Compressors
BALANCING
37. The balancing of a compressor rotor or impeller is an extremely important operation in its manufacture. In view of the high rotational speeds and the mass of materials any unbalance would affect the rotating assembly bearings and engine operation. Balancing on these parts is effected on a special balancing machine, the principles of which are briefly described in Part 25.
Rolls-Royce RB211 Trent
罗尔斯-罗伊斯公司 RB211
“遄达”(Trent)发动机
由于政府要求一种4200磅推力的涡轮喷气发动机，罗尔斯-罗伊斯公司于1944年3月17日开始了RB40的工作。在和“超海军”(Supermarine)飞机机体的设计师讨论之后，该发动机被缩小到要产生3400磅推力。但是，“尼恩”(Nene)最终的推力定到5000磅并装用到霍克公司的 海鹞”(Hawker Sea Hawk)和“超海军”攻击机上。
On 17 March 1944 Rolls-Royce commenced work on the RB40 as the result of a Government request for a turbo-jet of 4200 lb thrust. After discussions with Supermarine, the airframe designers, the engine was scaled down to produce 3400 lb. The resulting Nene was eventually rated at 5000 lb and powered the Hawker Sea Hawk and Supermarine Attacker.
罗尔斯-罗伊斯公司
RB41“尼恩”(Nene)发动机
Rolls-Royce RB41 Nene
目 录
4: Combustion chambers
Contents Page
Introduction 35 Combustion process 36 Fuel supply 38 绪言
燃烧过程
燃油供应
燃烧室的类型
Types of combustion chamber 38
Multiple combustion chamber Tubo-annular combustion chamber 多个单管燃烧室
环管形燃烧室
环形燃烧室
Annular combustion chamber
Combustion chamber performance 41 Combustion intensity Combustion efficiency Combustion stability Emissions 2．加到空气中的燃油量将取决于所要求的温升。然而，最高温度限制到850到1700℃．这是由制造涡轮转子叶片和导向器的材料决定的。压缩过程所做的功已经将空气加热到200和550℃之间，使燃烧过程产生的温升要求为650到1150℃。由于涡轮要求的燃气温度随发动机推力变化，在涡轮螺桨发动机中则取决于要求的功率，所以，燃烧室也必须能够在范围宽广的发动机工作状态下保持稳定而有效的燃烧。
绪言
1．燃烧室(图4-1)的困难任务是将燃油喷嘴(第10章)供应的大量燃油和压气机(第3章)供应的大体积的空气一起燃烧，释放热量，让空气膨胀和加速，以便在所有状态下供给涡轮(第5章)所需的均匀加热的平稳燃气流。这一任务必须以最小的压力损失来完成，并且在有限的可用空间里释放出最大的热量。
燃烧室性能
燃烧强度
燃烧效率
燃烧稳定性
排放尾气
材料
Materials 43
第四章 燃烧室
INTRODUCTION
1.
The combustion chamber (fig. 4-1) has the difficult task of burning large quantities of fuel, supplied through the fuel spray nozzles (Part 10), with extensive volumes of air, supplied by the compressor (Part 3), and releasing the heat in such a manner that the air is expanded and accelerated to give a smooth stream of uniformly heated gas at all conditions required by the turbine (Part 5). This task must be accomplished with the minimum loss in pressure and with the maximum heat release for the limited space available.
2.
The amount of fuel added to the air will depend upon the temperature rise required. However, the maximum temperature is limited to within the range of 850 to 1700 deg. C. by the materials from which
the turbine blades and nozzles are made. The air has already been heated to between 200 and 550 deg. C. by the work done during compression, giving a temperature rise requirement of 650 to 1150 deg. C. from the combustion process. Since the gas temperature required at the turbine varies with engine thrust, and in the case of the turbo-propeller engine upon the power required, the combustion chamber must also be capable of maintaining stable and efficient combustion over a wide range of engine operating conditions.
3. Efficient combustion has become increasingly important because of the rapid rise in commercial aircraft traffic and the consequent increase in atmospheric pollution, which is seen by the general public as exhaust smoke.
4．从发动机压气机来的空气以高达500英尺／秒的速度进入燃烧室。但是，因为这一速度太高，不适于燃烧，燃烧室必须做的第一件事是使空气扩压，即使之减速并提高其静压。因为在正常混合比下燃烧着的煤油速度只是几英尺／秒，所以，任何燃油的火焰，即使在扩压的空气流中，那里现有大约80英尺／秒的速度，也会被吹走。因此，必须在燃烧室中创造出一个低轴向速度的区域，以使火焰在发动机工作状态的整个范围内都一直在烧着。
3．因为商用飞机交通的迅速增加和随之而来的、一般公众从飞机排烟所看到的大气污染的加剧，有效的燃烧已经变得日益重要。
5．在正常工作时，燃烧室的总的空气／燃油比可在45：1和130：1之间变化。然而，煤油只能在，或者接近于15：1的比例下有效地燃烧，所以，燃油必须只和进入燃烧室的一部分空气在所谓的主燃烧区中燃烧。这依靠火焰筒(燃烧衬筒)来实现。火焰筒有使气流沿燃烧室按要求分布的各种限流装置。
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