Fuel Effects on Gas Turbine Combustion

Abstract

Approved for public release; distribution unlimited. 7lhis program is an analyticaG s;udy corre ating fuel properties and engine "design and operating parameters with engine combustion performance and hot section (combustor and turbine) durability. Standard fuel specification data and fuel composition data are considered, along with special fuel properties and characteristics not routinely measured.. Engine combustor design parameters considered are fuel injection and atomization, fuel/air mixing, residence times, temperatures and pressures, and flow velocities and other important design parameters. DTIC ELECTE- 4'of the fuel.In due course, the extensive research initiated by the major fuel and engine companies and the various governmental research establishments yielded increasing knowledge of fuel properties and the manner in which they affect aircraft performance, safety and reliability. This improved understanding helped to eliminate or ease many formidable problems, but from time to time various new problems emerged, mainly as a result of the continuing demand for increases in aircraft speed, range and operating altitude. In the late 1960s the growth of public concern over air pollution caused by combustion processes eventually culminated in legislation for closer control of exhaust emissions, notably in terms of reductions in carbon monoxide, unburned hydrocarbons, smoke and nicric oxides. The restraining effects of these requirements, coupled with the fact that the aircraft user has traditionally been able to draw his fuel supplies from the highest quality feedstock, fostered conservatism to the extent that current airline fuels do not differ markedly from the kerosine used by Whittle.In general, for any given aircraft application, the optimum fuel is one that represents the best compromise solution to the various problems confronting the fuel companies, the engine and aircraft manufacturers and the operator. For civil aircraft the main requirements are safety, reliability, low cost and ease of handling. For military aircraft fuel cost is of secondary importance compared with availability, supply logistics and the need for trouble-free operation over a wide range of conditions.The most dominant fuel issues of today are those of cost and availability. The steps now being taken to ensure future supplies of fuels for gas turbines, in addition to various measures of fuel conservation, include the exploitation of alternative fuel sources and the acceptance of a broader specification for aviation fuels. It is clearly of paramount importance that prediction techniques be established for estimating accurately, for iny given combustor, the impact of any change in fuel specification on hardware durability and the key aspects of combustion performance.A complicating factor in the attainment of this goal is that the effect of a change in fuel properties is not constant for all combustors but varies between one combustor and another, due to differences in operating conditions and differences in design. For example,...

Effects of Combustion Chamber Geometry Deviations Upon Exit Temperature Profiles for Populations With Varied Service Limitations

“…While the profile factor and turbine profile factor both provide an assessment of the radial temperature field along a turbine blade, pattern factor is still the parameter of choice to describe the exit temperature field [4][5][6][7][8][9][10][11]. This is mainly due to the fact that it outlines the maximum temperature deviation that hot section components may experience.…”

“…This is mainly due to the fact that it outlines the maximum temperature deviation that hot section components may experience. Contemporary published values for pattern factor over the span of operating conditions range from 0.2 to 0.4 [6,8].…”

“…A synopsis of research into pattern factor completed by Sjöblom [5], Friedman and Carlson [12], Cox and George [13], and Lefebvre [6,14] can be found in Ref. [2].…”

The Effects of Hydrocarbon Fuels Upon Exhaust Pollutants in Gas Turbine Combustors

“…However, in order to achieve at least an approximate comparison, Eqn (2) was applied, using an assumed air distribution, to a set of data for a J-79 taken from [9]. Figure 10 shows the result of the predictions, together with some predictions reported in [19] for the same engine.…”

Experimental Investigation of Performance of an Air Blast Atomizer by Planar Laser Sheet Imaging Technique

“…The fuel injector has been the focus of on-going research and development ever since the gas turbine engine was adopted as the prime mover for aircraft propulsion [1]. Increasingly stringent regulations on pollutant emissions, such as NO^, COx, and soot, are required to improve combustion efficiency and flame stability with a wide range of operation conditions for kerosene-fueled aeronautical gas turbines [2,3].…”