Title of Invention

AN IMPROVED JET FUEL STARTER FOR A GAS TURBINE ENGINE

Abstract

There is a longstanding need in the aviation industry to provide systems for "inflight starting" of the main engine in case of main engine flame out and designs for containment of disc bursts in JFS to prevent consequential damage of the main engine and air frame. There are no known starters, which can start the main engine of an aircraft during "inflight" conditions. This invention relates to an improved Jet Fuel Starter (JFS) for a Gas Turbine Engine to provide power 60 to 115 kW to start a main engine of an aircraft in the static and inflight conditions upto 6 km altitude with maximum power to weight ratio. Yet another object of the invention is to provide a containment system in the JFS to prevent consequential damage to the main engine and airframe in the event of JFS turbine disc bursts. Thus in accordance with this invention the JFS comprises a starter electric motor, plurality of compressors with diffuser, combustion chamber, plurality of turbines, containment ring, reduction gear box, fuel system, fuel dispensing and control system, lubrication system and ignition system. Further this JFS is capable of applications in gas turbine based locomotives, marine engines and other land based power generation systems.

Full Text

This invention relates to an improved Jet Fuel Starter (JFS) for a Gas Turbine Engine to provide power to start a main engine of an aircraft in the static and Inflight conditions upto 6 km altitude. Further the JFS of this invention is capable of applications in gas turbine based locomotives, marine engines and other land based power generation systems. Background of the Invention The main engine of an aircraft is started using an external power source such as air turbine starters, JFS, cartridge starters and electric motors. There are no known starters, which can start the main engine of an aircraft during "inflight" conditions. Starting of the main engine during "inflight" conditions is necessary in the event of a main engine flameout thereby providing a safety backup to the aircraft. Conventional method of starting the main engine during "inflight" conditions is by exploiting windmilling of the main engine followed by supply of fuel and Ignition. Existing starters as reported have restricted capability in that they can start the main engine only on ground "static" conditions upto an altitude of 3 km. During "inflight" conditions, the main engine is normally provided with means for containment of disc burst to prevent consequential damage to the aircraft. In situations when JFS is required to start the main engine during "Inflight" conditions, It is desirable to provide a containment system in the JFS. There are no prior art that discloses any designs for containment ring suitable for the JFS. US Patent 6290455 discloses an Improved containment structure for use with turbo machinery, such as turbo fan engines. A casing is provided with at least one impact resistance section of a thickness sufficient to resist being pierced upon impact by a blade. The impact resistance section has a smoothly contoured thickness along its axial length and is free from features likely to cause a local failure in the event of Impact by a blade released from a rotating disc. The limitation of this system is that it is not designed to contain disc bursts of the engine. us Patent 6182531 discloses a containment vessel for retaining projected high energy material fragments produced during a catastrophic failure of a high energy rotary mechanism, such as a composite flywheel. This design is not applicable to systems such as jet fuel starters and their like. US Patent 6059523 addresses a multiple layer blade burst control system for use in turbine engines. The system utilises a first inner containment ring and a second containment ring separated by a layer of thin ductile material. The inner containment ring and outer containment ring are each mounted to an engine housing by the use of a plurality of supporting legs. This design is meant for containment of a blade and does not teach methods for containment of disc bursts. There is a longstanding need in the aviation industry to provide systems for "inflight starting" of the main engine in case of main engine flame out and designs for containment of disc bursts in JFS to prevent consequential damage of the main engine and airframe. Summary of the Invention This invention relates to an improved jet fuel starter for a gas turbine engine to provide power to start a main engine of an aircraft in the static and inflight conditions upto 6 km altitude. Further the JFS of this invention may be used in gas turbine based locomotives, marine engines and other land based power generation systems. This improved jet fuel starter is compared with similar JFS available in other countries like NOELLE 60 of 45 KW power from Microturbo Ltd., France used in Mirage III, IV & V; JFS 190-1 of 123.7 kW power from Allied Signal. USA used in MIRAGE 2000; LUCAS CT 2106 of 64.8 kW power from Lucas Aerospace, UK; TC-21 of 60 kW power from Russia used in MiG-27 and GTDE-117 of 75 kW power from Russia used in MiG-29. All these starters have no in-flight start capability upto 6 km altitude. The main object of the invention Is to provide starting povi/er to an aircraft engine under static conditions on ground upto 6 km altitude with maximum power to weight ratio. Another object of the present invention is to provide starting power to the main engine during "inflight" conditions upto 6 km altitude in the event of main engine flameout. Yet another object of the invention is to develop power outputs from JFS of 60 to 115 kW. Yet another object of the invention is to provide a containment system in the JFS to prevent consequential damage to the main engine and airframe in the event of JFS turbine disc bursts. Yet another object of the invention is to provide a JFS that is capable of functioning with alternate fueis for non-aviation based application. Statement of Invention An improved jet fuel starter for a gas turbine engine to provide power to start the main gas turbine engine of an aircraft in static and in-flight conditions up to 6 km altitude and has improved