Patent Application
20110219784
This application relates to a gas turbine engine with an axial high pressure compressor, wherein a tie shaft holds the high pressure compressor section together.
Gas turbine engines are known, and typically include a compressor, which compresses air and delivers it downstream into a combustion section. The air is mixed with fuel in the combustion section and combusted. Products of this combustion pass downstream over turbine rotors, driving the turbine rotors to rotate.
Typically, the compressor section is provided with a plurality of rotor serial stages, or rotor sections. Traditionally, these stages were bolted together and included bolt flanges, or other structure to receive the attachment bolts. Other applications have rotors welded together.
More recently, it has been proposed to eliminate all of the bolts or weld joints and the flanges with a single coupling which applies a force through the compressor rotors using a tie shaft that clamps the rotors together and provides the friction necessary to transmit torque.
Typically, the compressor rotor stages alternate with stationary vanes. These non-rotating airfoils can be either variable or fixed. Variable vanes are known having an actuator which changes an angle of incidence of the vane relative to the air approaching the vane, and being delivered to the next downstream compressor rotor stage. These vanes are pivot mounted, have typically had their actuator at an outer periphery and feature abradable material that seals against the knife edges mounted on the mating compressor rotor.
Cantilever mounted vanes are a variety of fixed vanes used mostly for radially short airfoils that do not require a shrouded support at their inner end—they have not been utilized in compressor sections with a tie shaft coupling.
A compressor section to be mounted in a gas turbine engine has a plurality of compressor rotors arranged from an upstream location toward a downstream location. The compressor rotors stack is bounded by one hub at the upstream end and another hub at the downstream end. Vane sections are mounted intermediate the compressor rotors. The vane sections include pivot mounted variable vanes driven by actuators mounted at a radially outer position and fixed vanes. At least some of the fixed vanes are cantilever mounted, such that they are spaced from a compressor rotor, but unsecured at a radially inner end.
A gas turbine engine incorporating such structure is also claimed.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
A portion of gas turbine engine 20 is illustrated in
As can be appreciated, while a single blade and a single vane are shown at each axial location in
Fixed position vanes 40 are cantilever mounted, or unsecured and unconstrained at their inner periphery. The use of the cantilever vanes eliminates pivot mount structure. In combination with the use of the tie shaft, the cantilever mount vanes eliminate a good deal of structure, allowing the envelope of this high pressure compressor to be made much smaller in both axial and radial dimensions. Also, the assembly is simpler and lighter.
The compressor rotors 30 are clamped together between the upstream and downstream hubs, 24 and 34 respectively using the tie shaft 22 to apply the axial force. The axial force is applied to the downstream hub 34 by nut 32 that is threadably secured to the tie shaft 22; the force is transmitted from nut 32 to the downstream hub 34 through an end 35 abutting a ledge 33 on a nut 32. The upstream hub 34 applies a force at contact face 38 of the most downstream compressor stage 37. This stage 37 includes airfoils 36 positioned to be radially outwardly of contact face 38 of the tie shaft 34. The nut 32 is threadably secured to the tie shaft 22. In this manner, force is loaded to the downstream hub 34 and onto the most downstream compressor rotor section 37, which in turn applies the force to hold all of the other compressor rotor sections against the upstream hub 24 and creates the friction necessary to transmit torque.
As is known, air compressed by the compressor section 21 is delivered downstream into a combustion section 50 (shown schematically) and from the combustion section 50 into a turbine section 60. The turbine section 60 may also be secured using a tie shaft coupling, as is partially shown here.
The use of the tie shaft mount eliminates much of the structure as mentioned above, and further, the combination of this feature with the cantilever mount vanes, allows the more downstream sections of the compressor section to be made much smaller resulting in a smaller radial and axial envelope for the compressor section and a simplified mounting arrangement.
In addition, as can be appreciated, the contact face 38 is radially inward of the airfoils 36. The use of an axial compressor as the most downstream compressor thus provides a smaller radial envelope for the securement structure, again resulting in a smaller overall envelope.
All vanes feature a sealing arrangement against mating features incorporated into the compressor rotors.
Co-pending application serial number______, entitled “Gas Turbine Engine With Tie Shaft for High Pressure Compressor,” filed on even date herewith, focuses on the use of the tie shaft with axial compressor sections. The co-pending patent application serial number______, entitled “Single Tie Rod Connection for Securing Compressor Section and Turbine Section,” filed on even date herewith, focuses on the assembly of turbine and compressor sections. In addition, co-pending application serial number______, entitled “Gas Turbine Engine Rotor Sections Held Together by Tie Shaft, and With Blade Rim Undercut,” filed on even date herewith, focuses on structure to an integrally bladed rotor.
Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
