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
羅爾斯-羅伊斯公司 RB211
“遄達”(Trent)發動機
由于政府要求一種4200磅推力的渦輪噴氣發動機，羅爾斯-羅伊斯公司于1944年3月17日開始了RB40的工作。在和“超海軍”(Supermarine)飛機機體的設計師討論之后，該發動機被縮小到要產生3400磅推力。但是，“尼恩”(Nene)最終的推力定到5000磅并裝用到霍克公司的 海鷂”(Hawker Sea Hawk)和“超海軍”攻擊機上。
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.
羅爾斯-羅伊斯公司
RB41“尼恩”(Nene)發動機
Rolls-Royce RB41 Nene
目 錄
4: Combustion chambers
Contents Page
Introduction 35 Combustion process 36 Fuel supply 38 緒言
燃燒過程
燃油供應
燃燒室的類型
Types of combustion chamber 38
Multiple combustion chamber Tubo-annular combustion chamber 多個單管燃燒室
環管形燃燒室
環形燃燒室
Annular combustion chamber
Combustion chamber performance 41 Combustion intensity Combustion efficiency Combustion stability Emissions 2．加到空氣中的燃油量將取決于所要求的溫升。然而，最高溫度限制到850到1700℃．這是由制造渦輪轉子葉片和導向器的材料決定的。壓縮過程所做的功已經將空氣加熱到200和550℃之間，使燃燒過程產生的溫升要求為650到1150℃。由于渦輪要求的燃氣溫度隨發動機推力變化，在渦輪螺槳發動機中則取決于要求的功率，所以，燃燒室也必須能夠在范圍寬廣的發動機工作狀態下保持穩定而有效的燃燒。
緒言
1．燃燒室(圖4-1)的困難任務是將燃油噴嘴(第10章)供應的大量燃油和壓氣機(第3章)供應的大體積的空氣一起燃燒，釋放熱量，讓空氣膨脹和加速，以便在所有狀態下供給渦輪(第5章)所需的均勻加熱的平穩燃氣流。這一任務必須以最小的壓力損失來完成，并且在有限的可用空間里釋放出最大的熱量。
燃燒室性能
燃燒強度
燃燒效率
燃燒穩定性
排放尾氣
材料
Materials 43
第四章 燃燒室
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．從發動機壓氣機來的空氣以高達500英尺／秒的速度進入燃燒室。但是，因為這一速度太高，不適于燃燒，燃燒室必須做的第一件事是使空氣擴壓，即使之減速并提高其靜壓。因為在正常混合比下燃燒著的煤油速度只是幾英尺／秒，所以，任何燃油的火焰，即使在擴壓的空氣流中，那里現有大約80英尺／秒的速度，也會被吹走。因此，必須在燃燒室中創造出一個低軸向速度的區域，以使火焰在發動機工作狀態的整個范圍內都一直在燒著。
3．因為商用飛機交通的迅速增加和隨之而來的、一般公眾從飛機排煙所看到的大氣污染的加劇，有效的燃燒已經變得日益重要。
5．在正常工作時，燃燒室的總的空氣／燃油比可在45：1和130：1之間變化。然而，煤油只能在，或者接近于15：1的比例下有效地燃燒，所以，燃油必須只和進入燃燒室的一部分空氣在所謂的主燃燒區中燃燒。這依靠火焰筒(燃燒襯筒)來實現。火焰筒有使氣流沿燃燒室按要求分布的各種限流裝置。
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