Experimental Investigations of Flame Stabilization of a Gas Turbine Combustor

Abstract

While today’s gas turbine (GT) combustion systems are designed for specific fuels there is an urgent demand for fuel-flexible stationary GT combustors capable of burning natural gas as well as hydrogen-rich fuels in future. For the development of a fuel flexible, low-emission, and reliable combustion system a better understanding of the flow field – flame interaction and the flame stabilization mechanism is necessary. For this purpose, a down-scaled staged can combustion system provided with an optical combustion chamber was investigated in a high pressure test rig. Different optical diagnostic methods were used to analyze the combustion behavior with a focus on flame stabilization and to generate a comprehensive set of data for validation of numerical simulation methods (CFD) employed in the industrial design process. For different operating conditions the size and position of the flame zone were visualized by OH* chemiluminescence measurements. Additionally, the exhaust gas emissions (NOx and CO) and the acoustic flame oscillations were monitored. Besides many different operating conditions with natural gas different fuel mixtures of natural gas and hydrogen were investigated in order to characterize the flashback behavior monitored with OH* chemiluminescence. For selected operating conditions detailed laser diagnostic experiments were performed. The main flow field with the inner recirculation zone was measured with two-dimensional particle image velocimetry (PIV) in different measuring planes. One-dimensional laser Raman spectroscopy was successfully applied for the measurement of the major species concentration and the temperature. These results show the variation of the local mixture fraction allowing conclusions to be drawn about the good premix quality. Furthermore, mixing effects of unburnt fuel/air and fully reacted combustion products are studied giving insights into the process of the turbulence-chemistry interaction and reaction progress.

Investigation of Hydrogen Enriched Natural Gas Flames in a SGT-700/800 Burner Using OH PLIF and Chemiluminescence Imaging

“…The higher reactivity and higher flame speed associated with flames having hydrogen components in the fuel makes the flame front thinner and makes also the flame to move more upstream compared to flames without hydrogen in the fuel. Thus, the flame reaches shorter into the combustion chamber [10,11,14],…”

Experimental analysis of thermo-acoustic instabilities in a generic gas turbine combustor by phase-correlated PIV, chemiluminescence, and laser Raman scattering measurements

“…Frequently, minor geometrical modifications of the combustor or small changes in the operating or boundary conditions lead to drastic changes in the stability of the system, such as transition from attached to detached flames or flames with and without precessing vortex cores [Allison 2012, Arndt 2010, Biagioli 2008, Fritsche 2007, Hermeth 2014. In addition, understanding and predicting combustor thermo-acoustic behavior is complicated by significant effects of turbulence-chemistry interaction , Gicqel 2012, Lückerath 2011, Rebosio 2010, and spatially and temporally varying degrees of premixing [Bade 2014, Masri 2015, Stopper 2013. The occurrence of hydrodynamic instabilities like precessing vortex cores, vortex shedding, or other shear layer instabilities [Candel 2014, Caux-Brisebois 2014, Kim 2014, Moeck 2012, Stöhr 2013b further complicates the situation.…”

High-Momentum Jet Flames at Elevated Pressure, C: Statistical Distribution of Thermochemical States Obtained From Laser-Raman Measurements

“…The test rig was designed for combustion tests with different gaseous and liquid fuels up to 40 bar with a maximum combustion air mass flow of 1.2 kg/s at a maximum preheat temperature of 1000 K. The pressure casing of the test rig provides an extensive optical access in three rows on all four sides. More detailed descriptions of the test rig can be found in [1,9,[12][13][14].…”