BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to gas turbine engines of the turbofan type, and specifically a turbofan engine that has an inner bypass duct and an outer bypass duct combined in the engine.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Turbofan (or bypass) engines are well known in the prior art, in which a fan is included in the compressor/combustor/turbine assembly to provide airflow around the compressor/combustor/turbine portion. This arrangement is disclosed in U.S. Pat. No. 5,692,372 issued on Dec. 2, 1997 to Whurr and shown in FIG. 25. This outer bypass is used in most commercial aircraft engines for the purpose of providing high power at takeoff and low noise during operation.
Gas turbine engines having a central bypass duct are also known in the prior art. U.S. Pat. No. 6,532,731 issued to Springer on Mar. 18, 2003 (shown in FIG. 26 and U.S. Pat. No. 6,151,882 issued to Cavanagh on Nov. 28, 2000 (shown in FIG. 27) show gas turbine engines having a bypass extending through the central portion of the engine, radially inward of the compressor/combustor/turbine portions.
It is an object of the present invention to provide for gas turbine engine to have a greater bypass flow without increasing the radial size of the engine by incorporating a central bypass in a gas turbine engine.
It is also an object of the present invention to improve the efficiency of the high pressure compressor of a gas turbine engine by replacing standard centrifugal compressor with a high efficiency axial compressor.
It is also an object of the present invention to provide for a higher volume combustor with a reduced axial length to shorten the engine.
It is also an object of the present invention to provide for the fan blades have a shorter radial length which will allow for stiffer and higher frequency blades, and allow the turbine engine to operate under faster revolutions and/or increasing the potential operating range of the engine.
It is also an object of the present invention to provide for noise reduction and cooling of the outer combustor wall by including an outer bypass to the inner bypass flow in which the bypass flow mix to reduce turbine exhaust noise.
It is also an object of the present invention to provide for several embodiments of a central bypass gas turbine engine in which the bypass fans blades are supported in the engine.
These and other objects of the present invention will be described below in the Detailed Description of the Present Invention.
BRIEF SUMMARY OF THE INVENTION
The present invention in a gas turbine engine with both a central and an outer bypass flow to produce a high mass flow through the bypass and a minimum cross-sectional area for the engine.
The present invention also shows a gas turbine engine having a central bypass duct with several arrangements of the bearing supports for the spools and the bypass fans. Some fans are located forward of the combustor while some fans are located rearward. Other embodiments show various arrangements for the combustor chamber. These various arrangements for the bearings and the combustor chambers allow for the gas turbine engine having a central bypass duct to have several different configurations in order to be customized for different engine requirements.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 shows a first embodiment of the present invention in which a gas turbine engine having a single spool includes an outer bypass and a central bypass for airflow through the engine.
FIG. 2 shows a second embodiment of the present invention in which the gas turbine engine having two spools includes an outer bypass and a central bypass for airflow through the engine.
FIG. 3 shows a variation of the second embodiment in FIG. 5 with a different arrangement of the bearings.
FIG. 4 shows an outer circumferential view of the fan blade assembly being formed of a splitter blade.
FIG. 5 shows a gas turbine engine of the present invention having two spools and a central bypass, and guide vanes before the compressor and the turbine, where the bypass fan being located forward of the combustor.
FIG. 6 shows a variation of the gas turbine engine of FIG. 8 in which a mixer is used to combine the flow from the central bypass and the turbine exhaust.
FIG. 7 shows a variation of the gas turbine engine of FIG. 9 in which the combustor chamber is different.
FIG. 8 shows a gas turbine engine of FIG. 10 with a different fan blade structure.
FIG. 9 shows the gas turbine engine of FIG. 11 with a different fan blade structure.
FIG. 10 shows the gas turbine engine of FIG. 12 with a different combustor chamber configuration.
FIG. 11 shows the gas turbine engine with a single spool and a central bypass duct, a guide vane before each of the compressor and turbine, two turbine blades, and a fan blade arrangement located forward of the combustor.
FIG. 12 shows the gas turbine engine of FIG. 14 with only one turbine blade.
FIG. 13 shows the gas turbine engine of FIG. 15 with a smaller cross sectional flow path through the compressor/combustor/turbine section.
FIG. 14 shows a gas turbine engine of FIG. 16 with a different mixer assembly.
FIG. 15 shows a gas turbine engine of FIG. 17 with a smaller cross sectional flow path through the compressor/combustor/turbine section.
FIG. 16 shows a gas turbine engine with two spools and a central bypass duct, and a bypass fan located rearward of the combustor.
FIG. 17 shows the gas turbine engine of FIG. 19 with a longer combustion chamber.
