Introduction M AJOR increases in liquid-fueled propulsion performance have occurred in the past 100 years.TheWright brothers rst  ew on 14 December 1903 with an engine that generated slightly more than 130 lb of thrust for  ights that ranged from 120 to 850 ft (Ref. 1). Contrast that with current aircraft such as the Boeing 777, which can  y 8000 n miles, equipped with engines from the GE90 and PW4000 series that generate over 100,000 lb of thrust. The Wright brothers probably consumed less than a gallon of gasoline in that  rst day of  ight tests. In 1997, airlines consumedan average of 177 million gal/day of jet fuel worldwide.2¤ Robert Goddard’s  rst  ight of a liquid rocket on 16March 1926 reachedan altitudeof 41 ft and landed184 ft from the launchpoint (seeRef. 3). Again, the contrast with current vehicles such as the space shuttle, which can lift over 50,000 lb to 200C miles into low Earth orbit, is dramatic. The intent of this paper is to describe the evolution of liquid fuels for aircraft and rockets as the engines and vehicles they fuel have undergone these signi cant increases in performance.

Liquid Fuels and Propellants for Aerospace Propulsion: 1903-2003

This paper describes recent results of AF-sponsored research in the thermal stability of high temperature fuels. At temperatures of 550 °C (1000 °F) and above, both thermal -oxidative and pyrolytic deposition are important. A brief discussion of deposition characteristics and mitigation measures is presented.Copyright © 1997 by ASME

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Thermal Stability of High Temperature Fuels

Fuel provides the propulsive energy and is the primary coolant for advanced aircraft and engines. In order to cool critical engine components in advanced turbine and hypersonic engines, fuel may be exposed to temperatures in excess of 900 °F (500 °C). These advanced fuels must have both high autoxidative stability and high pyrolytic stability and must not produce gums, varnishes and coke in critical engine components. The thermal stability requirements of these advanced fuels indicate the types of hydrocarbons and potential additives that may be present in advanced fuels. Naphthenes have been shown in previous studies to offer the potential of high thermal stability and at the same time yield other desirable jet fuel properties, thus may be ideal candidates for a fuel such as JP-900. Recent research program have identified possible feedstocks for production of advanced fuels from conventional petroleum sources including low value streams such as cycle oils and light pyrolysis fuel oil. In addition, certain coal liquids offer high yield of naphthenes and other desirable jet fuel components. Endothermic fuels may require

Properties and producibility of advanced jet fuels

The effectiveness of hydrogen donor compounds as additives to reduce pyrolytic deposition in JP-8+100 at high temperatures was assessed. Decalin and 1,2,3,4 tetrahydroquinoline (THQ) were added to JP-8+100 at 0.5% (decalin only), 1.0 and 2.5% w/w concentrations and tested in a flow reactor at a fuel exit temperature of 600°C at 5.2 MPa. Measurements of carbon deposits along the tube and gas chromatography/mass spectrometry (GC/MS) analysis of the stressed and unstressed liquid fuel were used to assess effectiveness of the additive, and the degree of fuel decomposition. Additionally, liquid-to-gas conversion was determined, and the composition of the gas was determined via GC. Experimental results show significant reductions in pyrolytic deposition in JP-8+100 with the additives relative to the baseline fuel. Tests with decalin showed negligible effects on thermal oxidative deposits, while THQ produced significant increases in thermal oxidative deposits. The effects of the additives on fuel thermal decomposition and conversion rates are also discussed.Copyright © 1999 by ASME

Hydrogen Donors: Thermal Stabilizers for JP-8+100 at High Temperatures

The need for the development of jet fuels that are oxidatively and thermally stable to 480°C (900°F) has been previously detailed (Edwards and Liberio, 1996). Such a fuel is commonly referred to as JP-900. It is our belief that a new class of additives can be developed which, when added to JP-8, will provide both the oxidative and thermal stability requirements of JP-900.Our most recent data is presented which explores the potential of 1,2,5-trimethylpyrrole (TMP) as a potential oxygen scavenger.© 1999 ASME

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On the Development of Oxygen Scavenger Additives for Future Jet Fuels

This paper is the second in a series evaluating the high temperature behavior of hydrocarbon fuels. The goal of this work is a fuel thermally stable to 480°C (900°F), designed as JP-900. This paper expands the fuels tested to include other advanced (high temperature) fuels, such as decalin, JP-10, JPTS and MCH. Several other Jat A fuels are used as the baseline for tests involving varying pressures, flow rates, and other parameters.

T. Edwards

Papers

The thermal-oxidative stability of fuel at 480°C (900°F)