scholarly journals Taylor dispersion in premixed combustion: Questions from turbulent combustion answered for laminar flames

2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Joel Daou ◽  
Philip Pearce ◽  
Faisal Al-Malki
Keyword(s):  
Turbulent Combustion ◽  
Taylor Dispersion ◽  
Premixed Combustion ◽  
Laminar Flames

Numerical Simulation of Turbulent Combustion Flows for Coaxial Jet Cluster Burner

2013 ◽  
Author(s):  
Keita Yunoki ◽  
Tomoya Murota ◽  
Keisuke Miura ◽  
Teruyuki Okazaki
Keyword(s):  
Turbulent Combustion ◽  
High Efficiency ◽  
Premixed Combustion ◽  
Premixed Flame ◽  
Gas Temperature ◽  
Lean Premixed Combustion ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Lean Premixed ◽  
Multiple Holes

We have developed a burner for the gas turbine combustor, which was high efficiency and low environmental load. This burner is named the “coaxial jet cluster burner” and, as the name indicates, it has multiple fuel nozzles and holes in a coaxial arrangement. To form lean premixed combustion, this burner mixes fuel and air in the multiple holes rapidly. The burner can change the combustion form between premixed and non-premixed combustion by controlling the mixing. However, the combustion field coexisting with premixed and non-premixed combustion is complicated. The phenomena that occur in the combustion field should be understood in detail. Therefore, we have developed the hybrid turbulent combustion (HTC) model to calculate the form in which non-premixed flame coexists with premixed flame. Turbulent flow has been simulated using a large eddy simulation (LES) with a dynamic sub grid scale (SGS) model coupled with the HTC model. These models were programmed to a simulation tool based on the OpenFOAM library. However, there were unclear points about their applicability to an actual machine evaluation and the predictive precision of CO concentration which affects burner performance. In this study, we validate the HTC model by comparing its results with measured gas temperature and gas concentration distributions obtained with a coaxial jet cluster burner test rig under atmospheric pressure. In addition, we analyze the CO generation mechanism for the lean premixed combustion in the burner.

Simulation of Turbulent Lifted Flames Using a Partially-Premixed Coherent Flame Model (PCFM)

2008 ◽  
Author(s):  
Yongzhe Zhang ◽  
Rajesh Rawat
Keyword(s):  
Turbulent Combustion ◽  
Practical Interest ◽  
Flame Stabilization ◽  
Premixed Combustion ◽  
Pollutant Emissions ◽  
Jet Flame ◽  
Premixed Turbulent Combustion ◽  
Partially Premixed Combustion ◽  
Lifted Flames ◽  
Partially Premixed

Partially-premixed combustion occurs in many combustion devices of practical interest, such as gas-turbine combustors. Development of corresponding turbulent combustion models is important to improve the design of these systems in efforts to reduce fuel consumption and pollutant emissions. Turbulent lifted flames have been a canonical problem for testing models designed for partially-premixed turbulent combustion. In this paper we propose modifications to the coherent flame model (CFM) so that it can be brought to the simulation of partially-premixed combustion. For the primary premixed flame, a transport equation for flame area density is solved in which the wrinkling effects of the flame stretch and flame annihilation are considered. For the subsequent non-premixed zone, a laminar flamelet PPDF methodology, which accounts for the non-equilibrium and finiterate chemistry effects, is adopted. The model is validated against the experimental data on a lifted H2/N2 jet flame issuing into a vitiated coflow. In general there is fairly good agreement between the calculations and measurements both in profile shapes and peak values. Based on the simulation results the flame stabilization mechanism for lifted flames is investigated.

scholarly journals Study of the Wall Thermal Condition Effect in a Lean-Premixed Downscaled Can Combustor Using Large-Eddy Simulation

2016 ◽  
Author(s):  
D. Mira ◽  
M. Vázquez ◽  
G. Houzeaux ◽  
S. Gövert ◽  
J. W. B. Kok ◽  
...  
Keyword(s):  
Turbulent Combustion ◽  
Mixture Fraction ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Laminar Flames ◽  
Combustion Model ◽  
Test Case ◽  
Eddy Simulation ◽  
Condition Effect ◽  
Large Eddy

