氧
液體燃油
燃燒室
燃油噴嘴
14.
The application of the gas turbine to jet
propulsion has avoided the inherent weakness of the
rocket and the athodyd, for by the introduction of a
turbine-driven compressor a means of producing
thrust at low speeds is provided. The turbo-jet engine
operates on the 'working cycle' as described in Part
推進噴管
2. It draws air from the atmosphere and after
compressing and heating it, a process that occurs in
all heat engines, the energy and momentum given to
the air forces It out of the propelling nozzle at a
velocity of up to 2,000 feet per second or about 1,400
miles per hour. On its way through the engine, the air
gives up some of its energy and momentum to drive
the turbine that powers the compressor. Fig. 1-8 A rocket engine.
圖1-8火箭發動機
14.應用燃氣輪機于噴氣推進避免了火箭和沖壓噴氣發動機固有的弱點，因為通過采用渦輪驅動的壓氣機提供了低速時產生推力的一種手段。渦輪噴氣發動機按照第2章敘述的“工作循環”工作。它從大氣中吸進空氣，經壓縮和加熱這一所有熱力發動機中的過程之后，得到能量和動量的空氣以高達2000英尺/秒或大約1400英里/小時的速度從推進噴管中排出。在空氣通過發動機的過程中，它釋放一些能量和動量驅動給壓氣機提供動力的渦輪。
Basic mechanics
圖1-9-1幾種燃氣渦輪發動機的機械布局
Fig. 1-9-1 Mechanical arrangement of gas turbine engines.
Basic mechanics
雙軸內外涵渦輪-噴氣發動機(低涵道比)
圖1-9-2 幾種燃氣渦輪發動機的機械布局
Fig. 1-9-2 Mechanical arrangement of gas turbine engines.
and turbine blades, and the design of the exhaust system through which the gases are ejected to form the propulsive jet.
16. At aircraft speeds below approximately 450 miles per hour, the pure jet engine is less efficient than a propeller-type engine, since its propulsive efficiency depends largely on its forward speed; the pure turbo-jet engine is, therefore, most suitable for high forward speeds. The propeller efficiency does, however, decrease rapidly above 350 miles per hour due to the disturbance of the airflow caused by the high blade-tip speeds of the propeller. These charac-
16．飛機速度低于大約450英里／小時時,純噴氣發
動機的效率低于螺旋槳型發動機的效率，因為它的
推進效率在很大程度上取決于它的飛行速度；因而，純渦輪噴氣發動機最適合高的飛行速度。然而，由于螺旋槳的高葉尖速度造成的氣流擾動，在350英里／小時以上時螺旋槳效率迅速降低。這些特性使得中等速度飛行的飛機不用純渦輪噴氣推進裝置而采用螺旋槳和燃氣渦輪發動機的組合。
17．螺旋槳/渦輪組合的優越性在一定程度上被內
外涵發動機、涵道風扇發動機和漿扇發動機的引八
所抵消。這些發動機比純噴氣發動機流量大而噴氣
速度低。因而，其推進效率(第21章)與渦輪螺旋槳
的相當，超過了純噴氣發動機的推進效率(圖1-lO)。
Basic mechanics
teristics have led to some departure from the use of pure turbo-jet propulsion where aircraft operate at medium speeds by the introduction of a combination of propeller and gas turbine engine.
17. The advantages of the propeller/turbine combination have to some extent been offset by the introduction of the by-pass, ducted fan and propfan engines. These engines deal with larger comparative airflows and lower jet velocities than the pure jet engine, thus giving a propulsive efficiency (Part 21) which is comparable to that of the turbo-prop and exceeds that of the pure jet engine (fig. 1-10).
圖1-1O 推進效率的比較
Fig. 1-10 Comparative propulsive efficiencies.
18．渦輪／沖壓噴氣發動機(圖1-11)將渦輪噴氣發
動機(它用于馬赫數高達3的各種速度)與沖壓噴氣
發動機結合起來，在高馬赫數時具有良好的性能。
可調噴口(大面積)
可調進氣道(小面積)
可調噴口(小面積)
高馬赫數
進口導流葉片 (關閉)
低馬赫數
可調進氣道(大面積)
進口導流葉片 (打開)
Basic mechanics
圖1-11 一種渦輪／沖壓噴氣發動機
Fig. 1-11 A turbo/ram jet engine.
18. The turbo/ram jet engine (fig. 1-11) combines ventional turbo-jet with the afterburner lit; at other the turbo-jet engine (which is used for speeds up to flight conditions up to Mach 3, the afterburner is
Mach 3) with the ram jet engine, which has good inoperative. As the aircraft accelerates through Mach performance at high Mach numbers.
3, the turbo-jet is shut down and the intake air is diverted from the compressor, by guide vanes, and
19. The engine is surrounded by a duct that has a variable intake at the front and an afterburning jet ducted straight into the afterburning jet pipe, which
pipe with a variable nozzle at the rear. During take-becomes a ram jet combustion chamber. This engine 燃燒室
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