scholarly journals Quantitative measurements of fuel distribution and flame structure in a lean-premixed aero-engine injection system by kerosene/OH-PLIF measurements under high-pressure conditions

2019 ◽  
Vol 37 (4) ◽  
pp. 5215-5222 ◽  
Author(s):  
P. Malbois ◽  
E. Salaün ◽  
B. Rossow ◽  
G. Cabot ◽  
L. Bouheraoua ◽  
...  
Keyword(s):  
High Pressure ◽  
Flame Structure ◽  
Injection System ◽  
Fuel Distribution ◽  
Quantitative Measurements ◽  
Aero Engine ◽  
Lean Premixed

Experimental Investigation With Optical Diagnostics of a Lean-Premixed Aero-Engine Injection System Under Relevant Operating Conditions

2017 ◽  
Author(s):  
P. Malbois ◽  
E. Salaun ◽  
F. Frindt ◽  
G. Cabot ◽  
B. Renou ◽  
...  
Keyword(s):  
Flame Length ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Injection System ◽  
Exhaust Gas ◽  
Laser Propagation ◽  
Aero Engine ◽  
Lean Premixed ◽  
Gradient Based

A Lean-Premixed (LP) aero-engine injection system was experimentally studied using optically-based measurements. Experiments were conducted under relevant operating conditions up to 1.38 MPa and using commercial kerosene as fuel. First of all, the structure of the reaction zone and the flame length into the combustion chamber have been studied with CH* chemiluminescence. It is observed from the data measurements that combustion can produce two types of flames, a V-shaped flame in which combustion is stabilized a few mm downstream from the injector and a tulip flame in which combustion is developing inside the injection system. The flame is found to be shorter and more confined when increasing the pressure. To complement this study, experiments were also performed using the OH-PLIF measurement technique. Data processing of the absorption of OH fluorescence signals along the laser propagation allowed the determination of the absolute distribution of OH concentration without any calibration of the OH fluorescence signals. The obtained values are in agreement with estimated premixed adiabatic chemical equilibrium results. Furthermore, the flame front location and its structure were captured from gradient-based filtering operations on OH-PLIF signals. Finally, pollutant emissions were also measured with an exhaust gas sampling probe positioned downstream from the combustor outlet. It has been found that NOx emission increases with Fuel Air Ratio (FAR) and pressure whereas CO exhibits an inverse trend.

Evaluation of CH4/NOx Reduced Mechanisms Used for Modeling Lean Premixed Turbulent Combustion of Natural Gas

1998 ◽  
Vol 120 (4) ◽  
pp. 703-712 ◽  
Author(s):  
H. P. Mallampalli ◽  
T. H. Fletcher ◽  
J. Y. Chen
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Gas Turbine ◽  
Turbulent Combustion ◽  
Gas Turbines ◽  
Flame Structure ◽  
Computational Cost ◽  
Premixed Turbulent Combustion ◽  
Reduced Mechanism ◽  
Lean Premixed

This study has identified useful reduced kinetic schemes that can be used in comprehensive multidimensional gas-turbine combustor models. Reduced mechanisms lessen computational cost and possess the capability to accurately predict the overall flame structure, including gas temperatures and key intermediate species such as CH4, CO, and NOx. In this study, four new global mechanisms with five, six, seven, and nine steps based on the full GRI 2.11 mechanism, were developed and evaluated for their potential to model natural gas chemistry (including NOx chemistry) in gas turbine combustors. These new reduced mechanisms were optimized to model the high pressure and fuel-lean conditions found in gas turbines operating in the lean premixed mode. Based on perfectly stirred reactor (PSR) and premixed code calculations, the five-step reduced mechanism was identified as a promising model that can be used in a multidimensional gas-turbine code for modeling lean-premixed, high-pressure turbulent combustion of natural gas. Predictions of temperature, CO, CH4, and NO from the five-to nine-step reduced mechanisms agree within 5 percent of the predictions from the full kinetic model for 1 < pressure (atm) < 30, and 0.6 < φ < 1.0. If computational costs due to additional global steps are not severe, the newly developed nine step global mechanism, which is a little more accurate and provided the least convergence problems, can be used. Future experimental research in gas turbine combustion will provide more accurate data, which will allow the formulation of better full and reduced mechanisms. Also, improvement in computational approaches and capabilities will allow the use of reduced mechanisms with larger global steps, perhaps full mechanisms.

