scholarly journals Inlet Pressure Effects on Subatmospheric Flame Stabilization with an Optimum Size of a Cavity-Based Combustor

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Yakun Huang ◽  
Xiaomin He ◽  
Zhixin Zhu ◽  
Huanyu Zhu
Keyword(s):  
Equivalence Ratio ◽  
Experimental Studies ◽  
Flame Stabilization ◽  
Combined Cycle ◽  
Pressure Effects ◽  
Inlet Pressure ◽  
Flame Stability ◽  
Characteristic Time Scale ◽  
Optimum Size ◽  
Lean Blowout

Experimental studies are conducted to find an optimum size of the cavity flameholder, which is a new combustion concept of a turbine-based combined-cycle (TBCC) engine with an excellent flame stabilization. Besides, the effect of inlet pressure on the subatmospheric performance is investigated. The experimental results indicate that the increase of the cavity length improves the flame stability with an enlarged fuel/air mixture residence time, which suggests that the big length-height ratio in a proper range of the cavity with a stable dual-vortex should be chosen when designing the cavity-based combustor. In addition, the decrease in lean ignition and the lean blowout equivalence ratios can be attributed by either increase in the inlet pressure and temperature or decrease in the Mach number. The increase in inlet pressure will lead to a linear decrease in the lean blowout equivalence ratio with a slope of 0.66 per 0.1 MPa, whereas the lean ignition equivalence ratio has a rapid drop with the increase of pressure from 0.06 MPa to 0.08 MPa and reduces slowly with the growth of pressure in the range of 0.08 MPa to 0.1 MPa. The detailed analysis of the flow field indicates that the characteristic time-scale theory can ideally explain and predict the change of flame stability in the trapped vortex cavity.

Investigation of Reverse Flow Slinger Combustor with Jet A-1 and Methanol

2021 ◽  
Author(s):  
Abhishek Dubey ◽  
Pooja Nema ◽  
Abhijit Kushari
Keyword(s):  
Fuel Injection ◽  
Reverse Flow ◽  
Lightweight Design ◽  
Injection Pressure ◽  
Combustion Efficiency ◽  
Flame Stabilization ◽  
Liquid Fuels ◽  
Flame Stability ◽  
Lean Blowout ◽  
Lean Fuel

Abstract This paper describes experimental investigation of a Reverse Flow Slinger (RFS) combustor that has been developed in order to attain high flame stability and low emissions in gas turbine engines. The combustor employs centrifugal fuel injection through a rotary atomizer and performs flame stabilization at the stagnation zone generated by reverse flow configuration. The design facilitates entrainment of hot product gases and internal preheating of the inlet air which enhances flame stability and permits stable lean operation for low NOx. Moreover, the use of rotary atomizer eliminates the need for high injection pressure resulting in a compact and lightweight design. Atmospheric pressure combustion was performed with liquid fuels, Jet A-1 and Methanol at ultra-lean fuel air ratios (FAR) with thermal intensity of 28 - 50 MW/m3atm. Combustor performance was evaluated by analyzing the lean blowout, emissions and combustion efficiency. Test results showed high flame stability of combustor and a very low lean blowout corresponding to global equivalence ratio of around 0.1 was obtained. Sustained and stable combustion at low heat release was attained and NOx emissions as low as of 0.4 g/Kg and 0.1 g/Kg were obtained with Jet A-1 and Methanol respectively. Combustion efficiency of 55% and 90% was obtained in operation with Jet A-1 and Methanol. Performance of the combustor was significantly better with Methanol in terms of emissions and efficiency.