systems comprising of an air intake module consisting of a starter electric motor, front gear box, fuel pump, oil pump and intake shroud (1); a gas generator module consisting of plurality of compressors with diffuser, plurality of flow combustion chamber with fuel dispensing system, ignition system and plurality of gas generator turbine (2); a power turbine module comprising of plurality of free power turbine, the output gearbox and exhaust volute (3); an output module (4); a containment system positioned over the outer casing of combustion chamber (5); a free power turbine rotor (6); a free power turbine shaft (7); a gas generator turbine rotor (8) and a gas generator turbine shaft (9). Preamble The Improved jet fuel starter for a gas turbine engine of 60 to 115 kW is to provide power to start a main gas turbine engine of an aircraft in static and in¬flight conditions up to 6 km altitude. Detailed description of the Invention The invention with its advantages is now illustrated with non-limiting examples with the reference to the figures 1 to 5. Thus In accordance with this invention the JFS comprises a starter electric motor, plurality of compressors with diffuser, combustion chamber, plurality of turbines, containment ring, reduction gear box, fuel system, fuel dispensing and control system, lubrication system and ignition system. Fig 1& 2 represent the assembly of Jet Fuel Starter of the present invention. Part no. 1: air intake module comprising of a starter electric motor, front gear box, fuel pump, oil pump and intake shroud. Part no.2; gas generator module consisting of a centrifugal compressor, reverse flow combustion chamber with fuel burners and gas generator turbine (axial type). Part no.3: power turbine module comprising of free power turbine (axial type), the output geariiox and exhaust volute. Part no.4: output module. Part no.5: containment ring positioned over the outer casing of combustion Part no.6 Part no.7 Part no.8 Part no.9 chamber. free power turbine rotor, free power turbine shaft, gas generator turbine rotor, gas generator turbine shaft. Air intake module (part no. 1) is attached to the gas generator module (part no. 2). Air is sucked in by the centrifugal compressor of pressure ratio of about 3.5 through air intake duct. The air is compressed In the compressor to a high pressure and the air then flows to the combustion chamber, which is a component of gas generator module (part no. 2). Fuel is added in combustion chamber and combustion takes place in combustor and the temperature of the air rises. Hot gases from the combustor then pass through gas generator turbine (part no.8). Gas generator turbine extracts the work from the hot gases, sufficient to drive the compressor. The hot gases then pass through free power turbine (part no. 6). Here the turbine extracts the work from high-pressure hot gases and the power is transmitted to the main engine through reduction gearbox, which is housed in output module (part no. 4). The starter electric motor gets energised from aircraft's batteries on a start command, rotates the compressor and gas generator rotor. Simultaneously, fuel and ignition are supplied after which the engine lights up and begins to accelerate using the starter electric motor power assisted by the gas generator power. When the gas generator speed reaches around 20000 to 25000 rpm, the starter electric motor and the ignition get cut off. The gas generator turbine accelerates on its own power and reaches a speed of around 50500 rpm. Simultaneously, the free power turbine also starts to speed up to around 40,000 rpm. The free power generates the required power. A reduction gearbox is used to transmit the power to the starting system of the main engine of aircraft. The engine has a self-contained lubrication system, which draws lubrication oil from the oil tank of aircraft mounted accessory gearbox with a pressure pump driven by the engine to lubricate the bearings. The used oil flows by gravity to a collector tank from where it is pumped back to the aircraft mounted accessory gear box by a scavenge pump. The fuel control system cuts off the fuel supply and automatically stops the JFS when output shaft speed reaches around 9750 rpm at which the main engine reaches its self-sustaining speed. Effective functioning of the system is achieved with optimisation of the thermodynamic parameters based on the turbine inlet temperatures and pressure ratio of the compressor, selection of the ignition system and ensuring appropriate distribution of air into the zones of the primary, secondary and tertiary zones of the combustion chamber. Example 1 Testing of High Altitude Starting Capabiiity of JFS To establish the functioning of JFS at high altitude, JFS was tested under simulated altitude conditions in a high altitude test facility. Tests were conducted simulating conditions corresponding to 4 to 7.5 km altitude. The engine was instmmented to monitor the performance parameters such as gas generator speed, free power turbine speed, compressor exit pressure, compressor exit temperature, jet pipe pressure, jet pipe temperature, torque, fuel flow etc. Fig. 3 presents torque speed characteristics of improved JFS under simulated altitude conditions around 5 km. Fig. 4 presents torque speed characteristics of the improved JFS under simulated altitude conditions around 6 km. Figs. 3 and 4 illustrate that the improved JFS is capable of operating at high altitude conditions upto at least 6 km altitude. The improved JFS was also tested on ground at the following altitudes: a) Around Sea Level - static conditions b) Around 3 km altitude - static conditions. As mentioned in the eariier example, performance parameters were monitored. Fig. 5 presents the torque speed characteristics obtained during test at ground static conditions at an altitude of around 3 km. Example 2 Testing of Containment Ring The Containment ring was subjected to simulated tests at the Projectile Ingestion Test Bed where projectiles corresponding to one third disc segment were released with kinetic energy levels corresponding to maximum speed of around 40,000 rpm. The test results indicate that the containment ring has absorbed the kinetic energy and contained the projectile. The Improved JFS may be used for a wide range of aircrafts. It has further applications in gas turbine based locomotives, marine gas turbine engines etc. The applications of this improved JFS also extend to its use in starting land based power generation systems and driving an alternator to generate electric power. The improved JFS described in this invention has several advantages over the prior art. They include: 1) The capability of inflight starting in case of main engine flame out, thus providing additional safety features for tlie aircraft. 