et al., 2006, Autoignition Initiation and Development of n-Heptane HCCI Combustion Assisted by Inlet Air Heating, Internal EGR or Spark Discharge: An Optical Investigation, SAE Technical Papers
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