Impact of Cooling Air Injection on the Combustion Stability of a Premixed Swirl Burner Near Lean Blowout

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
A. Marosky ◽  
V. Seidel ◽  
T. Sattelmayer ◽  
F. Magni ◽  
W. Geng
Keyword(s):  
Flame Front ◽  
Equivalence Ratio ◽  
Flame Stabilization ◽  
Air Injection ◽  
Combustion Stability ◽  
Nox Emissions ◽  
Test Rig ◽  
Lean Blowout ◽  
Burner Exit ◽  
Cooling Air

In most dry, low-NOx combustor designs of stationary gas turbines, the front panel impingement cooling air is directly injected into the combustor primary zone. This air partially mixes with the swirling flow of premixed reactants from the burner and reduces the effective equivalence ratio in the flame. However, local unmixedness and the lean equivalence ratio are supposed to have a major impact on combustion performance. The overall goal of this investigation is to answer the question of whether the cooling air injection into the primary combustor zone has a beneficial effect on combustion stability and NOx emissions or not. The flame stabilization of a typical swirl burner with and without front panel cooling air injection is studied in detail under atmospheric conditions close to the lean blowout limit (LBO) in a full-scale, single-burner combustion test rig. Based on previous isothermal investigations, a typical injection configuration is implemented for the combustion tests. Isothermal results of experimental studies in a water test rig adopting high-speed planar laser-induced fluorescence (HSPLIF) reveal the spatial and temporal mixing characteristics for the experimental setup studied under atmospheric combustion. This paper focuses on the effects of cooling air injection on both flame dynamics and emissions in the reacting case. To reveal dependencies of cooling air injection on combustion stability and NOx emissions, the amount of injected cooling air is varied. OH*-chemiluminescence measurements are applied to characterize the impact of cooling air injection on the flame front. Emissions are collected for different cooling air concentrations, both global measurements at the chamber exit, and local measurements in the region of the flame front close to the burner exit. The effect of cooling air injection on pulsation level is investigated by evaluating the dynamic pressure in the combustor. The flame stabilization at the burner exit changes with an increasing degree of dilution with cooling air. Depending on the amount of cooling, only a specific share of the additional air participates in the combustion process.

Impact of Cooling Air Injection on the Combustion Stability of a Premixed Swirl Burner Near Lean Blowout

2013 ◽  
Author(s):  
A. Marosky ◽  
V. Seidel ◽  
T. Sattelmayer ◽  
F. Magni ◽  
W. Geng
Keyword(s):  
Flame Front ◽  
Equivalence Ratio ◽  
Flame Stabilization ◽  
Air Injection ◽  
Combustion Stability ◽  
Nox Emissions ◽  
Test Rig ◽  
Lean Blowout ◽  
Burner Exit ◽  
Cooling Air

In most dry low NOx combustor designs of stationary gas turbines the front panel impingement cooling air is directly injected into the combustor primary zone. This air partially mixes with the swirling flow of premixed reactants from the burner and reduces the effective equivalence ratio in the flame. However, local unmixedness and the lean equivalence ratio are supposed to have a major impact on combustion performance. Overall goal of this investigation is to answer the question whether the cooling air injection into the primary combustor zone has a beneficial effect on combustion stability and NOx emissions or not. The flame stabilization of a typical swirl burner with and without front panel cooling air injection is studied in detail under atmospheric conditions close to the lean blowout limit (LBO) in a full scale single burner combustion test rig. Based on previous isothermal investigations a typical injection configuration is implemented for the combustion tests. Isothermal results of experimental studies in a water test rig adopting high speed planar laser-induced fluorescence (HSPLIF) reveal the spatial and temporal mixing characteristics for the experimental setup studied under atmospheric combustion. This paper focuses on the effects of cooling air injection on both flame dynamics and emissions in the reacting case. To reveal dependencies of cooling air injection on combustion stability and NOx emissions, the amount of injected cooling air is varied. OH*-chemiluminescence measurements are applied to characterize the impact of cooling air injection on the flame front. Emissions are collected for different cooling air concentrations, both global measurements at the chamber exit and local measurements in the region of the flame front close to the burner exit. The effect of cooling air injection on pulsation level is investigated by evaluating the dynamic pressure in the combustor. The flame stabilization at the burner exit changes with an increasing degree of dilution with cooling air. Depending on the amount of cooling only a specific share of the additional air participates in the combustion process.

