Aircraft in the scope of maintenance, aircraft ignition crew, the transfer of energy to the APU, and started the engine first, second, or even until the fourth engine on for takeoff and hovering in the air and then to the goal of landing
X . I BATTERY
Figure 1 car starter system
Figure 2 . aircraft starter system
On the Job System Starting System and classification
Most of the aircraft engine, reciprocating or turbine, in need of assistance during the starting process. Therefore, the tool is called the starter. Starter is an electromechanical gained from the development of a large amount of mechanical energy that can be applied to an engine, causing the engine to spin. Reciprocating engines require only played with relatively slow rotational speed until the engine start and spinning by itself. Once reciprocating engine on start and produce a flame, the starter is removed and has no further function until the next start. In the case of turbine engine, the starter must rotate the engine until the speed that provides enough air flow into the engine to be mixed with fuel and then burned. Then, the starter must continue to help accelerate the engine until it reaches the engine rotational speed. Starter turbine engine has a critical role in the process of starting the engine. If the starter rotate the turbine engine until the engine does not reach the speed of rotation itself, the start will not be successful. There are only a few types or methods used to rotate the engine. Most all reciprocating engines use some form of electric motors geared to the engine. Modern turbine engine using electric motor starter / generator (electric motors and a generator in the same house), and air turbine starters. Air turbine starter is driven by compressed air through a turbine wheel which is mechanically linked via reduction gears to one of several engine compressor shaft, generally on the highest presure compressor.
Reciprocating Engine Starting System
In the early stages of aircraft development, a relatively reciprocating engine at the start by turning the propeller through a rotating part by hand. Difficult experience often occurs when starting in cold weather when the oil temperature is near freezing. In addition, the magneto system also often sends a weak spark at the speed of rotation were very weak. Therefore, it is often compensated by providing an equipment that can produce hot spark in the ignition system equipment is composed as follows: booster coil, induction vibrator, or impulse coupling.
Some aircraft with the low power using a hand crank propeller, or propping for starting during operation. General instructions for starting the process this type of aircraft, can follow the instructions in the Aviation Maintenance Technician - General Handbook, Chapter 11, Safety, Ground Operation, and Servicing. Through the development of reciprocating aircraft engine from starting the initial use of the system up to now, a number of starter system has been used. Most reciprocating engine starter is cranking electric direct type. Just a little older aircraft models equipped with inertia starter.Sehingga there is little briefed sarting system of this type.
inertia Starter
There are three general types of inertia starters: hand, electric, and a combination of hand and electric. Operation of all types rely on kinetic energy which is provided on a fly wheel is rotated rapidly to perform cranking (playback). Kinetic energy is the energy stored by a body that is free to move, which may move along a straight line or spinning action.
In the inertia starter, the energy stored energy slowly during the charging process with a manual hand crank or electric through a small motor. Flywheel and the ability to move gear at an electric hand combination inertia starter. electric circuits for an inertia starter proved that During the charging process the energy of the starter, all parts contained therein, one of which flywheel, also move. After starter stuffed full of energy, then connected to the engine crank shaft through a cable pulled manually or with a meshing solenoid actuated electric. When the starter is connected, the energy stored in the flywheel is then transferred to the engine via a series of reduction gear and a torque overload release clutch
Figure 3 operating procedures in conducting aircraft battery recharging
Engine Starting
How do mennghidupkan Engine ?? certainly not difficult, as well as with the engine, just turn the starter (electric starter) that will drive the piston, causing a suction and compressed air, with the Igniter is working, at the same time the right foot slightly on the gas pedal to give inducement fuel enough, so there burning until the IDLE.
