Turbojets

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. 

Dispersed mixtures of boron and another metal are used as deoxidizing and degassing agents to harden steel (qv) (5,6), to increase the conductivity of copper (qv) in turbojet engines, and in the making of brass and bronze (see Copper alloys). Two examples are alloys of ferroboron and manganese boron. 

The idea for the turbojet did not come to Whittle suddenly, but over a period of some years initially while he was a final year flight cadet at RAF Cranwell about 1928 subsequently as a pilot officer in a fighter squadron and then... 

English inventor Frank Whittle patents the basic design of the turbojet engine. 

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... 

In fact, the clearly posed problem of the final state of an unstable laminar flame is a limiting case of turbulent flame for vanishing initial turbulence of the oncoming flow, but the general case, for any initial velocity fluctuations, is clearly of great interest in practical devices such as spark-ignited engines, turbojet, or gas turbine combustion chambers. 

Matador Regulus Separating boost. Turbojet sustainer. 

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... 

In either case, bluff body or aerodynamic, blowout is the primary concern. In ramjets, the smallest frontal dimension for the highest flow velocity to be used is desirable in turbojets, it is the smallest volume of the primary recirculation zone that is of concern and in dump combustors, it is the least severe step. 

Figure 30.5 Comparison of specific impulse and flight Mach number for hydrogen (1) and hydrocarbons (2). PDE performance estimated using ASI Performance deck turbojet, ramjet, and scramjet performance levels reflect well-designed systems for man-rated thrust classes. TJ — turbojets RJ — ramjets SJ — scramjets PDE — pulse detonation engines PIL — preignition hmit [12]...

THE MISSILE — propelled by a Teledyne turbojet engine - is 17.5 feet long, weighs 1100 j pounds, and carries a conventional warhead. It flies at wave height under midcourse inertial guidance until the radar seeker locks onto the target. The missile climbs for a brief instant near the target, then dives on it... 

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... 

If, in a continuous flow jet, only the compression resulting from ram effect in the inlet diffuser is utilized, the compression and expansion machinery is eliminated, and the turbojet becomes a ramjet... 

Note The power generator system for the turboprop is essentially the same as in the turbojet... 

The advantages of a turboprop are in its greater efficiency, ie more of the gas generator energy is converted into useful work than in the turbojet. Its main disadvantages lie in the heavier and more cumbersome machinery that it requires... 

Engine Jet Development Turbojet Development Ramjet Development Development of Intermittent Jets Other Forms of Air Flow Jet... 

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