The primary purpose of this study is to evaluate the ability of LES, with a turbulent combustion model based on steady flamelets, to predict the flame stabilization mechanisms in an industrial can combustor at full load conditions. The test case corresponds to the downscaled Siemens can combustor tested in the high pressure rig at the DLR. The effects of the wall temperature on the prediction capabilities of the codes is investigated by imposing several heat transfer conditions at the pilot and chamber walls. The codes used for this work are Alya and OpenFOAM, which are well established CFD codes in the fluid mechanics community. Prior to the simulation, results for 1-D laminar flames at the operating conditions of the combustor are compared with the detailed solutions. Subsequently, results from both codes at the mid-plane are compared against the experimental data available. Acceptable results are obtained for the axial velocity, while discrepancies are more evident for the mixture fraction and the temperature, particularly with Alya. However, both codes showed that the heat losses influence the size and length of the pilot and main flame.

Large Eddy Simulation of a Multiple-Injection Dry Low NOx Combustor for Hydrogen-Rich Syngas Fuel at High Pressure

2016 ◽  
Author(s):  
Keita Yunoki ◽  
Tomoya Murota ◽  
Tomohiro Asai ◽  
Teruyuki Okazaki
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Turbulent Combustion ◽  
Flow Model ◽  
Propagation Model ◽  
Premixed Combustion ◽  
Multiple Injection ◽  
Eddy Simulation ◽  
Injection Burner ◽  
Large Eddy

The successful development of coal-based integrated gasification combined cycle (IGCC) technology requires gas turbines capable of achieving the dry low-nitrogen oxides (NOx) combustion of hydrogen-rich syngas for low emissions and high plant efficiency. Therefore we have been developing a multiple-injection burner for hydrogen-rich syngas fuel in order to achieve high efficiency and low environmental load. This burner consists of a perforated plate with multiple air holes and fuel nozzles. The multiple air holes and the fuel nozzles are arranged coaxially. The burner is based on the concept of premixed combustion configured by mixing fuel and air in the each air hole rapidly and dispersing fuel with multiple fuel-air jet. This rapid mixing can reduce NOx emissions by getting homogeneous lean premixed combustion, and preventing flashback despite the high flame speed for hydrogen-rich syngas fuels. The unsteady phenomena that occur in the combustion field should be understood in detail in order to confirm this burner concept. However, their measurement under high pressure is difficult. Meanwhile computational fluid dynamics (CFD) is able to investigate the detailed distributions of various emissions and temperature even though under combustion fields of high pressure and high temperature. The purpose of this paper is to validate this concept of the multiple-injection burner by using CFD. The burner can change the combustion form between premixed and non-premixed combustion by controlling the mixing, so the combustion field coexisting with premixed combustion and non-premixed combustion is complicated. Therefore, we have developed a hybrid turbulent combustion (HTC) model applicable to both non-premixed and premixed flames. The HTC model is hybridized with the flamelet progress variable (FPV) model and a flame propagation model. The FPV model is based on the laminar flamelet concept. The flame propagation model considers the flame stretch effect, diffusion enhancement effect, and increasing rate of flame surface area. The turbulent flow model adopts large eddy simulation (LES) with a dynamic sub-grid scale (SGS) based on the local inter-scale equilibrium assumption (LISEA4). Both the turbulent combustion model and turbulent flow model were programmed into a simulation tool based on the OpenFOAM library. We validated the concept of this burner for hydrogen-rich syngas fuel by using the simulation tool. The simulation results showed the rapid mixing of fuel and air in the air holes, and by using HTC model we confirmed that premixed combustion is the combustion configuration of this multiple-injection burner. In addition, the multiple-injection burner has high flame stability. There is no zone of high temperature in the air hole and high temperature is maintained near the burner. The multiple-injection burner can thus maintain flame stability without any flashback.