Similarly Starting for various types of ENGINE is generally the same basic and not difficult.There are three basic elements that cause the burning process is no air (oxygen), no fuel (Aviation Fuel) and there was a fire (Igniter). How is the third essential element is arranged so that it can occur that cause complete combustion engines can live (running).We know that the engine in flight (running) get a supply of air from the compressor rotating. So what if its engine dead, from which the air supply in order to turn the engine ??? ...Well ... this is where the beginning to be able to turn on the engine (Engine starting), its mean we need a tool to rotate the compressor so that no air supply. Two other elements such as fire / Igniter've stayed lit standby power "Igniter ON". Similarly, the fuel / jet fuel stayed stir Throttle "Fuel Shut-Off Valve Open" means the fuel ready to be streamed from the 'Fuel tanks' through 'Fuel flow regulator' heading 'Fuel Nozzle' are ready to be sprayed into the combustion chamber (Combustion Chamber).We return to the air element is needed for the combustion process. The air element can be provided if Compressor SPINNING, how to rotate the Compressor ???
From the pictures we can see that the compressor is required to play the pressurized air source (High Pressure Water Source) which can be obtained from;
1). External ground supply2). APU (Auxiliary Power Unit)3). Cross-feed from a running engine4). High Pressure Water Tank (on Test Cell)
After the pressurized air provided about 50 psi (minimum air pressure that, depending on the type of engine), pressure air are supplied through the Turbine Air STARTER to move Accessory Gear Box which will then drive the Horizontal Drive Shaft and in the Transfer Gear Box, round horizontal Drive Shaft is then transferred into Radial Drive Shaft. Shaft is what ultimately directly drive the HP compressor (N2 shaft). Here is the beginning of the process of Starting. After HP Compressor rotates, the air (Mass Airflow) already flowing, sucked and compressed, then did Igninter 'ON'dan Fuel Shut-off Valve' OPEN 'and become involved in the process of combustion in Space Fuel (Combustion Chamber). Beginning the process of this combustion causes the engine start spinning or acceleration occurs characterized by increased N2 / N1 rpm and EGT, then this is described with LIGHT-UP. Until it reaches a specific round which the engine is already rotating itself without the help of a round of STARTER (Starter Cut-Off). Then this condition is called 'Selft Sustaining Speed'. And then there IDLE.IDLE condition this is the end of the 'Engine Starting'.
Figure 4 operating procedures in conducting aircraft battery recharging
Figure 5 how to make a battery recharging aircraft
ELECTRICAL DC
electrical DCDC Power Source
DC power source is a battery on the aircraft. Battery used on the aircraft at the time of engine start at the time of emergency as a DC power source and as the excitation source for starting the APU. If the battery when not in use will dicharger by bettery battery charger attached. Battery used is the type of NiCad (Nickel Cadmium Battery). On the Boeing 737NG aircraft consists of 3 TRU and 2 battery.
Systems DC Power Output
DC electricity is generally provided by self-exciting generator containing electromagnetic, wherein the power generated by the commutator which regulates the output voltage of 28VDC. AC power is usually at a voltage of 115V phase, generated by the alternator, generally within a three-phase system and the frequency of 400Hz.
How it works and Distribution System
For the distribution of electricity, air wears a bus system that connects the power source to the load. Various DC bus contained on Boeing 737-800 planes1. 28VDC bus, the bus is connected to the transformer2. 28VDC battery bus, the bus is connected to the transformer then a normal condition, and the battery in the alternative conditions.3. Stanby (STBY) bus, standby bus is a bus that would still have the power source in case of emergency. STBY obtain 115 VAC power source of 28 VDC static inverter while STBY obtain electricity from the battery.
Figure 7 water heater carried by the aircraft when it airs
GENERATOR AIRCRAFT
In B737NG aircraft AC power source is generated from three generators, two pieces of the engine (engine 1 and engine 2) and 1 generator that contained in the APU (auxiliary power unit). generator on the engine generates electricity from round the engine itself, the electricity that is needed by air amounted to 115VAC with a frequency of 400Hz resultant dri generator, but because Rpm engine that turn a generator is not always stable, then mounted was a contraption called CSD (constan speed drive) where that tool serves to control the generator to always constan round, on B737NG generator and CSD have been integrated into the IDG (intergrated drive generators), whereas for the previous series aircraft B737 clasic generator and CSD still separated. while at APU there CSD, why? because the APU generator rotates constantly ill as engine fickle, because there never an idle APU power or full power. in addition there is one more tool generator that produces AC power source is static inverter where it serves to change the DC voltage from the battery into AC voltage. but the static inverter is only used in an emergency, in other words, although the plane in an emergency air system that requires an AC power source can work.
