Lean Blowout Research in a Generic Gas Turbine Combustor With High Optical Access

1997 ◽  
Vol 119 (1) ◽  
pp. 108-118 ◽  
Author(s):  
G. J. Sturgess ◽  
D. Shouse

The U. S. Air Force is conducting a comprehensive research program aimed at improving the design and analysis capabilities for flame stability and lean blowout in the combustors of aircraft gas turbine engines. As part of this program, a simplified version of a generic gas turbine combustor is used. The intent is to provide an experimental data base against which lean blowout modeling might be evaluated and calibrated. The design features of the combustor and its instrumentation are highlighted, and the test facility is described. Lean blowout results for gaseous propane fuel are presented over a range of operating conditions at three different dome flow splits. Comparison of results with those of a simplified research combustor is also made. Lean blowout behavior is complex, so that simple phenomenological correlations of experimental data will not be general enough for use as design tools.

Author(s):  
G. J. Sturgess ◽  
D. Shouse

The U.S. Air Force is conducting a comprehensive research program aimed at improving the design and analysis capabilities for flame stability and lean blowout in the combustors of aircraft gas turbine engines. As part of this program, a simplified version of a generic gas turbine combustor is used. The intent is to provide an experimental data base against which lean blowout modeling might be evaluated and calibrated. The design features of the combustor and its instrumentation are highlighted, and the test facility is described. Lean blowout results for gaseous propane fuel are presented over a range of operating conditions at three different dome flow splits. Comparison of results with those of a simplified research combustor is also made. Lean blowout behavior is complex, so that simple phenomenological correlations of experimental data will not be general enough for use as design tools.


2021 ◽  
Author(s):  
Saurabh Patwardhan ◽  
Pravin Nakod ◽  
Stefano Orsino ◽  
Rakesh Yadav ◽  
Fang Xu ◽  
...  

Abstract Carbon monoxide (CO) has been identified as one of the regulated pollutants and gas turbine manufacturers target to reduce the CO emission from their gas turbine engines. CO forms primarily when carbonous fuels are not burnt completely, or products of combustion are quenched before completing the combustion. Numerical simulations are effective tools that allow a better understanding of the mechanisms of CO formation in gas turbine engines and are useful in evaluating the effect of different parameters like swirl, fuel atomization, mixing etc. on the overall CO emission for different engine conditions like idle, cruise, approach and take off. In this paper, a thorough assessment of flamelet generated manifold (FGM) combustion model is carried out to predict the qualitative variation and magnitude of CO emission index with the different configurations of a Honeywell test combustor operating with liquid fuel under idle condition, which is the more critical engine condition for CO emission. The different designs of the test combustor are configured in such a way that they yield different levels of CO and hence are ideal to test the accuracy of the combustion model. Large eddy simulation (LES) method is used for capturing the turbulence accurately along with the FGM combustion model that is computationally economical compared to the detailed/reduced chemistry modeling using finite rate combustion model. Liquid fuel spray breakup is modeled using stochastic secondary droplet (SSD) model. Four different configurations of the aviation gas turbine combustor are studied in this work referring to earlier work by Xu et al. [1]. It is shown that the FGM model can predict CO trends accurately. The other global parameters like exit temperature, NOx emissions, pattern factor also show reasonable agreement with the test data. The sensitivity of the CO prediction to the liquid fuel droplet breakup model parameters is also studied in this work. Although the trend of CO variation is captured for different values of breakup parameters, the absolute magnitude of CO emission index differs significantly with the change in the values of breakup parameters suggesting that the spray has a larger impact on the quantitative prediction of CO emission. An accurate prediction of CO trends at idle conditions using FGM model extends the applicability of FGM model to predict different engine operating conditions for different performance criteria accurately.


Author(s):  
Y. Levy ◽  
F. C. Christo ◽  
I. Gaissinski ◽  
V. Erenburg ◽  
V. Sherbaum

This study investigates the performance and the conditions under which flameless oxidation can be achieved for a given annular adiabatic combustor. Numerical modelling of velocity, temperature and species fields are performed for different flow configurations of air and methane streams injected into a proposed design of a gas-turbine combustor. Parametric analysis was performed by systematically varying several parameters: radius of a recirculation zone, radius of the combustor, location of air and fuel ports, air and fuel velocities magnitudes and injection angles. The analysis was performed initially using a three-step global chemistry model to identify a design (geometry and operating conditions) that yield flameless combustion regime. The selected design was then modelled using a skeletal (46 reactions) and a detailed (309 reactions) chemical kinetics mechanism. The k–ε turbulence model was used in the most calculations. Overall, similar qualitative flow, temperature, and species patterns were predicted by both kinetics models; however the detailed mechanism provides quantitatively more realistic predictions. An optimal flow configuration was achieved with exhaust NOx emissions of < 7.5 ppm, CO < 35ppm, and a pressure-drop < 5%, hence meeting the design criteria for gas turbine engines. This study demonstrates the feasibility of achieving ultra-low NOx and CO emissions utilising a flameless oxidation regime.


