Numerical Simulation to Characterize Homogeneity of Air-Fuel Mixture for Premixed Combustion in Gas Turbine Combustor

2012 ◽  
Author(s):  
Kamalika Chatterjee ◽  
Arkadeep Kumar ◽  
Souvick Chatterjee ◽  
Achintya Mukhopadhyay ◽  
Swarnendu Sen
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Flow Rate ◽  
Combustion Zone ◽  
Equivalence Ratio ◽  
Fuel Mixture ◽  
Premixed Combustion ◽  
Internal Diameter ◽  
Gas Turbine Combustor ◽  
Ansys Fluent

Homogeneity in mixing of air and fuel in premixed combustion for a gas turbine combustor is a critical criterion to ensure efficient combustion and less environmental hazards. The current work deals with determining this homogenous characteristic of air-fuel mixture through computational simulation to specify homogeneity for a particular premixing length and equivalence ratio required for gas turbine combustion. A 3-D geometry of combustion chamber with combustion zone of internal diameter 6 cm is constructed. A premixing tube is augmented with the combustion chamber which has one air inlet port at the bottom and 3 fuel inlet ports. Air-fuel mixture is considered to enter the combustion zone with inlet swirl. The homogeneity of the mixture is found out at the dump plane and other important planes from simulation done with ANSYS FLUENT® for the meshed geometry. The results show whether mixing of air and fuel is full or partial and the extent of partial premixing. The parameters varied in the ANSYS FLUENT®. based simulation are the premixing length i.e. port of entry of fuel, the fuel flow rate i.e. the equivalence ratio and the air flow rate.

Experimental Characterization of Premixed Flame in Gas Turbine Combustor With Spectroscopy and RGB Analysis

2012 ◽  
Author(s):  
Arkadeep Kumar ◽  
Kamalika Chatterjee ◽  
Achintya Mukhopadhyay ◽  
Swarnendu Sen
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Equivalence Ratio ◽  
Graphical Representation ◽  
Chemical Species ◽  
Fuel Mixture ◽  
Electromagnetic Spectrum ◽  
Gas Turbine Combustor ◽  
Flame Monitoring

Gas turbine combustion has been one of the principal sources for power generation and propulsion systems. Recent research thrust on flame monitoring for characterization of flame behavior has gained prominence for several reasons — notably for performance of combustor in aerospace propulsion and power plant applications, reduction in pollutant levels like NOx, and fire safety engineering, Lean air-fuel mixture leads to efficient combustion with lesser emissions, albeit with risk of Lean blow out (LBO). Flame monitoring is done to find out LBO point-which occurs by progressively varying the Air-fuel ratio or equivalence ratio. The current paper monitors the characteristics of lean premixed, swirl-stabilized, LPG fueled, dump combustor with the help of spectroscopy and high resolution camera images. Chemiluminescence is being used for determination of combustion characteristics. The spectroscopic peaks for chemical species like - OH* and CH* radicals and water vapor are found at varying parameters like air-fuel premixing and equivalence ratio. Blow off characteristics which occur in gas turbine combustor when going from rich to lean mixture are investigated. The comparison of the averaged red, green and blue (R, G, B) values has been done by graphical representation. The spectroscopic data are co-related with the RGB analysis results- and the location of spectroscopic peaks of intensities and their correspondence with electromagnetic spectrum in investigated. The behavior of peak intensities of Red, Green, Blue alongwith irradiation by chemical species – with the change in parameters like air flow rate, fuel flow rate or equivalence ratio and the extent of air-fuel premixing are investigated. Metrics for detecting the approach of impending LBO are proposed from the spectroscopic results.