Generator
Generator contained in the Boeing 737NG there are 3 generators, namely:1. 2 pieces generator on the engine (engine 1 and engine 2)2. 1 piece generator on the APU (Auxiliary Power Unit)
function Generator
The function of the generator is to produce a power source on the aircraft. Electricity generated on the aircraft is 115VAC and 28VDC. To transform into a 28VDC 115VAC using a tool called TRU (Transformer Power Unit) in which there are 2 parts of the transformer and rectifier. The function of the transformer to lower the voltage of 115VAC into 28VAC while the rectifier works to transform into a 28VAC voltage 28VDC.
How it Works Generator
The workings of the generator on the aircraft is to transform electrical energy into mechanical energy by using magnetic induction in the air generator, ie the magnet and the coil of wire conductors. In each engine must have contained one piece generator so if there are two engines there are two generators and therefore the number of generator depends on the number of engines. Turnover on the generator is not always stable therefore the generator was installed with a device called CSD (Constan Speed Drive) where the unit is used to control / maintain stable rotation generator errands. While at APU is not using a tool called CSD is because the velocity of the APU itself is constant / stable.
The main function of aircraft electrical systems is to produce, manage and distribute electrical power throughout the aircraft. Aircraft electrical power systems used to operate (a) aircraft flight instruments, (b) the important systems like anti-icing etc and (c) passenger services. Important power is the power that the aircraft should be able to resume safe operations. Passenger services of electricity is the power used for lighting the cabin, the operation of entertainment systems and food preparation.
There are several different resources on the aircraft for aircraft electric power system. The resources include: engine driven AC generator, auxiliary power units (APU), external power and ram air turbine.
Aircraft electrical components operating at different voltages both AC and DC. However, most of the air system uses 115 volts (V) AC at 400 hertz (Hz) or 28 volts DC. 26 volt AC is also used in some aircraft for the purpose of lighting. DC electricity is generally provided by the "self-exciting" containing electromagnetic generator, in which the power generated by the commutator which regulates the output voltage of 28 volts DC. AC power, typically at a voltage of 115 V phase, generated by the alternator, generally within a three-phase system and at a frequency of 400 Hz.
WHY AIRCRAFT POWER 115 V AC 400 Hz 3phase?
In general the electrical system / electricity in the air as well as home electrical systems is no source of electricity, distribution systems, and load. the power source can be divided into 2 kinds of AC (alternating current) and DC (direct current)
Generator on the engine generates electricity from its own engine speed.electric air required for 115V AC with a frequency of 400Hz 3 Phase resultant dri generator ,,, the question is why should the frequency of 400 Hz AC 115v 3 Phase?Due to take into smaller and more efficient if the transformer high frekueensi in its use ,, why not just use all frequencies above 400Hz or 1000Hz ??Can imagine jiga d frequencies above 400Hz -1000hz bad effects for humans and if the audio frequency of 1000 hz until then his voice sounded ,,,If the 115 V it in dapet where ??It was in dapet from the calculation of the frequency = rpm x angle
60Example: f = 8000 x 3 = 400 Hz
60
Back to the ancient use of electricity is not wearing 110 v 115 v instead ... and also 400 Hz was obtained from f = 1 / T. Initially the frequency of 360 Hz instead of 400, but seen from an angle of 360 ° / 360 clock. experiments performed by reducing and increasing the frequency but the result is an error, so it can be concluded that the most stable frequency of 400 Hz and up to now used.
