Fuel Hydrogen Content Research Articles

The Influence of Fuel Composition on Smoke Emission from Gas-Turbine-Type Combustors : Effect of Combustor Design and Operating Conditions

Abstract The influence of fuel composition on smoke emission/combustor wall temperatures has been studied in a laboratory-scale gas-turbine-type combustor over the range of operating conditions of modern turbine combustors and as a function of combustor design. Fuel hydrogen content is shown to give the best prediction of smoke emission and of variations in flame tube wall temperature caused by changes in flame radiation. The major finding is that the influence of fuel composition on smoke emission/flame radiation falls virtually to zero at combustor pressures above about 10 bar. Significant reduction in sensitivity to fuel composition can also be obtained by varying combustor design and are tentatively correlated with increasing combustion intensity. The implication of these effects for aircraft operation is discussed and an explanation for the results is put forward based on changes in the chemical mechanisms leading to soot formation.

Combustion considerations for future jet fuels

This paper presents recent results which contribute to the combustion technology base necessary for the future development of aircraft jet fuels from non-petroleum resources. Specifically, the effects of fuel hydrogen and nitrogen content have been studied using a T56 combustor rig. Although most of this work has involved fuel blending to simulate alternate fuel properties, data acquired using an actual oil shale jet fuel have been included. Increases of combustor liner temperature with decreased fuel hydrogen content were found to be substantial. A new, non-dimensional temperature parameter is presented which provides an excellent means of correlating results for combustors having rich primary zones designs. Limited data for new, low-smoke lean designs indicate much less sensitivity of combustor liner temperature to fuel hydrogen content. Although smoke emission also increased with decreased hydrogen content, gaseous exhaust emissions were unchanged. Fuel bound nitrogen conversion to NO x under practical aircraft combustion conditions (up to 838°K inlet temperature) was found to be dependent on both fuel nitrogen concentration and combustor inlet temperature. Finally, future directions for alternate jet fuel combustion efforts are summarized. Recommendations range from an expanded scope of combustor and engine testing to required fundamental combustion research.

Studies of the effects of water on gasoline engine wear at low temperature

Wear of a cold-running gasoline engine was measured by use of a radioactive piston ring and also by using a neutron activation analysis of oil for iron content. These measurements showed wear to increase greatly when jacket water temperature was reduced, when water was added to the crankcase oil, or when fuel hydrogen content was increased. A tentative explanation of these effects is proposed in which liquid water in the oil is assumed to act as a collector of the acids which cause cold wear. Water is alternately condensed when cylinder pressures are high and reevaporated when cylinder pressures are low. The average amount of liquid water in the oil, and hence also the wear rate, depends upon the relative magnitudes of condensation and re-evaporation.