Comparison Between In-Cylinder PIV Measurements, CFD Simulations and Steady-Flow Impulse Torque Swirl Meter Measurements

Nordgren, Henrik; Hildingsson, L.; Johansson, Bengt; Dahlén, Lars; Konstanzer, Dennis

doi:10.4271/2003-01-3147

Cited by 24 publications

(10 citation statements)

References 5 publications

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“…They are easily seeded into the intake air and do not have any negative influence on the engine behavior, but cleaning of the intake manifold, piston rings, cylinder head and piston is necessary after a few measurements. A similar kind of approach using microspheres can be found in the papers by Towers and Towers (2004), Ekenberg et al (2001) and Nordgren et al (2003).…”

Section: High-speed Piv Setupmentioning

confidence: 96%

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: 96%

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

et al. 2012

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“…The tumble flow disturbs the swirling flow and tilts the swirl centre axis. Some of the tumble flow is transformed into small-scale turbulence during compression, but the off-centre location of the swirl centre, also observed in [5], survives the compression and the combustion, as seen in the following figures. In the case with the flat piston bowl and low SN-head, the trend was opposite.…”

Section: Optical Engine Testmentioning

confidence: 84%

“…With two ports, the swirling flow had less structure that did not rotate around a swirl centreline. Unstructured flow makes it harder to organize the flow around a centre-point, as observed in [5]. Low SN gives less structure.…”

Section: Optical Engine Testmentioning

confidence: 92%

“…To create an understanding of how the in-cylinder flow behaves, particle image velocitmetry (PIV) measurements are commonly used in both constant flow rigs and motored engines. In [5], PIV measurements were done from inlet stroke until close to firing TDC and compared with CFD calculations on the same engine geometry as used in this paper. The main conclusion was that, before TDC, the swirl centre moves around and does not coincide with the geometrical cylinder centre.…”

Section: Introductionmentioning

confidence: 99%

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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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“…These investigations have shown that complex flow structures like swirl, tumble and turbulence exist inside the engine cylinder, even after the closure of the intake valve [16]. Nordgren et al [17] studied the in-cylinder air motion through experimental and theoretical methods viz., PIV and CFD. Sweetland and Reitz [18] used the KIVA code to study the in-cylinder flow field during the intake and compression strokes using real intake port geometry and moving intake valves.…”

Section: Introductionmentioning

confidence: 99%

Effects of Scavenging System Configuration on In-Cylinder Air Flow Organization of an Opposed-Piston Two-Stroke Engine

Zhao

Zhang

et al. 2015

Energies

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Abstract:In-cylinder air flow is very important from the point of view of mixture formation and combustion. In this direction, intake chamber structure and piston crown shape play a very crucial role for in-cylinder air pattern of opposed-piston two-stroke (OP2S) engines. This study is concerned with the three-dimensional (3D) computational fluid dynamics (CFD) analysis of in-cylinder air motion coupled with the comparison of predicted results with the zero-dimensional (0D) parametric model. Three configurations viz., a flat piston uniform scavenging chamber, a flat piston non-uniform scavenging chamber and a pit piston non-uniform scavenging chamber have been studied. 0D model analysis of in-cylinder air flow is consistent with 3D CFD simulation. It is concluded that a pit piston non-uniform scavenging chamber is the best design from the point of view of tumble ratio, turbulent kinetic energy and turbulent intensity, which play very important roles in imparting proper air motion. Meanwhile a flat piston uniform scavenging chamber can organize a higher swirl ratio and lower tumble ratio which is important to improve the scavenging process.

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Comparison Between In-Cylinder PIV Measurements, CFD Simulations and Steady-Flow Impulse Torque Swirl Meter Measurements

Cited by 24 publications

References 5 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

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

Effects of Scavenging System Configuration on In-Cylinder Air Flow Organization of an Opposed-Piston Two-Stroke Engine

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