Figure 12 inverter generator tool for generating aircraft with a frequency of 400 Hz
"Electrical system" used in the aircraft means the parts of the aircraft that generate, distribute and use electrical energy, including supporting equipment. The electrical power system consists of AC and DC Power Electrical Power Generation. AC Electrical Power, the generator is the main source of power for the main AC bus and the entire power system. The generator is rotated by the engine and the generator is rotated by the auxiliary power unit (APU). External power, supplied via an external power source air / Ground Power Unit (GPU).The transformer provides power to the AC bus by lowering the power supply voltage AC. A static inverter changes the DC power from the battery into AC power. Each machine is equipped with the CSD, the generator is rotated directly by the CSD with the nearly constant rotational speed for the generator, regardless of the actual engine RPM. KerjaCSD way similar to an automatic transmission car. Each generator result in a three-phase, 115 volt and 400 cps alternating current to a maximum load of 40 KVA or 111 Ampere.DC Electric Power, A 28volt DC battery supply for starting the APU. Transformer-rectifier (TR) unit provides DC power by converting AC power into DC power. Most terrestrial power systems using alternating current (AC) rather than direct current (DC), mainly because the transformer can only be used on AC power. An AC distribution systems usually contain one or more AC generator (technically known as alternators in aircraft systems).Aircraft electrical system consists of:
AC power generation
Conversion of AC to DC power
Electric control devices
Power distribution
Figure schematic electrical system
Figure 13 Generator aircraft instrument
Figure 14 aircraft hangar
X . II Gas Turbine Engine
The gas turbine is a heat engine combustion, the process works as motor fuel is inhaled atmospheric air entering a compressor and compressed, then the compressed air enter the combustion chamber and is used for the combustion process, in order to obtain a large heat energy. The heat energy is expanded in the turbine and produce mechanical energy to the shaft. Remaining gas turbine combustion outward thrust into energy (gas turbine aircraft). So it is clear that the gas turbine is a machine that can convert heat energy into mechanical energy or thrust. Equation gas turbine with a motor fuel is in the combustion process that occurs in the machine itself. Besides, the working process is the same, namely: suction, compression, combustion, expansion and exhaust. The difference lies in the construction. Motor fuel mostly worked back and forth motion (reciprocating) while the gas turbine is a machine rotation, motor fuel work process stages (intermittent), for the gas turbine exhaust gas is continuous and the internal combustion engine had not been used for the thrust.The gas turbine works continuously not betahap, all processes, namely the suction, compression, combustion and exhaust are taking place simultaneously. In motor fuel which a gradual process that is called a step, that step suction, compression, combustion, expansion and exhaust step. Between steps one and more interdependent and working alternately. In the process of expansion of the gas turbine, a change in the energy of heat energy form the mechanical energy of the turbine shaft rotation, whereas in motor fuel in the expansion step changes of heat energy into mechanical energy back and forth motion of the piston. Under these conditions, the gas turbine works much smoother and not a lot of vibration.
Gas turbines used for propulsion or jet engines, automotive engines, power generation or propulsion power equipment industries such as driving a compressor or a pump. The power generated from the gas turbine for power generation 250,000 HP to 5 HP turbocharger on the engine. The advantages of the gas turbine engine is a lightweight and small size but can produce great power. An example is the gas turbines used for propulsion of small lisitrik generator. These generators are widely used to anticipate peak load network, so it can replace the function in case of power outages. Office buildings, hospitals, universities, corporations and others, many who use this type of generator. Compared with the use of propulsion diesel generator, the gas turbine propulsion size becomes smaller, thus saving space and easy to move.Airplanes need a machine with specific requirements ie machines with great power to thrust, but it is light and in terms of size should be small. For these reasons, the use of gas turbines in aircraft is the right choice, and not be substituted for other engine types. In the industrial and power generation gas turbine is very advantageous because the machine is installed, its operation is not complicated, and does not require a large room.
History ofThe development of gas turbines as one of the driving engine had already spent a long time yet. Beginning
the 19th century Charles Curtis filed a patent for a gas turbine that
is on June 24, 1985. Later in 1903 Aegedius Elling managed to make a gas
turbine engine with 11 HP power. In 1939 the Swiss firm Brown Boverei Company succeeded in making gas turbines for power plants with a power of 4,000 kW. For the aircraft industry was developed in the 1930s. Hans von Ohains (Germany) successfully run a gas turbine in March
1937. Frank whittles in April 1937 was also successfully run a gas
turbine engine.The
first airplane that flew by the gas turbine engine is a jet engine
Germany on 27 August 1939, while the British in 1941. The use of gas
turbines for the first locomotive in 1941 in Switzerland, and car
engines in 1950 in England. Development continued up to the modern era, machinery advanced fighter jet has been successfully created. Efficiency also continue to be improved so that the gas turbine today become one of the main propulsion engine.
