34.
Turbo-propeller engines use a slightly higher viscosity oil due to the additional requirements of the reduction gear and propeller pitch change mechanism.
33．由于燃氣渦輪發動機沒有往復運動零件及重載荷齒輪，所以大多數發動機使用低粘度潤滑油。這就減少了起動特別在低溫條件下起動需要的功率。實際上，可以在溫度低達-40℃的條件下正常起動，而無需對滑油預熱。
34．渦輪螺槳發動機由于減速齒輪和螺旋漿變距機構的額外要求，使用粘度稍高的滑油。
“馬姆巴”(Mamba)軸流式渦輪螺槳發動機是于1945年作為一臺1000馬力的發動機開始設計的。1946年4月首次運轉，“馬姆巴”發動機在肖特公司的“海鷗”(Short Seamew)飛機上投入使用，功率為1770當量馬力。進一步發展為雙“馬姆巴”，由兩臺“馬姆巴”組臺在一個動力裝置中發出3875當量馬力。雙“馬姆巴”發動機裝在“塘鵝”(Fairey Gannet)飛機上使用。
羅爾斯-羅伊斯公司RBl62-86發動機
Rolls-Royce RB162-86
阿姆斯特朗-西德利公司
“馬姆巴”發動機
Armstrong Siddeley Mamba
The Mamba axial-flow turbo-prop was conceived in 1945 as a 1000 hp engine. First run in April 1946, the single Mamba eventually went into service with the Short Seamew at 1770 ehp. A further development was the Double Mamba, a combination of two single Mambas in one power unit. Providing up to 3875 ehp, the Double Mamba saw service with the Fairey Gannet.
9: Internal air system
第九章 內部空氣系統
軸承載荷控制
飛機服務
封嚴
篦齒式封嚴件
環形封嚴件
液壓封嚴件
石墨封嚴件
刷式封嚴件
熱燃氣吸入
渦輪冷卻
軸承腔冷卻
附件冷卻
目錄
緒言
冷卻
Contents Page
Introduction 85 Cooling 86 Turbine cooling Bearing chamber cooling Accessory cooling Sealing 89 Labyrinth seals Ring seals Hydraulic seals Carbon seals Brush seals
Hot gas ingestion Control of bearing loads 91 Aircraft services 93
2.當空氣逐級流過壓氣機時，對空氣做的功在增加，從而提高了其壓力和溫度。因此，為了減少發動機的性能損失，空氣應當按照每個特定的功能要求盡可能從壓氣機前幾級抽取。冷卻空氣經由通風系統排出機外或在最高可能的壓力下進入發動機的主燃氣流，這時可以恢復一小部分性能。
INTRODUCTION
1. The engine internal air system is defined as those airflows which do not directly contribute to the engine thrust. The system has several important functions to perform for the safe and efficient operation of the engine. These functions include internal engine and accessory unit cooling, bearing chamber sealing prevention of hot gas ingestion into the turbine disc cavities, control of bearing axial loads, control of turbine blade tip clearances (Part 5) and engine anti-icing (Part 13). The system also supplies air for the aircraft services. Up to one fifth of the total engine core mass airflow may be used for these various functions.
2. An increasing amount of work is done on the air, as it progresses through the compressor, to raise its
冷卻
3.在燃氣渦輪發動機設計階段的一項重要考慮是保證發動機的某些零件以及在有的情況下的某些附件吸收的熱達不到危及其安全工作的程度。需要空氣冷卻的主要區域是燃燒室和渦輪。參見第4章燃燒室冷卻技術。
pressure and temperature. Therefore, to reduce engine performance losses, the air is taken as early as possible from the compressor commensurate with the requirement of each particular function. The cooling air is expelled overboard via a vent system or into the engine main gas stream, at the highest possible pressure, where a small performance recovery is achieved.
COOLING
3. An important consideration at the design stage of a gas turbine engine is the need to ensure that certain parts of the engine, and in some instances certain accessories, do not absorb heat to the extent that is detrimental to their safe operation. The principal areas which require air cooling are the combustor and turbine. Refer to Part 4 for combustor cooling techniques.
Internal air system
4. Cooling air is used to control the temperature of the compressor shafts and discs by either cooling or heating them. This ensures an even temperature dis-tribution and therefore improves engine efficiency by controlling thermal growth and thus maintaining minimum blade tip and seal clearances. Typical cooling and sealing airflows are shown in fig. 9-1.
Turbine cooling
5. High thermal efficiency is dependent upon high turbine entry temperature, which is limited by the turbine blade and nozzle guide vane materials. Continuous cooling of these components allows their environmental operating temperature to exceed the material's melting point without affecting the blade and vane integrity. Heat conduction from the turbine blades to the turbine disc requires the discs to be cooled and thus prevent thermal fatigue and uncon-trolled expansion and contraction rates. 低壓渦輪軸承
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