Modelling of the Combustion Process of a Premixed DLE Gas Turbine

2000 ◽  
Author(s):  
R. L. G. M. Eggels
Keyword(s):  
Reaction Mechanism ◽  
Flow Field ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Reaction Mechanisms ◽  
Gas Turbines ◽  
Combustion Process ◽  
Operating Conditions ◽  
Dimensional Manifold ◽  
Global Reaction

To obtain a better understanding of the internal combustion processes of gas turbines, CFD computations of a combustion chamber, based on a Rolls-Royce industrial gas turbine, were performed. Minor simplifications are made to generate a 3-D rotational symmetric geometry. Computations are performed at typical gas turbine conditions and natural gas is used as the fuel. An internal Rolls-Royce CFD code is applied to perform the computations. This paper explains the models used for the CFD computations and describes the advantages and limitations on the applied models. The combustion process has been modelled using a two-step global reaction mechanism and Intrinsic Low Dimensional Manifold (ILDM) reduced reaction mechanisms. The global reaction mechanisms are optimised for the considered operating conditions by modification of the reaction rates so that the same burning velocity and the amplitude CO-peak are obtained as predicted by detailed reaction mechanism (GRI 2.11, Bowman 1995). This optimisation is done considering a one-dimensional laminar flame. Although the global reaction mechanism is optimised for one particular operating condition, it appears that it is suitable for use over the entire range of operating conditions. The ILDM reduced reaction mechanisms are derived from GRI 2.11. Two ILDM tables are used to model two operating conditions, as they are specific for the pressure and inlet temperature. The interaction between turbulence and chemistry is modelled using presumed Probability Density Functions (PDF). The flow field in the combustion chamber is studied at isothermal and combusting conditions. It appeared that the flow field for burning and non-burning circumstances is quite different. There is a lack of experimental data so that it is not possible to verify the CFD results in detail. However, there is knowledge about the mechanisms by which the flame is stabilised and emissions are measured in the exhaust. The predicted flame front position agrees with that which is experimentally observed. The predicted increase of CO at low power is at the same order of magnitude as the measured emissions.

Experimental Investigations of Pressure Drop in the Combustion Chamber of Gas Turbine

1989 ◽  
Author(s):  
Marek Dzida ◽  
Krzysztof Kosowski
Keyword(s):  
Pressure Drop ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Relative Pressure ◽  
Wide Range ◽  
Few Data

In bibliography we can find many methods of determining pressure drop in the combustion chambers of gas turbines, but there is only very few data of experimental results. This article presents the experimental investigations of pressure drop in the combustion chamber over a wide range of part-load performances (from minimal power up to take-off power). Our research was carried out on an aircraft gas turbine of small output. The experimental results have proved that relative pressure drop changes with respect to fuel flow over the whole range of operating conditions. The results were then compared with theoretical methods.

Comparison of Numerical and Experimental Results of a Premixed DLE Gas Turbine Combustor

2001 ◽  
Author(s):  
Ruud L. G. M. Eggels ◽  
Christopher T. Brown
Keyword(s):  
Reaction Mechanism ◽  
Gas Turbine ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Gas Turbine Combustor ◽  
Cfd Modelling ◽  
Recirculation Length ◽  
Global Reaction ◽  
Presumed Pdf ◽  
Pdf Model

A numerical and experimental study on a premixed DLE gas turbine combustor has been performed. Experiments and CFD modelling have been carried out at isothermal and combusting conditions. The measurements were obtained at ERC using two component Laser Doppler Velocimetry. To be able to access the inner part of the combustor, the liners of the combustion chamber were outfitted with quartz windows. Temperature measurements were obtained at a few planes using a thermocouple. Modelling of the combustor has been performed using an in-house CFD code. The combustion process has been modelled using a global reaction mechanism and a Flame Generated Manifold reaction mechanism in combination with a presumed PDF model to incorporate the effect of turbulent fluctuations. The Flame Generated Manifold method uses a flame library, which has been generated by performing a number of laminar one-dimensional flame calculations at representative conditions. Comparing the numerical and experimental quite some differences are observed. The CFD model is able to predict the main features of the flow and combustion process, but does not predict the recirculation length accurately. Both combustion models, however, are able to predict the low combustion efficiency measured at the 1atm test condition.

