In-Cylinder Flow Analysis in a Two-Stroke Engine - A Comparison of Different Turbulence Models Using CFD
08 Apr 2013-
About: The article was published on 2013-04-08. It has received 29 citations till now. The article focuses on the topics: Two-stroke engine & Turbulence.
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TL;DR: In this article, the in-cylinder flow field analysis in a two-stroke engine under motoring conditions by particle image velocimetry (PIV) and computational fluid dynamics (CFD) was conducted.
43 citations
TL;DR: In this paper, the effect of injection strategy and intake valve lift (IVL) on super-knock frequency and engine performance through experimental study was investigated, and the validated numerical models revealed the mechanisms behind experimental results.
27 citations
TL;DR: In this paper, the effect of engine parameters on the characteristics of a GDI engine by CFD analysis was carried out at three engine speeds (2000, 3000, and 4000 rev/min), at three compression ratios (10, 11, and 12) and at three fuel injection pressures (200, 300, and 400 bar).
Abstract: The present study focuses on the evaluation of the effect of engine parameters on the characteristics of a GDI engine by CFD analysis. The analysis was carried out at three engine speeds (2000, 3000, and 4000 rev/min), at three compression ratios (10, 11, and 12) and at three fuel injection pressures (200, 300, and 400 bar). The overall equivalence ratio of the in-cylinder mixture was maintained at 0.75 in all the above cases. Finally, it is observed that, the turbulent kinetic energy and tumble ratio were more sensitive to the engine speed than to other parameters. The fuel injection pressure was found to play a vital role in obtaining combustible mixture near the spark plug at the time of spark. In addition, a low heat release rate occurred at the engine speed of 4000 rev/min compression ratio of 10 and fuel injection pressure of 200 bar.
22 citations
Cites background or methods from "In-Cylinder Flow Analysis in a Two-..."
...The flow turbulence is analyzed using the renormalized group (RNG) k-e model [16,17]....
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...where xi is the angular speed of flow in i direction and xcrank shaft is the angular speed of crank shaft [16,23]....
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TL;DR: In this article, the authors present complementary metrics, weighted using a function of the local velocity, for robust quantification of the alignment and magnitude differences between vector fields, the weighted relevance index (WRI) and the weighted magnitude index(WMI).
Abstract: The in-cylinder flow field plays a key role in determining the combustion performance of internal combustion engines (ICEs) and it is critically important to validate numerical simulations of the flow field by comparison to experimental measurements using techniques such as particle image velocimetry (PIV). With the current trend for high-speed diagnostics, methods for quantitative comparison of vector fields are required which can provide robust spatially averaged results, without inspection of individual flow fields. The quality of match between vector fields, when quantified using current metrics such as the relevance index (RI), can be overly sensitive to the alignment of regions of low velocity such as the tumble vortex centre. This work presents complementary metrics, weighted using a function of the local velocity, for robust quantification of the alignment and magnitude differences between vector fields, the weighted relevance index (WRI) and the weighted magnitude index (WMI). These metrics are also normalized and combined in the combined magnitude and relevance index (CMRI). PIV measurements taken up to every 2 crank angle degrees within the tumble plane of a motored, optically accessible ICE are used to demonstrate the motivation for development and the application of the WRI, WMI, and CMRI metrics. The metrics are used to determine the number of cycles required to provide a representative mean flow field and to identify single cycles of interest. Variability of the flow field is quantified using the metrics and shows high variability in the region of the spark plug near typical ignition timings. Graphic abstract
14 citations
TL;DR: In this article, the performance of a hydrogen ORP engine under part load and stoichiometric conditions was investigated using a 3D numerical simulation approach, and the results indicated that peak in-cylinder pressure during combustion was significantly dependent on the intake manifold pressure and the corresponding crank angle was almost kept the same for 1000 RPM and 3000 RPM.
14 citations
References
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TL;DR: In this paper, the authors present a review of the applicability and applicability of numerical predictions of turbulent flow, and advocate that computational economy, range of applicability, and physical realism are best served by turbulence models in which the magnitudes of two turbulence quantities, the turbulence kinetic energy k and its dissipation rate ϵ, are calculated from transport equations solved simultaneously with those governing the mean flow behaviour.
11,866 citations
TL;DR: In this article, a dynamic renormalization group (RNG) method for hydrodynamic turbulence was developed, which uses dynamic scaling and invariance together with iterated perturbation methods, allowing us to evaluate transport coefficients and transport equations for the large scale (slow) modes.
Abstract: We develop the dynamic renormalization group (RNG) method for hydrodynamic turbulence. This procedure, which uses dynamic scaling and invariance together with iterated perturbation methods, allows us to evaluate transport coefficients and transport equations for the large-scale (slow) modes. The RNG theory, which does not include any experimentally adjustable parameters, gives the following numerical values for important constants of turbulent flows: Kolmogorov constant for the inertial-range spectrumCK=1.617; turbulent Prandtl number for high-Reynolds-number heat transferPt=0.7179; Batchelor constantBa=1.161; and skewness factor¯S3=0.4878. A differentialK-\(\bar \varepsilon \) model is derived, which, in the high-Reynolds-number regions of the flow, gives the algebraic relationv=0.0837 K2/\(\bar \varepsilon \), decay of isotropic turbulence asK=O(t−1.3307), and the von Karman constantκ=0.372. A differential transport model, based on differential relations betweenK,\(\bar \varepsilon \), andν, is derived that is not divergent whenK→ 0 and\(\bar \varepsilon \) is finite. This latter model is particularly useful near walls.
3,342 citations
TL;DR: In this paper, a review of the limited number of LES applications to engine flows is given, and most significant results from these studies are presented, along with the main characteristics of in-cylinder flows.
Abstract: While engineering applications of the large eddy simulation (LES) technique are becoming a common reality in many branches of engineering and science, its application to engine flows has lagged behind due to the relatively more complex nature of both the flow and the geometry relevant to in-cylinder flows. In this paper a review of the limited number of LES applications to engine flows is given, and most significant results from these studies are presented. Also, the LES formulation appropriate for engine applications is briefly described, along with the main characteristics of in-cylinder flows. As expected, engine applications of LES are not of the so-called ‘high-fidelity’ type, but rather they employ formally second-order accurate numerical schemes in conjunction with finite volume formulation. The subgrid scale (SGS) models used are also kept as simple as possible, mostly using a variant of the Smagorinsky model. Nevertheless, this review reveals that even with relatively coarse grids, LES ca...
131 citations
TL;DR: In this paper, the authors used particle image velocimetry (DPIV) to examine the flow field in a vessel agitated by an axial-flow impeller in turbulent operation.
Abstract: Digital particle image velocimetry (DPIV) has been used to examine the flow field in a vessel agitated by an axial-flow impeller in turbulent operation. Both a pitched-blade turbine and a high-efficiency impeller were studied. Time series analysis indicates that the flow field is not steady; rather, it is subject to transients with frequencies well below the blade passage frequency (periods ranging from 40 to over 300 impeller revolutions have been observed). This result has important implications for computational modeling because current descriptions of agitated vessels are based upon time-averaged flow fields with superimposed turbulence. This modeling approach may not accurately capture the mixing associated with the low-frequency phenomena observed in this study.
68 citations
TL;DR: In this paper, the evolution processes of the in-cylinder flows in the axial and diametral planes of a motored two-valve, singlecylinder, four-stroke engine during the intake and compression strokes are diagnosed by using a particle image velocimeter.
66 citations