Combustion Instabilities in a Lean Premixed Pre-Vaporized Combustor at High-Pressure High-Temperature

2017 ◽  
Author(s):  
Xiao Han ◽  
Xin Hui ◽  
Chi Zhang ◽  
Yuzhen Lin ◽  
Pei He ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Flame Structure ◽  
Low Frequency ◽  
Main Stage ◽  
Combustion Instabilities ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
High Pressure High Temperature ◽  
Lean Premixed

Experimental results correlating combustion instability and staging ratio in a RP-3 fueled lean premixed pre-vaporized (LPP) combustor is presented. All the experiments are operated at high-pressure and high-temperature conditions, and processed data has been collected and classified by the staging ratio. A low-frequency oscillation is found in the conditions that the main stage and pilot stage work together. There are two discrete frequencies laying in 50∼120 Hz and 420∼470 Hz, the former changes with staging ratio (SR) while the latter remains constant. Sensitivity analysis of flame model reveals that the low-frequency oscillation at 50∼120 Hz is highly suspected to be caused by an intrinsic mode of this combustor. RANS simulation of flame structure finds that delay time could be extended by decreasing SR, which is consistent with the theoretical analysis.

Experimental Investigation on Lean Blow Out of a Piloted Aero-Engine Burner

2014 ◽  
Author(s):  
R. Bhagwan ◽  
J. C. Wollgarten ◽  
P. Habisreuther ◽  
N. Zarzalis
Keyword(s):  
Liquid Fuel ◽  
Laser Doppler Anemometry ◽  
Flame Structure ◽  
Field Measurements ◽  
Flame Stabilization ◽  
Nox Formation ◽  
Fuel Distribution ◽  
Lean Combustion ◽  
Aero Engine ◽  
Operational Range

One of the preferred ways to reduce NOX formation in an aero-engine is to operate lean throughout the whole operational range; however the lean combustion suffers from poor stability. To avoid the problem associated with stability, often a rich pilot flame is used along with a main flame to act as a source of heat and radicals to the main flame. The focus of the paper is to discuss the influence of the liquid fuel spray characteristics and effect of flow parameters on the lean blow out (LBO) limits of a piloted burner. In order to understand the observed remarkable LBO limits of the pilot flame with Jet A-1 (LBO = 145 kg-air to kg-fuel at 0.1 MPa of combustor pressure), velocity field measurements by laser Doppler Anemometry (LDA) technique have been performed. Furthermore, the flame structure has been analyzed with OH* chemiluminescence imaging. Experimental results show that the LBO limits of the burner running with liquid fuel further improves with an increase in combustor pressure. Such improvement in LBO limits is attributed to the change in the liquid fuel distribution caused by the change in the combustor pressure. For gaseous fuel measurements, results indicate that the equivalence ratio and the momentum ratio of the pilot jet to the co-annular flow are the dominating parameters that control the mixing process in the combustor and the ensuing effect on the flame structure and location of flame stabilization is substantial. The flame stabilizes either along the centreline or along the shear layer between two jets. Such information is useful in designing a lean partially premixed combustion system where a pilot flame is required to stabilize a main lean flame.

Measurement of Biodiesel Blend and Conventional Diesel Spray Structure Using X-Ray Radiography

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
A. L. Kastengren ◽  
C. F. Powell ◽  
K.-S. Im ◽  
Y.-J. Wang ◽  
J. Wang
Keyword(s):  
Cone Angle ◽  
Injection Pressure ◽  
Fuel Distribution ◽  
X Ray ◽  
Spray Structure ◽  
Quantitative Measurements ◽  
Biodiesel Blend ◽  
Temporal And Spatial ◽  
Nozzle Geometries ◽  
Fuel Effects

The near-nozzle structure of several nonevaporating biodiesel-blend sprays has been studied using X-ray radiography. Radiography allows quantitative measurements of the fuel distribution in sprays to be made with high temporal and spatial resolution. Measurements have been made at different values of injection pressure, ambient density, and with two different nozzle geometries to understand the influences of these parameters on the spray structure of the biodiesel blend. These measurements have been compared with corresponding measurements of Viscor, a diesel calibration fluid, to demonstrate the fuel effects on the spray structure. Generally, the biodiesel-blend spray has a similar structure to the spray of Viscor. For the nonhydroground nozzle used in this study, the biodiesel-blend spray has a slightly slower penetration into the ambient gas than the Viscor spray. The cone angle of the biodiesel-blend spray is generally smaller than that of the Viscor spray, indicating that the biodiesel-blend spray is denser than the Viscor spray. For the hydroground nozzle, both fuels produce sprays with initially wide cone angles that transition to narrow sprays during the steady-state portion of the injection event. These variations in cone angle with time occur later for the biodiesel-blend spray than for the Viscor spray, indicating that the dynamics of the injector needle as it opens are somewhat different for the two fuels.

