PIV Measurements in the Swirl-Plane of a Motored Light-Duty Diesel Engine

Petersen, Benjamin; Miles, Paul C.

doi:10.4271/2011-01-1285

Cited by 33 publications

(25 citation statements)

References 19 publications

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“…In particular, no direct information is obtained from the flow fields within the piston bowl or velocities in the vertical plane. Using a completely transparent bowl, for instance as used by Cosadia et al (2007), Chartier et al (2011) and Petersen and Miles (2011), might further improve the knowledge on the influence of spray injections on the flow fields and therefore the mixing.…”

Section: High-speed Piv Setupmentioning

confidence: 99%

“…Recently, Müller et al (2010), Peterson and Sick (2009) and Krishna and Mallikarjuna (2010) showed the applicability of (HS-)PIV near the spark plug region in SI engines. PIV measurements in a light-duty diesel engine with a typical production piston with reentrant shape and valve cutout geometries were presented by Petersen and Miles (2011) and Yu et al (2006). The optical distortion observed through the curved surfaces of the fused silica piston bowl was successfully corrected.…”

Section: Introductionmentioning

confidence: 99%

“…However, when investigating the injection of a fuel spray in the swirl plane of a combustion engine, in which there is rotational symmetry in both flow and geometry, transforming the velocity information onto a polar grid, as done by Petersen and Miles (2011), can be expected to give more insight. By representing the data in radial and azimuthal directions, the influence of a radial injection of fuel on the dominantly azimuthal swirl can be investigated in more detail.…”

Section: Coordinate Definitionmentioning

confidence: 99%

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Pre- and post-injection flow characterization in a heavy-duty diesel engine using high-speed PIV

et al. 2012

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High-speed particle image velocimetry (HS-PIV) using hollow microspheres has been applied to characterize the flow in a heavy-duty diesel engine during and after fuel injection. The injection timings were varied in the range representing those used in premixed charge compression ignition (PCCI) regimes, and multiple injections have been applied to investigate their influence on the flow inside the combustion chamber. By injecting into pure nitrogen, combustion is avoided and the flow can be studied long after injection. The results show a sudden change of air motion at the start of injection as a result of the air entrainment at the core of the spray. Furthermore, as expected, spray injection causes a considerable increase in the cycle-to-cycle fluctuations of the flow pattern, the more so for longer injection durations.

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Section: High-speed Piv Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Coordinate Definitionmentioning

confidence: 99%

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Pre- and post-injection flow characterization in a heavy-duty diesel engine using high-speed PIV

et al. 2012

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“…Highly swirling flow has been successfully incorporated in both conventional gasoline and diesel engines to organize fuel-air mixing and combustion [19][20][21][22][23]. Swirl, possibly in combination with tumble and squish, is designed to promote large-scale transport of fuel-air mixture during fuel injection and to enhance the late-cycle mixing.…”

Section: Introductionmentioning

confidence: 99%

The role of spray-enhanced swirl flow for combustion stabilization in a stratified-charge DISI engine

