Fluid-Structure Interaction in Combustion System of a Gas Turbine—Effect of Liner Vibrations

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
A. K. Pozarlik ◽  
J. B. W. Kok
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Pressure Fluctuations ◽  
Feedback System ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Thermoacoustic Instabilities ◽  
Pressurized Combustion ◽  
Loop Feedback ◽  
Computational Structural Dynamics

Prediction of mutual interaction between flow, combustion, acoustic, and vibration phenomena occurring in a combustion chamber is crucial for the reliable operation of any combustion device. In this paper, this is studied with application to the combustion chamber of a gas turbine. Very dangerous for the integrity of a gas turbine structure can be the coupling between unsteady heat release by the flame, acoustic wave propagation, and liner vibrations. This can lead to a closed-loop feedback system resulting in mechanical failure of the combustor liner due to fatigue and fatal damage to the turbine. Experimental and numerical investigations of the process are performed on a pressurized laboratory-scale combustor. To take into account interaction between reacting flow, acoustics, and vibrations of a liner, the computational fluid dynamics (CFD) and computational structural dynamics (CSD) calculations are combined into one calculation process using a partitioning technique. Computed pressure fluctuations inside the combustion chamber and associated liner vibrations are validated with experiments performed at the state-of-the-art pressurized combustion setup. Three liner structures with different thicknesses are studied. The numerical results agree well with the experimental data. The research shows that the combustion instabilities can be amplified by vibrating walls. The modeling approach discussed in this paper allows to decrease the risk of the gas turbine failure by prediction, for given operating conditions, of the hazardous frequency at which the thermoacoustic instabilities appear.

Application of Active Combustion Instability Control to a Heavy Duty Gas Turbine

1998 ◽  
Vol 120 (4) ◽  
pp. 721-726 ◽  
Author(s):  
J. R. Seume ◽  
N. Vortmeyer ◽  
W. Krause ◽  
J. Hermann ◽  
C.-C. Hantschk ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Instability ◽  
Pressure Fluctuations ◽  
Preventive Measure ◽  
Feedback System ◽  
Operating Conditions ◽  
Combustion Instabilities ◽  
Instability Control ◽  
Heavy Duty Gas Turbine

During the prototype shop tests, the Model V84.3A ring combustor gas turbine unexpectedly exhibited a noticeable “humming” caused by self-excited flame vibrations in the combustion chamber for certain operating conditions. The amplitudes of the pressure fluctuations in the combustor were unusually high when compared to the previous experience with silo combustor machines. As part of the optimization program, the humming was investigated and analyzed. To date, combustion instabilities in real, complex combustors cannot be predicted analytically during the design phase. Therefore, and as a preventive measure against future surprises by “humming,” a feedback system was developed which counteracts combustion instabilities by modulation of the fuel flow rate with rapid valves (active instability control, AIC). The AIC achieved a reduction of combustion-induced pressure amplitudes by 86 percent. The Combustion instability in the Model V84.3A gas turbine was eliminated by changes of the combustor design. Therefore, the AIC is not required for the operation of customer gas turbines.

scholarly journals Application of Active Combustion Instability Control to a Heavy Duty Gas Turbine

1997 ◽  
Author(s):  
J. R. Seume ◽  
N. Vortmeyer ◽  
W. Krause ◽  
J. Hermann ◽  
C.-C. Hantschk ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Instability ◽  
Pressure Fluctuations ◽  
Preventive Measure ◽  
Feedback System ◽  
Operating Conditions ◽  
Combustion Instabilities ◽  
Instability Control ◽  
Heavy Duty Gas Turbine

During the prototype shop tests, the Model V84.3A ring combustor gas turbine unexpectedly exhibited a noticeable “humming” caused by self-excited flame vibrations in the combustion chamber for certain operating conditions. The amplitudes of the pressure fluctuations in the combustor were unusually high when compared to the previous experience with silo combustor machines. As part of the optimization program, the humming was investigated and analyzed. To date, combustion instabilities in real, complex combustors cannot be predicted analytically during the design phase. Therefore, and as a preventive measure against future surprises by “humming”, a feedback system was developed which counteracts combustion instabilities by modulation of the fuel flow rate with rapid valves (Active Instability Control, AIC). The AIC achieved a reduction of combustion-induced pressure amplitudes by 86%. The combustion instability in the Model V84.3A gas turbine was eliminated by changes of the combustor design. Therefore, the AIC is not required for the operation of customer gas-turbines.

