Table of Contents
22. Systems and consumables.
Similar to the alive nature an aeroengine is only functioning with its systems and consumables. In the following under system, a machinery with specific functions is understood . Airsystem, fuel system, oilsystem and hydrailic system distinguish itself by the influencing medium/consumable. Typical systems in aeroengines, its functions and important components shows the following chart.
The function of the system is closely connected. This especially is true for the oilsystem and airsystem and therefore we speak about the oil-air-system. At the OEM are often tasks of these systems organisational centralised. Also the control system/governor can be seen like the fuel injection system as a subsystem of the fuel system. The fuel system (chapter 22.2) and the oil system (chapter 22.3) are addicted distinct chapters. Aspectes of the air system will be discussed at several passages of this book. To those will be referred in a summary of Ill.22.1-1. In the foreground of chapter 22 are problems of the systems and media, but not there design/dimensioning and function. To aquaint oneself in these subjects excellent literature is offered. As entrance Lit. 22.1-1 up to Lit. 22.1-3 offers itself. Important, detailed, type spezific informations promise maintenance manuals and overhaul manuals.
Fig. "Sensoren 1": The air system influences, often interactive, a multitude of functionens. They are of high importance for the operation of an aeroengine. An air system consists correspondent to its
numerous functions of many components. But to these the main gasflow does not belong, although naturally
a connection exist (e.g., by the bleed air).
This as well functions and components of the air system will be discussed more in detail and if
necessary referred to other volumes of this book series:
Axial loads of the main bearings (volume 2, Ill. 7.2.1.-2 and Ill. 7.2.1-3) are
determined by piston forces. They are governed by gas pressures which act at disks. This happens with the help of rotating
air seals. Concerned are labyrinth seals and brush seals (volume 2, chapter 7.2 and 7.3).
Air seals have high influence at the efficiency of the aeroengine and its
deterioration (decrease of efficiency over the opreation time, volume 2, Ill. 7.0-2). Here are especially
labyrinths at interstage seals to
mention (volume 2, Ill. 7.2.1-13) and tip
shrouds of turbine rotor blades (volume 2, Ill.
7.2.1-15). Further functions are the seals for oil-air mixtures in bearing chambers (labyrinths, sealing
air) and seals in actuators/air motors (Lit. 22.1-4). Fore example used for the actuating of the thrust
nozzele and thrust reverser. Here also contact seals like
O rings (chapter 23.4.1), Rotary shaft seals
(chapter 18.104.22.168) and face seals (chapter 22.214.171.124) are used
Just the sealing of oil-air-mixtures has a high danger potential. A failure can trigger further failures
of important components like main bearings and /or the ignition of an oil fire (volume 2, chapter 9.2).
The cooling of hot parts (volume 3, Ill. 126.96.36.199-3 and Ill. 188.8.131.52-12) is of fundamental
importance for the operation temperature and with this the
lifetime (creep, volume 3, chapter 12.5 and
thermal fatigue volume 3, chapter 12.6.2).
The adjustment of sealing gaps (volume 2, Ill. 7.1.4-5, Ill. 7.1.4-6 and Ill. 7.1.4-7) happens by
the thermal expansion. For this a directed, often controlled
impingement of casings and sealing segments with discrete air
jets (Active Clearance Control = ACC) is used. So it is possible to optimize
for different operation conditions its expansions and with this the
tip gaps to the rotor (labyrinths, blade tips).
The deicing normally takes place at the components of the compressor intake and the front region of the compressor/fan (volume 1, Ill. 5.1.4-3 and Ill. 5.1.4-4). Thereby components like nose cone (e.g., spinner; volume 1, Ill. 5.1.4-9), intake guide vanes (IGVs), casing struts and casing edges.