1967 ◽  
Vol 89 (1) ◽  
pp. 23-27 ◽  
Author(s):  
L. J. Fiedler ◽  
R. M. N. Pelloux

Materials for the turbine and combustor sections of gas turbine engines were evaluated for their resistance to sulfidation corrosion. The basic evaluation was conducted in a test facility by exposing the materials to a combustion gas atmosphere which simulates conditions of gas composition, corrosive combustion residue, gas velocity, and temperature that are encountered while operating a gas turbine engine in a marine environment. The influence of alloy composition, protective coatings, salt ingestion rates, and fuel sulfur content is discussed in relation to the degree of sulfidation corrosion. The mechanism of sulfidation corrosion attack, as determined by electron microprobe analyses and X-ray diffraction studies of corroded materials, is also discussed.


Author(s):  
Somnath De ◽  
Prasanna Mondal ◽  
Gourav Manohar Sardar ◽  
Rakin Bin Bokhtiar ◽  
Arijit Bhattacharya ◽  
...  

Abstract The main problem for using reliable and stable diffusion combustion in modern gas turbine engines is the production of NOx at a higher level which is not permissible for maintaining the healthy environment. Thus, combustion in lean premixed mode has become the most promising technology in many applications related to power generation gas turbine, industrial burner etc. Although the lean combustion minimizes NOx production, it suffers from an increased risk of lean blowout (LBO) when the requirement of thrust or load is low. It mainly occurs at the lean condition when the equilibrium between the flame speed and the unburnt air-fuel mixture velocity is broken. Current aircraft gas turbine engines operate fuel close to the combustion chamber which leads to the partially premixed combustion. Partially premixed combustion is also susceptible to lean blowout. Therefore, we have designed a swirl-stabilized dump combustor, where different lengths of fuel-air mixing are available. Our present work aims at improving the combustion stability by incorporating a secondary fuel injection through a pilot arrangement connected with the combustion chamber for premixed as well as partially premixed flames. Incorporation of the pilot system adds a small fraction of the total fuel into the combustion chamber directly. This investigation shows significant extension of the LBO limit towards leaner fuel-air mixture while the NOx emission in the combustion chamber is within the permissible limit. This result can be used for aircraft operators during the process of landing when fuel supply has to be decreased to reduce engine thrust or for power plants operating at low loads. The study of control is based on the colour variation of the flame which actually defines the changes in combustion characteristics. For early detection of LBO, the ratio between the intensity of red and blue colour obtained from flame images with a high speed camera is used. As LBO is approached, the ratio of red to blue intensity falls monotonically. When the ratio falls below a preset threshold, a small fraction of the total fuel is added to the central pilot line. This strategy allows the LBO limit to be shifted to a much lower equivalence ratio (maximum 20% and 11% for fully premixed and least premixed flames, respectively) without any significant increase in NOx production. The analysis includes a feedback control algorithm which is computed in MATLAB and the code is embedded in Labview for hardware implementation.


2019 ◽  
Vol 62 (2) ◽  
pp. 298-303
Author(s):  
A. V. Il’inkov ◽  
A. M. Ermakov ◽  
V. V. Takmovtsev ◽  
A. V. Shchukin ◽  
A. M. Erzikov

Author(s):  
Erlendur Steinthorsson ◽  
Adel Mansour ◽  
Brian Hollon ◽  
Michael Teter ◽  
Clarence Chang

