Multi Eulerian PDF Transport Modelling of Turbulent Swirling Flame

2012 ◽  
Author(s):  
Abhinav Kapoor ◽  
Ashoke De ◽  
Rakesh Yadav
Keyword(s):  
Transport Equation ◽  
Transport Model ◽  
Turbulent Flame ◽  
Turbulence Models ◽  
Reacting Flows ◽  
Substantial Improvement ◽  
Reacting Flow ◽  
Transport Modelling ◽  
Solution Approach ◽  
Lagrangian Solution

The paper presents numerical investigation using Multi environmental Eulerian PDF (MEPDF) transport model for turbulence-chemistry interaction. A turbulent flame (SM1) from Sydney swirling burner database is simulated along with two isothermal cases (N29S054, N16S159) of different swirl numbers. MEPDF methodology, a probability density function (PDF) transport modeling, exploits the advantages of the PDF transport equation and is also computationally less expensive compared to popularly used Lagrangian solution approach of PDF transport equation. In the MEPDF approach, the PDF transport equation is represented by direct quadrature method of moments with presumed shape PDF and the closure of micro-mixing is achieved by interaction by exchange with mean (IEM) model. In the current work, the reacting flow results using MEPDF are reported for SM1 flame, which is a part of the database of turbulent reacting flows and widely considered as benchmark test cases for validating turbulent-chemistry interaction models. Initially, the non-reacting flows are simulated to properly choose the boundary conditions, turbulence models as well as the grid; followed by reacting flow calculations. SKE and RKE predictions show good agreement with each other while the other turbulence model exhibit substantially different behavior, especially for non-reacting case. However, RKE model exhibits substantial improvement in the case of reacting flows.

Computation of 3D Turbulent Not-Premixed Reacting Flows Using an Implicit Unstructured Solver

2000 ◽  
Author(s):  
P. Adami ◽  
F. Martelli
Keyword(s):  
Bluff Body ◽  
Cfd Simulation ◽  
Turbulent Flame ◽  
Steady State Solution ◽  
Reacting Flows ◽  
Tvd Scheme ◽  
Reacting Flow ◽  
Riemann Solver ◽  
Turbulent Reactive Flows ◽  
Volume Method

A 3D CFD simulation of turbulent reactive flows is discussed. The original compressible version of the solver HybFlow designed for turbine rows investigation is here applied for low speed burning flow. A conserved scalar approach is considered to simulate the turbulent reacting flow field of non-premixed flames. The spatial discretization is based on an upwind finite volume method for unstructured grids using the Roe’s Riemann solver with a non-linear TVD scheme. The steady state solution is computed by means of an implicit relaxed Newton method. The linear solver is GMRES coupled with an ILU(0) preconditioning scheme. The turbulence chemistry interaction is described using a presumed β-PDF Flamelet approach. Two test applications are here presented to verify the methodology characteristics for a pilot-jet turbulent flame and a bluff-body stabilized flame both using CH4. A model combustor supplied with propane is also briefly shown as an example of application to a more realistic configuration.

CFD Modeling of Non-Premixed Combustion in a Gas Turbine Combustor

2002 ◽  
Author(s):  
Kitano Majidi
Keyword(s):  
Gas Turbine ◽  
Transport Model ◽  
Direct Injection ◽  
Turbulence Models ◽  
Cfd Modeling ◽  
Navier Stokes ◽  
Reacting Flow ◽  
Gas Temperature ◽  
Gas Turbine Combustor ◽  
Reynolds Stress Transport Model

In the present study numerical calculations are used to solve reacting flow in a gas turbine combustor. A 3-D Favre-Averaged Navier-Stokes solver for a mixture of chemically reacting gases is applied to predict the flow pattern, gas temperature and fuel and species concentrations in the entire combustor. The complete combustor geometry with all important details such as air swirler vane passages and secondary holes are modeled. The calculations are carried out using three different turbulence models. Comparisons are made between the standard k-ε model, RNG k-ε model and a Reynolds stress transport model. To provide a closure for the chemical source term the Eddy Dissipation model is used. A lean direct injection of a liquid fuel is employed. Furthermore the influence of radiation will be investigated.