Simulation of Turbulent Lifted Flames Using a Partially Premixed Coherent Flame Model

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Yongzhe Zhang ◽  
Rajesh Rawat
Keyword(s):  
Turbulent Combustion ◽  
Practical Interest ◽  
Flame Stabilization ◽  
Premixed Combustion ◽  
Pollutant Emissions ◽  
Jet Flame ◽  
Premixed Turbulent Combustion ◽  
Partially Premixed Combustion ◽  
Lifted Flames ◽  
Partially Premixed

Partially premixed combustion occurs in many combustion devices of practical interest, such as gas-turbine combustors. Development of corresponding turbulent combustion models is important to improve the design of these systems in efforts to reduce fuel consumption and pollutant emissions. Turbulent lifted flames have been a canonical problem for testing models designed for partially premixed turbulent combustion. In this paper we propose modifications to the coherent flame model so that it can be brought to the simulation of partially premixed combustion. For the primary premixed flame, a transport equation for flame area density is solved in which the wrinkling effects of the flame stretch and flame annihilation are considered. For the subsequent nonpremixed zone, a laminar flamelet presumed probability density function (PPDF) methodology, which accounts for the nonequilibrium and finite-rate chemistry effects, is adopted. The model is validated against the experimental data on a lifted H2∕N2 jet flame issuing into a vitiated coflow. In general there is fairly good agreement between the calculations and measurements both in profile shapes and peak values. Based on the simulation results, the flame stabilization mechanism for lifted flames is investigated.

Lewis Number Effects in Premixed Turbulent Combustion and Highly Perturbed Laminar Flames

1998 ◽  
Vol 137 (1-6) ◽  
pp. 277-298 ◽  
Author(s):  
A. N. LIPATNIKOV ◽  
J. CHOMIAK
Keyword(s):  
Turbulent Combustion ◽  
Lewis Number ◽  
Laminar Flames ◽  
Premixed Turbulent Combustion

scholarly journals Assessment of RANS-Based Turbulent Combustion Models for Prediction of Emissions from Lean Premixed Combustion of Methane

2010 ◽  
Vol 182 (7) ◽  
pp. 794-821 ◽  
Author(s):  
J. R. Nanduri ◽  
D. R. Parsons ◽  
S. L. Yilmaz ◽  
I. B. Celik ◽  
P. A. Strakey
Keyword(s):  
Turbulent Combustion ◽  
Premixed Combustion ◽  
Lean Premixed Combustion ◽  
Combustion Models ◽  
Lean Premixed

scholarly journals Active-grid turbulence effect on the topology and the flame location of a lean premixed combustion

2018 ◽  
Vol 22 (6 Part A) ◽  
pp. 2425-2438 ◽  
Author(s):  
Mohammed Alhumairi ◽  
Özgür Ertunç
Keyword(s):  
Turbulent Combustion ◽  
Turbulent Flame ◽  
Jet Flow ◽  
Flame Speed ◽  
Premixed Combustion ◽  
Grid Turbulence ◽  
Closure Model ◽  
Lean Premixed Combustion ◽  
Turbulent Flame Speed ◽  
Combustion Models

Lean premixed combustion under the influence of active-grid turbulence was computationally investigated, and the results were compared with experimental data. The experiments were carried out to generate a premixed flame at a thermal load of 9 kW from a single jet flow combustor. Turbulent combustion models, such as the coherent flame model and turbulent flame speed closure model were implemented for the simulations performed under different turbulent flow conditions, which were specified by the Reynolds number based on Taylor?s microscale, the dissipation rate of turbulence, and turbulent kinetic energy. This study shows that the applied turbulent combustion models differently predict the flame topology and location. However, similar to the experiments, simulations with both models revealed that the flame moves toward the inlet when turbulence becomes strong at the inlet, that is, when Re? at the inlet increases. The results indicated that the flame topology and location in the coherent flame model were more sensitive to turbulence than those in the turbulent flame speed closure model. The flame location behavior on the jet flow combustor significantly changed with the increase of Re?.

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