13．排气系统应当能够承受很高的燃气温度，因此是用镍或钛合金制成。它还应当防止向周围飞机结构有任何的热量传递。这是通过在喷管周围流过通风空气，或通过在排气系统的热段套一个隔热层(图6-6)而实现的。每个隔热层有一个由纤维隔热材料制成的内层，外面由薄的不锈钢外皮包裹，外层制
成波纹形以增加强度。另外，在排气系统中有时还应用吸声材料，以减小发动机的噪声(第19章)。
14.当燃气温度非常高的时候(例如，采用加力燃烧室时)，整个喷管通常是双壁结构(第16章)，两壁之问有一个环腔。热燃气离开推进喷管时，通过引射作用，引射一股空气流过发动机短舱的环形通道时，该空气流冷却喷管的内壁，通过减少自内壁向外界的传热，起着隔热层的作用。
15．排气系统的锥体及流线形整流罩承受排气的压力，因此，为了防止变形，要开通气孔，保持压力平衡。
16．低涵道比发动机所用的混合器装置上有许多槽，使外涵空气由斜槽流入排出的燃气流中。在涵道比发动机的整体式喷管组件上采用了粘接的蜂窝结构，使这种大部件能够得到轻重量、高强度。
17．由于排气系统承受的温度变化范围很宽，它的安装及其各段的连接方式应允许膨胀和收缩，而不致变形或损坏。
图6-6 一种隔热层
Fig. 6-6 An insulating blanket.
an outer skin of thin stainless steel, which is dimpled to increase its strength. In addition, acoustically absorbent materials are sometimes applied to the exhaust system to reduce engine noise (Part 19).
14.
When the gas temperature is very high (for example, when afterburning is employed), the complete jet pipe is usually of double-wall construc-tion (Part 16) with an annular space between the two walls. The hot gases leaving the propelling nozzle induce, by ejector action, a flow of air through the annular space of the engine nacelle. This flow of air cools the inner wall of the jet pipe and acts as an insulating blanket by reducing the transfer of heat from the inner to the outer wall.
15.
The cone and streamline fairings in the exhaust unit are subjected to the pressure of the exhaust gases; therefore, to prevent any distortion, vent holes are provided to obtain a pressure balance.
16.
The mixer unit used in low by-pass ratio engines consists of a number of chutes through which the bypass air flows into the exhaust gases. A bonded honeycomb structure is used for the integrated nozzle assembly of high by-pass ratio engines to give lightweight strength to this large component.
17.
Due to the wide variations of temperature to which the exhaust system is subjected, it must be mounted and have its sections joined together in such a manner as to allow for expansion and contraction without distortion or damage.
Rolls-Royce Gnome
罗尔斯-罗伊斯公司“诺姆”(Gnome)发动机
De Havilland H2 Ghost
“幽灵”(Ghost)发动机是作为“妖魔”(Goblin)的尺寸和功率加大型而设计的。在1945年9月2日首次运转之后,它获准装在阿弗罗“兰开斯特”(Avro Lancastrian)飞机的外侧发动机短舱中，推力4000磅。后来，“幽灵”发动机投产，推力达5000磅，装用于德 哈维兰(de Havilland)公司的“彗星”（Comet）I客机和“毒辣”(Venom)歼山机上。
The Ghost was designed as a larger and more powerful version of the Goblin. After running for the first time on 2 September 1945 the engine was cleared for flight in the outer nacelles of an Avro Lancastrian at 4000 lb thrust. The Ghost later went into production at 5000 lb thrust to power the de Havilland Comet 1 airliner and Venom fighter.
德 哈维兰公司
H2“幽灵”发动机
2．通常，附件装置是由发动机的旋转轴，经过内部齿轮箱传向外部齿轮箱来驱动。外部齿轮箱用作附件的安装座，并向各个附件装置分配相应的齿轮传动机构。其上还可能装一个起动机，为发动机提供输入扭矩。在高涵道比发动机上，一套附件传动系统从发动机吸取的功率在400到500马力之间
绪言
1．附件装置为飞机液压、气压和电气系统提供动力，而且为发动机有效工作提供各种泵和控制系统的动力。由于这些装置存在很高的依赖性，所以要求传动系统具有极高的可靠性。
第七章 附件传动装置
7: Accessory drives
目 录
Contents Page
Introduction 65
绪言
齿轮箱及传动装置
Gearboxes and drives 65
Internal gearbox
Radial driveshaft
Direct drive
Gear train drive
Intermediate gearbox
内部齿轮箱
径向传动轴
直接传动
齿轮链条传动
中间齿轮箱
外部齿轮箱
辅助齿轮箱
External gearbox
Auxiliary gearbox Construction and materials 69
Gears
Gearbox sealing
结构和材料
齿轮
齿轮箱封严
材料
Materials
INTRODUCTION
1.
Accessory units provide the power for aircraft hydraulic, pneumatic and electrical systems in addition to providing various pumps and control systems for efficient engine operation. The high level of dependence upon these units requires an extremely reliable drive system.
2.
The drive for the accessory units is typically taken from a rotating engine shaft, via an internal gearbox, to an external gearbox which provides a mount for the accessories and distributes the appropriate geared drive to each accessory unit. A starter may also be fitted to provide an input torque to the engine. An accessory drive system on a high by-pass engine takes between 400 and 500 horsepower from the engine.
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