Basic Gas Turbine Work
The gas turbine is one of the aircraft gas turbine engines, as for the way it works is as follows. The starter motor is turned on, the compressor spins and began to work sucking surrounding air, the air is then compressed. The first phase of compressed air at first on low-pressure compressor, high-pressure compressor passed. Compressed air then enter the combustion chamber, mixing with the fuel that has been sprayed. The fuel-air mixture of compressed and then ignited and the combustion process occurs. Gas combustion process results expand on the turbine, there is a change of heat energy into rotation energy of the turbine shaft, the majority of combustion gases into the thrust. After giving the rest of the driving force, the gases of combustion to the outside through the exhaust saluaran. Of the working process of the airplane gas turbine, the turbine generated power is used to drive the compressor, generate thrust, and move other auxiliary equipment.Industrial gas turbines used and how it works with gas turbine aircraft. The starter motor is turned on to rotate the compressor, fresh air sucked and compressed. Then the compressed air to the temperature and pressure are quite high (2000C, 6 bar) flow into the combustion chamber mixes with fuel. Compressed air mixture fuel then ignited and the process of combustion, combustion gas temperature rise dramatically. Gas combustion at high temperatures (6 bar, 7500C) expansion in the turbine, resulting in a change of energy, of heat energy into rotation energy of the turbine shaft. The combustion gases after expansion in the turbine, then came out as the former gas. Furthermore, the gas turbine working with the turbine shaft rotation, is as a source of energy driving the compressor and electrical generator.From the description of the workings of the gas turbine above, there can be mentioned components of gas turbine engines are important, namely the compressor, combustor, and turbine. Thus, power
Thus, the generated power turbines are not only move the load, the electric generator, but also have to drive the compressor.
Gas turbine fuelFuel for gas turbines must meet certain requirements before being used in the combustion process. The requirements that the fuel has a high ash content not. The grounds, fuel that has a high ash content, in the combustion process resulting combustion gas containing ash particles harsh and corrosive. Gas combustion with these characteristics, will hit and damage the blades of the turbine at the time of the expansion process at high temperatures.With the above mentioned requirements, a fuel that meets the requirements is a liquid fuel and gas. Liquid fuels and gas tend to have low ash content when compared to solid fuel, making it safer to use as fuel for gas turbines.Fuel used gas turbine aircraft, thirst dipenui requirements are more stringent, it is because it concerns the safety and success during gas turbine operation. The requirements are:1. The calorific value per unit weight of fuel must be high.With the little amount of fuel and light with high but the value kalornya very beneficial because it reduces the overall weight of aircraft.2. Ability to evaporate (volatility) of the fuel is not too high, because of the high price of fuel volatility will easily evaporate, especially at high altitudes. It would be dangerous because the fuel becomes flammable. In addition, the fuel lines can easily become clogged because fuel vapors.3. The purity and stability of the fuel has to be assured, that the fuel does not easily precipitate, do not contain substances such as water, dust, and sulfur. The content of these substances if too many would be very dangerous in the combustion process. Especially for sulfur, it will be corrosive substance once the turbine blade material.4. Flash point and flash point is not too low, so the storage is more secure.5. gradenya must be high, the fuel must have good quality, do not contain harmful elements such as dyes and tretaetyl leadWith the characteristics of the fuel for the gas turbine aircraft as mentioned above, it appears that the fuel is high quality, to guarantee the safety factor is high on gas turbine operation during flight. The failure of the operation have fatal consequences, namely gas turbines dead, aircraft lose thrust, this condition can be ascertained aircraft will fall. Aircraft fuel used is of the type of gasoline and kerosene or a mixture of both, of course, already purified from harmful elements. For example, the standards issued by the American Society for tinting Material Specification (ASTM) D-1655 series, the Jet A, Jet A1, Jet B. Notation A, A, and B differentiate its freezing point.