The Influence of Film Cooling on Emissions for a Low NOx Radial Swirler Gas Turbine Combustor

2001 ◽  
Author(s):  
G. E. Andrews ◽  
M. N. Kim
Keyword(s):  
Mach Number ◽  
Gas Turbine ◽  
Flow Rate ◽  
Film Cooling ◽  
Equivalence Ratio ◽  
Air Flow ◽  
Gas Turbine Combustor ◽  
Cooling Flow ◽  
Full Coverage ◽  
Primary Zone

An experimental investigation was undertaken of the influence on emissions of full coverage discrete hole film cooling of a lean low NOx radial swirler natural gas combustor. The combustor used radial swirler vane passage fuel injection on the centre of the vane passage inlet. The test configuration was similar to that used in the Alstom Power Tornado and related family of low NOx gas turbines. The test conditions were simulated at atmospheric pressure at the flow condition of lean low NOx gas turbine primary zones. The tests were carried out at an isothermal flow Mach number of 0.03, which represents 60% of industrial gas turbine combustor airflow through the swirl primary zone. The effusion film cooling used was Rolls-Royce Transply, which has efficient internal cooling of the wall as well as full coverage discrete hole film cooling. Film cooling levels of 0, 16 and 40% of the primary zone airflow were investigated for a fixed total primary zone air flow and reference Mach number of 0.03. The results showed that there was a major increase in the NOx emissions for 740K inlet temperature and 0.45 overall equivalence ratio from 6ppm at zero film cooling air flow to 32ppm at 40% coolant flow rate. CO emissions increased from 25ppm to 75ppm for the same increase in film cooling flow rate. It was shown that the main effect was the creation of a richer inner swirler combustion with a surrounding film cooling flow that did not mix well with the central swirling combustion. The increase in NOx and CO could be predicted on the basis of the central swirl flow equivalence ratio.

scholarly journals High-Resolution One-Dimensional Modeling of a Gas Turbine Combustor Using Eulerian-Lagrangian Method

2019 ◽  
Author(s):  
Reza Khodadadi ◽  
Nima Zamani Meymian
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Flow Rate ◽  
Energy Equation ◽  
Source Term ◽  
Outlet Temperature ◽  
Lagrangian Coordinates ◽  
Gas Turbine Combustor ◽  
Time Step ◽  
One Dimensional

In this paper, a dynamic combustor model for inclusion into a one-dimensional full gas turbine engine simulation model, with high numerical accuracy is developed. Effects of dominant parameters, such as frequency and amplitude of the inlet air and fuel mass flow rate fluctuations, on outlet temperature of the combustion chamber, are investigated. The main goal of this research is to analyze the response of the gas turbine combustor to dynamic events that occur in the compressor. In the present work, for modeling combustion, the equations of chemical equilibrium (a second-law concept) are developed and applied to combustion-product mixtures. Thus the heat released from combustion is computed and used as a source term in the energy equation. Ignition effects either would be considered with a time lag equation as a source term in the energy equation. The combustor flammability limits are determined by using available experimental data for various gases and also Le Chatelier’s law. Source terms of governing equations are added using the operator splitting method. To operate this, the modified version of the PPM algorithm called PPMLR is used which solves the Euler equations in Lagrangian coordinates. At the end of each time step, results calculated in the Lagrangian coordinates would remap to the original Eulerian coordinate. The results revealed that to achieve a grid-independent solution, the accuracy of 0.002 m over the length of the combustion chamber should be applied. By reducing the accuracy of simulation, numerical diffusion causes a rise in flow temperature along with the combustion chamber. Through the dynamic modeling aspect, it is found that by increasing inlet fuel flow rate frequency up to 25 Hz, the amplitude of the fluctuations of outlet temperature, increases. Further increase in frequency up to 100 Hz, the amplitude of the fluctuations remains unchanged. However further increases in frequency from 100 Hz, causes amplitudes of outlet temperature fluctuations to decrease.

scholarly journals Simulation of Premixed Combustion with Varying Equivalence Ratio in Gas Turbine Combustor