An Investigation of Turbine Erosion by Combustor Generated Carbon in a Light Weight Marine Gas Turbine

1978 ◽  
Author(s):  
R. J. Russell ◽  
J. J. Witton
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Fuel Type ◽  
Test Rig ◽  
Erosion Process ◽  
Marine Application ◽  
Mineral Dusts

A study has been made of the turbine erosion problem encountered in a marinized aero gas turbine which arose from the change of fuel type necessitated by the marine application. The work has involved the development of a technique for collecting carbon shed from the combustion chamber under engine operating conditions. Tests using the collector were made with a single combustor test rig and compared to engine experience. Combustion chamber modifications were developed having low solids emissions and their emissions characterized using the collector. The data from the collector show that smaller particles than hitherto collected can produce significant long-term erosion and that reduction on both size and quantity of particles is necessary to reduce erosion to acceptable levels. The data obtained in this study are compared with other published information on the basic erosion process and erosion in gas turbines by natural mineral dusts. The implications of the results to current and future engines are discussed.

Combination of 1D Code and CFD for Performance Analysis of a Silo Type Gas Turbine Combustor

2010 ◽  
Author(s):  
N. Rasooli ◽  
S. Besharat Shafiei ◽  
H. Khaledi
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Mass Distribution ◽  
Gas Turbines ◽  
Pressure Loss ◽  
Combustion Efficiency ◽  
Operating Conditions ◽  
Empirical Correlations ◽  
Combustion Chambers ◽  
Cfd Simulations

Whereas Gas Turbines are the most important producers of Propulsion and Power in the world and with attention to the importance of combustion chamber as one of the three basic components of Gas Turbine, various activities in different levels have been done on this component. Because of the environmental limitations and laws related to the pollutants such as NOx and CO, Lean Premixed Combustion Chambers are specially considered in gas turbine industries. This study is part of a Multi-Layer simulation of the whole gas turbine cycle in MPG Company. In this work, the combination of a general 1D code and CFD is used for deriving appropriate performance curves for a 1D and 0D gas turbine design, off-design and dynamic cycle code. This 1D code is a general code which has been developed for different combustion chambers; annular, can-annular, can type and silo type combustion chambers. The purpose of generating this 1D code is the possibility of fast analysis of combustors in different operating conditions and reaching required outputs. This 1D code is a part of a general simulation 1D code for gas turbine and was used for a silo type combustor performance prediction. This code generates required quantities such as pressure loss, exit temperature, liner temperature and mass distribution through the combustion chamber. Mass distribution and pressure loss are analyzed and determined with an electrical analogy. Results derived from 1D code are validated with empirical data available for different combustors. There is appropriate agreement between these experimental and analytical results. Drag coefficients for liner holes are available from experimental data and for burner are calculated as a curve with CFD simulations. What differs this code from other 1D codes for gas turbine combustors is the advantage of using combustion efficiencies evolved from numerical simulation results in different loads. These efficiencies are determined with CFD simulations and are available as maps and inserted into the gas temperature calculation algorithm of 1D code. In other 1D codes in this field, empirical correlations are used for combustion efficiency determination. Combustion efficiency curves for design and off-design conditions in this study are achieved by 2D and 3D simulation of combustion chamber with application of EBU/Finite Rate model and 8 step reactions of CH4 burning. Diffusion flame in low loads and premixed flame in high loads are considered. Flame stability and Lean Blow Out charts are evolved from CFD simulation and Heat transfer is applied with empirical correlations.

