圖4-3 火焰穩定和總的氣流圖形
Fig. 4-3 Flame stabilizing and general airflow pattern.
13．在汽化方式中(圖4-5)，燃油從供油管噴入位于火焰筒內部的汽化管中。這些汽化管將燃油折轉180度，并且，隨著它們被燃燒所加熱時，燃油汽化，然后流入火焰筒。主空氣流流過帶著燃油的汽化管，同時也流入火焰筒進口段中的許多孔，形成空氣“風扇’的作用，將火焰吹得向后傾斜。冷卻和稀釋空氣經限流后進入火焰筒，其方式與進入霧化式火焰筒相似。
11．燃燒室的設計和加入燃油的方式可有很大變化。但是，用來 影響和維持燃燒的空氣流分布卻總是與描述的情形極其類似。
燃油供應
12．燃油用二種不同方式之一供入空氣流中。最普通的是用噴嘴(第10章)將霧化良好的燃油噴入回旋的空氣流中。第二種方式是讓燃油預先汽化，然后進入燃燒區。
Combustion chambers
圖4-4 幾種火焰筒冷卻方式
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
蒸發式冷卻
多個單管燃燒室
15．這種燃燒室用于離心壓氣機發動機和早期型別的軸流壓氣機發動機中。它是早期型惠特爾(Whittie)燃燒室的直接發展。其主要區別是惠特爾燃燒室有回流。如圖4-6所示。但是，由于這造成相當大的壓力損失，約瑟夫-盧卡斯公司便發展了這種通流多個單管燃燒室。
燃燒窒的類型
14．用于燃氣渦輪發動機的燃燒室有三種主要類型。即多個單管燃燒室、環管形燃燒室和環形燃燒室。
16．這些燃燒室布置在發動機周圍(圖4-7)，壓氣機出口空氣用管道引入一個個單獨的燃燒室中。每一燃燒室內部均有一個火焰筒，圍繞它的是空氣機匣。空氣流入火焰筒的錐形進口，并且流入火焰筒和外機匣之間的空間，其情形已如第6段所述。
17．單獨的火焰簡互相連接，這使所有火焰筒在同樣的壓力下工作，并且，使燃燒在發動機起動期間傳
遍所有火焰簡。
氣化管
二股氣流管
燃油供油管
渦輪導向器葉片
火焰筒
稀釋空氣孔
Combustion chambers
圖4-5 一種汽化式燃燒室
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 漩渦葉片
空氣機匣
聯焰管
燃氣排氣管
噴嘴
火焰筒
壓氣機出口
氣慮
冷卻空氣孔
短管
主燃燒區
casing as already described in para. 6. around the flame tubes during engine starting.
圖4-6 一種早期的惠特爾燃燒室
Fig. 4-6 An early Whittle combustion chamber.
環形燃燒室
19．這種燃燒室有一個火焰筒，其形狀完全是環形的，裝在內外機匣之間(圖4-9)。流過火焰筒的氣流與已經描述的情形類似，燃燒室前部向壓氣機敞開，而后端則連接渦輪導向器。
20.環形燃燒室的主要優點是，就同一功率輸出而
言，燃燒室的長度只有同樣直徑的環管形系統長度的75％，大大節省了重量和生產成本。另一優點是消除了各燃燒室之間的燃燒傳播問題。
21．與環管燃燒系統比較，與之相當的環形燃燒室的壁面積少得多，因而，防止火焰筒壁燒穿所要求的冷卻空氣量大約也少15％。冷卻空氣量的這一減少將燃燒效率(笫27段)提高，因此實際上消除了未燃燒的燃油，并將一氧化碳氧化成無毒的二氧化碳，從而減少了對空氣的污染。 中國航空網 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(20)
