Comparing Different Turbulence Modelling Approaches for Square Duct Simulations Using the Kiva Code

2004 ◽  
Author(s):  
V. Huijnen ◽  
L. M. T. Somers ◽  
R. S. G. Baert ◽  
L. P. H. de Goey
Keyword(s):  
Internal Combustion Engines ◽  
Turbulence Modelling ◽  
Time Dependent ◽  
Combustion Engines ◽  
Strong Anisotropy ◽  
Square Duct ◽  
Algebraic Stress Model ◽  
Duct Geometry ◽  
Computational Resources ◽  
Les Model

In internal-combustion engines (ICE) the fluid dynamics is characterized by strong anisotropy. The standard two equation k–ε model is well known to be not appropriate in this case. A detailed study of the numerical modelling properties of the well known Kiva-3V code has been performed for two different approaches to anisotropic turbulence modelling. In the first approach a Smagorinsky-type LES model is evaluated. In the second approach a Time-Dependent RANS model has been adopted, using the Explicit Algebraic Stress Model of Gatski and Speziale [1]. For validation of both approaches numerical simulations of a turbulent flow in a square duct geometry are compared to DNS data. It is concluded from this work that the applied RANS approach is the best available practise to model the anisotropic properties of the fluid flow for ICE simulations as long as the computational resources to perform real LES simulations remain limited.

Sensitivity Analysis of the Air Flow inside a Single Cylinder Engine for Different Turbulence Models Using CFD

2014 ◽  
Vol 1016 ◽  
pp. 624-629
Author(s):  
Felipe Grossi L. Amorim ◽  
Jean Helder M. Ribeiro ◽  
Marília Gabriela J. Vaz ◽  
Ramon Molina Valle
Keyword(s):  
Internal Combustion Engines ◽  
Turbulence Models ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Single Cylinder ◽  
Greenhouse Gases Emissions ◽  
Single Cylinder Engine ◽  
Computational Resources ◽  
Experimental Pressure

Theincrease of greenhouse gases emissions makes necessary to improve the comprehension of the Internal Combustion Engines operation. One of the factors that affect the combustion in these engines is the turbulence, since it can raise the quality of the fuel-air mixture inside the combustion chamber. However, when modeling internal combustion engines using CFD, the turbulence model choice is always a relevant problem. The present paper analyzes the results for three different turbulence models (k-ε Realizable, RNG k-ε and Menter k-ω SST) ina single-cylinder engine geometry, comparing numerical and experimental pressure data. For this experiment, the k-ε models obtained more trustable results than the k-ω SST, using less computational resources. The models achieved good results for eddy recirculation inside de cylinder and in regions of free shear flow at the valve openings, which makes possible to observe the correlation between parameters such as tumble and turbulent kinetic energy.

scholarly journals Development and validation of a hybrid temporal LES model in the perspective of applications to internal combustion engines

2019 ◽  
Vol 74 ◽  
pp. 56
Author(s):  
Al Hassan Afailal ◽  
Jérémy Galpin ◽  
Anthony Velghe ◽  
Rémi Manceau
Keyword(s):  
Steady Flow ◽  
Channel Flow ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Core Region ◽  
Wall Region ◽  
Combustion Engines ◽  
The Core ◽  
Les Model ◽  
Near Wall

