In-Cylinder Flow Analysis in a Two-Stroke Engine - A Comparison of Different Turbulence Models Using CFD

2013 ◽  
Author(s):  
Addepalli S Krishna ◽  
Jawali Maharudrappa Mallikarjuna ◽  
Kumar Davinder ◽  
Y Ramachandra Babu
Keyword(s):  
Flow Analysis ◽  
Turbulence Models ◽  
Cylinder Flow ◽  
Stroke Engine

Multidimensional Predictions of In-Cylinder Turbulent Flows: Contribution to the Assessment of k-ε Turbulence Model Variants for Bowl-in-Piston Engines

2005 ◽  
Vol 127 (4) ◽  
pp. 883-896 ◽  
Author(s):  
Mirko Baratta ◽  
Andrea E. Catania ◽  
Ezio Spessa ◽  
Rui L. Liu
Keyword(s):  
Turbulent Flows ◽  
Turbulence Model ◽  
Internal Combustion Engines ◽  
Flow Analysis ◽  
Combustion Process ◽  
Turbulence Models ◽  
Wall Functions ◽  
Spacing Effects ◽  
Flow Phenomena ◽  
Cylinder Flow

Multidimensional computational fluid dynamics (CFD) codes with reliable turbulence models are useful investigation and design tools for internal combustion engines, in-cylinder flow phenomena being critical to the combustion process and related emission sources. Although a variety of turbulence models has long been proposed, the assessment of even the most widely used k-ε model is still lacking, especially for bowl-in-piston engines. This paper provides a survey of k-ε turbulence model variants and their numerical implementation for in-cylinder flow analysis. Mean motion and turbulence quantities were simulated in the axisymmetric combustion chamber of a motored model engine featuring one centrally located valve and each of a flat-piston and cylindrical bowl-in-piston arrangements. A noncommercial CFD code developed by the authors was applied for calculation, using a finite-volume conservative implicit method and applying various order-of-accuracy numerical schemes. Simulation results are presented at the engine speed of 200 rpm throughout the whole engine cycle. These were obtained using three k-ε turbulence model versions, standard, renormalization group (RNG) and two scale, each of which focuses on one main engine flow feature, i.e., compressibility, anisotropy, and high unsteadiness, respectively. Modified boundary conditions with respect to conventional logarithmic wall functions were applied. Effects of equation-differencing scheme and computational-grid spacing effects on flow predictions were tested. The numerical results were compared to those of laser Doppler velocimetry measurements and the influence of the k-ε model variants on the flow-field features was examined during the induction stroke and around compression top dead center. For the flat-piston case, a comparison between the homemade and commercial STAR-CD® code results was also made.

Study of the Change of Performance of an Elastic Vertical Hydrofoil With Deformation

2014 ◽  
Author(s):  
Alexander Führing ◽  
Subha Kumpaty ◽  
Chris Stack
Keyword(s):  
Water Flow ◽  
Lift Coefficient ◽  
Flow Analysis ◽  
Turbulence Models ◽  
Flow Property ◽  
Performance Data ◽  
Cfd Analysis ◽  
Ansys Fluent ◽  
Drag Forces ◽  
Fluid Flow Analysis

In external and internal fluid flow analysis using numerical methods, most attention is paid to the properties of the flow assuming absolute rigidity of the solid bodies involved. However, this is often not the case for water flow or other fluids with high density. The pressure forces cause the geometry to deform which in turn changes the flow properties around it. Thus, a one-way and two-way Fluid-Structure Interaction (FSI) coupling is proposed and compared to a CFD analysis of a windsurfing fin in order to quantify the differences in performance data as well as the properties of the flow. This leads to information about the necessity of the use of FSI in comparison to regular CFD analysis and gives indication of the value of the enhanced results of the deformable analysis applied to water flow around an elastically deformable hydrofoil under different angles of attack. The performance data and flow property evaluation is done in ANSYS Fluent using the k-ω SST and k-ε model with a y+ of 1 and 35 respectively in order to be able to compare the behavior of both turbulence models. It is found that the overall lift coefficient in general is lower and that the flow is less turbulent because of softer transition due to the deformed geometry reducing drag forces. It is also found that the deformation of the tip of the hydrofoil leads to vertical lift forces. For the FSI analysis, one-way and two-way coupling were incorporated leading to the ability to compare results. It has been found that one-way coupling is sufficient as long as there is no stall present at any time.

