EMISSION CHARACTERISTICS OF JP-8, JP-900, FISCHER-TROPSCH (FT) AND JP-8/FT BLENDS IN A MODEL GAS TURBINE COMBUSTOR
Open Access
- Author:
- Kalaskar, Vickey Baliram
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- None
- Committee Members:
- Robert John Santoro, Thesis Advisor/Co-Advisor
Robert John Santoro, Thesis Advisor/Co-Advisor - Keywords:
- jet fuels
coal-based
gas turbine
model combustor - Abstract:
- The increasing usage of coal-based fuels in aviation turbines and fluctuating prices of the crude oil imports emphasizes the need to study and analyze alternate coal-based fuels like JP-900 and Fischer-Tropsch (FT), which can be obtained from nationally owned sources. Currently, JP-8 fuel is being used as an aviation fuel for the U.S. Air Force operations. The properties of JP-900 and FT need to be characterized and compared with JP-8 in order to determine their feasibility as the next generation aviation fuels. JP-900 is a coal-based fuel which has been developed to serve two purposes: providing propulsion energy and providing good heat sink capabilities. FT fuel, in contrast, is a clean burning fuel expected to produce very low pollutant emissions, soot and highly stable operation. Gas turbine engines have temperature limitations. All efforts are being made to increase the operating pressure regimes of modern day combustors to improve overall combustion performance and achieve greater efficiencies. Increase in the operating pressures gives rise to higher adiabatic flame temperatures. High temperature is undesirable for the combustor linings and components downstream of the combustor, therefore, new methods are being developed to improve heat transfer from the combustor walls. A fuel with excellent heat sink capabilities can serve as a coolant for hot engine components. JP-900 exhibits good heat sink capability and oxidative stability at higher temperatures (9000F). However, successful development of a versatile, multiple-use fuel must achieve the desired operational characteristics of high combustion efficiency, excellent combustion stability, acceptable pollutant emission levels, and compatibility with current engine seals. Current requirements of strict emissions standards and improved stability are major areas of concern with regards to the usage of alternative jet fuels. Combustion instability can have damaging effects on combustor components. These instabilities are closely tied to the combustion geometry, fuel injection, fuel/air mixing properties and heat release characteristics. Combustion instability, CO and NOx emissions, and mean soot volume fraction vary with fuel composition. Therefore, changes in fuel composition may drastically affect the overall combustion and emission characteristics. These fuels would require a vigilant consideration through a well synchronized research program prior to being used in existing engines. The current study investigates the feasibility of alternative coal-based jet fuels considering the combustion requirements of aviation turbines. JP-900, FT and (25/75), (50/50) JP-8/FT blends are studied and compared with JP-8. Experiments included in this research involve studying the combustion instability patterns, mapping emission levels and determining the sooting proclivity of the alternative fuels and blends. Results of this study indicate that the FT fuel produces lower soot volume fraction and emissions; however, this fuel cannot be used solely in current combustors due to inadequate seal swelling characteristics and fuel lubricity requirements. JP-900 and (25/75), (50/50) JP-8/FT blends, on the other hand, show acceptable results and, hence, can directly replace the existing JP-8 fuel, thereby reducing the dependence on crude imports.