mechanical), a combustion chamber, and a tailpipe orexit nozzle, as shown in figure 6-5.While the ramjet will deliver no static thrust, thepulsejet engine can produce static thrust. However, thethrust developed under static conditions is not sufficientto enable a pulsejet aircraft or guided missile to take offunder its own power, at least not on conventionalrunways. Consequently, missiles or other devicespowered by pulsejet engines must be boosted toself-sustaining flight speeds by catapults or rockets.Possible applications for the pulsejet engine, otherthan for powering pilotless military weapons, includeflight research, powering helicopters by attaching smallpulsejet engines to the rotor blade tips, and emergencypower plants for small aircraft and gliders.GAS TURBINE ENGINESAs stated earlier, there are four types of gas turbineengines: turbojet, turboprop, turboshaft, and turbofan.Each of these engines is briefly discussed in thefollowing paragraphs.Turbojet EnginesThere are over 40 different Navy models of theturbojet engine. The A-6 and T-2 are examples ofaircraft that use this direct thrust engine. The turbojetengine consists of five major components: an inletduct, a compressor, a combustion chamber (orchambers), a turbine (or turbines), and an exhaust coneassembly, as shown in figure 6-6.INLET DUCT.—The inlet duct is an opening inthe front of the aircraft that allows outside (ambient) airto enter the engine. The compressor compresses theincoming air and delivers it to the combustion (orburner) section. In the combustion chamber, fuel issprayed into and mixed with the compressed air. Anigniter then ignites the fuel-air mixture. The burningmixture continues to burn in the presence of the properfuel-air mixture. The fuel-air mixture burns at arelatively constant pressure. Only about 25 percent ofthe air is used in the combustion process. The rest of theair (75 percent) is mixed with the combustion products(exhaust) for cooling before the gases enter the turbinesection.The turbine section extracts and uses a majorportion of the energy in the gas stream to turn thecompressor and accessories. After leaving the turbine,the remaining pressure forces the hot gases through theengine exhaust duct at very high speeds. The air that6-4Figure 6-5.—The pulsejet engine.Figure 6-6.—Five major components of the turbojet.
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