Combustion Instabilities of Ultra-Lean Premixed H2/Air Mixtures by Prechamber Turbulent Jet Ignition

2018 ◽  
Vol 34 (5) ◽  
pp. 1166-1177 ◽  
Author(s):  
Sayan Biswas ◽  
Li Qiao
Keyword(s):  
Turbulent Jet ◽  
Combustion Instabilities ◽  
Lean Premixed

Combustion Instabilities in Lean Premixed Systems

2016 ◽  
pp. 231-259 ◽  
Author(s):  
J. O'Connor ◽  
S. Hemchandra ◽  
T. Lieuwen
Keyword(s):  
Combustion Instabilities ◽  
Lean Premixed

scholarly journals Measurement of Air-Fuel Ratio Fluctuations Caused by Combustor Driven Oscillations

1998 ◽  
Author(s):  
Rajiv Mongia ◽  
Robert Dibble ◽  
Jeff Lovett
Keyword(s):  
Power Spectrum ◽  
Mole Fraction ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Premixed Combustion ◽  
Pollutant Emissions ◽  
Combustion Instabilities ◽  
Pressure Oscillations ◽  
Lean Premixed Combustion ◽  
Lean Premixed

Lean premixed combustion has emerged as a method of achieving low pollutant emissions from gas turbines. A common problem of lean premixed combustion is combustion instability. As conditions inside lean premixed combustors approach the lean flammability limit, large pressure variations are encountered. As a consequence, certain desirable gas turbine operating regimes are not approachable. In minimizing these regimes, combustor designers must rely upon trial and error because combustion instabilities are not well understood (and thus difficult to model). When they occur, pressure oscillations in the combustor can induce fluctuations in fuel mole fraction that can augment the pressure oscillations (undesirable) or dampen the pressure oscillations (desirable). In this paper, we demonstrate a method for measuring the fuel mole fraction oscillations which occur in the premixing section during combustion instabilities produced in the combustor that is downstream of the premixer. The fuel mole fraction in the premixer is measured with kHz resolution by the absorption of light from a 3.39 μm He-Ne laser. A sudden expansion combustor is constructed to demonstrate this fuel mole fraction measurement technique. Under several operating conditions, we measure significant fuel mole fraction fluctuations that are caused by pressure oscillations in the combustion chamber. Since the fuel mole fraction is sampled continuously, a power spectrum is easily generated. The fuel mole fraction power spectrum clearly indicates fuel mole fraction fluctuation frequencies are the same as the pressure fluctuation frequencies under some operating conditions.

Influence of Exhaust Gas Recirculation on Combustion Instabilities in CH4 and H2/CH4 Fuel Mixtures

2010 ◽  
Author(s):  
Don Ferguson ◽  
Joseph A. Ranalli ◽  
Peter Strakey
Keyword(s):  
Exhaust Gas Recirculation ◽  
Premixed Combustion ◽  
Fuel Composition ◽  
Exhaust Gas ◽  
Combustion Instabilities ◽  
Lean Premixed Combustion ◽  
Lean Premixed ◽  
Fuel Mixtures ◽  
Gas Recirculation ◽  
The Impact

This paper evaluates the impact of two strategies for reducing CO2 emissions on combustion instabilities in lean-premixed combustion. Exhaust gas recirculation can be utilized to increase the concentration of CO2 in the exhaust stream improving the efficiency in the post-combustion separation plant. This coupled with the use of coal derived syngas or hydrogen augmented natural gas can further decrease CO2 levels released into the environment. However, changes in fuel composition have been shown to alter the dynamic response in lean-premixed combustion systems. In this study, a fully premixed, swirl stabilized, atmospheric burner is operated on various blends of H2/CH4 fuels with N2 and CO2 dilution to simulate EGR. Acoustic pressure and velocity, and global heat release measurements were performed at fixed adiabatic flame temperatures to evaluate the impact of fuel composition and dilution on various mechanisms that drive the instabilities.

Experimental Investigation of Self-Excited Combustion Instabilities in a Lean, Premixed, Gas Turbine Combustor at High Pressure

2017 ◽  
Author(s):  
Timo Buschhagen ◽  
Rohan Gejji ◽  
John Philo ◽  
Lucky Tran ◽  
J. Enrique Portillo Bilbao ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
High Pressure ◽  
Operating Conditions ◽  
Chamber Pressure ◽  
Dynamic Mode ◽  
Combustion Instabilities ◽  
Compression Phase ◽  
Wide Range ◽  
Lower Amplitude ◽  
Lean Premixed

An experimental investigation of self-excited combustion instabilities in a high pressure, single-element, lean, premixed, natural gas dump-combustor is presented in this paper. The combustor is designed for optical access and is instrumented with high frequency pressure transducers at multiple axial locations. A parametric survey of operating conditions including inlet air temperature and equivalence ratio has been performed, which presents a wide range of peak to peak pressure fluctuations (p′) of the mean chamber pressure (pc). Two cases, Flame A and B with p′ /pc = 28% and p′/pc = 15% respectively, both presenting self-excited instabilities at the fundamental longitudinal (1L) mode of the combustion chamber, are discussed to study the coupling mechanism between flame-vortex interactions and the acoustic field in the chamber. OH*-chemiluminescence is used to obtain a map of global heat release distribution in the combustor. Phase conditioned analysis and Dynamic Mode Decomposition (DMD) analysis is performed, to highlight the contrasting mechanisms that lead to the two distinct instability regimes. Flame interactions with shear layer vortex structures just downstream of the dump plane during the compression phase of the acoustic cycle are found to augment the instability amplitude. Flame A engages strongly in this coupling, whereas Flame B is less affected and establishes a lower amplitude limit cycle.

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