Design of a Non-Reactive Warm Rig With Real Lean-Premix Combustor Swirlers and Film-Cooled First Stage Nozzles

2020 ◽  
Author(s):  
Simone Cubeda ◽  
Tommaso Bacci ◽  
Lorenzo Mazzei ◽  
Simone Salvadori ◽  
Bruno Facchini ◽  
...  
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Heavy Duty ◽  
Design Practices ◽  
Standard Design ◽  
Real Hardware ◽  
Heavy Duty Gas Turbine

Abstract Modern industrial gas turbines typically employ lean-premix combustors, which can limit pollutant emissions thanks to premixed flames, while sustaining high turbine inlet temperatures that increase the single-cycle thermal efficiency. As such, gas-turbine first stage nozzles can be characterized by a highly-swirled and temperature-distorted inlet flow field. However, due to several sources of uncertainty during the design phase, wide safety margins are commonly adopted, having a direct impact on engine performance and efficiency. Therefore, aiming at increasing the knowledge on combustor-turbine interaction and improving standard design practices, a non-reactive test rig composed of real hardware was assembled at the University of Florence, Italy. The rig, accommodating three lean-premix swirlers within a combustion chamber and two first stage film-cooled nozzles of a Baker Hughes heavy-duty gas turbine, is operated in similitude conditions. The rig has been designed to reproduce the real engine periodic flow field on the central vane channel, also allowing for measurements far enough from the lateral walls. The periodicity condition on the central sector was achieved by the proper design of both the angular profile and pitch value of the tailboards with respect to the vanes, which was carried out in a preliminary phase via a Design of Experiments procedure. In addition, circular ducts needed to be installed at the injectors outlet section to preserve the non-reactive swirling flow down to the nozzles’ inlet plane. The combustor-turbine interface section has been experimentally characterized in nominal operating conditions as per the temperature, velocity and pressure fields by means of a five-hole pressure probe provided with a thermocouple, installed on an automatic traverse system. To study the evolution of the combustor outlet flow through the vanes and its interaction with the film-cooling flow, such measurements have been replicated also downstream of the vanes’ trailing edge. This work allowed for designing and providing preliminary data on a combustor simulator capable of equipping and testing real hardware film-cooled nozzles of a heavy-duty gas turbine. Ultimately, the activity sets the basis for an extensive test campaign aimed at characterizing the metal temperature, film effectiveness and heat transfer coefficient at realistic aerothermal conditions. In addition, and by leveraging experimental data, this activity paves the way for a detailed validation of current design practices as well as more advanced numerical methodologies such as Scale-Adaptive Simulations of the integrated combustor-turbine domain.

Experimental Research of Combustion Chamber With Hybrid Burner and Variable Regulation of Primary Air

2007 ◽  
Author(s):  
S. Vesely´ ◽  
S. Pary´zek ◽  
E. Vinogradov ◽  
Y. Zakharov ◽  
A. Soudarev
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Process ◽  
The European Union ◽  
Real Gas ◽  
The Real ◽  
Wide Range ◽  
Emission Limits ◽  
Turbine Output

The environmentally friendly modification of gas turbine combustion chambers is a process for altering the structure of combustion, mainly in the primary zone in order to reduce the emission of NOx, CO, and solids into the atmosphere. The ecological modernization of gas turbines that are currently in operation is a continually topical subject because there are several thousand turbine units in Europe that do not meet current emission limits. At the same time, it can be expected that the emission limits for these turbines operating in the European Union will be reduced to NOx≤75 mg/m3, CO≤100 mg/m3 in working range of 40–100% of the gas turbine output after the year 2010. The authors have developed a new construction of a hybrid low-emission natural gas burner. Developmental work was performed both on one burner and also in a burner group consisting of seven hybrid burners. Results will be presented in this paper for model conditions for the atmospheric test rig and their re-calculation to the operational parameters on the real gas turbine. A conception with variable primary section combustion chamber geometry has been used to achieve low emissions in a wide range of gas turbine output allowing the organization of the combustion process with a constant gas/air mixing ratio coefficient. A prototype of a combustion chamber with a hybrid burner group with control of the primary air mass flow has been manufactured and tested in a 6 MW gas turbine operating in a gas pipeline compressor plant. The achieved emission characteristics will be presented and compared with precalculations. The experiments made on the real gas turbine have proven the possibility of meeting the target emission limit performance of NOx≤50 mg/m3, CO≤50 mg/m3. Other possibilities how to reduce harmful emissions for this burner type will be presented in this paper.

