图4-3 火焰稳定和总的气流图形
Fig. 4-3 Flame stabilizing and general airflow pattern.
13．在汽化方式中(图4-5)，燃油从供油管喷入位于火焰筒内部的汽化管中。这些汽化管将燃油折转180度，并且，随着它们被燃烧所加热时，燃油汽化，然后流入火焰筒。主空气流流过带着燃油的汽化管，同时也流入火焰筒进口段中的许多孔，形成空气“风扇’的作用，将火焰吹得向后倾斜。冷却和稀释空气经限流后进入火焰筒，其方式与进入雾化式火焰筒相似。
11．燃烧室的设计和加入燃油的方式可有很大变化。但是，用来 影响和维持燃烧的空气流分布却总是与描述的情形极其类似。
燃油供应
12．燃油用二种不同方式之一供入空气流中。最普通的是用喷嘴(第10章)将雾化良好的燃油喷入回旋的空气流中。第二种方式是让燃油预先汽化，然后进入燃烧区。
Combustion chambers
图4-4 几种火焰筒冷却方式
Fig. 4-4 Flame tube cooling methods.
11. The design of a combustion chamber and the method of adding the fuel may vary considerably, but the airflow distribution used to effect and maintain combustion is always very similar to that described.
FUEL SUPPLY
12.
Fuel is supplied to the airstream by one of two distinct methods. The most common is the injection of a fine atomized spray into the recirculating airstream through spray nozzles (Part 10). The second method is based on the pre-vaporization of the fuel before it enters the combustion zone.
13.
In the vaporizing method (fig.4-5) the fuel is sprayed from feed tubes into vaporizing tubes which are positioned inside the flame tube. These tubes turn the fuel through 180 degrees and, as they are heated by combustion, the fuel vaporizes before passing into the flame tube. The primary airflow passes down the vaporizing tubes with the fuel and also through holes in the flame tube entry section which provide 'fans' of air to sweep the flame rearwards. Cooling and dilution air is metered into
the flame tube in a manner similar to the atomizer flame tube.
TYPES OF COMBUSTION CHAMBER
14. There are three main types of combustion chamber in use for gas turbine engines. These are the multiple chamber, the tubo-annular chamber and the annular chamber.
Multiple combustion chamber
15.
This type of combustion chamber is used on centrifugal compressor engines and the earlier types of axial flow compressor engines. It is a direct development of the early type of Whittle combustion chamber. The major difference is that the Whittle chamber had a reverse flow as illustrated in fig. 4-6 but, as this created a considerable pressure loss, the straight-through multiple chamber was developed by Joseph Lucas Limited.
16.
The chambers are disposed around the engine (fig. 4-7) and compressor delivery air is directed by ducts to pass into the individual chambers. Each
蒸发式冷却
多个单管燃烧室
15．这种燃烧室用于离心压气机发动机和早期型别的轴流压气机发动机中。它是早期型惠特尔(Whittie)燃烧室的直接发展。其主要区别是惠特尔燃烧室有回流。如图4-6所示。但是，由于这造成相当大的压力损失，约瑟夫-卢卡斯公司便发展了这种通流多个单管燃烧室。
燃烧窒的类型
14．用于燃气涡轮发动机的燃烧室有三种主要类型。即多个单管燃烧室、环管形燃烧室和环形燃烧室。
16．这些燃烧室布置在发动机周围(图4-7)，压气机出口空气用管道引入一个个单独的燃烧室中。每一燃烧室内部均有一个火焰筒，围绕它的是空气机匣。空气流入火焰筒的锥形进口，并且流入火焰筒和外机匣之间的空间，其情形已如第6段所述。
17．单独的火焰简互相连接，这使所有火焰筒在同样的压力下工作，并且，使燃烧在发动机起动期间传
遍所有火焰简。
气化管
二股气流管
燃油供油管
涡轮导向器叶片
火焰筒
稀释空气孔
Combustion chambers
图4-5 一种汽化式燃烧室
Fig. 4-5 A vaporizer combustion chamber.
chamber has an inner flame tube around which there 17. The separate flame tubes are all interconnect-is an air casing. The air passes through the flame ed. This allows each tube to operate at the same tube snout and also between the tube and the outer pressure and also allows combustion to propagate 漩涡叶片
空气机匣
联焰管
燃气排气管
喷嘴
火焰筒
压气机出口
气虑
冷却空气孔
短管
主燃烧区
casing as already described in para. 6. around the flame tubes during engine starting.
图4-6 一种早期的惠特尔燃烧室
Fig. 4-6 An early Whittle combustion chamber.
环形燃烧室
19．这种燃烧室有一个火焰筒，其形状完全是环形的，装在内外机匣之间(图4-9)。流过火焰筒的气流与已经描述的情形类似，燃烧室前部向压气机敞开，而后端则连接涡轮导向器。
20.环形燃烧室的主要优点是，就同一功率输出而
言，燃烧室的长度只有同样直径的环管形系统长度的75％，大大节省了重量和生产成本。另一优点是消除了各燃烧室之间的燃烧传播问题。
21．与环管燃烧系统比较，与之相当的环形燃烧室的壁面积少得多，因而，防止火焰筒壁烧穿所要求的冷却空气量大约也少15％。冷却空气量的这一减少将燃烧效率(笫27段)提高，因此实际上消除了未燃烧的燃油，并将一氧化碳氧化成无毒的二氧化碳，从而减少了对空气的污染。 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：劳斯莱斯喷气引擎－中英(20)