Numerical study of the pseudo-boiling phenomenon in the transcritical liquid oxygen/gaseous hydrogen flame

2020 ◽  
pp. 095441002096469
Author(s):  
Hamed Zeinivand ◽  
Mohammad Farshchi
Keyword(s):  
Turbulence Model ◽  
Numerical Study ◽  
Turbulence Models ◽  
Reacting Flows ◽  
Gaseous Hydrogen ◽  
Liquid Oxygen ◽  
Combustion Model ◽  
Reacting Flow ◽  
Good Prediction ◽  
Oxygen Injection

The interactions and effects of turbulent mixing, pseudo-boiling phenomena, and chemical reaction heat release on the combustion of cryogenic liquid oxygen and gaseous hydrogen under supercritical pressure conditions are investigated using RANS simulations. Comparisons of the present numerical simulation results with available experimental data reveal a reasonably good prediction of a supercritical axial shear hydrogen-oxygen flame using the standard k-ε turbulence model and the eddy dissipation concept combustion model with a 23 reaction steps kinetics for H2-O2 reaction. The present simulation qualitatively reproduced oxygen injection and its reaction with the co-flowing hydrogen, which is characterized by rapid flame expansion, downstream flame propagation, and expansion induced flow recirculation. Several turbulence models were used for numerical simulations. It is shown that the selection of an appropriate turbulence model for transcritical reacting flows is crucial and far more important than for subcritical reacting flows. It is indicated that the pseudo-boiling phenomena is the main reason for the considerable differences between the turbulence models in a transcritical flame. Also, it is demonstrated that the liquid oxygen core disappears faster in a non-reacting flow than in a reacting flow. The shear layer in the non-reacting flow is much stronger than reacting case; providing a large transfer of energy from the outer layer to the inner layer. At the supercritical injection conditions, the difference between the turbulence models is much less than the transcritical injection conditions.

Numerical Simulation of Non-Reacting and Reacting Flows in a 5MW Commercial Gas Turbine Combustor

2009 ◽  
Author(s):  
Daero Jeong ◽  
Kang Y. Huh
Keyword(s):  
Numerical Simulation ◽  
Gas Turbine ◽  
Measurement Data ◽  
Turbulence Models ◽  
Swirl Flow ◽  
Reacting Flows ◽  
Reacting Flow ◽  
Mean Flow ◽  
Gas Turbine Combustor ◽  
Swirl Flame

This study is concerned with numerical simulation of a simple swirl flame and a 5MW commercial gas turbine combustor both operating on methane/air. Validation is performed for turbulent flow and combustion models against some measurement data (http://public.ca.sandia.gov/TNF/swirlflames.html). Evaluation is performed for the standard k-e and the realizable k-e models in the nonreacting swirl flow and the EBU (eddy breakup) and the PPDF (presumed probability density function) models in the reacting flow of the 5 MW commercial combustor. Independent simulations are carried out for the main and pilot nozzles to avoid flashback and to provide realistic inflow boundary conditions for the combustor. Important geometrical details such as air swirlers, vane passages and liner holes are taken into account. Different turbulence models result in similar flow patterns with varying sizes of the recirculation pockets in the central region and at the outside corner. The EBU and the PPDF models show similar downstream distributions of mean flow and temperature, while the EBU shows a lifted flame with a stronger effect of swirl due to limited increase of axial momentum by volume expansion near the nozzle.

An Efficient Computational Model for Premixed Turbulent Combustion at High Reynolds Numbers Based on a Turbulent Flame Speed Closure

1997 ◽  
Author(s):  
Vladimir Zimont ◽  
Wolfgang Polifke ◽  
Marco Bettelini ◽  
Wolfgang Weisenstein
Keyword(s):  
Computational Model ◽  
Transport Equation ◽  
Turbulent Combustion ◽  
Turbulent Flame ◽  
Reynolds Numbers ◽  
Flame Speed ◽  
Closed Form Expression ◽  
Turbulent Length Scale ◽  
Premixed Turbulent Combustion ◽  
Turbulent Flame Speed

