The present invention generally relates a combustor liner in a turbine engine, and, more specifically, to a multi-axial pivoting combustor liner that minimizes thermal interference during engine operation. A gas turbine engine includes a compressor that provides pressurized air to a combustor wherein the air is mixed with fuel and burned for generating hot combustion gases. These gases flow downstream to one or more turbines that extract energy therefrom to power the compressor and provide useful work such as powering an aircraft in flight. Combustors used in aircraft engines typically include a combustor liner to protect surrounding engine structure from the intense heat generated by the combustion process.
A conventional can combustor liner has a cylindrical shape with one open end. A thin sheet metal material, capable of withstanding high temperature conditions, is usually used to fabricate the body through a forming process. The liner is often supported on one end or suspended by a few points. The conventional liner assembly and fabrication technique is adequate only for low cycle and low performance engines.
U.S. Pat. No. 3,911,672 discloses a combustor having a ceramic liner. Referring to FIGS. 1 and 2 of the patent, an abutment 22 includes a flange 24 engaging the liner surface of a dome 6 around an opening 7. A slightly yieldable or resilient gasket 25 is disposed between flange 24 and the ceramic liner. This conventional system relies on bolts and screws to make the assembly. The combustor described in the patent does not, however, have multi-axial pivoting capabilities.
U.S. Pat. No. 4,446,693 discloses a cooled wall structure for a gas turbine engine in which the wall is capable of providing a relative movement to cope with the thermal strains experienced by the combustion process. Referring to FIGS. 3, 7 and 8, the wall structure has an inner wall 20 and an outer wall 18. Attachment is provided by a central pin 28a passing through an opening 30 in the outer wall. Central pin 28a is secured to outer wall 18 by welding. Outer pins 28b, on each side of central pin 28a, pass through an opening 32, and a collar 34 is attached to each wall outer pin 28b. Thus, the downstream end of each wall element is securely attached to the outer wall by central pin 28a and is located on the outer wall by outer pins 28b so that the wall element moves to a limited extent with respect to central pin 28a. The wall of this patent is a cooled slidable wall that does not have multi-axial pivoting capabilities, and, more to the point, is not capable of any pivoting motion.
As can be seen, there is a need for an improved combustor liner for gas turbine engines. Such an improved combustor liner must have the ability to control small amounts of air leakage, provide easy assembly, have no flow path steps, and tolerate thermal and mechanical stresses while minimizing thermal wear and fretting for the life of the liner.
In one aspect of the present invention, a liner for a turbine engine, comprises a lower joint that moveably connects the liner with a combustion gas output receiving device; and an upper joint that movably attaches the liner to the sleeve and combustor cap/housing; with the lower joint and the upper joint providing multiple axes of movement for the liner.
In another aspect of the present invention, a combustor liner for a gas turbine engine comprises a lower joint that moveably connects the liner with a turbine scroll; an upper joint that movably attaches the liner to the sleeve and combustor cap/housing; the lower joint and the upper joint providing multiple axes of movement for the liner; a vibration damper/thermal and mechanical spring; the vibration damper/thermal and mechanical spring providing resiliency to the liner in a first direction from the atomizer to the turbine scroll, thereby maintaining the upper joint in a connected state; the vibration damper/thermal and mechanical spring providing resiliency to the liner in a second direction, orthogonal to the first direction, thereby minimizing movement of the liner in the second direction; a hole in the liner for inserting an igniter; and a grommet for moveably holding the igniter in the hole. More importantly, the mechanical spring provides constant contact during all flight maneuvering conditions and shipment.