Participating in NASA’s Environmentally Responsible Aviation (ERA) Project, Parker Hannifin built and tested multipoint Lean Direct Injection (LDI) fuel injectors designed for NASA’s N+2 55:1 Overall Pressure-Ratio (OPR) gas turbine engine cycles. The injectors are based on Parker’s earlier three-zone injector (3ZI) which was conceived to enable practical implementation of multipoint LDI schemes in conventional aviation gas turbine engines. The new injectors offer significant aerodynamic design flexibility, excellent thermal performance, and scalability to various engine sizes. The injectors built for this project contain 15 injection points and incorporate staging to enable operation at low power conditions. Ignition and flame stability were demonstrated at ambient conditions with ignition air pressure drop as low as 0.3% and fuel-to-air ratio (FAR) as low as 0.011. Lean Blowout (LBO) occurred at FAR as low as 0.005 with air at 460 K and atmospheric pressure. A high pressure combustion testing campaign was conducted in the CE-5 test facility at NASA Glenn Research Center at pressures up to 250 psi and combustor exit temperatures up to 2,033 K (3,200 °F). The tests demonstrated estimated LTO cycle emissions that are about 30% of CAEP/6 for a reference 60,000 lbf thrust, 54.8-OPR engine. This paper presents some details of the injector design along with results from ignition, LBO and emissions testing.


Author(s):  
John Blouch ◽  
Hejie Li ◽  
Mark Mueller ◽  
Richard Hook

The LM2500 and LM6000 dry-low-emissions aeroderivative gas turbine engines have been in commercial service for 15 years and have accumulated nearly 10 × 106 hours of commercial operation. The majority of these engines utilize pipeline quality natural gas predominantly comprised of methane. There is; however, increasing interest in nonstandard fuels that contain varying levels of higher hydrocarbon species and/or inert gases. This paper reports on the demonstrated operability of LM2500 and LM6000 DLE engines with nonstandard fuels. In particular, rig tests at engine conditions were performed to demonstrate the robustness of the dual-annular counter-rotating swirlers premixer design, relative to flameholding with fuels containing high ethane, propane, and N2 concentrations. These experiments, which test the ability of the hardware to shed a flame introduced into the premixing region, have been used to expand the quoting limits for LM2500 and LM6000 gas turbine engines to elevated C2+ levels. In addition, chemical kinetics analysis was performed to understand the effect of temperature, pressure, and fuel compositions on flameholding. Test data for different fuels and operating conditions were successfully correlated with Damkohler number.


Author(s):  
John Blouch ◽  
Hejie Li ◽  
Mark Mueller ◽  
Richard Hook

The LM2500 and LM6000 dry-low-emissions (DLE) aeroderivative gas turbine engines have been in commercial service for 15 years and have accumulated nearly 10 million hours of commercial operation. The majority of these engines utilize pipeline quality natural gas predominantly comprised of methane. There is, however, increasing interest in nonstandard fuels that contain varying levels of higher hydrocarbon species and/or inert gases. This paper reports on the demonstrated operability of LM2500 and LM6000 DLE engines with nonstandard fuels. In particular, rig tests at engine conditions were performed to demonstrate the robustness of the dual-annular counter-rotating swirlers (DACRS) premixer design, relative to flameholding with fuels containing high ethane, propane, and N2 concentrations. These experiments, which test the ability of the hardware to shed a flame introduced into the premixing region, have been used to expand the quoting limits for LM2500 and LM6000 gas turbine engines to elevated C2+ levels. In addition, chemical kinetics analysis was performed to understand the effect of temperature, pressure, and fuel compositions on flameholding. Test data for different fuels and operating conditions were successfully correlated with Damkohler number.


Author(s):  
M. A. Mawid ◽  
C. A. Arana ◽  
B. Sekar

An advanced thermal management analysis tool, named Advanced Thermal Hydraulic Energy Network Analyzer (ATHENA), has been used to simulate a fuel system for gas turbine engines. The ATHENA tool was modified to account for JP-8/dodecane fuel properties. The JP-8/dodecane fuel thermodynamic properties were obtained from the SUPERTRAP property program. A series of tests of a fuel system simulator located at the Air Force Research Laboratory (AFRL)/Wright Patterson Air Force Base were conducted to characterize the steady state and dynamic behavior of the fuel system. Temperature, pressures and fuel flows for various fuel pump speeds, pressure rise and flow control valve stem positions (orifice areas), heat loads and engine fuel flows were measured. The predicted results were compared to the measured data and found to be in excellent agreement. This demonstrates the capability of the ATHENA tool to reproduce the experimental data and, consequently, its validity as an analysis tool that can be used to carry out analysis and design of fuel systems for advanced gas turbine engines. However, some key components in the fuel system simulator such as control components, which regulate the engine fuel flow based on predetermined parameters such as fan speed, compressor inlet and exit pressures and temperatures, combustor pressure, turbine temperature and power demand, were not simulated in the present investigation due to their complex interactions with other components functions. Efforts are currently underway to simulate the operation of the fuel system components with control as the engine fuel flow and power demands are varied.


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