Power plants – Combustion products used as motive fluid – Combined with regulation of power output feature
Reexamination Certificate
2000-01-25
2001-12-04
Freay, Charles G. (Department: 3746)
Power plants
Combustion products used as motive fluid
Combined with regulation of power output feature
C060S039780, C029S889210
Reexamination Certificate
active
06324831
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to gas turbine engines, and more particularly, to rotors employed in gas turbine engines. Even more particularly, the invention relates to monorotors for gas turbine engines.
BACKGROUND OF THE INVENTION
Radial flow, gas turbine engines have long been known and employed in a variety of applications. Quite obviously, they are desirable for those applications where axial compactness is required. They have also seen extensive use in applications where their relative simplicity is highly desirable as, for example, in auxiliary power units for aircraft. Indeed, they have even been employed in thrust jet applications for small aerodynamic vehicles as, for example, drones and cruise missiles.
Many of today's radial flow, gas turbine engines employ so-called “monorotors” wherein the monorotor consists of a single rotating mass defining both the compressor section and the turbine wheel section of the engine. Because the rotor must stand up to the high temperatures encountered in the hot section of the engine, i.e., the temperatures to which the turbine wheel section of the monorotor is exposed, it is made of a single alloy. Typically, the alloy employed is a cast nickel based superalloy which will accommodate the elevated temperature that is experienced in the hot section. Alloys such as nickel based superalloys or the like, while providing excellent resistance to the high temperatures encountered, have substantial density and thus result in a monorotor having a relatively high mass. The relatively high mass of the monorotor results in relatively large inertia which in turn makes the engine more difficult to start than would be the case if the inertia of the rotor was less. Similarly, the high mass of such monorotors results in relatively high loading of the engine bearings. Such loading can, in turn, require larger bearings than would otherwise be necessary and/or result in a shorter useful life of the gas turbine engine and/or necessitate the use of improved lubrication systems.
All of the foregoing contributes to the cost of the gas turbine engine, as well as affects its reliability in terms of ease of starting, longevity, etc.
The present invention is directed to overcoming one or more of the above problems.
SUMMARY OF THE INVENTION
It is the principal object of the invention to provide a new and improved monorotor for a gas turbine engine. More specifically, it is an object of the invention to provide a new and improved method of making a monorotor for a gas turbine engine. It is also an object of the invention to provide a new and improved monorotor for a gas turbine engine, as well as a gas turbine engine incorporating the new and improved monorotor.
According to one facet of the invention, there is provided a method of making a monorotor for a gas turbine engine which comprises the steps of:
(a) providing a turbine section of the rotor fabricated of a nickel based alloy of high temperature resistance and having an intended axis of rotation;
(b) providing a compressor section of the rotor fabricated of a relatively low density alloy selected from the group consisting of titanium, aluminum, zirconium, and vanadium based alloys, and having an intended axis of rotation;
(c) inertia welding a body of stainless steel or niobium alloy to each of said turbine section and said compressor section on the irrespective intended axes of rotation; and
(d) thereafter metallurgically bonding the bodies together so that the intended axes of rotation are concentric.
In a preferred embodiment, both of the bodies are stub shafts.
In one form of the method, step (d) is preceded by the step of machining the bodies so they may be fitted together in a desired orientation with the intended axes of rotation concentric, and fitting the bodies together in the desired orientation prior to the performance of step (d).
Still another facet of the invention contemplates that step (d) is performed by a welding process selected from the group consisting of laser, electron beam, inertia and TIG welding.
In a highly preferred embodiment of the invention, the welding process is laser welding or electron beam welding.
In a highly preferred embodiment of the invention, the bodies are formed of stainless steel and in an even more preferred embodiment of the invention, the stainless steel is wrought stainless steel.
According to another facet of the invention, a monorotor for a gas turbine engine is provided. The gas turbine engine is of the type having a hot section containing a turbine wheel and a cold section containing a rotary compressor wheel joined to the turbine wheel for rotation therewith. The monorotor of the invention includes a turbine wheel formed of a material resistant to high temperatures and rotatable about an axis along with a rotary compressor wheel formed of a material different from the turbine wheel and having a lesser density than the turbine wheel material. The compressor wheel is also rotatable about the axis.
A first body of a material different from those of the turbine and compressor wheels is provided and is metallurgically bonded to one of the wheels.
A second body of material that is also different from those of the turbine and compressor wheels is metallurgically bonded to the other of the wheels. The monorotor is completed by a weld metallurgically bonding the bodies together for joint rotation about the axis.
In a preferred embodiment, the bodies are both stub shafts. In an embodiment of the invention that is preferred, the turbine wheel material is a nickel based alloy and the first and second bodies are formed of a material selected from the group consisting of stainless steel or niobium based alloys; and the compressor wheel material is selected from the group consisting of alloys based on titanium, aluminum, zirconium, and vanadium.
The invention also contemplates a gas turbine engine which includes a compressor shroud with a combustion air inlet in the shroud. An annular combustor defines an engine axis and the combustor receives combustion air from an outlet from the compressor shroud. A monorotor made as set forth previously is oriented with the compressor wheel being disposed in the compressor shroud and the turbine wheel within the annular combustor and receiving gases of combustion therefrom. The monorotor axis is concentric with the engine axis.
Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings.
REFERENCES:
patent: 2822974 (1958-02-01), Mueller
patent: 4122673 (1978-10-01), Leins
patent: 4177638 (1979-12-01), Wood
patent: 4424003 (1984-01-01), Brobeck
patent: 4490622 (1984-12-01), Osborn
patent: 4521155 (1985-06-01), Osborn
patent: 4705463 (1987-11-01), Joco
patent: 4798320 (1989-01-01), Fang
patent: 4872817 (1989-10-01), De Kruif
patent: 4962586 (1990-10-01), Clark et al.
patent: 5129284 (1992-07-01), Brueckner et al.
patent: 5129784 (1992-07-01), Yoshikawa
patent: 5549449 (1996-08-01), McInerney
patent: 5639209 (1997-06-01), Pollini
patent: 5987938 (1984-05-01), None
Elgin Richard L.
Izadi Said
Freay Charles G.
Gartenberg Ehud
Hamilton Sundstrand Corporation
Wood Phillips VanSanten Clark & Mortimer
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