2015 ◽  
Vol 31 (3) ◽  
pp. 861-871 ◽  
Author(s):  
S. Ruan ◽  
N. Swaminathan ◽  
M. Isono ◽  
T. Saitoh ◽  
K. Saitoh
Keyword(s):  
Gas Turbine ◽  
Equivalence Ratio ◽  
Premixed Combustion ◽  
Gas Turbine Combustor

Comparing Different Solutions for the Micro-Gas Turbine Combustor

2004 ◽  
Author(s):  
Maria Cristina Cameretti ◽  
Raffaele Tuccillo
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Equivalence Ratio ◽  
The Self ◽  
Combustion Chambers ◽  
Gas Turbine Combustor ◽  
Lean Mixture ◽  
Micro Gas Turbine ◽  
Different Types ◽  
Annular Combustor

This paper compares different types of combustion chambers for a micro-gas turbine which operates with both different fuels and variations in the inlet air conditions. The combustor types examined cover a wide variety of conditions for the primary combustion, whose fuel/air equivalence ratio ranges from typical lean-premixed levels up to dramatically rich values. The latter is attained in a combustion chamber of the RQL type, while the lean mixture burns in a tubular swirled combustor also equipped with a pilot igniter. The comparison is completed by including an annular combustor with a primary diffusive burner. The CFD based analysis highlights the main differences among the three types of combustors, in terms of temperature and pollutant distributions, and by focusing the attention on the self-ignition occurrence.

The Histogram of Pressure Oscillations Amplitudes, in Lean Premixed Combustions, Caused by Thermo-Acoustic Instabilities

2010 ◽  
Author(s):  
Nasser Seraj Mehdizadeh ◽  
Nozar Akbari
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Equivalence Ratio ◽  
Combustion Instability ◽  
Premixed Combustion ◽  
Space Distribution ◽  
Rayleigh Criterion ◽  
Pressure Oscillations ◽  
Lean Premixed

Lean premixed combustion is widely used in recent years as a method to achieve the environmental standards with regard to NOx emission. In spite of the mentioned advantage, premixed combustion systems, with equivalence ratios less than one, are susceptible to the combustion instability. To study the lean combustion instability, by experiments, one premixed combustion setup, equipped with reactant supplying system, is designed and manufactured in Amirkabir University of Technology. In this research, gaseous propane is introduced as fuel and several experiments are performed at nearly atmospheric pressure, with equivalence ratios within the range of 0.7 to 1.5. In this experiments fuel mass flow rate is varied between 2 and 4 gr/s. Unstable operating condition has been observed in combustion chamber when equivalence ratio is less than one. To distinguish the combustion instability for various operating conditions, probability density functions, spectral diagrams, and space distribution of pressure oscillations, along with Rayleigh Criterion, are utilized. Accordingly, effect of equivalence ratio on stabilizing the unstable combustion system is investigated. Moreover, convective delay time is calculated for all experiments and the results are compared with Rayleigh Criterion. This comparison has shown good agreement the experimental results and Rayleigh Criterion. Finally, stability limits are identified based on inlet mass flow rate and equivalence ratio.

Towards the Multiobjective Optimisation of Gas Turbine Combustors

2006 ◽  
Author(s):  
S. G. Wyse ◽  
G. T. Parks ◽  
R. S. Cant
Keyword(s):  
Transfer Function ◽  
Tabu Search ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Design Space ◽  
Objective Functions ◽  
Multiobjective Optimisation ◽  
Gas Turbine Combustor ◽  
Linear Network ◽  
Good Design

Gas turbine combustor design entails multiple, and often contradictory, requirements for the designer to consider. Multiobjective optimisation on a low-fidelity linear-network-based code is suggested as a way of investigating the design space. The ability of the Tabu Search optimiser to minimise NOx and CO, as well as several acoustic objective functions, is investigated, and the resulting “good” design vectors presented. An analysis of the importance of the flame transfer function in the model is also given. The mass flow and the combustion chamber width and area are shown to be very important. The length of the plenum and the widths of the plenum exit and combustor exit also influence the design space.

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