scholarly journals Voltage rise anemometry in turbulent flows applied to internal combustion engines

2021 ◽  
Vol 62 (6) ◽  
Author(s):  
Michael Wörner ◽  
Gregor Rottenkolber
Keyword(s):  
Turbulent Flows ◽  
Internal Combustion Engines ◽  
Clear Correlation ◽  
Combustion Engines ◽  
Mean Flow ◽  
Voltage Rise ◽  
Mathematical Correlation ◽  
Thermodynamic Conditions ◽  
Secondary Voltage ◽  
Cylinder Flow

AbstractIn an experimental procedure, a voltage rise anemometry is developed as a measurement technique for turbulent flows. Initially, fundamental investigations on a specific wind tunnel were performed for basic understanding and calibration purpose. Thus, a mathematical correlation is derived for calculating flow from measured secondary voltage of an ignition system under different thermodynamic conditions. Subsequently, the derived method was applied on a spark-ignited engine to measure in-cylinder flow. Therefore, no changes on combustion chamber were necessary avoiding any interferences of the examined flow field. Comparing four different engine configurations, a study of mean flow and turbulence was performed. Moreover, the results show a clear correlation between measured turbulence and analysed combustion parameters. Graphic abstract

Investigating the Origins of Cyclic Variability in Internal Combustion Engines Using Wall-Resolved Large Eddy Simulations

2021 ◽  
Author(s):  
Sicong Wu ◽  
Saumil S. Patel ◽  
Muhsin M. Ameen
Keyword(s):  
Energy Distribution ◽  
Combustion Chamber ◽  
Internal Combustion Engines ◽  
Engine Performance ◽  
Internal Combustion ◽  
Operating Conditions ◽  
Large Eddy Simulations ◽  
Combustion Engines ◽  
Large Eddy ◽  
Cylinder Flow

Abstract Modern internal combustion engines (ICE) operate at the ragged edge of stable operation characterized by high cycle-to-cycle variations (CCV). A key scientific challenge for ICE is the understanding, modeling, and control of CCV in engine performance, which can contribute to partial burns, misfire, and knock. The objective of the current study is to use high-fidelity numerical simulations to improve the understanding of the causes of CCV. Nek5000, a leading high-order spectral element, open source code, is used to simulate the turbulent flow in the engine combustion chamber. Multi-cycle, wall-resolved large-eddy simulations (LES) are performed for the General Motors (GM), Transparent Combustion Chamber (TCC-III) optical engine under motored operating conditions. The mean and root-mean-square (r.m.s.) of the in-cylinder flow fields at various piston positions are validated using PIV measurements during the intake and compression strokes. The large-scale flow structures, including the swirl and tumble flow patterns, are analyzed in detail and the causes for cyclic variabilities in these flow features are explained. The energy distribution across the different scales of the flow are quantified using one-dimensional energy spectra, and the effect of the tumble breakdown process on the energy distribution is examined. The insights from the current study can help us develop improved engine designs with reduced cyclic variabilities in the in-cylinder flow leading to enhanced engine performance.

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.

Application of Reynolds Stress Modeling to Engine Flow Calculations

1996 ◽  
Vol 118 (4) ◽  
pp. 710-721 ◽  
Author(s):  
L. Lebre`re ◽  
M. Buffat ◽  
L. Le Penven ◽  
B. Dillies
Keyword(s):  
Reynolds Stress ◽  
Turbulence Model ◽  
Internal Combustion Engines ◽  
Plane Channel ◽  
Combustion Engines ◽  
Mean Flow ◽  
Compression Stroke ◽  
Precise Knowledge ◽  
Combustion Processes ◽  
Plane Channel Flow

To improve the prediction of turbulence inside internal combustion engines, a Reynolds stress turbulence model is implemented in the Kiva-II code. After a rapid description of the Launder-Reece-Rodi model (noted LRR), two validation test cases (the plane channel flow and the flow over a backward facing step) are presented. The advantages of a second order closure and the shortcomings of the LRR model are then analyzed. Finally, a simulation of an intake and compression stroke using both the standard k – ε model and the LRR model is described. As a precise knowledge of the velocity and turbulent fields near TDC is necessary for the prediction of the mixing and the combustion processes, we have analyzed the influence of the turbulence model on the flow field. Results are compared with experimental data and show a strong influence of the turbulence model even on the mean flow, especially at the end of the compression stroke (TDC).

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