12.戽斗式盾牌系統(tǒng)為液壓傳動(dòng)系統(tǒng)，利用戽斗式門將熱燃?xì)饬鞣聪颉Ｍ屏Ψ聪蜓b置門通過常規(guī)推桿系統(tǒng)來傳動(dòng)。一個(gè)液壓作動(dòng)筒與一個(gè)傳動(dòng)中介輪相連接，通過一對(duì)推桿來操縱門（每個(gè)門上有一根推桿）。
11. The clamshell doors are operated by pneumatic rams through levers that give the maximum load to the doors in the forward thrust position; this ensures effective sealing at the door edges, so preventing gas leakage. The door bearings and operating linkage operate without lubrication at temperatures of up to 600 deg. C.
Bucket target system
12.
The bucket target system is hydraulically actuated and uses bucket-type doors to reverse the hot gas stream. The thrust reverser doors are actuated by means of a conventional pushrod system. A single hydraulic powered actuator is connected to a drive idler, actuating the doors through a pair of pushrods (one for each door).
13.
The reverser doors are kept in synchronization through the drive idler. The hydraulic actuator incor-porates a mechanical lock in the stowed (actuator extended) position.
14.
In the forward thrust mode (stowed) the thrust reverser doors form the convergent-divergent final nozzle for the engine.
Thrust reversal
Cold stream reverser system
15.
The cold stream reverser system (fig. 15-4) can be actuated by an air motor, the output of which is converted to mechanical movement by a series of flexible drives, gearboxes and screwjacks, or by a system incorporating hydraulic rams.
16.
When the engine is operating in forward thrust, the cold stream final nozzle is 'open' because the cascade vanes are internally covered by the blocker doors (flaps) and externally by the movable (translating) cowl; the latter item also serves to reduce drag.
17.
On selection of reverse thrust, the actuation system moves the translating cowl rearwards and at the same time folds the blocker doors to blank off the cold stream final nozzle, thus diverting the airflow through the cascade vanes.
Turbo-propeller reverse pitch system
18. As mentioned in para. A, reverse thrust action is affected on turbo-propeller powered aircraft by changing the pitch of the propeller blades through a hydro-mechanical pitch control system (fig. 15-5). Movement of the throttle or power control lever 油門桿
圖15-5 一種螺旋槳槳距控制系統(tǒng)
Fig. 15-5 A propeller pitch control system.
渦輪螺槳反槳系統(tǒng)
正如第4段所述，通過液壓機(jī)械式槳葉角度控制系統(tǒng)(圖15-5)來改變螺旋槳槳葉的角度產(chǎn)生反推力對(duì)以渦輪螺槳為動(dòng)力的飛機(jī)產(chǎn)生影響。油門桿即功率控制桿把滑油從控制系統(tǒng)引導(dǎo)致螺旋槳機(jī)構(gòu)，將槳葉角度減少到零，,再到負(fù)(反)槳距。油門桿移動(dòng)時(shí)，通過與槳葉角度控制裝置相連接的油門桿活門來調(diào)整向發(fā)動(dòng)機(jī)的燃油供給，使發(fā)動(dòng)機(jī)功率和槳葉角度相協(xié)調(diào)，以獲得所學(xué)的反推力值。反推力也可用以操縱已停下的渦輪螺槳飛機(jī)使之后退。
Thrust reversal
19.在螺旋槳控制系統(tǒng)中已考慮到若干在螺旋槳出現(xiàn)故障時(shí)有用的安全因素，這些裝置通常是液壓機(jī)械式槳距鎖定裝置或止動(dòng)裝置。
圖15-6 熱氣流推力反向裝置
Fig. 15-6 Hot stream thrust reverser installations.
結(jié)構(gòu)和材料
20.第9和第12段中介紹的哈殼形門和戽斗式盾牌門（圖15-6）形成噴管的一部分。反推器的機(jī)匣與飛機(jī)機(jī)構(gòu)連接或直接與發(fā)動(dòng)機(jī)連接。此機(jī)匣支撐著兩個(gè)反推器的門和操縱機(jī)構(gòu)，在哈殼形門系統(tǒng)中，還支持裝有葉柵葉片的排氣管。燃?xì)饬鞯慕嵌群兔娣e是通過每一排氣管中的葉片數(shù)量來控制的。
directs oil from the control system to the propeller mechanism to reduce the blade angle to zero, and then through to negative (reverse) pitch. During throttle lever movement, the fuel to the engine is trimmed by the throttle valve, which is interconnect-ed to the pitch control unit, so that engine power and blade angle are co-ordinated to obtain the desired amount of reverse thrust. Reverse thrust action may also be used to manoeuvre a turbo-propeller aircraft backwards after it has been brought to rest.
19. Several safety factors are incorporated in the propeller control system for use in the event of propeller malfunction, and these devices are usually hydro-mechanical pitch locking devices or stops.
CONSTRUCTION AND MATERIALS
20. The clamshell and bucket target doors (fig. 15-6) described in paras. 9 and 12 form part of the jet
中國航空網(wǎng) www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：勞斯萊斯噴氣引擎－中英(83)