2) An additional safety provided by the containment ring providing protection to the main engine and the aircraft from damage in the event of turbine disc burst in JFS. 3) The capability to use diesel as alternate fuel making it economical for use for gas turbine based locomotives, marine engines and other land based power generation systems. We Claim 1. An improved jet fuel starter for a gas turbine engine to provide power to start the main gas turbine engine of an aircraft in static and in-fligfit conditions up to 6 km altitude and has improved systems comprising of an air intake module consisting of a starter electric motor, front gear box, fuel pump, oil pump and intake shroud (1); a gas generator module consisting of plurality of compressors with diffuser, plurality of flow combustion ciiamber with fuel dispensing system, ignition system and plurality of gas generator turbine (2); a power turbine module comprising of plurality of free power turbine, the output gearbox and exhaust volute (3); an output module (4); a containment system positioned over the outer casing of combustion chamber (5); a free power turbine rotor (6); a free power turbine shaft (7); a gas generator turbine rotor (8) and a gas generator turbine shaft (9). 2. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein it has power outputs of 60 to 115 kW. 3. An improved jet fuel starter for a gas turtaine engine as claimed in Claim 1 wherein the combustion chamber linked to the fuel dispensing and control system is designed to have a combustor, a fuel pumping system and an electronic control unit. 4. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein the combustor has ratio of combustor inlet area to exit area in the range 1.28 to 1.35, air mass flow distribution in the combustion chamber for swirier air mass flow from 6 to 8 %, primary air mass flow from 24 to 29 %, dilution air mass flow from 44 to 50 %, cooling air mass flow from 18 to 24 % and ratio of length of the combustion chamber to combustor width from 2.7 to 2.9. 5. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein the fuel pumping system comprises of a fuel pump consisting of a gear pump, pressure drop regulator, a jet pump, an enrichment valve and a stepper motor driven metering plate which meters the fuel through the metering orifice by changing the fuel flow metering area. 6. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein the fuel pump is capable of delivering of a very small fuel flow of about 0.4 lltre/min at light up and about 0.8 litre/min for gas generator rotor speed of around 50500 rpm with a reliable smooth acceleration and governing of the JFS from light up to maximum speed of 50500 rpm at altitude around 6 km. 7. An improved jet fuel starter for a gas turbine engine as claimed in Oaim 1 wherein the electronic control system drives the stepper motor of the fuel pumping system provides the required fuel flow metering area for all ranges of operating conditions of ambient temperature, gas generator speed and altitudes up to at least 6 km. 8. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein the combustion chamber linked to the fuel system, fuel dispensing and control system has combustion efficiency of 75-96% varying with altitude and fuel flow turn down ratio {ratio of maximum fuel flow at ISA SLS condition to minimum fuel flow at 7.6 Km altitude) of about 4 to 7. 9. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein JFS has gas generator turbine and free power turbine coupled to form a single turbine. 10. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein JFS has the radial turbine. 11. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein JFS has the axial compressor. 12. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein JFS has containment ring. 13. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein the containment ring is fabricated from materials selected from compositesKevlaras well as metal Inconel. i 14. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein the containment ring is located from outer ring to turbine shroud of JFS. 15. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein JFS has reverse flow combustion chamber. 16. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein the gear box is replaced with a multistage free power turbine to develop and transmit the power to the main engine. 17. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein the JFS drives an altemator to generate electric power. 18. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein a reduction gearbox is coupled with free power turbine to transmit the output power to the starting system of the main engine 19. An improved jet fuel starter for a gas turbine engine as claimed in Claim 1 wherein the jet fuel starter has a self-contained lubrication system which draws lubrication oil from the oil tank of aircraft mounted accessory gearbox. 20. An improved jet fuel starter for a gas turbine engine substantially as herein described with reference to accompanying drawings.

Documents:

0845-mas-2002 abstract duplicate.pdf

0845-mas-2002 abstract.pdf

0845-mas-2002 claims duplicate.pdf

0845-mas-2002 claims.pdf

0845-mas-2002 correspondence-others.pdf

0845-mas-2002 correspondence-po.pdf

0845-mas-2002 description (complete) duplicate.pdf

0845-mas-2002 description (complete).pdf

0845-mas-2002 description (provisional) duplicate.pdf

0845-mas-2002 description (provisional).pdf

0845-mas-2002 drawings (provisional) duplicate.pdf

0845-mas-2002 drawings (provisional).pdf

0845-mas-2002 drawings duplicate.pdf

0845-mas-2002 drawings.pdf

0845-mas-2002 form-1.pdf

0845-mas-2002 form-19.pdf

0845-mas-2002 form-3.pdf

0845-mas-2002 form-5.pdf