Numerical investigation of the flame stabilization in a divergent porous media burner

2017 ◽  
Vol 231 (3) ◽  
pp. 173-181 ◽  
Author(s):  
Seyed Mohammad Hashemi ◽  
Seyed Abdolmehdi Hashemi
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Equivalence Ratio ◽  
Flame Stabilization ◽  
Heat Transfer Analysis ◽  
Divergence Angle ◽  
Flame Stability ◽  
Gas Temperature ◽  
Heat Recirculation ◽  
Porous Media Burner

In the present work, a numerical study on the flame stabilization in a divergent porous media burner was carried out. The purpose of this study was to peruse the influence of different conditions on the flame status in a porous medium. Two-dimensional axisymmetric model was used to simulate the process of premixed methane–air combustion. Nonequilibrium condition between the solid and gas temperature was considered and heat recirculation in the porous medium was quantified. The present numerical method was validated by comparison of solid and gas temperature profiles against the experimental data. The results showed that the stable flame within the porous medium can be controlled by velocity and equivalence ratio of the incoming mixture. Also, it was proved that the alteration of divergence angle can change the flame stability limit so that the optimum divergence angle that results in the highest limit of flame stability range was 60°. The heat transfer analysis indicated that the heat recirculation efficiency decreases with increase in the equivalence ratio and inlet velocity.

Numerical study of the flame stability of premixed methane–air combustion in a combined porous-free flame burner

2018 ◽  
Vol 233 (4) ◽  
pp. 530-544 ◽  
Author(s):  
Seyed Mohammad Hashemi ◽  
Seyed Abdolmehdi Hashemi
Keyword(s):  
Equivalence Ratio ◽  
Numerical Study ◽  
Flame Stabilization ◽  
Pollutant Emissions ◽  
Pollutant Emission ◽  
Flame Stability ◽  
Emission Analysis ◽  
Porous Burner ◽  
Flame Burner ◽  
Stability Limits

Premixed methane–air combustion process within a combined porous-free flame burner was investigated numerically in the present study. The burner consisted of a perforated porous ceramic pellet forming combination of submerged and free flame zones. Nonequilibrium thermal condition between the gas and solid phases was implemented and governing equations were solved in a two-dimensional model using finite volume method. Detailed chemistry based on reduced GRI 3.0 mechanism with 41 reaction steps and 16 species including NOx mechanisms was utilized to simulate the combustion processes and pollutant emissions. In order to investigate the validation of the implemented numerical model, the burner was manufactured and tested. The predicted results were consistent with the experimental data. Comparison of the combined porous-free flame burner with porous burner showed that the flame stability limits of the combined burner were higher than those of porous burner. Multimode heat transfer within the porous medium was perused and the effect of heat recirculation on the flame stabilization was discussed. Investigation of the effect of pore density on the flame stabilization showed that the lower pore densities were desirable in order to improve the flame stability limits. Pollutant emission analysis proved that the NO concentration increased with increasing the equivalence ratio while the minimum quantity of CO concentration was evaluated at an equivalence ratio of 0.6.

Characteristics of Flame Bases for V-Gutters Stabilized Premixed Flames

2013 ◽  
Author(s):  
Fan Gong ◽  
Yong Huang
Keyword(s):  
Thermal Conductivity ◽  
Temperature Gradient ◽  
Equivalence Ratio ◽  
Premixed Flames ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Heat Conducting ◽  
Inlet Velocity ◽  
The Impact