Chemical Reactor Network Application to Emissions Prediction for Industial DLE Gas Turbine

2006 ◽  
Author(s):  
I. V. Novosselov ◽  
P. C. Malte ◽  
S. Yuan ◽  
R. Srinivasan ◽  
J. C. Y. Lee
Keyword(s):  
Gas Turbine ◽  
Chemical Reactor ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Ongoing Research ◽  
Chemical Reactor Network ◽  
Reaction Zones ◽  
Reactor Network

A chemical reactor network (CRN) is developed and applied to a dry low emissions (DLE) industrial gas turbine combustor with the purpose of predicting exhaust emissions. The development of the CRN model is guided by reacting flow computational fluid dynamics (CFD) using the University of Washington (UW) eight-step global mechanism. The network consists of 31 chemical reactor elements representing the different flow and reaction zones of the combustor. The CRN is exercised for full load operating conditions with variable pilot flows ranging from 35% to 200% of the neutral pilot. The NOpilot. The NOx and the CO emissions are predicted using the full GRI 3.0 chemical kinetic mechanism in the CRN. The CRN results closely match the actual engine test rig emissions output. Additional work is ongoing and the results from this ongoing research will be presented in future publications.

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.

Active Control of Fuel Splits in Gas Turbine DLE Combustion Systems

2007 ◽  
Author(s):  
Ghenadie Bulat ◽  
Dorian Skipper ◽  
Robin McMillan ◽  
Khawar Syed
Keyword(s):  
Gas Turbine ◽  
Active Control ◽  
Control Algorithm ◽  
Pressure Fluctuations ◽  
Stability Limit ◽  
Operating Conditions ◽  
Direct Result ◽  
Operational Parameter ◽  
Engine Operation ◽  
The Impact

This paper presents a system for the active control of the fuel split within a two-stream Dry Low Emissions (DLE) gas turbine. The system adjusts the fuel split based upon the amplitude of combustor pressure fluctuations and burner metal temperature. The active control system, its implementation and its performance during engine tests on Siemens SGT-200 is described. The paper describes the active fuel split control algorithm. Engine test results are then presented for steady and transient loads with different rates of change of the engine operation temperature, including rapid load acceptance and load shedding. Additionally, cycling operating conditions were tested to evaluate the performance of the algorithm in typical island mode and mechanical drive applications. The active control algorithm was successful in providing stable and reliable control of the turbine allowing very low emissions levels to be attained without manual intervention. In fact it allows areas to be reached that until now were excluded. The impact of operational parameter changes (e.g. load change, ambient temperature, fuel composition etc.) on the engine operability proved the active control software’s ability to respond seamlessly. In addition, it prevented flameout and/or high pressure fluctuation while keeping burner temperatures within limits. Recorded emissions showed a reduction in NOx was achieved when the fuel split was controlled by the algorithm compared to standard operation. This was a direct result of the algorithm successfully identifying the lean stability limit and operating close to it.

Acoustic Resonances of an Industrial Gas Turbine Combustion System

2000 ◽  
Author(s):  
S. Hubbard ◽  
A. P. Dowling
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Acoustic Waves ◽  
Low Frequency ◽  
Operating Conditions ◽  
Combustion System ◽  
Resonant Frequencies ◽  
Bulk Mode ◽  
Acoustic Resonances ◽  
Industrial Gas Turbine

A theory is developed to describe low frequency acoustic waves in the complicated diffuser/combustor geometry of a typical industrial gas turbine. This is applied to the RB211-DLE geometry to give predictions for the frequencies of the acoustic resonances at a range of operating conditions. The main resonant frequencies are to be found around 605 Hz (associated with the plenum) and around 461 Hz and 823 Hz (associated with the combustion chamber), as well as one at around 22 Hz (a bulk mode associated with the system as a whole).

Investigation of Flame Stabilization in a High-Pressure Multi-Jet Combustor by Laser Measurement Techniques

2014 ◽  
Author(s):  
Oliver Lammel ◽  
Tim Rödiger ◽  
Michael Stöhr ◽  
Holger Ax ◽  
Peter Kutne ◽  
...  
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Recirculation Zone ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Single Shot ◽  
Optical Access

In this contribution, comprehensive optical and laser based measurements in a generic multi-jet combustor at gas turbine relevant conditions are presented. The flame position and shape, flow field, temperatures and species concentrations of turbulent premixed natural gas and hydrogen flames were investigated in a high-pressure test rig with optical access. The needs of modern highly efficient gas turbine combustion systems, i.e., fuel flexibility, load flexibility with increased part load capability, and high turbine inlet temperatures, have to be addressed by novel or improved burner concepts. One promising design is the enhanced FLOX® burner, which can achieve low pollutant emissions in a very wide range of operating conditions. In principle, this kind of gas turbine combustor consists of several nozzles without swirl, which discharge axial high momentum jets through orifices arranged on a circle. The geometry provides a pronounced inner recirculation zone in the combustion chamber. Flame stabilization takes place in a shear layer around the jet flow, where fresh gas is mixed with hot exhaust gas. Flashback resistance is obtained through the absence of low velocity zones, which favors this concept for multi-fuel applications, e.g. fuels with medium to high hydrogen content. The understanding of flame stabilization mechanisms of jet flames for different fuels is the key to identify and control the main parameters in the design process of combustors based on an enhanced FLOX® burner concept. Both experimental analysis and numerical simulations can contribute and complement each other in this task. They need a detailed and relevant data base, with well-known boundary conditions. For this purpose, a high-pressure burner assembly was designed with a generic 3-nozzle combustor in a rectangular combustion chamber with optical access. The nozzles are linearly arranged in z direction to allow for jet-jet interaction of the middle jet. This line is off-centered in y direction to develop a distinct recirculation zone. This arrangement approximates a sector of a full FLOX® gas turbine burner. The experiments were conducted at a pressure of 8 bar with preheated and premixed natural gas/air and hydrogen/air flows and jet velocities of 120 m/s. For the visualization of the flame, OH* chemiluminescence imaging was performed. 1D laser Raman scattering was applied and evaluated on an average and single shot basis in order to simultaneously and quantitatively determine the major species concentrations, the mixture fraction and the temperature. Flow velocities were measured using particle image velocimetry at different section planes through the combustion chamber.