CFD simulation tools are increasingly used nowadays to design more fuel-efficient and clean Internal Combustion Engines (ICE). Within this framework, there is a need to benefit from a turbulence model which offers the best compromise between prediction capabilities and computational cost. The Hybrid Temporal LES (HTLES) approach is here retained within the perspective of an application to ICE configurations. HTLES is a hybrid Reynolds-Averaged Navier Stokes/Large Eddy Simulation (RANS/LES) model based on a solid theoretical framework using temporal filtering. The concept is to model the near-wall region in RANS and to solve the turbulent structures in the core region if the temporal and spatial resolutions are fine enough. In this study, a dedicated sub-model called Elliptic Shielding (ES) is added to HTLES in order to ensure RANS in the near-wall region, regardless of the mesh resolution. A modification of the computation of the total kinetic energy and the dissipation rate was introduced as first adaptions of HTLES towards non-stationary ICE configurations. HTLES is a recent approach, which has not been validated in a wide range of applications. The present study intends to further validate HTLES implemented in CONVERGE code by examining three stationary test cases. The first validation consists of the periodic hill case, which is a standard benchmark case to assess hybrid turbulence models. Then, in order to come closer to real ICE simulations, i.e., with larger Reynolds numbers and coarser near-wall resolutions, the method is validated in the case of a channel flow using wall functions and in the steady flow rig case consisting in an open valve at a fixed lift. HTLES results are compared to RANS k-ω SST and wall-modeled LES σ simulations performed with the same grid and the same temporal resolution. Unlike RANS, satisfactory reproduction of the flow recirculation has been observed with HTLES in the case of periodic hills. The channel flow configuration has underlined the capability of HTLES to predict the wall friction properly. The steady flow rig shows that HTLES combines advantages of RANS and LES in one simulation. On the one hand, HTLES yields mean and rms velocities as accurate as LES since the scale-resolving simulation is triggered in the core region. On the other hand, hybrid RANS/LES at the wall provides accurate pressure drop in contrast with LES performed on the same mesh. Future work will be dedicated to the extension of HTLES to non-stationary flows with moving walls in order to be able to tackle realistic ICE flow configurations.

DIESEL ENGINE OPERATION IN USE OF FUEL WITH ADDITIVES

2018 ◽  
pp. 18-24
Author(s):  
Petar Kazakov ◽  
Atanas Iliev ◽  
Emil Marinov
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Diesel Fuel ◽  
Internal Combustion Engines ◽  
Experimental Studies ◽  
Combustion Engines ◽  
Engine Operation ◽  
Factors Affecting ◽  
Operating Modes ◽  
Positive Effects

Over the decades, more attention has been paid to emissions from the means of transport and the use of different fuels and combustion fuels for the operation of internal combustion engines than on fuel consumption. This, in turn, enables research into products that are said to reduce fuel consumption. The report summarizes four studies of fuel-related innovation products. The studies covered by this report are conducted with diesel fuel and usually contain diesel fuel and three additives for it. Manufacturers of additives are based on already existing studies showing a 10-30% reduction in fuel consumption. Comparative experimental studies related to the use of commercially available diesel fuel with and without the use of additives have been performed in laboratory conditions. The studies were carried out on a stationary diesel engine СМД-17КН equipped with brake КИ1368В. Repeated results were recorded, but they did not confirm the significant positive effect of additives on specific fuel consumption. In some cases, the factors affecting errors in this type of research on the effectiveness of fuel additives for commercial purposes are considered. The reasons for the positive effects of such use of additives in certain engine operating modes are also clarified.

https://elibrary.ru/item.asp?id=44369782&pf=1

2020 ◽  
Author(s):  
QI CHEN ◽  
◽  
JINTAO SUN ◽  
JIANYU LIU ◽  
BAOMING ZHAO ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Internal Combustion Engines ◽  
Nonequilibrium Plasma ◽  
Combustible Mixture ◽  
Combustion Engines ◽  
Combustion Chemistry ◽  
Microwave Radio ◽  
Different Types ◽  
Gas Molecules ◽  
Ignition And Combustion

Plasma-assisted ignition and combustion, widely applied in gas turbines, scramjets, and internal combustion engines, has been considered as a promising technique in shortening ignition delay time, improving combustion energy efficiency, and reducing emission. Nonequilibrium plasma can excite the gas molecules to higher energy states, directly dissociate or ionize the molecules and, thereby, has the potential to produce reactive species at residence time and location in a combustible mixture and then to efficiently accelerate the overall pyrolysis, oxidation, and ignition. Previous studies have demonstrated the effectiveness of plasma-assisted combustion by using direct current, alternating currant, microwave, radio frequency, and pulsed nanosecond discharge (NSD). Due to the complicated interaction between plasma and combustion in different types of plasma, detailed plasma-combustion chemistry is still not well understood.

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