Turbojet fuels

Table 1 gives the typical chemical compositions of some of the main fuels by individual molecules, by families of molecules or by analysis of the elements. These include natural gases (NG), liquefied petroleum gases (LPG), unleaded petrols, turbojet fuels, diesel fuels and diesel fuel oils, heavy fuels, low-energy gases. 

Table 2 shows the names and the graphic formulae of model molecules encotmtered in petrols, turbojet fuels and diesel fuels, belonging to different chemical families. 

Table 2 Model molecules for fuels (petrols, turbojet fuels, diesel fuei oils).

A detailed analysis of petrols primarily using chromatography, shows that they are made by blending one to three hundred individual molecules. A similar number of molecules is used for turbojet fuels and many more for diesel fuels and diesel fuel oils. Therefore, it is common practice to group the molecules into major families alkanes, alkenes, cyclanes, aromatics, cyclano-aromatics. 

The jet A1 fuel is used by the jet-planes of the international civilian lines. The turbojet fuels of the national lines and military planes are very similar to the jet Al. 

Missile turbojet fuels must, for reasons of space economy, possess a very high volume energy. The fuels RJ 4, 5 and 6 are used with the Ramjets, the fuels IP 9 and JP 10 for... 

Aircraft Turbine Fueis turbojet fuels 85 0-360 8 Resistant-slight changes in mass or dimensions no irreversible change Ultraform BASF... 

H. F. Butze and R. C. Ehlers, Effect of Fuel Properties on Peformance of a Single Aircraft Turbojet Combustor, NASA TM X-71789, National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio, Oct. 1975. 

Mixtures of Methylamine Nitrate with Compounds which have Explosive Properties. A mixt with 70—80% AN is called Nitramite No 2 in Fr (Ref 2). When detond with 2g of MF in 30mm tubes it has a deton vel of 2550m/sec at a d of l.OOg/cc and3250m/sec at 1.25g/cc (Ref 2). Mixts of Methylamine Nitrate with AN, Ca nitrate, or Na nitrate form low melting eutectics which are castable expls (Ref 1). A soln of 200g of Methylamine Nitrate in 800 lbs of methyl ale is a useful fuel for turbojets (Ref... 

Figure 1.1. Schematic of spray combustion process (a) annular combustion chamber in a single spool turbojet with an axial flow compressor (b) fuel injection and droplet formation in combustion chamber.

The subject of chemical reactions under supercritical conditions is well outside the scope of matters of major concern to combustion related considerations. However, a trend to increase the compression ratio of some turbojet engines has raised concerns that the fuel injection line to the combustion chamber could place the fuel in a supercritical state that is the pyrolysis of the fuel in the line could increase the possibility of carbon formations such as soot. The... 

The values of laminar flame speeds for hydrocarbon fuels in air are rarely greater than 45cm/s. Hydrogen is unique in its flame velocity, which approaches 240cm/s. If one could attribute a turbulent flame speed to hydrocarbon mixtures, it would be at most a few hundred centimeters per second. However, in many practical devices, such as ramjet and turbojet combustors in which high volumetric heat release rates are necessary, the flow velocities of the fuel-air mixture are of the order of 50m/s. Furthermore, for such velocities, the boundary layers are too thin in comparison to the quenching distance for stabilization to occur by the same means as that obtained in Bunsen burners. Thus, some other means for stabilization is necessary. In practice, stabilization... 

Hibbard Olson (Ref 10) discuss turbojet ramjet fuels and their relation to fuel systems... 

For propulsion in the atmosphere, where ambient air is available, this air may be induced by the jet engine in order to participate essentially in the chemical transformation of the fuel the engine is then properly called an air flow jet engine (in Fig 1 the Turboprop, Turbojet, Ramjet Pulse Jet are examples of air flow jet engines) in contrast to the rocket, which does not use any air and is the only jet engine which can be used for propulsion in vacuum... 

Variations in turbojet engine altitude, flight speed, and thrust require combustion to be maintained over a wide range of inlet air and fuel environment. Furthermore, the combustion must be nearly complete in order to achieve maximum aircraft range. Combustion limits and efficiency are, then, two major performance criteria of the turbojet combustion system. Under conditions very favorable to combustion, the influence of operating, design, and fuel variables are minimized, and only in adverse combustion environment is their influence measurable. 

Effect of Petroleum Fuel Properties. Three primary requirements must be met by practical fuels for aircraft turbojets. These requirements are They must be available in large quantities at low cost, they must produce satisfactory performance in all types of engines, and they must be suitable for aircraft fuel systems. Petroleum fuels vary in volatility, chemical composition, and concentrations of minor nonhydrocarbon compo-... 

Effect of Petroleum Fuel Properties. One of the earliest fuels problems to be recognized in turbojet combustor development was the coking problem, and, consequently, numerous investigators have obtained data showing the effect of various fuel properties on deposition. 

Fuel in Nene Turbojet Engine, Naval Air Material Center, Aeronaut Engine Lab., Philadelphia, Pa., NAM-PP503 (1954). 

Graves, C. C., Burning Rates of Single Fuel Drops and Their Application to Turbojet... 

Hibbard, R. R., Barnett, H. C., Fuels for Turbojet Powered Aircraft, Second Com-... 

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