FIG. 18 shows a gas turbine engine having two spools and a bypass duct, a fan blade located upstream of the combustor, and a mixer assembly to mix the fan bypass flow and the turbine exhaust flow.
FIG. 19 shows the gas turbine engine of FIG. 21, with arrows indicating flow paths for the bypass flow and the turbine exhaust.
FIG. 20 shows a gas turbine engine with two spools and a central bypass duct, guide vanes upstream of the compressor and the turbine, and a fan assembly upstream of the compressor.
FIGS. 21 and 22 shows a gas turbine engine of FIG. 23 with a different combustor chamber arrangement.
FIG. 23 shows a turbine with twin spools and a central bypass duct having fan blades extending all the way through.
FIG. 24 shows a turbine with twin spools and a central bypass duct having a fan blade in the upstream entrance to the duct and a fan blade in the downstream exit of the duct, the exit of the duct turning upward to mix the bypass flow with the turbine exhaust flow.
FIG. 25 shows the prior art gas turbine engine (U.S. Pat. No. 5,692,372 issued to Whurr) with an outer bypass duct.
FIG. 26 and 27 show the prior art gas turbine engines (U.S. Pat. No. 6,532,731 issued to Springer; U.S. Pat. No. 6,151,882 issued to Cavanagh) with a central bypass duct.
DETAILED DESCRIPTION OF THE INVENTION
The gas turbine engine of the present invention is best shown in FIGS. 1-3. FIG. 1 shows a turbine with a single spool and bypass ducts through the central portion and outer portions of the turbine engine. FIGS. 2 and 3 show gas turbine engines with two spools and central and outer bypass ducts, but with different bearing arrangements to support the two spools.
The gas turbine engine of FIG. 1 shows a single spool turbine with a central bypass duct 46 and an outer bypass duct formed between outer casing 10 and member 48. In this embodiment, the outer bypass duct is of such size that the airflow through it is enough to provide a stream of air to surround the exhaust gas flow from the turbine in order to reduce noise. The outer bypass flow is not sized such that much thrust is provided form the outer duct airflow as would be provided due to the central duct airflow.
A fan blade comprises blade 22 and blade 24 extending from a shaft 44. Blade 22 has a longer cord length than blade 24, the blade arrangement forming a splittered rotor as disclosed in U.S. Pat. No. 5,299,914 issued to Schilling on Apr. 5, 1994 and incorporated herein by reference. FIG. 4 shows this blade arrangement. A bypass fan blade 26 is also connected to the shaft 44 and provides the bypass flow through the central bypass passage 46. A guide vane 28 is secured to the outer casing 10 and is located upstream of compressor blades 30 and 32. Blades 30 and 32 also form a splittered rotor arrangement for the compressor blade rotor. A combustor 34 is located downstream from the compressor blades 30 and 32. Combustor guide vane 33 guides the flow into the combustor, while turbine nozzle 35 directs the combustor exhaust gas flow to the turbine. Turbine blade 46 is located downstream from the combustor 34 and nozzle 35. Both the compressor rotor with blades 30 and 32 and the turbine rotor with blade 36 are rotatably secured to shaft 44. Combustor 34 is secured to the outer casing 10 via the casing member 48. Casing member 48 is secured to the inner wall of the outer casing by struts or other joining members that are of low resistance to airflow through the outer bypass duct. Rotation of the shaft 44 causes the fan blades 22, 24, and 26 to rotate and force airflow into the outer bypass duct, the compressor, and the central bypass duct. An exhaust mixer 38 is located downstream of the turbine, and is secured to the outer casing 10. Airflow from both ducts and the turbine are combined to reduce noise. The spool shaft 44 is supported for rotation by bearings 42 and 43. The guide vane 28 supports bearing 42, while the mixer 38 supports bearing 43.
The FIG. 2 embodiment shows a turbine engine having two spools with a central bypass duct and an outer bypass duct of larger flow volume than the first embodiment FIG. 1. A fan arrangement includes blades 22, 24, and 26, where blades 22 and 24 are of the splittered rotor type blade set as shown in FIG. 4. Blades 22, 24, and 26 are rotatably secured to hub 40 that is joined to shaft 50 forming the innermost spool. Compressor guide vane 28 is secured to the outer casing 10, as is the turbine guide vane 37. The inner spool includes compressor blades 30 and 32 forming a spluttered blade set as shown in FIG. 4, and turbine blade 36. Guide vanes 33 and nozzles 35 are used as in the FIG. 1 embodiment. In the FIG. 2 embodiment, the guide vanes 28 and 37 support bearings 42, 54, 56, and 58 that support the two spools having shafts 44 and 50. A combustor section 34 is located between the compressor and the turbine, and a mixer 38 is located downstream of the turbine to mix the bypass flow and the exhaust flow from the turbine. Casing member 48 is secured to the outer casing 10 by struts 52 and 54, these struts providing structural support for the casing member 48 and the combustor 34 while minimizing the airflow resistance through the outer bypass duct 56. Rotation of the turbine blade 36 causes the compressor blades 30 and 32 to rotate, while rotation of the turbine blade 39 causes rotation of the fan blades 22, 24, and 26.