The burning processwe can be seen from the construction component of the combustion chamber, where are reproduced by the combustion process is as follows:The combustion process of the gas turbine is similar to a diesel engine combustion, ie the combustion process at a constant pressure. The process is as follows, compressed air from the compressor enter the combustion chamber, the air is divided into two, namely primary air entering primary channel, is a place with a nozzle and compressed air through the secondary outer casing of the combustion chamber. Primary air enter the combustion chamber past the swirler, so that the flow is spinning. Fuel is then sprayed from the nozzle to the primary zone,after the two met, there is mixing. Rotating the primary air flow will help the mixing process, it causes the mixture more homogeneous, more complete combustion. fuel nozzle air swirel primary zone secondary zone mixing zone and a secondary air flow cooling the primary air flow compressed air compressor to the combustion gas turbine secondary air entering through holes in the outer casing of the combustion chamber will assist the combustion process in the secondary zone. Thus, the secondary zone would enhance the combustion of the primary zone. Besides, to assist the combustion process in the secondary zone, the secondary air also helps in cooling the combustion chamber. The combustion chamber must be cooled, because of the combustion process generated high temperatures that destroy material combustion chamber. Thus, by way of a secondary air cooling, the temperature of the combustion chamber becomes controlled and do not exceed allowable.
mixing (dillute zone), is a mixing zone with high temperature combustion gas with secondary air portion. The function of the secondary air in the zone it was cool the high-temperature combustion gas into a safe temperature when the blades of the turbine when the combustion gases to expand. In addition, secondary air will also increase the mass of combustion gases before entering the turbine, with a mass greater potential energy of the combustion gas also increases. If W is the kinetic kinetic energy of combustion gases with velocity V, the mass before plus secondary air is m1, the kinetic energy is as follows:From the above description, looked combustion in gas turbines requires air excess, typically up to 30% of normal conditions for the combustion process with a certain amount of fuel. These conditions have been the opposite, if the combustion air is too abundant (over 30%), the air actually cools the combustion process and die, because a lot of wasted heat to the outside through the former gas mixed with the cold air secondary. By the same logic, if the amount of air is less than normal, ie overheating, material combustion chamber and the blades of the turbine work beyond his strength and the combustion chamber can rupture, this means that the gas turbine stops working or the combustion process stalled.
X . III Auxiliary Power Unit (APU) Aircraft
Auxiliary Power Unit (APU) is a device on a vehicle that provide energy for functions other than propulsion. APU is usually installed on large aircraft, as well as some large land vehicles. The aircraft APU generally produces 115V at 400 Hz (instead of 50/60 Hz power supply), to run the aircraft's electrical system, but it can produce a 28V DC. APU is also installed on naval ships. APU can provide power through a system of single or 3-phase.
The main purpose of the aircraft APU is to provide power for starting the main engines for flight. The turbine engine must be accelerated to high rotational speeds to provide sufficient air compression during engine operation. Jet engines are smaller usually distart by an electric motor, while the larger engine usually started by the motor air turbine engine . before move, APU start, generally by batteries or hydraulic accumulators. After moving APU, APU provides power (electrical, pneumatic, or hydraulic, depending on the design) to start the main engine plane.APU on Commercial AircraftFunctionThe main purpose of the aircraft APU is to provide power for starting the main engines for flight. The turbine engine must be accelerated to high rotational speeds to provide sufficient air compression during engine operation. Jet engine smaller usually starting by an electric motor, while the larger engines typically distarting by air turbine motors. Before moving engine, APU generally to starting by batteries or hydraulic accumulators. After moving APU, APU provides power (electrical, pneumatic, or hydraulic, depending on the design) to start the main engine plane.APU is also used to run other air accessories when the engine died. This allows the cabin to be comfortable when passengers board the plane before the engine is turned on. Electricity used to run during system preflight check. Some APU is also connected to a hydraulic pump, allowing the crew to operate the equipment hydraulic (such as Flight Control or flaps) before the engine starts up. This function can also be used, in some aircraft, as a backup during the flight or hydraulic system is damaged.APIC APS3200 APU for the Airbus A318, A319, A320, and A321
Aircraft with APU can also use electric and pneumatic power from ground equipment when the APU is damaged or unusable.APU is installed on the aircraft extended-range twin-engine operations (ETOPS), which is a safety critical condition, because the APU to provide backup power and air pressure in the engine is dead or broken main generator. While each APU may not startable in flight, APUETOPS-compliant to be flight-startable at altitudes up to for service ceiling. the new application pre determined starting up to a height 43.000 feet (13,000 m) from cold-soak conditions as like as Hamilton Sundstrand APS5000 for the Boeing 787 Dreamliner. if APU or electricity generators are not available, aircraft are not allowed to ETOPS flights and are required to take these non - ETOPS.
