Large-Eddy Simulation of Turbulent Mixing of a Jet in Cross-Flow

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Mostafa Esmaeili ◽  
Asghar Afshari ◽  
Farhad A. Jaberi
Keyword(s):  
Large Eddy Simulation ◽  
Velocity Profile ◽  
Turbulent Mixing ◽  
Mass Density ◽  
Cross Flow ◽  
Vortex Pair ◽  
Complex Flow ◽  
Eddy Simulation ◽  
Jet In Cross Flow ◽  
Large Eddy

An Eulerian–Lagrangian mathematical/computational methodology is employed for large-eddy simulation (LES) and detailed study of turbulent mixing in jet in cross-flow (JICF) configuration. Accurate prediction of mixing in JICF is crucially important to the development of advanced combustion systems. A high-order multiblock finite difference (FD) computational algorithm is used to solve the Eulerian velocity and pressure equations in a generalized coordinate system. The composition field, describing the mixing, is obtained from the filtered mass density function (FMDF) and its stochastic Lagrangian Monte-Carlo (MC) solver. Our simulations are shown to accurately predict the important flow features present in JICF such as the counter-rotating vortex pair (CVP), horseshoe, shear layer, and wake vortices. The consistency of the FD and MC parts of the hybrid LES/FMDF model is established for the simulated JICF in various conditions, indicating the numerical accuracy of the model. The effects of parameters influencing the jet penetration, entrainment, and turbulent mixing such as the jet velocity profile, and jet pulsation are investigated. The results show that the jet exit velocity profile significantly changes the trajectory and mixing of injected fluid. The jet pulsation is also shown to enhance the mixing depending on the flow Strouhal number. The LES/FMDF results are shown to be in good agreement with the available experimental data, confirming the reliability of LES/FMDF method for numerical simulation of turbulent mixing in complex flow configurations.

Large Eddy Simulation of a Supercritical Fuel Jet in Cross Flow using GPU-Acceleration

2016 ◽  
Author(s):  
Kalyana C. Gottiparthi ◽  
Ramanan Sankaran ◽  
Anthony M. Ruiz ◽  
Guilhem Lacaze ◽  
Joseph C. Oefelein
Keyword(s):  
Large Eddy Simulation ◽  
Cross Flow ◽  
Gpu Acceleration ◽  
Eddy Simulation ◽  
Jet In Cross Flow ◽  
Fuel Jet ◽  
Large Eddy

LES/FMDF of turbulent reacting jet in cross-flow

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mostafa Esmaeili ◽  
Asghar Afshari
Keyword(s):  
Mass Density ◽  
Cross Flow ◽  
Combustion Efficiency ◽  
Content Type ◽  
Eddy Simulation ◽  
Jet In Cross Flow ◽  
Large Eddy ◽  
Flow Features ◽  
Hybrid Solver ◽  
Good Agreement

Purpose This study aims to numerically investigate the flow features and mixing/combustion efficiencies in a turbulent reacting jet in cross-flow by a hybrid Eulerian-Lagrangian methodology. Design/methodology/approach A high-order hybrid solver is employed where, the velocity field is obtained by solving the Eulerian filtered compressible transport equations while the species are simulated by using the filtered mass density function (FMDF) method. Findings The main features of a reacting JICF flame are reproduced by the large-eddy simulation (LES)/FMDF method. The computed mean and root-mean-square values of velocity and mean temperature field are in good agreement with experimental data. Reacting JICF’s with different momentum ratios are considered. The jet penetrates deeper for higher momentum ratios. Mixing and combustion efficiency are improved by increasing the momentum ratio. Originality/value The authors investigate the flow and combustion characteristics in subsonic reacting JICFs for which very limited studies are reported in the literature.

Large-Eddy Simulation of a Reacting Jet in Cross Flow With NOx Prediction

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Johannes Weinzierl ◽  
Michael Kolb ◽  
Denise Ahrens ◽  
Christoph Hirsch ◽  
Thomas Sattelmayer
Keyword(s):  
Large Eddy Simulation ◽  
Cross Flow ◽  
Nox Emissions ◽  
Staged Combustion ◽  
Nox Formation ◽  
Full Load ◽  
Eddy Simulation ◽  
Jet In Cross Flow ◽  
Large Eddy ◽  
Combustion Systems