Hydrogen Blending Into Ansaldo Energia AE94.3A Gas Turbine: High Pressure Tests, Field Experience and Modelling Considerations

2021 ◽  
Author(s):  
A. Ciani ◽  
L. Tay-Wo-Chong ◽  
A. Amato ◽  
E. Bertolotto ◽  
G. Spataro
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Power Plants ◽  
Flame Structure ◽  
Flux Ratio ◽  
Fuel Blends ◽  
Pressure Tests ◽  
Fuel Staging ◽  
Combustion Tests ◽  
The Impact

Abstract Fuel flexibility in gas turbine development has become increasingly important and modern engines need to cope with a broad variety of fuels. The target to operate power plants with hydrogen-based fuels and low emissions will be of paramount importance in a future focusing on electric power decarbonization. Ansaldo Energia AE94.3A engine acquired broad experience with operation of various natural gas and hydrogen fuel blends, starting in 2006 in the Brindisi (Italy) power plant. Based on the exhaustive experience acquired in the field, this paper describes the latest advancements characterizing the operation of the AE94.3A burner with high pressure combustion tests adding hydrogen blends ranging from 0 to 40% in volume. The interpretation of the test results is supported by reactive and non-reactive simulations describing the effects of varying fuel reactivity on the flame structure as well as the impact of fuel / air momentum flux ratio on the fuel / air interaction and fuel distribution in the combustion chamber. As expected, increasing amounts of hydrogen in the fuel are also associated with higher amounts of NOx production, however this effect could be countered by optimization of the fuel staging strategy, based on the mentioned CFD considerations and feedback from high pressure tests.

Flow Field and Hot Streak Migration Through a High Pressure Cooled Vanes With Representative Lean Burn Combustor Outflow

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Tommaso Bacci ◽  
Tommaso Lenzi ◽  
Alessio Picchi ◽  
Lorenzo Mazzei ◽  
Bruno Facchini
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Flow Field ◽  
Fuel Injection ◽  
Leading Edge ◽  
Flame Stabilization ◽  
Lean Burn ◽  
Aero Engine ◽  
University Of Florence ◽  
Hot Streak

Modern lean burn aero-engine combustors make use of relevant swirl degrees for flame stabilization. Moreover, important temperature distortions are generated, in tangential and radial directions, due to discrete fuel injection and liner cooling flows respectively. At the same time, more efficient devices are employed for liner cooling and a less intense mixing with the mainstream occurs. As a result, aggressive swirl fields, high turbulence intensities, and strong hot streaks are achieved at the turbine inlet. In order to understand combustor-turbine flow field interactions, it is mandatory to collect reliable experimental data at representative flow conditions. While the separated effects of temperature, swirl, and turbulence on the first turbine stage have been widely investigated, reduced experimental data is available when it comes to consider all these factors together.In this perspective, an annular three-sector combustor simulator with fully cooled high pressure vanes has been designed and installed at the THT Lab of University of Florence. The test rig is equipped with three axial swirlers, effusion cooled liners, and six film cooled high pressure vanes passages, for a vortex-to-vane count ratio of 1:2. The relative clocking position between swirlers and vanes has been chosen in order to have the leading edge of the central NGV aligned with the central swirler. In order to generate representative conditions, a heated mainstream passes though the axial swirlers of the combustor simulator, while the effusion cooled liners are fed by air at ambient temperature. The resulting flow field exiting from the combustor simulator and approaching the cooled vane can be considered representative of a modern Lean Burn aero engine combustor with swirl angles above ±50 deg, turbulence intensities up to about 28% and maximum-to-minimum temperature ratio of about 1.25. With the final aim of investigating the hot streaks evolution through the cooled high pressure vane, the mean aerothermal field (temperature, pressure, and velocity fields) has been evaluated by means of a five-hole probe equipped with a thermocouple and traversed upstream and downstream of the NGV cascade.

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