9.空氣起動(dòng)應(yīng)用于大多數(shù)民用和若干軍用噴氣發(fā)動(dòng)機(jī)中。與其它起動(dòng)系統(tǒng)相比，它有重量較輕，簡(jiǎn)單而且使用經(jīng)濟(jì)等許多優(yōu)點(diǎn)。
10.空氣起動(dòng)機(jī)馬達(dá)將功率通過(guò)減速齒輪和離合器傳遞給起動(dòng)機(jī)輸出軸，該軸與發(fā)動(dòng)機(jī)相連。典型的空氣起動(dòng)馬達(dá)示于圖11-6。
11.
The starter turbine is rotated by air taken from an external ground supply, an auxiliary power unit (A.P.U.) or as a cross-feed from a running engine. The air supply to the starter is controlled by an elec-trically operated control and pressure reducing valve that is opened when an engine start is selected and is automatically closed at a predetermined starter speed. The clutch also automatically disengages as the engine accelerates up to idling r.p.m. and the
11.起動(dòng)機(jī)渦輪由來(lái)自外部地面氣源的空氣帶轉(zhuǎn)，也可以用輔助動(dòng)力裝置（APU）帶轉(zhuǎn)，或者用正在運(yùn)轉(zhuǎn)的發(fā)動(dòng)機(jī)進(jìn)行交叉供氣驅(qū)動(dòng)。向起動(dòng)機(jī)供氣的外部氣源由電控制器和減壓活門加以控制。該活門在起動(dòng)機(jī)起動(dòng)時(shí)打開，當(dāng)達(dá)到預(yù)定的起動(dòng)機(jī)轉(zhuǎn)速時(shí)自動(dòng)關(guān)閉。當(dāng)發(fā)動(dòng)機(jī)加速到慢車轉(zhuǎn)速時(shí)，離合器自動(dòng)打開，同時(shí)起動(dòng)停止轉(zhuǎn)動(dòng)。一種典型的空氣起動(dòng)系統(tǒng)示于圖11-7。
高壓開關(guān)
排氣管
轉(zhuǎn)速控制開關(guān)
電嘴
點(diǎn)火開關(guān)
起動(dòng)機(jī)馬達(dá)
點(diǎn)火器
燃油旁路
燃油和空氣回油泵
控制盒
旁路空氣
燃油箱
起動(dòng)機(jī)按鈕
飛機(jī)電源
Starting and ignition
圖11-5 一種異丙基硝酸酯起動(dòng)系統(tǒng)
Fig. 11-5 An iso-propyl-nitrate starting system.
12.有時(shí)在已裝有空氣起動(dòng)機(jī)的發(fā)動(dòng)機(jī)上還有燃燒室起動(dòng)機(jī)，當(dāng)沒有外部空氣源的情況下用于向起動(dòng)機(jī)供氣。這種起動(dòng)機(jī)有一個(gè)小型的燃燒室，它使用飛機(jī)丄佩帶的氣瓶的高壓空氣，及發(fā)動(dòng)機(jī)燃油系統(tǒng)的燃油控制活門調(diào)節(jié)氣源的供氣，氣源對(duì)燃油蓄壓器加壓，以提供足夠的燃油壓力進(jìn)行霧化，而且還激發(fā)連續(xù)點(diǎn)火系統(tǒng)。燃油、空氣混合氣在燃燒室中點(diǎn)燃，產(chǎn)生的燃?xì)獗灰肟諝馄饎?dòng)機(jī)的渦輪。當(dāng)起動(dòng)循環(huán)完成之后，有一個(gè)電路將氣源斷開，并進(jìn)而終止燃油和點(diǎn)火系統(tǒng)的工作。
渦輪轉(zhuǎn)子
減速齒輪
空氣進(jìn)口
離合器
13.有些渦輪噴氣發(fā)動(dòng)機(jī)上不裝起動(dòng)機(jī)馬達(dá)，但利用空氣沖擊渦輪葉片作為帶轉(zhuǎn)發(fā)動(dòng)機(jī)的一種方法。空氣可以取自外部氣源、或正在運(yùn)轉(zhuǎn)的發(fā)動(dòng)機(jī)，并經(jīng)單向活門和導(dǎo)向器導(dǎo)入渦輪葉片。一種空氣沖擊起動(dòng)的典型方法示于圖11-8。
發(fā)動(dòng)機(jī)驅(qū)動(dòng)軸
空氣出口
Starting and ignition
燃?xì)鉁u輪起動(dòng)
14.燃?xì)鉁u輪起動(dòng)機(jī)用于某些噴氣發(fā)動(dòng)機(jī)中，這種起動(dòng)方式是完全自立的。它具有自己的燃油和點(diǎn)火系統(tǒng)、起動(dòng)系統(tǒng)（通常是電的或液壓的），以及自備滑油系統(tǒng)。這種起動(dòng)機(jī)使用經(jīng)濟(jì)，而且以比較輕的重量提供高的功率輸出。
15.這種起動(dòng)機(jī)含有一臺(tái)小而緊湊的燃?xì)鉁u輪發(fā)動(dòng)機(jī)，其一般特點(diǎn)是采用渦輪驅(qū)動(dòng)的離心壓氣機(jī)，回油式燃燒系統(tǒng)和一個(gè)機(jī)械上獨(dú)立的自由動(dòng)力渦輪。它由動(dòng)力渦輪經(jīng)由兩級(jí)游星式減速齒輪、自動(dòng)離合器和輸出軸與主發(fā)動(dòng)機(jī)相連。一種典型的燃?xì)鉁u輪起動(dòng)機(jī)示于圖11-9。
圖11-6 一種空氣起動(dòng)機(jī)馬達(dá)
Fig. 11-6 An air starter motor.