The objective of this work is to investigate the flame stabilization mechanism and the impact of the operating conditions on the characteristics of the steady, lean premixed flames. It’s well known that the flame base is very important to the existence of a flame, such as the flame after a V-gutter, which is typically used in ramjet and turbojet or turbofan afterburners and laboratory experiments. We performed two-dimensional simulations of turbulent premixed flames anchored downstream of the heat-conducting V-gutters in a confined passage for kerosene-air combustion. The flame bases are symmetrically located in the shear layers of the recirculation zone immediately after the V-gutter’s trailing edge. The effects of equivalence ratio of inlet mixture, inlet temperature, V-gutter’s thermal conductivity and inlet velocity on the flame base movements are investigated. When the equivalence ratio is raised, the flame base moves upstream slightly and the temperature gradient dT/dx near the flame base increases, so the flame base is strengthened. When the inlet temperature is raised, the flame base moves upstream very slightly, and near the flame base dT/dx increases and dT/dy decreases, so the flame base is strengthened. As the V-gutter’s thermal conductivity increases, the flame base moves downstream, and the temperature gradient dT/dx near the flame base decreases, so the flame base is weakened. When the inlet velocity is raised, the flame base moves upstream, and the convection heat loss with inlet mixture increases, so the flame base is weakened.

Experimental Studies of the Primary Zone Flow Field and Combustion Performance of a Triple Swirler Combustor

2005 ◽  
Author(s):  
Yunhui Peng ◽  
Quanhong Xu ◽  
Yuzhen Lin
Keyword(s):  
Flow Field ◽  
Experimental Studies ◽  
Fuel Injector ◽  
Lean Blowout ◽  
Combustion Performance ◽  
Primary Zone ◽  
Image Velocimetry ◽  
Aero Engine ◽  
Exit Temperature ◽  
Promising Solution

Improvement of the lean blowout limit and more uniform combustor exit temperature distribution are particularly desirable for future aero engine. A triple swirler combination plus an airblast fuel injector might be a promising solution. The design with the triple swirler plus the airblast fuel injector including design A and B was presented and investigated in this paper. Single rectangle sector module combustor was used in the experiment for lean blowout (LBO), and three cups rectangle sector combustor was used for pattern factor (PF) experiments. The LBO and PF experiment data were provided. The primary zone flow field was measured by PIV (Particle Image Velocimetry) under atmospheric pressure and temperature. The result showed that the design A was a promising design, and the primary jet played very important role for flow field of primary zone. The insight relation between flow field and combustion performance could be found out from this paper.

Combustion Optimization for the ALSTOM GT13E2 Gas Turbine

2006 ◽  
Author(s):  
Ch. Steinbach ◽  
N. Ulibarri ◽  
M. Garay ◽  
H. Lu¨bcke ◽  
Th. Meeuwissen ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Flame Temperature ◽  
Air Entrainment ◽  
Flame Stabilization ◽  
Flame Stability ◽  
Nox Emissions ◽  
Combustion Control ◽  
Control Logic ◽  
The Individual ◽  
Combustion Optimization

The NOx emissions of low NOx premix combustors are not only determined by the burner design, but also by the multi burner interaction and the related distribution of air and fuel flows to the individual burners. Often the factors that have a positive impact on NOx emission have a negative impact on the flame stability, so the main challenge is to find an optimum point with the lowest achievable NOx while maintaining good flame stability. The hottest flame zones are where most of the NOx is formed. Avoiding such zones in the combustor (by homogenization of the flame temperature) reduces NOx emissions significantly. Improving the flame stability and the combustion control allows the combustor to operate at a lower average flame temperature and NOx emissions. ALSTOM developed a combustion optimization package for the GT13E2. The optimization package development focused on three major issues: • Flame stability; • Homogenization of flame temperature distribution in the combustor; • Combustion control logic. The solution introduced consists of: • The reduction of cooling air entrainment in the primary flame zone for improved flame stability; • The optical measurement of the individual burner flame temperatures and their homogenization by burner tuning valves; • Closed loop control logic to control the combustion dependent on the pulsation signal. This paper shows how fundamental combustion research methods were applied to derive effective optimization measures. The flame temperature measurement technique will be presented along with results of the measurement and their application in homogenization of the combustor temperature distribution in an engine equipped with measures to improve flame stabilization. The main results achieved are: • Widening of the main burner group operation range; • Improved use of the low NOx operation range; • NOx reduction at the combustor pulsation limit and hence, large margins to the European emission limit (50 mg/m3 @ 15%O2).

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