Theoretical background, details of implementation and validation results of a computational model for turbulent premixed gaseous combustion at high turbulent Reynolds numbers are presented. The model describes the combustion process in terms of a single transport equation for a progress variable; closure of the progress variable’s source term is based on a model for the turbulent flame speed. The latter is identified as a parameter of prime significance in premixed turbulent combustion and is determined from theoretical considerations and scaling arguments, taking into account physico-chemical properties of the combustible mixture and local turbulent parameters. Specifically, phenomena like thickening, wrinkling and straining of the flame front by the turbulent velocity field are considered, yielding a closed form expression for the turbulent flame speed that involves, e.g., speed, thickness and critical gradient of a laminar flame, local turbulent length scale and fluctuation intensity. This closure approach is very efficient and elegant, as it requires only one transport equation more than the non-reacting flow case, and there is no need for costly evaluation of chemical source terms or integration over probability density functions. The model was implemented in a finite-volume based computational fluid dynamics code and validated against detailed experimental data taken from a large scale atmospheric gas turbine burner test stand. The predictions of the model compare well with the available experimental results. It has been observed that the model is significantly more robust and computationally efficient than other combustion models. This attribute makes the model particularly interesting for applications to large 3D problems in complicated geometries.

The Role of Turbulence Models for Predicting a Thermal Stratification

2006 ◽  
Vol 128 (4) ◽  
pp. 656-662 ◽  
Author(s):  
Seok-Ki Choi ◽  
Seong-O Kim
Keyword(s):  
Liquid Metal ◽  
Thermal Stratification ◽  
Transport Model ◽  
Numerical Study ◽  
Turbulence Models ◽  
Liquid Metal Reactor ◽  
Temporal Oscillation ◽  
Elliptic Relaxation ◽  
Shear Stress Transport Model

A numerical study of the evaluation of turbulence models for predicting the thermal stratification phenomenon is presented. The tested models are the elliptic blending turbulence model (EBM), the two-layer model, the shear stress transport model (SST), and the elliptic relaxation model (V2-f). These four turbulence models are applied to the prediction of a thermal stratification in an upper plenum of a liquid metal reactor experimented at the Japan Nuclear Cooperation (JNC). The EBM and V2-f models predict properly the steep gradient of the temperature at the interface of the cold and hot regions that is observed in the experimental data, and the EBM and V2-f models have the capability of predicting the temporal oscillation of the temperature. The two-layer and SST models predict the diffusive temperature gradient at the interface of a thermal stratification and fail to predict a temporal oscillation of the temperature. In general, the EBM predicts best the thermal stratification phenomenon in the upper plenum of the liquid metal reactor.

scholarly journals Turbulent Flame Shape Switching at Conditions Relevant for Gas Turbines

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Ivan Langella ◽  
Johannes Heinze ◽  
Thomas Behrendt ◽  
Lena Voigt ◽  
Nedunchezhian Swaminathan ◽  
...  
Keyword(s):  
Turbulent Combustion ◽  
Gas Turbines ◽  
Turbulent Flame ◽  
Interaction Model ◽  
Numerical Approach ◽  
Reacting Flow ◽  
Combustion Chambers ◽  
Lean Burn ◽  
Large Eddy ◽  
Flame Behavior

Abstract A numerical investigation is conducted to shed light on the reasons leading to different flame configurations in gas turbine (GT) combustion chambers of aeronautical interest. Large eddy simulations (LES) with a flamelet-based combustion closure are employed for this purpose to simulate the DLR-AT big optical single sector (BOSS) rig fitted with a Rolls-Royce developmental lean burn injector. The reacting flow field downstream this injector is sensitive to the intricate turbulent–combustion interaction and exhibits two different configurations: (i) a penetrating central jet leading to an M-shape lifted flame; or (ii) a diverging jet leading to a V-shaped flame. The LES results are validated using available BOSS rig measurements, and comparisons show the numerical approach used is consistent and works well. The turbulent–combustion interaction model terms and parameters are then varied systematically to assess the flame behavior. The influences observed are discussed from physical and modeling perspectives to develop physical understanding on the flame behavior in practical combustors for both scientific and design purposes.

