Gas Turbine Combustion

Premixed Burner Studies: Swirl, Geometry, Mixing and Flame Structure Issues
Investigators: Song Qi, Harald Kafitz
Research Facility: Premixed Co-Annular Swirl Burner

The objective of this research is to examine unmixedness, flow non-uniformities and flow structure of premixed flames. Different swirlers are employed in the burner that the facility allows determination of the effect of swirl, flow momentum ratio between annuli, equivalence ratio on combustion characteristics downstream of the swirlers. A co-annular premixed burner is used to investigate the distribution of thermal field, velocity and fuel fraction and product composition in flames. Special attention is given to flame intensity, stability, emissions and lean blow-off limits of the flames. The results are complemented with theoretical calculations. The comprehensive data obtained are used to develop advanced mixing configurations for achieving high efficiency and low pollution combustors.




Primary Zone Fuel-Air Mixing Studies for Low NOx Advanced Subsonic Transport Combustor Development
Investigators: Gregory Crowley, Martin Bruegmann
Research Facility: Isothermal Mixing Flow Facility

The pressure ratio for advanced subsonic transport ( AST ) engines is anticipated to be in the area of 40/1 in the near term, with eventual goals of achieving pressure ratios of 100/1. As a result, the thermodynamic efficiency of the engines is expected to yield significant improvements than that of conventional subsonic transport systems. However, NOx and smoke levels from AST engines are expected to be much higher than that experienced in current low pressure ratio engines ( typically having pressure ratios of about 20/1 ). Also, while AST combustors are expected to be generally shorter than contemporary combustors, performance requirements such as flame stability limits, combustion efficiency, exit gas temperature pattern factor, pressure drop, specific fuel consumption and thrust-to-weight ratio must meet at least current standards.

Increases in inlet fuel and air pressure/temperature beyond fluid critical conditions brings added complexity to the AST goals, since there is still much more to be learned about thermophysical charateristics of multicomponent jet fuels under supercritical conditions. This study seeks to answer many of these questions by utilizing several novel fuel/air mixing techniques to analyze the dynamic interactions of these "irregular" primary zone flows for subsequent use in AST combustors. An isothermal mixing flow facility is used in experimental program that simulates high pressure and temperature conditions in AST combustors. The data are complemented with mathematical modeling studies.





Distributing Inlet Jet Momentum in the Primary Zone to Enhance Combustor Performance
Investigator: Andre W. Marshall
Research Facility: Non-Premixed Co-Annular Swirl Burner

Combustion characteristics from a coannular swirl burner with various inlet jet momentum distributions are critically evaluated in this study. The heat loading, Ein, and overall equivalence ratio, are held constant while the swirl and flow distribution between the two air jets in non-premixed coannular swirl burner are systematically varied. Each flame is characterized via flow visualization, mean and rms temperature maps, velocity maps, and product gas concentration profiles.

 

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Last Edited: May 13, 2006