The FIG. 3 embodiment differs from the FIG. 2 embodiment in the bearing arrangement that supports the spool carrying the compressor and turbine blades. FIG. 3 includes structure similar to that in FIG. 2, and therefore the reference numerals are not shown. The FIG. 3 embodiment differs from that of FIG. 2 in that the outer spool is supported by bearings that are supported on the combustor and guide vane and nozzle. The inner spool having inner shaft supports the fan blades, and is supported by bearings and carried on the guide vanes. The outer spool having outer shaft supports the compressor blades, and the turbine blade. The outer shaft is supported by bearings and that are supported on the combustor casing. The guide vanes are secured to the outer casing and the combustor casing is secured to the inner casing member. The inner casing member is secured to the outer casing by struts as disclosed above in the FIG. 2 embodiment. A mixer is located downstream of the turbine, and mixes the bypass flows and the exhaust from the turbine to reduce noise. Outer bypass duct is formed between outer casing and middle casing member. Inner spool or shaft forms central bypass duct. Rotation of the turbine blade causes the compressor blades to rotate, while rotation of the turbine blade causes rotation of the fan blades.
FIGS. 23 and 24 show a turbine having twin spools and a central bypass duct. The combustor carries two bearings that support the outer spool carrying the compressor blade and the first stage turbine blades. The guide vanes support the bearings that support the inner spool carrying the fan blades and the second stage turbine blade. The central bypass duct includes a blade set that passes from the entrance to the exit of the duct.
In the FIG. 24 embodiment, the central bypass duct has a blade in the entrance of the duct and another blade at the exit of the duct with an open passage between these two blades. Also, the exit of the central bypass duct is turned upward to mix the bypass airflow with the exhaust from the turbine.
FIGS. 2-20 show embodiments of a gas turbine engine having a central bypass duct with various structures for the rotational support of shafts and various arrangements for the fan blades. FIG. 2 shows a turbine with two spools and a fan blade assembly located upstream of the combustor, and the spools being supported by bearings carried on the vanes. FIG. 3 shows a twin spool turbine like FIG. 2 but with a mixer located downstream of the turbine. FIG. 4 shows the turbine of FIG. 3, but with a modified combustion chamber arrangement. FIG. 5 shows the turbine of FIG. 4, but with fan blades having a leading edge curved in the radial direction. FIG. 6 shows a turbine with twin spools supported for rotation by bearings carried on the vanes, and a modified combustion chamber arrangement. FIG. 7 shows the turbine of FIG. 6, but with a further modification of the combustion chamber arrangement. FIG. 8 shows a turbine with a single spool and vanes that carry bearing to support rotation of the spool or shaft. FIG. 9 shows the turbine of FIG. 8, but with the rear bearing carried by the mixer frame. FIG. 10 shows a turbine of FIG. 9, but with a flow passage area through the compressor/turbine portion of smaller volume. FIG. 11 shows a turbine of the FIG. 9 embodiment, but with a flow passage area through the compressor/turbine portion of smaller volume than the FIG. 10 embodiment. FIG. 12 shows a turbine of the FIG. 9 embodiment, but with a flow passage area through the compressor/turbine portion of smaller volume than the FIG. 11 embodiment.
FIG. 13 shows a turbine having twin spools, where the inner spool is supported by bearings carried on the combustor assembly, while the outer spool is supported by bearings carried on the inner spool (front bearing) and the mixer frame (rear bearing). The fan blades are located downstream of the combustor. FIG. 14 shows a turbine of the embodiment in FIG. 13, but with a longer combustion chamber. FIG. 15 shows a turbine with twin spools of the FIG. 14 embodiment, but with the fan blades are located upstream of the combustor and are carried on a shaft that supports the rear bearing of the inner spool or shaft. FIG. 16 shows the air flow paths through the mixer of the FIG. 15 embodiment. FIG. 17 shows a turbine with twin spools and vanes that carry the bearings, the fan blades are located upstream of the combustor. FIG. 18 shows a turbine of the FIG. 17 embodiment, but with a modified combustor shape. FIG. 19 shows a turbine of the FIG. 18 embodiment, but with a further modified combustor shape.
Patent Application
20070240424
