Motored SI IC Engine In-Cylinder Flow Field Measurement Using Time Resolved Digital PIV for Characterisation of Cyclic Variation

Jarvis, S.; Justham, T; Clarke, A.G.; Garner, Colin P.; Hargrave, Graham K.; Richardson, Dave

doi:10.4271/2006-01-1044

Cited by 38 publications

(37 citation statements)

References 17 publications

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“…It was also noticed that around this time (93-97° CA ATDC) the leading edges of the spray appear to be suddenly affected by the now established in-cylinder tumble flow and deflected sideways towards the intake side and upwards in the cylinder away from the piston crown, also contributing to the lack of piston impingement. The cross-flow on top of the piston at this point in the cycle has a velocity in excess of 20 m/s as shown by Particle Image Velocimetry (PIV) carried out on an identical engine [24] and this compares to spray tip velocities at the same time after SOI measured in an injection rig [19] which have now been substantially reduced due to drag and leading edge evaporation from their initial velocities of ~80 m/s. The above mentioned flow effects are also observed for SOI 60° CA ATDC.…”

Section: Asoi 7°mentioning

confidence: 99%

Mixture Preparation and Combustion Variability in a Spray-Guided DISI Engine

Serras-Pereira¹,

Aleiferis²,

Richardson

et al. 2007

SAE Technical Paper Series

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In an attempt to study the numerous contributors towards cyclic variations in combustion in a direct injection spark ignition engine, simultaneous high-speed imaging of fuel injection and flame growth are undertaken on a crankangle resolved basis in a single-cylinder optical research engine. Batches of images from 100 consecutive cycles are acquired for all conditions with synchronised incylinder pressure logging. The engine is motored and fired at stoichiometric conditions at 1500 RPM under part-load and wide-open-throttle conditions (0.5-1.0 bar intake pressure), with injection timing set early in the intake stroke to promote homogeneous mixture formation with a centrally mounted multi-hole injector. Liquid impingement is observed on the cylinder walls and on the piston crown with early intake injection and multiple injection strategies are employed in an attempt to reduce impingement and alter mixture preparation and subsequent combustion. The effects are investigated for iso-octane and pump-grade gasoline at engine coolant temperatures of 50 and 90 °C. Gasoline sprays showed severe deformation and partial collapse of the individual spray plumes at 90 °C, leading to a different mixture formation process relative to iso-octane, which showed no such effects at this engine temperature. Using multiple fuel injections per cycle, but maintaining the same overall air-to-fuel ratio with single-injection strategies, a significant reduction in direct impingement on the walls was observed, together with different flame growth relative to single injection. These results suggest that injection strategy and type of fuel is playing an important role in the mixture preparation process, even for homogeneous early direct injection, and that different types of multiple-injection strategies alone have the potential to modify significantly in-cylinder phenomena, affect combustion and potentially exhaust emissions.

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Section: Asoi 7°mentioning

confidence: 99%

Mixture Preparation and Combustion Variability in a Spray-Guided DISI Engine

Serras-Pereira¹,

Aleiferis²,

Richardson

et al. 2007

SAE Technical Paper Series

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“…On the other hand, at high temperatures, the increased levels of evaporation and therefore mixture homogeneity (with early injection) may bias the sensitivity of flame motion toward dependency on the local velocity flow field, over the concentration field. This would explain to some extent the greater similarity of the flame motion for all fuels at high temperatures; it has been shown by Particle Image Velocimetry (PIV) studies [30,31] that the mean flow-field for this engine on the swirl plane is nearly symmetrical between the left and right side of the combustion chamber, with a central channel running through the centre of the combustion chamber from intake to exhaust side. However, the striking similarity in Figure 17 between the behaviour of the two alcohols versus the behaviour of iso-octane and gasoline, is worth pointing out and requires further investigation.…”

Section: Flame Growth and Motionmentioning

confidence: 99%

Characteristics of Ethanol, Butanol, Iso-Octane and Gasoline Sprays and Combustion from a Multi-Hole Injector in a DISI Engine

Serras-Pereira

Aleiferis

Richardson³

et al. 2008

SAE Int. J. Fuels Lubr.

