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?xì)鉁u輪發(fā)動(dòng)機(jī)沒(méi)有往復(fù)運(yùn)動(dòng)零件及重載荷齒輪，所以大多數(shù)發(fā)動(dòng)機(jī)使用低粘度潤(rùn)滑油。這就減少了起動(dòng)特別在低溫條件下起動(dòng)需要的功率。實(shí)際上，可以在溫度低達(dá)-40℃的條件下正常起動(dòng)，而無(wú)需對(duì)滑油預(yù)熱。
34．渦輪螺槳發(fā)動(dòng)機(jī)由于減速齒輪和螺旋漿變距機(jī)構(gòu)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(fā)動(dòng)機(jī)是于1945年作為一臺(tái)1000馬力的發(fā)動(dòng)機(jī)開(kāi)始設(shè)計(jì)的。1946年4月首次運(yùn)轉(zhuǎn)，“馬姆巴”發(fā)動(dòng)機(jī)在肖特公司的“海鷗”(Short Seamew)飛機(jī)上投入使用，功率為1770當(dāng)量馬力。進(jìn)一步發(fā)展為雙“馬姆巴”，由兩臺(tái)“馬姆巴”組臺(tái)在一個(gè)動(dòng)力裝置中發(fā)出3875當(dāng)量馬力。雙“馬姆巴”發(fā)動(dòng)機(jī)裝在“塘鵝”(Fairey Gannet)飛機(jī)上使用。
羅爾斯-羅伊斯公司RBl62-86發(fā)動(dòng)機(jī)
Rolls-Royce RB162-86
阿姆斯特朗-西德利公司
“馬姆巴”發(fā)動(dòng)機(jī)
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(nèi)部空氣系統(tǒng)
軸承載荷控制
飛機(jī)服務(wù)
封嚴(yán)
篦齒式封嚴(yán)件
環(huán)形封嚴(yán)件
液壓封嚴(yán)件
石墨封嚴(yán)件
刷式封嚴(yán)件
熱燃?xì)馕?br />
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(dāng)空氣逐級(jí)流過(guò)壓氣機(jī)時(shí)，對(duì)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(fā)動(dòng)機(jī)的性能損失，空氣應(yīng)當(dāng)按照每個(gè)特定的功能要求盡可能從壓氣機(jī)前幾級(jí)抽取。冷卻空氣經(jīng)由通風(fēng)系統(tǒng)排出機(jī)外或在最高可能的壓力下進(jìn)入發(fā)動(dòng)機(jī)的主燃?xì)饬鳎@時(shí)可以恢復(fù)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?xì)鉁u輪發(fā)動(dòng)機(jī)設(shè)計(jì)階段的一項(xiàng)重要考慮是保證發(fā)動(dòng)機(jī)的某些零件以及在有的情況下的某些附件吸收的熱達(dá)不到危及其安全工作的程度。需要空氣冷卻的主要區(qū)域是燃燒室和渦輪。參見(jiàn)第4章燃燒室冷卻技術(shù)。
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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