APU generates electricity of 400 Hz is smaller and lighter than the 50/60 Hz counterpart, but the price is more expensive; weakness is the system, high frequency cause the voltage to decrease.
HistoryEngine 2-stroke Riedel pioneer APU is used as an example, to turn on the central shaft jet engine Junkers Jumo 004 aircraft in World War II.Intake diverter on Jumo 004 engine that was in APU Riedel, complete with D-shaped pull handle on the center diverter.
During World War I, British Coastal class blimp, one satudari several types of aircraft operated by the Royal Navy, brought an auxiliary engine 1.75 HP (1:30 kW) ABC. Engine is powered by a generator for the radio transmitter and in an emergency can be used hydroelectric additional blower (continue to supply air pressure needed to keep the airships' Ballonet remain inflated, and keep the structure gasbag). In normal flight, it is obtained from propeller slipstream through the water scoop.One country that was first used on military aircraft APU is Britain, in World War 1, the Supermarine Nighthawk, anti-Zeppelin fighter. Using a small ABC engine, which is produced from the generator to highlight the on-board.
American military aircraft APU is the first time using USAF Douglas Globemaster II. Boeing 727 in 1963 is a commercial jet for the first time features a gas turbine APU, which allows it to operate at smaller airports. Independent from onshore facilities. APU can be seen in many airline modem through the exhaust pipe at the tail of the aircraft.
Type gas turbine APU for commercial aircraft is composed of three main parts:
Power SectionPower section is part of the gas generator engine and produce all the APU power shaft.
Load Compressor SectionLoad compressor is generally a shaft-mounted compressor that produces pneumatic air, while some few extract APU bleed air generated by the compressor power section. There are two means of propulsion, ie Inlet guide vanes which regulate the flow of air flowing into the compressor load and surge control valve that stabilizes the operation of the turbo engine.
gearbox sectionGearbox main shaft transfers power from the engine to the oil-cooled generator for electricity. Through the gearbox, power is also transferred to engine accessories such as fuel control unit, module lubrication and cooling fan. In addition, there is also a starter motor which is connected through a gear train to perform the initial function of APU. APU designs use a combination starter / generator to power the APU and power plants to reduce complexity.
On the Boeing 787 aircraft that require a large power supply, APU serves only provide power to the aircraft. The absence of a pneumatic system simplifies the design, but the magnitude of the electrical needs require a large generator.
ManufactureThere are two major companies competing in the market of air APU is United Technologies Corporation (through its subsidiary Pratt & Whitney Canada, Hamilton Sundstrand and Goodrich Corporation), and the second is Honeywell International Inc.
Military aircraftSmall-type military aircraft, such as the type of fighter and attack type, features the auxiliary power system different to that used by commercial aircraft. The function of engine starting and electrical and hydraulic power supply is divided into two units, namely, jet fuel starter and emergency power units.
Jet Fuel StarterJet Fuel Starter (JFS) is a small turboshaft engine that is designed to encourage and accelerate the jet engine RPM. Bleed air supply to the motor starter APU. JFS output shaft mechanically connected to the engine. After that JFS began to move, the engine moves; unlike the APU, the starter is not designed to produce burning electricity when the engine died.
JFS uses free power turbine, the method of connecting to the engine depending on the design of the aircraft. In the single-engine aircraft such as the A-7Corsair II and F-16 Fighting Falcon, JFS power section is always connected to the main engine through the engine accessory gearbox. Unlike the twin-engine aircraft F-15 Eagle consisting of a single JFS and JFS power section is connected through a central gearbox that can be combined into a single engine.