A NOx Prediction Scheme for Lean-Premixed Gas Turbine Combustion Based on Detailed Chemical Kinetics

1996 ◽  
Vol 118 (4) ◽  
pp. 765-772 ◽  
Author(s):  
W. Polifke ◽  
K. Do¨bbeling ◽  
T. Sattelmayer ◽  
D. G. Nicol ◽  
P. C. Malte
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Concentration Field ◽  
Operating Conditions ◽  
Chemical Mechanism ◽  
Reacting Flow ◽  
Oxides Of Nitrogen ◽  
Detailed Chemical Kinetics ◽  
Nox Formation ◽  
Lean Premixed

The lean-premixed technique has proven very efficient in reducing the emissions of oxides of nitrogen (NOx) from gas turbine combustors. The numerical prediction of NOx levels in such combustors with multidimensional CFD codes has only met with limited success so far. This is to some extent due to the complexity of the NOx formation chemistry in lean-premixed combustion, i.e., all three known NOx formation routes (Zeldovich, nitrous, and prompt) can contribute significantly. Furthermore, NOx formation occurs almost exclusively in the flame zone, where radical concentrations significantly above equilibrium values are observed. A relatively large chemical mechanism is therefore required to predict radical concentrations and NOx formation rates under such conditions. These difficulties have prompted the development of a NOx postprocessing scheme, where rate and concentration information necessary to predict NOx formation is taken from one-dimensional combustion models with detailed chemistry and provided—via look-up tables—to the multidimensional CFD code. The look-up tables are prepared beforehand in accordance with the operating conditions and are based on CO concentrations, which are indicative of free radical chemistry. Once the reacting flow field has been computed with the main CFD code, the chemical source terms of the NO transport equation, i.e., local NO formation rates, are determined from the reacting flow field and the tabulated chemical data. Then the main code is turned on again to compute the NO concentration field. This NOx submodel has no adjustable parameters and converges very quickly. Good agreement with experiment has been observed and interesting conclusions concerning superequilibrium O-atom concentrations and fluctuations of temperature could be drawn.

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.

Fuel Nozzle Performance Analysis Using Laser Techniques and Combustion Chamber With Optical Access

2006 ◽  
Author(s):  
G. R. Pucher ◽  
P. R. Underhill ◽  
W. D. Allan ◽  
G. Wang ◽  
S. Guy
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Scattered Light ◽  
Laser Sheet ◽  
Video Camera ◽  
Operating Conditions ◽  
Cross Sectional ◽  
Efficient Operation ◽  
Spray Pattern ◽  
Optical Access

Correct functioning of fuel nozzles is paramount to the efficient operation of gas turbine engines. Nozzles exhibiting poor distribution of droplets can be detrimental to combustion and overall engine life due to the creation of hot spots and potential for torching. The traditional technique of assessing nozzle performance involves operation in stagnant air conditions. Fuel spray is collected in the subdivided bins of a mechanical patternation system to determine spray symmetry. Recent improvements in spray analysis involve the use of laser light sheets to illuminate specific ‘slices’ of sprays in either cross sectional or axial planes. Typically, scattered light from the intersection of a laser sheet and a spray is recorded by a digital video camera, and images are averaged and corrected to determine the quality of the spray pattern. Such optical means of assessing spray quality provide great improvement over conventional means in terms of speed, convenience, and information retrieved. Nonetheless, data obtained in stagnant air conditions do not give an indication of spray geometry within combustion chambers under realistic operating conditions of airflow and combustion. This paper describes a project which applied laser-based optical patternation in a T-56 gas turbine combustion chamber rig with optical access under realistic flow conditions. As such, nozzle spray pattern was observed for various air and fuel flows in both cross sectional and plume (chamber axial) orientations. A deliberately damaged nozzle was also assessed for comparison with a good nozzle. Using optical filtration, spray patterns were observed under operationally representative combustion conditions.

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