Effect of the piston top contour on the tumble flow and combustion features of a GDI engine with a CMCV: a CFD study

Yin, Congbo; Zhang, Zhendong; Sun, Yao; Sun, Tao; Zhang, Ren‐Jie

doi:10.1080/19942060.2016.1157099

Cited by 17 publications

(12 citation statements)

References 31 publications

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“…As previously highlighted, PumpLinx adopts the k-ε model, which is widely used in the prediction of several turbulent flow calculations due to its robustness, economy, and reasonable accuracy for a wide range of flows. However, it has been also demonstrated that this model performs poorly when faced with non-equilibrium boundary layers as in the case of -tumble‖ motion at the entrance [50].…”

Section: Scroll Simulation Without Axial Gapmentioning

confidence: 99%

Analysis of the Inner Fluid-Dynamics of Scroll Compressors and Comparison between CFD Numerical and Modelling Approaches

Cavazzini¹,

Giacomel²,

Benato³

et al. 2021

Advances in Energy Research

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Scroll compressors are widely adopted machines in both refrigeration systems and heat pumps. However, their efficiency is basically poor and constitutes the main bottleneck for improving the overall system performance. In fact, due to the complex machine fluid dynamics, scroll design is mainly based on theoretical and/or semi-empirical approaches. Designs strategies that do not guarantee an in-depth analysis of the machine behavior can be supplemented with a Computation Fluid Dynamics (CFD) approach. To this purpose, in the present work, the scroll compressor inner fluid dynamics is numerically analyzed in detail using two CFD software and two different modelling strategies for the axial gap. The analysis of the fluid evolution within the scroll wraps reveals unsteady phenomena developing during the suction and discharge phases, amplified by the axial clearance with negative impact on the main fluid flow (e.g., −13% of average mass flow rate for an axial gap of 30 µ) and on the scroll performance (e.g., +26% of average absorbed power for an axial gap of 30 µ). In terms of accuracy, the k-ε offers good performance on the estimation of average quantities but proves to be inadequate for capturing the complexity of the unsteady phenomena caused by the axial gap (e.g., −19% of the absorbed power in case of perfect tip seal). The need for Advances in Energy Research: 2 nd Edition 3 www.videleaf.com considering specific geometric details in design procedures is highlighted, and guidelines on the choice of the most suitable numerical model are provided depending on the analysis needs.

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Section: Scroll Simulation Without Axial Gapmentioning

confidence: 99%

Analysis of the Inner Fluid-Dynamics of Scroll Compressors and Comparison between CFD Numerical and Modelling Approaches

Cavazzini¹,

Giacomel²,

Benato³

et al. 2021

Advances in Energy Research

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show abstract

“…Such simplifying assumptions, even if may affect the consistency of the heat transfer estimation at a local level, should not drastically influence the accuracy of the prediction the in-cylinder flow and turbulence fields, which are the main focuses of the presented work. A similar approach was followed in other researches oriented to the flow description, such as, for instance, [11,12].…”

Section: Cfd 3d Model Setup and Preliminary Validationmentioning

confidence: 99%

CFD 3D Analysis of Charge Motion and Combustion in a Spark-Ignition Internal Combustion Engine under Close-to-Idle Condition

Bozza

Bellis

Fantoni³

et al. 2020

E3S Web Conf.

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The increasingly stringent limitations on noxious missions of transport sector highly affect the development of new engines. The operating conditions of the engine at low-load and idle play a relevant role along the regulatory homologation cycles, contributing to overall emissions. In this work, the effectiveness of some solutions to improve the behaviour under close-to-idle operation of a Spark-Ignition motorcycle engine are compared by 3D CFD analyses. Specifically, the effects of two designs of the intake port and of the opening direction of the throttle valve, either clockwise or counterclockwise, are investigated. Multi-cycle simulations are carried out, under motored and fired conditions, for a single close-to-idle operating point. The various designs are compared in terms of capability to generate a stable tumble vortex during the intake phase and to produce an adequate turbulence level at the beginning of the combustion process. The analyses revealed that a clockwise throttle opening can produce enhanced turbulence levels at the end of the compression stroke, especially in a close-to-spark region (increase of about 5% and 27 % at the TDC at a global and local level, respectively, compared to the base configuration). Additional limited improvements are obtained with the high tumbling design, where, however, a penalty on the maximum power output could emerge. The flow and turbulence motion differences among the tested geometries reflect on combustion development in its early stage, and on its degree of completeness at the exhaust valve opening. A clockwise opening of the throttle valve leads to an increase of the mass fraction burned of 5 percent points, compared to the base configuration.

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“…The cylinder-to-cylinder variation is closely associated with the intake process in GDI engines, and it is inevitable, but it has a crucial impact on engine performance 16 . Additionally, in the GDI engine system, the tumble flow in the cylinder generated by intake process determine the turbulent intensity, mixing process, and further the combustion process 17 . Therefore, the intake system needs to be developed because the difference of charged air mass and turbulent intensity by intake manifold geometry between cylinders causes the variation of combustion characteristics 18 .…”

Section: Introductionmentioning

confidence: 99%

Effect of Intake Manifold Geometry on Cylinder-to-Cylinder Variation and Tumble Enhancement in Gasoline Direct Injection Engine

Shin

Kim

Son

et al. 2022

Preprint

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In order to improve the performance of the gasoline direct injection engine system, it is fundamentally important to reduce the cylinder-to-cylinder variation which affected by the intake manifold geometry. Furthermore, the early tumble development which influences the characteristics of the mixture as followed by the atomization and evaporation of the fuel, also greatly affects engine performance. Thus, in this study, the cylinder-to-cylinder variation in volumetric efficiency and tumble for two different type of intake manifold (curved type and straight type) was investigated using computational fluid dynamic program, CONVERE v2.4. And influence of the intake manifold curve radius to the early flow intensity and tumble development was analyzed. As a result, it was advantageous for cylinder-to-cylinder variation in the straight intake manifold compared to the curved intake manifold. When the intake manifold curve radius was increased in the straight intake manifold, it was effective in strengthening the early flow and tumble intensity. At 3000 rpm, the distance from the intake manifold inlet to the port also had an effect. Therefore, it is possible to improve the intake manifold performance by increasing the intake manifold curve radius and adapting turbocharging at engine speeds above 3000 rpm.

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Effect of the piston top contour on the tumble flow and combustion features of a GDI engine with a CMCV: a CFD study

Cited by 17 publications

References 31 publications

Analysis of the Inner Fluid-Dynamics of Scroll Compressors and Comparison between CFD Numerical and Modelling Approaches

Analysis of the Inner Fluid-Dynamics of Scroll Compressors and Comparison between CFD Numerical and Modelling Approaches

CFD 3D Analysis of Charge Motion and Combustion in a Spark-Ignition Internal Combustion Engine under Close-to-Idle Condition

Effect of Intake Manifold Geometry on Cylinder-to-Cylinder Variation and Tumble Enhancement in Gasoline Direct Injection Engine

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