Zeng¹,

Sjöberg²,

Reuss³

et al. 2016

Combustion and Flame

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Implementation of spray-guided stratified-charge direct-injection spark-ignited (DISI) engines is inhibited by the occurrence of misfire and partial burns. Engine-performance tests demonstrate that increasing engine speed induces combustion instability, but this deterioration can be prevented by generating swirling flow during the intake stroke. In-cylinder pressure-based heat-release analysis reveals that the appearance of poor-burn cycles is not solely dependent on the variability of early flame-kernel growth. Cycles can experience burning-rate regression during later combustion stages and may or may not recover before the end of the cycle. Thermodynamic analysis and optical diagnostics are used here to clarify why swirl improves the combustion repeatability from cycle to cycle.The fluid dynamics of swirl/spray interaction was previously demonstrated using high-speed PIV measurements of in-cylinder motored flow. It was found that the sprays of the multi-hole injector redistribute the intake-generated swirl flow momentum, thereby creating a better-centered higher angularmomentum vortex with reduced variability. The engine operation with high swirl was found to have significant improvement in cycle-to-cycle variations of both flow pattern and flow momentum. This paper is an extension of the previous work. Here, PIV measurements and flame imaging are applied to fired operation for studying how the swirl flow affects variability of ignition and subsequent combustion phases. PIV results for fired operation are consistent with the measurements made of motored flow. They demonstrate that the spark-plasma motion is highly correlated with the direction of the gas flow in the vicinity of the spark-plug gap. Without swirl, the plasma is randomly stretched towards either side of the spark plug, causing variability in the ignition of the two spray plumes that are straddling the spark plug. In contrast, swirl flow always convects the spark plasma towards one spray plume, causing a more repeatable ignition. The swirl decreases local RMS velocity, consistent with an observed reduction of early-burn variability. Broadband flame imaging demonstrates that with swirl, the flame consistently propagates in multiple directions to consume fuel-air mixtures within the piston bowl. In contrast, operation without swirl displays higher variability of flame-spread patterns, occasionally causing the appearance of partial-burn cycles.

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“…In [7], it was observed that the SN was fluctuating at different cycles which were repeated after each other. The SN also differs depending on how close to the fire deck the measurement is done [8]. In [9], PIV measurements were combined with CFD simulations and optical spray images.…”

Section: Introductionmentioning

confidence: 99%

Optical Study of Swirl during Combustion in a CI Engine with Different Injection Pressures and Swirl Ratios Compared with Calculations

Dembinski¹,

Ångström²

2012

SAE Technical Paper Series

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Spray and mixture formation in a compression-ignition engine is of paramount importance in the diesel combustion process. In an engine transient, when the load increases rapidly, the combustion system needs to handle low λ operation without producing high NO x emissions and large amounts of particulate matter. By changing the in-cylinder flow, the emissions and engine efficiency are affected. Optical engine studies were therefore performed on a heavy-duty engine geometry at different fuel injection pressures and inlet airflow characteristics. By applying different inlet port designs and valve seat masking, swirl and tumble were varied. In the engine tests, swirl number was varied from 2.3 to 6.3 and the injection pressure from 500 to 2500 bar. To measure the in-cylinder flow around TDC, particle image velocimetry software was used to evaluate combustion pictures. The pictures were taken in an optical engine using a digital high-speed camera. Clouds of glowing soot particles were captured by the camera and traced with particle image velocimetry software. The velocity-vector field from the pictures was thereby extracted and a mean swirl number was calculated. The swirl number was then compared with 1D simulation program GT-POWER and CFD based correlations. The GT-POWER simulations and CFD based correlation calculations were initiated from steady-state flow bench data on tested cylinder heads.The main conclusions from this study were that the mean swirl numbers, evaluated with the PIV software from combustion pictures around TDC, agreed with CFD based correlations and the low swirl numbers also correlated with the 1D-simulation program. Most of the induced swirl motion survives the compression and combustion, while the induced tumble does not survive to the late combustion phase. The tumble however, disturbs the swirl motion and offsets the swirl centre. This offset survives the compression and combustion. The diesel sprays that are injected symmetrically in the combustion chamber are thereby exposed to the swirl asymmetrically. This study also shows that the angular velocity at different piston bowl radii deviates from solid body rotation. The angular velocity is higher closer to the centre and decreases to be at the lowest value at the outer piston bowl edge. When the injection pressure is increased, the deviation from solid body rotation increases due to spray effects.

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PIV Measurements in the Swirl-Plane of a Motored Light-Duty Diesel Engine

Cited by 33 publications

References 19 publications

Pre- and post-injection flow characterization in a heavy-duty diesel engine using high-speed PIV

Pre- and post-injection flow characterization in a heavy-duty diesel engine using high-speed PIV

The role of spray-enhanced swirl flow for combustion stabilization in a stratified-charge DISI engine

Optical Study of Swirl during Combustion in a CI Engine with Different Injection Pressures and Swirl Ratios Compared with Calculations

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