A spark-plug LDV probe for in-cylinder flow analysis of production IC engines

2005 ◽  
Vol 16 (10) ◽  
pp. 2038-2047 ◽  
Author(s):  
Ergin Esirgemez ◽  
Semih M Ölçmen
Keyword(s):  
Flow Analysis ◽  
Spark Plug ◽  
Ic Engines ◽  
Cylinder Flow

Flow Analysis of a Hydrocyclone Designed to High Oil Content Application

2009 ◽  
Author(s):  
G. M. Raposo ◽  
A. O. Nieckele
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Oil Content ◽  
Flow Analysis ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Tangential Component ◽  
Inlet Flow ◽  
Unit Process ◽  
Inlet Flow Rate

Development of small size and weight separation equipment are crucial for the petroleum off-shore exploration. Since centrifugal fields are several times stronger than the gravity field, cyclonic separation has became very important as a unit process for compact gas-liquid, liquid-liquid and solid-liquid separation. The major difference between the various cyclones is their geometry. Cyclone optimization for different uses is, every year, less based on experiments and more based on mathematical models. In the present work, the flow field inside high oil content hydrocyclones is numerically obtained with FLUENT. The performance of two turbulence models, Reynolds Stress Model (RSM) and Large Eddy Simulation (LES), to predict the flow inside a high oil content hydrocyclone, is investigated by comparing the results with experimental data available in the literature. All models overpredicted the tangential component, especially at the reverse cone region. However, the prediction of the tangential turbulent fluctuations with LES was significant better than the RSM prediction. The influences of the inlet flow rate and hydrocyclone length in the flow were also evaluated. RSM model was able to foresee correctly, in agreement with experimental data, the correct tendency of pressure drop reduction with decreasing inlet flow rate and increasing length.

On the Effects of Turbulence Modeling on the Fluid-Structure Interaction of a Rigid Cylinder

2016 ◽  
Author(s):  
Guilherme Feitosa Rosetti ◽  
Guilherme Vaz ◽  
André Luís Condino Fujarra
Keyword(s):  
Turbulence Modeling ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Boundary Layer Separation ◽  
Turbulent Transition ◽  
Moving Cylinder ◽  
Wide Range ◽  
Cylinder Flow ◽  
Laminar Turbulent Transition

The cylinder flow is a canonical problem for Computational Fluid Dynamics (CFD), as it can display several of the most relevant issues for a wide class of flows, such as boundary layer separation, vortex shedding, flow instabilities, laminar-turbulent transition and others. Several applications also display these features justifying the amount of energy invested in studying this problem in a wide range of Reynolds numbers. The Unsteady Reynolds Averaged Navier Stokes (URANS) equations combined with simplifying assumptions for turbulence have been shown inappropriate for the captive cylinder flow in an important range of Reynolds numbers. For that reason, recent improvements in turbulence modeling has been one of the most important lines of research within that issue, aiming at better prediction of flow and loads, mainly targeting the three-dimensional effects and laminar-turbulent transition, which are so important for blunt bodies. In contrast, a much smaller amount of work is observed concerning the investigation of turbulent effects when the cylinder moves with driven or free motions. Evidently, larger understanding of the contribution of turbulence in those situations can lead to more precise mathematical and numerical modeling of the flow around a moving cylinder. In this paper, we present CFD calculations in a range of moderate Reynolds numbers with different turbulence models and considering a cylinder in captive condition, in driven and in free motions. The results corroborate an intuitive notion that the inertial effects indeed play very important role in determining loads and motions. The flow also seems to adapt to the motions in such a way that vortices are more correlated and less influenced by turbulence effects. Due to good comparison of the numerical and experimental results for the moving-cylinder cases, it is observed that the choice of turbulence model for driven and free motions calculations is markedly less decisive than for the captive cylinder case.

Three-Dimensional Flow Analysis for Estimation of Measuring Error of Orifice Flowmeter Due to Upstream Flow Distortion

2002 ◽  
Author(s):  
Hong-Min Kim ◽  
Kwang-Yong Kim ◽  
Jae-Young Her ◽  
Young-Chul Ha
Keyword(s):  
Flow Analysis ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Measuring Error ◽  
Flow Distortion ◽  
Three Dimensional Flow ◽  
Pipe System ◽  
Orifice Flow ◽  
Orifice Flow Meter ◽  
Upstream Flow

Three-dimensional pipe flows with elbows and tees are calculated to estimate the effect of upstream flow distortion on measuring accuracy of orifice flow meter. Axisymmetric flows through orifice are calculated first to evaluate the performances of various numerical schemes and turbulence models. In three-dimensional calculations of the flow in pipe system, it is evaluated how the pressure difference across the orifice is dependent on the length of upstream straight pipe in a branch. From the results, it is found that, regardless of flow rate, the effect of the length can be neglected for the lengths larger than thirty diameters although there still remain significant swirl at the orifice.

Visual Experiment of In-cylinder Flow by Laser Sheet Method : Scavenging Flow of Two-stroke Engine with Poppet Valves

2003 ◽  
Vol 2003 (0) ◽  
pp. 265-266
Author(s):  
Shinichiro ITOH ◽  
Masamitsu NAKANO ◽  
Kensuke USUI ◽  
Kazuo SATO
Keyword(s):  
Laser Sheet ◽  
Cylinder Flow ◽  
Stroke Engine ◽  
Poppet Valves
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