Emergency Power UnitEmergency Hydraulic and Electric power generated by the types of gas turbine engines are different. Unlike gas turbines in general, emergency power units do not have a gas compressor or ignitor, and use a combination of hydrazine and water, rather than jet fuel. When hydrazine and mixed water is released and passed all of iridium, spontaneously fused, generating hot gases that drive the turbine. Power generated is passed through the gearbox and then move the electric generator and hydraulic pump. Hydrazine contains seal, nitrogen-charged accumulator. By the time the system is ready, hydrazine is released whenever the engine-driven generator is offline, or if the entire engine-driven hydraulic pump is damaged.
X . IIII the electrical system in the aircraft
But in general the electrical system in the same plane with the electrical system in general. Consisting of three things: the power source (electrical power source), the distribution system and load (load).
1. The power source air
Of its kind, the power source can be divided into two, namely the AC power source and a DC power source.
AC power source (AC power source)
For B737-800 aircraft, as shown in the schematic above, there are three AC power source. Ie 2 generator mounted engine and one generator installed at APU.
This generator is driven by the rotation of the engine or APU, so it can generate electricity.
Especially for the generator in the engine, it rotates in a constant speed, the engine speed does not follow that change needs to be installed a system called CSD (constant speed drive).For B737-800 aircraft between CSD and generator are combined into one system called the IDG (integrated drive generator). As for the B737 Classic, still separated between CSD and generator.
For APU generator at CSD isn't not, because the constant rotation APU.
AC power generated by the air generator is 115 VAC to 400 Hz. Different yes with electricity in our homes is 220 VAC 60 Hz.
Aside from the generator, there is one more source of AC power in the air, the static inverter. Static inverter function to change the DC power from the battery into AC power. Static inverter is used only during emergency conditions. When all existing generators are not able to provide the AC power source. Thus, in emergency conditions, air systems that require AC power sources can still work.
DC power source (DC power source)
DC power source in the plane consists of transformers and batteries. Depending on the type of aircraft, the number of transformers and batteries are installed will vary. For B737-800 aircraft, installed three transformers and two batteries.
Transformer (TR) function to convert AC power into DC power. It opposite to that carried out by the static inverter. The magnitude of the DC voltage is 28 VDC to air.
Batteries contained in the air serves to generate DC electricity with a voltage of 28 VDC. The battery used is the type of Nickel Cadmium (NiCd) so that it can be recharged (rechargeable). When the battery is not in use, the battery will be charged by a battery charger attached.
In use, air batteries used in some circumstances:
As the excitation source for starting the APU.
When emergency condition as a DC power source.
DC power is also being revamped static inverter into AC electricity.
2. The best electricity distribution system
For power distribution, air wears a bus system that connects the power source to the load.
Wide bus contained in B737-800 aircraft are:
AC bus Transfer (XFR), consisting of one bus transfers and bus transfers 2. In normal conditions, the transfer bus 1 is connected to the generator 1 and the transfer bus 2 is connected to the generator 2. While the condition darura t, such as generator 1 is not functioning, then 1 bus transfer to connect with APU or connected to the generator 2 via the transfer bus 2.
Main AC bus, consisting of the main bus AC 1 and AC 2 play bus.
Galley bus, for electrical purposes in aircraft galleys. The number depends on the number of galleys installed on the plane.
28 VDC bus, the bus is connected to the transformer.
28 VDC battery bus, the bus is connected to the transformer in normal conditions, and the battery in the alternative conditions.
Standby (STBY) bus, standby bus is a bus that would still have the power source in case of emergency. STBY obtain 115 VAC power source of 28 VDC static inverter while STBY obtain electricity from the battery.
3. Load (Load)
The burden on the air connected to the electrical distribution system air through the bus. Depending on power source required, and also its role, the load can be connected on a different bus.
For the best system that still must function in an emergency, will be connected with the standby bus.
While the aircraft systems are "less important" will be connected to the AC Main Bus.
One to note, the attached load should not exceed the capacity of the existing power source. Calculation of the capacity of the power source and the load, contained in document ELA.
Tidak ada komentar:
Posting Komentar