rotation of the starter ceases. A typical air starting system is shown in fig. 11-7.
12.
A combustor starter is sometimes fitted to an engine incorporating an air starter and is used to supply power to the starter when an external supply of air is not available. The starter unit has a small combustion chamber into which high pressure air, from an aircraft-mounted storage bottle, and fuel, from the engine fuel system, are introduced. Control valves regulate the air supply which pressurizes a fuel accumulator to give sufficient fuel pressure for atomization and also activates the continuous ignition system. The fuel/air mixture is ignited in the combustion chamber and the resultant gas is directed onto the turbine of the air starter. An electrical circuit is provided to shut off the air supply which in turn terminates the fuel and ignition systems on completion of the starting cycle.
13.
Some turbo-jet engines are not fitted with starter motors, but use air impingement onto the turbine blades as a means of rotating the engine. The air is obtained from an external source, or from an engine that is running, and is directed through non-return valves and nozzles onto the turbine blades. A typical method of air impingement starting is shown in fig. 11-8.
Gas turbine
14.
A gas turbine starter is used for some jet engines and is completely self-contained. It has its own fuel and ignition system, starting system (usually electric or hydraulic) and self-contained oil system. This type of starter is economical to operate and provides a high power output for a comparatively low weight.
15.
The starter consists of a small, compact gas turbine engine, usually featuring a turbine-driven centrifugal compressor, a reverse flow combustion system and a mechanically independent |free-power turbine. The free-power turbine is connected to the main engine via a two-stage epicyclic reduction gear, automatic clutch and output shaft. A typical gas turbine starter is shown in fig. 11-9.
16.
On initiation of the starting cycle, the gas turbine starter is rotated by its own starter motor until it reaches self-sustaining speed, when the starting and ignition systems are automatically switched off. Acceleration then continues up to a controlled speed of approximately 60,000 r.p.m. At the same time as the gas turbine starter engine is accelerating, the exhaust gas is being directed, via nozzle guide vanes, onto the free-power turbine to provide the drive to the main engine. Once the main engine reaches self-sustaining speed, a cut-out switch
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