Influence of Excess Air Factor on NOx Emissions From a 200 kW Swirl Burner

2015 ◽  
Author(s):  
Abdallah Ahmed ◽  
Essam E. Khalil ◽  
Hatem Kayed ◽  
Mohamed M. A. Hassan
Keyword(s):  
Combustion Chamber ◽  
Air Temperature ◽  
Gas Turbines ◽  
Flame Temperature ◽  
Combustion Process ◽  
Operating Conditions ◽  
Swirl Burner ◽  
Nox Formation ◽  
Excess Air ◽  
Thermal Nox

NOx formation during the combustion process occurs mainly through the oxidation of nitrogen in the combustion air (thermal NOx) and through oxidation of nitrogen with the fuel (prompt NOx). The present study aims to investigate numerically the problem of NOx pollution using a model of combustion chamber with 200 kW swirl burner utilizing propane as fuel. The importance of this problem is mainly due to its relation to the pollutants produced by boiler furnaces and gas turbines, which used widely in thermal industrial plants. Governing conservation equations of mass, momentum and energy, and equations representing the transport of species concentrations, turbulence, combustion and radiation modeling in addition to NOx modeling equations were solved together to present temperature and OH distribution inside the combustion chamber, and the NOx concentration at the combustion chamber exit, at various operating conditions of fuel to air ratio. In particular, the simulation provided more insight on the correlation between the peak flame temperature and the thermal NOx concentration. The results have shown that the peak flame temperature and NOx concentration decrease as the excess air factor λ increases. When considering a fixed value of mass flow rate of fuel, the results show that increasing λ results in a maximum value of thermal NOx concentration at the exit of the combustion chamber at λ = 1.05. As the combustion air temperature increases, and the thermal NOx concentration increases sharply. However, when λ exceeds this value NOx concentration starts to decrease due to the combustion air temperature decrease.

A Study on Low NOx Combustion in LBG-Fueled 1500°C-Class Gas Turbine

1994 ◽  
Author(s):  
Toshihiko Nakata ◽  
Mikio Sato ◽  
Toru Ninomiya ◽  
Takeharu Hasegawa
Keyword(s):  
Power Generation ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Coal Gasification ◽  
Combustion Process ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Gas Temperature ◽  
Secondary Air

Developing integrated coal gasification combined cycle systems ensures cost-effective and environmentally sound options for supplying future power generation needs. The reduction of NOx emissions and increasing the inlet temperature of gas turbines are the most significant issues in gas turbine development in an Integrated Coal Gasification Combined Cycle (IGCC) power generation systems. The coal gasified fuel, which is produced in a coal gasifier of air-blown entrained-flow type has calorific value as low as 1/10 of natural gas. Furthermore the fuel gas contains ammonia when a gas cleaning system is a hot type, and ammonia will be converted to nitrogen oxides in the combustion process of a gas turbine. This study is performed in a 1500°C-class gas turbine combustor firing low-Btu coal-gasified fuel in IGCC systems. An advanced rich-lean combustor of 150-MW class gas turbine was designed to hold stable combustion burning low-Btu gas and to reduce fuel NOx emission that is produced from the ammonia in the fuel. The main fuel and the combustion air is supplied into fuel-rich combustion chamber with strong swirl flow and make fuel-rich flame to decompose ammonia into intermediate reactants such as NHi and HCN. The secondary air is mixed with primary combustion gas dilatorily to suppress the oxidization of ammonia reactants in fuel-lean combustion chamber and to promote a reducing process to nitrogen. By testing it under atmospheric pressure conditions, the authors have obtained a very significant result through investigating the effect of combustor exit gas temperature on combustion characteristics. Since we have ascertained the excellent performance of the tested combustor through our extensive investigation, we wish to report on the results.

