An Investigation of Methods of Producing Sulfur Trioxide in Jet Exhausts through Addition of Fuel Additives to Jp4

i Work was performed to determine the possible effectiveness of sulfur-containing fuel additives as contrail suppressents. Such suppression would require production of significant levels of sulfur trioxide, a known suppressent, in the exhaust. A model combustor capable of simulating turbojet operation at 40,000 feet was designed and built, and a gas sampling and analysis procedure developed for measuring the concentration of sulfar trioxide i Organic fuel additives containing sulfur in various valence states were tested at many concentration levels, with and without the use of potentially catalytic co-additives such as nitrocompounds and organometallics. The level of sulfur trioxide in the exhaust was found to depend very little on the sulfur compound used, or its concentration above some threshold value, and the use of co-additives generally provided no improvement. The use of higher-valent sulfur compounds seems to have no advantage, and relatively low concentrations of inexpensive sulfur compounds, such as 0.5/, carbon disuJfide, merit operational testing. On the basis of limited data, the injection of sulfur dioxide into the intake air is significantly more effective than combustion of sulfur-containing fuels, and should also be investigated