scholarly journals Sediment transport modelling in a distributed physically based hydrological catchment model

2010 ◽  
Vol 7 (5) ◽  
pp. 7591-7631 ◽  
Author(s):  
M. Konz ◽  
M. Chiari ◽  
S. Rimkus ◽  
J. M. Turowski ◽  
P. Molnar ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Hydrological Model ◽  
Transport Model ◽  
Water Cycle ◽  
Transport Processes ◽  
Distributed Hydrological Model ◽  
Water Fluxes ◽  
Transport Modelling ◽  
Erosion Processes ◽  
Grid Level

Abstract. Sediment transport and erosion processes in channels are important components of water induced natural hazards in alpine environments. A distributed hydrological model, TOPKAPI, has been developed to support continuous simulations of river bed erosion and deposition processes. The hydrological model simulates all relevant components of the water cycle and non-linear reservoir methods are applied for water fluxes in the soil, on the surface and in the channel. The sediment transport simulations are performed on a sub-grid level, which allows for a better discretization of the channel geometry, whereas water fluxes are calculated on the grid level in order to be CPU efficient. Flow resistance due to macro roughness is considered in the simulation of sediment transport processes. Several transport equations as well as the effects of armour layers on the transport threshold discharge are considered. The advantage of this approach is the integrated simulation of the entire water balance combined with hillslope-channel coupled erosion and transport simulation. The comparison with the modelling tool SETRAC and with LiDAR based reconstructed sediment transport rates demonstrates the reliability of the modelling concept. The modelling method is very fast and of comparable accuracy to the more specialised sediment transport model SETRAC.

scholarly journals Verification and Validation of CFD for Surface Combatant 5415 for Straight Ahead and 20 Degree Static Drift Conditions

2015 ◽  
Author(s):  
S. Bhushan ◽  
H. Yoon ◽  
F. Stern ◽  
E. Guilmineau ◽  
M. Visonneau ◽  
...  
Keyword(s):  
Transport Model ◽  
Separation Bubble ◽  
Turbulence Models ◽  
Breaking Waves ◽  
Verification And Validation ◽  
Tip Vortex ◽  
Future Research ◽  
Recent Experimental Data ◽  
Wave Elevation ◽  
Surface Combatant

Collaboration is described on verification and validation of CFD for surface combatant model 5415 for static drift B=0 and 20 degrees using recent experimental data for: forces and moment, wave elevations, and tomographic PIV planar and volume measurements of velocity, vorticity and turbulent kinetic energy (TKE), including analysis of vortex onset of separation, progression, instability and TKE budget. Results were obtained from five different solvers, which used different numerical and discretization schemes, free-surface and turbulence models and adapted grids ranging from 2.5M to 102M for =0 and 4.6M to 250M for =20. For =0, resistance and wave-elevation predictions compare within 2% and 3.5% of the data, respectively. Solvers agreed with the data for the onset of the primary vortices, but showed large variation in their progression and decay. URANS turbulence models predicted premature decay of vortices, whereas DES predicted too strong vortical structures and low resolved turbulence. The primary vortices exhibited open-type separation. For =20, forces and moment compared within 3.7% of the data, and wave-elevation within 8.5% of data. Simulations agreed with the data for the onset of primary vortices, but showed large variations for their progression and decay, and for the leeward sonar dome separation bubble and breaking waves. DES performed better than URANS for the prediction of vortex strength and TKE. The vortices show many open-, closed- or open-closed type separations. The primary vortices show helical mode instability, and the instability frequency for the sonar dome tip vortex at x/LPP =0.4 compared within 11.3%D of the data. TKE budget revealed that the production occurs at the vortex inception and is transported by pressure or turbulent fluctuations. The finite-difference solver provided better vortex decay predictions than finite-volume solvers for  = 0. Level-set and VoF provided similar wave elevation predictions except for breaking waves. The study indicates the need for more accurate turbulence closures. Future research should focus on investigation of: improved RANS models such as Reynolds stress transport model; and improved hybrid RANS/LES models to address the turbulence trigger and modeled stress depletion issues of DES.

Sign in / Sign up

Export Citation Format

Share Document