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Recent pressures on vehicle manufacturers to reduce their average fleet levels of CO 2 emissions have resulted in an increased drive to improve fuel economy and enable use of fuels developed from renewable sources that can achieve a net reduction in the CO 2 output of each vehicle. The most popular choice for spark-ignition engines has been the blending of ethanol with gasoline, where the ethanol is derived either from agricultural or cellulosic sources such as sugar cane, corn or decomposed plant matter. However, other fuels, such as butanol, have also arisen as potential candidates due to their similarities to gasoline, e.g. higher energy density than ethanol. To extract the maximum benefits from these new fuels through optimized engine design and calibration, an understanding of the behaviour of these fuels in modern engines is necessary. In particular, the use of direct injection spark-ignition technology requires spray formation and combustion characteristics to be quantified in order to improve both injector design and operating strategies. To this end an optical investigation of spray development and combustion was undertaken in a single-cylinder direct-injection spark-ignition engine with a centrally mounted multi-hole injector. Specifically, crank-angle resolved imaging studies were performed and batches of images from 100 consecutive cycles were acquired with synchronised in-cylinder pressure logging. The engine was motored and fired at 1500 RPM stoichiometrically under part load (0.5 bar intake pressure), with injection timing set early in the intake stroke to promote homogeneous mixture formation. The effects were investigated at engine coolant temperatures of 20 °C and 90 °C using gasoline, iso-octane, ethanol and butanol. Projected spray areas as seen through the piston crown were calculated to reveal information about the atomization and evaporation processes for each fuel. Additionally, flame areas and centroids were calculated to analyse the combustion process relative to measured in-cylinder pressure histories.

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“…The flow affects predominantly the two plumes, 1 and 6, that are directed towards the spark plug at a much larger angle to the vertical, in comparison to plumes 2 and 5 and plumes 3 and 4. Plumes 1 and 6 are therefore much more sensitive to the incoming flow which is dominated by the strong intake valve jet around this injection timing, peaking in intensity at ~90° CA ATDC as measured by Jarvis et al [12] using Particle Image Velocimetry (PIV) in an engine of identical nominal geometry and with the same valve timings. The other plumes 2-5, are also affected by the intake flow but to a lesser extent.…”

Section: Spray Formation and Flow Effectsmentioning

confidence: 99%

“…Arrows have been drawn on the first image of each sequence in Figure 9 to show schematically the 'mean' incylinder flow in the engine as has been measured by PIV [12], to aid interpretation. These sequences of images are discussed below for each view individually.…”

Section: Spray Formation and Flow Effectsmentioning

confidence: 99%

Spray Development, Flow Interactions and Wall Impingement in a Direct-Injection Spark-Ignition Engine

Serras-Pereira¹,

Aleiferis²,

Richardson³

et al. 2007

SAE Technical Paper Series

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Levels of liquid fuel impingement on in-cylinder surfaces in direct injection spark ignition engines have typically been higher than those in port-fuel injection engines due to in-cylinder injection and higher injection pressures. The result is typically an increase in the levels of un-burned hydrocarbons and smoke emissions which reduce the potential fuel economy benefits associated with direct injection engines. Although different injection strategies can be used to reduce these effects to some extent, full optimisation of the injection system and combustion process is only possible through improved understanding of spray development that can be obtained from optical engine investigations under realistic operating conditions. To this extent, the spray formation from a centrally mounted multihole injector was studied in a single-cylinder optical directinjection spark-ignition engine under part-load conditions (0.5 bar intake plenum pressure) at 1500 RPM. A highspeed camera and laser illumination were used to obtain Mie-scattering images of the spray development on different in-cylinder planes for a series of consecutive engine cycles. The engine temperature was varied to reflect cold-start (20 °C) and fully warm (90 °C) engine conditions. A multicomponent fuel (commercial gasoline) and a singlecomponent fuel (iso-octane) were both tested and compared to investigate the effects of fuel properties on spray formation and wall impingement. An experimental arrangement was also developed to detect in-cylinder liquid fuel impingement using heat flux sensors installed on the cylinder liner. Two different injection strategies were tested; a typical single-injection strategy in the intake stroke to promote homogeneous mixture formation, as well as a triple-injection strategy around the same timing to assess the viability of using multiple-injection strategies to reduce wall impingement and improve mixture preparation. A sweep of different locations around the cylinder bore revealed the locations of highest fuel impingement levels which did not correspond directly to the nominal spray plume trajectories as a result of spray-flow interactions. These results were analysed in conjunction with the observed effects from the parallel imaging investigation.

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Motored SI IC Engine In-Cylinder Flow Field Measurement Using Time Resolved Digital PIV for Characterisation of Cyclic Variation

Cited by 38 publications

References 17 publications

Mixture Preparation and Combustion Variability in a Spray-Guided DISI Engine

Mixture Preparation and Combustion Variability in a Spray-Guided DISI Engine

Characteristics of Ethanol, Butanol, Iso-Octane and Gasoline Sprays and Combustion from a Multi-Hole Injector in a DISI Engine

Spray Development, Flow Interactions and Wall Impingement in a Direct-Injection Spark-Ignition Engine

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