Numerical Investigation of a Swirl Stabilized Methane Fired Burner and Validation With Experimental Data

2019 ◽  
Author(s):  
Federica Farisco ◽  
Philipp Notsch ◽  
Rene Prieler ◽  
Felix Greiffenhagen ◽  
Jakob Woisetschlaeger ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Heat Release ◽  
Reaction Zone ◽  
Gas Turbines ◽  
Combustion Process ◽  
Operating Conditions ◽  
Main Reaction ◽  
Combustion Models ◽  
Flamelet Generated Manifold

Abstract In modern gas turbines for power generation and future aircraft engines, the necessity to reduce NOx emissions led to the implementation of a premixed combustion technology under fuel-lean conditions. In the combustion chamber of these systems, extreme pressure amplitudes can occur due to the unsteady heat release, reducing component life time or causing unexpected shutdown events. In order to understand and predict these instabilities, an accurate knowledge of the combustion process is inevitable. This study, which was provided by numerical methods, such as Computational Fluid Dynamics (CFD) is based on a three-dimensional (3D) geometry representing a premixed swirl-stabilized methane-fired burner configuration with a known flow field in the vicinity of the burner and well defined operating conditions. Numerical simulations of the swirl-stabilized methane-fired burner have been carried out using the commercial code ANSYS Fluent. The main objective is to validate the performance of various combustion models with different complexity by comparing against experimental data. Experiments have been performed for the swirl-stabilized methane-fired burner applying different technologies. Velocity fluctuation measurements have been carried out and validated through several techniques, such as Laser Doppler Anemometry (LDA) and Particle Image Velocimetry (PIV). Laser Interferometric Vibrometry (LIV) provided information on heat release fluctuations and OH*-chemiluminescence measurements have been done to identify the position of the main reaction zone. During the first part of the CFD investigation, the cold flow has been simulated applying different turbulence models and the velocity flow field obtained in the experiments has been compared with the numerical results. As next, the study focuses on the numerical analysis of the thermo-chemical processes in the main reaction zone. Few combustion models have been investigated beginning from Eddy Dissipation Model (EDM) and proceeding with increased complexity investigating the Steady Flamelet Model (SLF) and Flamelet Generated Manifold (FGM). An evaluation of the velocity field and temperature profile has been performed for all models used in order to test the validity of the numerical approach for the chosen geometry. The best option for future investigations of gas turbines has been identified.

Global Reaction Mechanism Optimization for CO Prediction With DARS and HEEDS

2020 ◽  
Author(s):  
Navin Mahto ◽  
Ayan Nath ◽  
Ramsatish Kaluri
Keyword(s):  
Reaction Mechanism ◽  
Reaction Mechanisms ◽  
Laminar Flame ◽  
Operating Conditions ◽  
Kinetic Rate ◽  
Mechanism Optimization ◽  
Accurate Design ◽  
Baseline Case ◽  
Global Reaction ◽  
Co Emission

Abstract Prediction of carbon monoxide (CO) emission is critical in gas turbine combustion. Compact yet accurate reaction mechanisms are required to predict CO with reasonable computing cost. This study uses SHERPA optimization algorithm to optimize the kinetic rate parameters of a 3-step methane-air global reaction mechanism for improved CO predictions. DARS is used as the chemical kinetics solver. Freely propagating laminar flame and constant pressure reactor solutions with GRI-Mech 3.0 reaction mechanism are used as references for optimization. Tradeoffs in the choice of solution techniques and solver settings for fast and accurate design runs are discussed in the paper. Optimization results and their interpretation for improving the design study is also presented. The optimal results show significant improvements in predictions compared to the baseline case. The workflow and best practices presented in this paper may be extended to optimize global reaction mechanisms for any given range of operating conditions.

Sign in / Sign up

Export Citation Format

Share Document