The reduction of full and part load emissions and the increase of the turndown ratio are important goals for gas turbine combustor development. Combustion techniques, which generate lower NOx emissions than unstaged premixed combustion in the full load range, and which have the potential of reducing minimum load while complying with emission legislation, are of high technical interest. Therefore, axial-staged combustion systems have been designed, either with or without expansion in a turbine stage between both stages. In its simpler form without intermediate expansion stage, a flow of hot combustion products is generated in the first stage of the premixed combustor, which interacts with the jets of premixed gas injected into the second stage. The level of NOx formation during combustion of the premixed jets in the hot cross flow determines the advantage of axially staged combustion regarding full load NOx emission reduction. Employing large-eddy simulation in openfoam, a tool has been developed, which allows to investigate staged combustion systems including not only temperature distribution but also NOx emissions under engine conditions. To be able to compute NOx formation correctly, the combustion process has to be captured with sufficient level of accuracy. This is achieved by the partially stirred reactor model. It is combined with a newly developed NOx model, which is a combination of a tabulation technique for the NOx source term based on mixture fraction and progress variable and a partial equilibrium approach. The NOx model is successfully validated with generic burner stabilized flame data and with measurements from a large-scale reacting jet in cross flow experiment. The new NOx model is finally used to compute a reacting jet in cross flow under engine conditions to investigate the NOx formation of staged combustion in detail. The comparison between the atmospheric and the pressurized configuration gives valuable insight in the NOx formation process. It can be shown that the NOx formation within a reacting jet in cross flow configuration is reduced and not only diluted.

scholarly journals LARGE EDDY SIMULATION OF AN ELLIPTIC JET INJECTED INTO A SUPERSONIC CROSSFLOW

2012 ◽  
Vol 19 ◽  
pp. 109-113
Author(s):  
GUO-LEI WANG ◽  
XI-YUN LU
Keyword(s):  
Large Eddy Simulation ◽  
Vortex Pair ◽  
Horseshoe Vortex ◽  
Mach Disk ◽  
Spanwise Direction ◽  
Complex Flow ◽  
Transverse Jet ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Flow Features

A transverse jet issuing from an elliptic injector into a supersonic crossflow has been investigated using large eddy simulation. The complex flow structures and the relevant flow features are analyzed to exhibit the evolution of shock structures, vertical structures and jet shear layer. A horseshoe vortex is formed in the upstream of the jet and the shock structures exhibit small fluctuations due to the flow interaction. The kidney-shaped counter-rotating vortex pair dominates the flow field in the downstream of the jet. The elliptic jet spreads rapidly in the spanwise direction and then the axis-switching phenomenon occurs. Intense turbulent fluctuations are identified behind the Mach disk because of the large velocity gradients.

LES/FMDF of Mixing in Turbulent Jet in Cross-Flows

2014 ◽  
Author(s):  
Mostafa Esmaeili ◽  
Asghar Afshari
Keyword(s):  
Velocity Profile ◽  
Numerical Scheme ◽  
Mass Density ◽  
Cross Flow ◽  
Mixing Enhancement ◽  
Complex Flow ◽  
Mixing Condition ◽  
Eddy Simulation ◽  
Jet Velocity ◽  
Flow Configurations

In this study, an Eulerian-Lagrangian computational methodology is utilized for large eddy simulation (LES) of mixing phenomena in jet in cross-flows. A high-order multi-block algorithm is used to solve Eulerian equations in a generalized coordinate system. The composition is formulated based on the filtered mass density function (FMDF) and its equivalent stochastic Lagrangian equations, which is solved by Lagrangian Monte-Carlo method. Parameters influencing mixing enhancement including jet velocity profile, and jet pulsation are investigated. A good consistency between Eulerian and Lagrangian components of the numerical scheme is established. In jet in cross-flow (JICF) simulations, the vortical structures and flow features are predicted with the current numerical scheme. The results also show that the jet velocity profile affects both trajectory and mixing condition and the jet pulsation can enhance mixing depending on the Strouhal numbers. The obtained results including concentration distributions are in good agreement with available experimental data ensuring the performance and reliability of LES/FMDF methodology to study mixing in relatively complex flow configurations such as JICF.

Large-Eddy Simulation of Shaped Hole Film Cooling with the Influence of Cross Flow

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Wang Qingsong ◽  
Xinrong Su ◽  
Xin Yuan
Keyword(s):  
Large Eddy Simulation ◽  
Film Cooling ◽  
Large Scale ◽  
High Efficiency ◽  
Cross Flow ◽  
Vortex Pair ◽  
Hairpin Vortices ◽  
Eddy Simulation ◽  
Large Eddy ◽  
End Wall

AbstractIn the highly-loaded turbine blade passage, cross flow is driven by the lateral gradient. It strongly influences the cooling performances in the endwall region. In this research, the effect of cross flow on the shaped film cooling hole is studied by Large Eddy Simulation (LES); modal analysis is conducted with an incremental POD (iPOD) approach, which makes the analysis of the large data sets from LES feasible. It is shown that the symmetry of the counter rotating vortex pair (CRVP) is destroyed. The large-scale vortex induced by end-wall cross flow plays an important role in both shape and convection of hairpin vortices and horseshoe vortices, which influences the coolant distribution. This study suggests that the effects of cross flow should be considered for the design of end-wall film cooling. It also indicates the high efficiency of the iPOD approach, which can be used to analyze large amounts of high-dimensional data.

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