In yet another aspect of the present invention, a combustor liner for a gas turbine engine of a high performance aircraft comprises a lower joint that moveably connects the liner with a turbine scroll; an upper joint that movably attaches the liner to the sleeve and combustor cap/housing; the lower joint and the upper joint providing multiple axes of movement for the liner; a vibration damper/thermal and mechanical spring; the vibration damper/thermal and mechanical spring providing resiliency to the liner in a first direction from the atomizer to the turbine scroll, thereby maintaining the upper joint in a connected state; the vibration damper/thermal and mechanical spring providing resiliency to the liner in a second direction, orthogonal to the first direction, thereby minimizing movement of the liner in the second direction; a hole in the liner for inserting an igniter; a grommet for moveably holding the igniter in the hole; a forging ring, the forging ring having a first surface for movably contacting the turbine scroll and a second, opposite surface attached to the liner; the first surface forming a substantially spherical point of contact between the liner and the turbine scroll; the second surface having a diameter smaller than a diameter of the first surface; fine holes in the forging ring; an upper joint louver for deflecting air from the upper joint; dilution holes in the upper joint, the dilution holes providing cooling for the upper joint; and a carbon deflector extending into the combustion zone around the upper joint.
In a further aspect of the present invention, a turbine engine comprises a combustor liner having a lower joint that moveably connects the liner with a combustion gas output receiving device and an upper joint that movably attaches an atomizer to the liner, the lower joint and the upper joint providing multiple axes of movement for the liner.
In still a further aspect of the present invention, a method for operating a turbine engine, comprises encasing a combustor zone with a combustor liner; providing a fuel source to the combustor zone; providing an ignition source to the combustor zone; and passing the combustion gases through a turbine scroll to drive a turbine; wherein the combustor liner is a multi-axial pivoting liner having a lower joint that moveably connects the liner with the turbine scroll and an upper joint that movably attaches the fuel source to the liner, the lower joint and the upper joint providing multiple axes of movement for the liner.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.
The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
The present invention provides a multi-axial pivoting liner within the combustion system of a turbine engine. The pivoting liner allows the system to work with minimum thermal interference, especially during system operation at transient conditions, by allowing the liner to pivot and slide about its centerline and relative to the turbine scroll. The pivoting liner should also have the ability to control and minimize air leakage from part to part, for example, from the liner to the turbine scroll, during various operating conditions. Additionally, the liner should also provide for easy assembly with no steps in the combustion gas flow path. Finally, the liner should tolerate thermal and mechanical stresses and minimize thermal wear.
Conventional combustor liners are often supported on one end or suspended by a few points. The conventional liner assembly and fabrication technique is adequate only for low cycle and low performance engines. Thermal and mechanical stresses on a conventional liner in a high performance engine may result in liner damage and/or air leakage. The thermal and mechanical stress on the liner must be minimized to meet a fatigue requirement. In accommodating this fatigue requirement, the liner of the present invention is designed to pivot to wherever the thermal displacement dictates.
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A vibration damper/thermal and mechanical spring 26 may provide a pre-load on an upper joint 28 at all times. This pre-load is especially useful to maintain contact during shipment and flight maneuvers when there may be unusually high g-forces acting on the turbine engine. At the end of vibration damper/thermal and mechanical spring 26 there may be welded to a machined segment 30 to act as a surging stopper by preventing damage to an igniter 32 due to shear force.
Upper joint 28 may be formed by contacting two substantial spherical surfaces, upper inner surface 74 and upper outer surface 50 to minimize leakage, provide wear surface area, and allow angular pivoting motion while constraining motion along liner axial axis. Dimension “d” is the distance from upper joint 28 to an offset center point 70 of a sphere projected diameter 72. Dimension “d” is optimized to provide the appropriate contact angle formed between liner centerline 68 and the surface of upper joint 28 that formed upper inner surface contact 74 and upper outer surface 50. The optimization of dimension “d” is critical to prevent excessive friction force by maximizing the pivoting contact surfaces.
Upper inner surface 74 may be brazed to or integrally formed with a bushing 36 and a swirler 38 to form an inner race 40. Upper inner surface 74 may also include a carbon deflector 42 to reduce or prevent carbon build up in the system. Sweep holes 44 may be provided to cool upper joint 28 and prevent carbon formation. A louver 46 and a series of louver holes 48 may be provided to deflect air and prevent carbon build up in the dome 76. Effusion cooling may be provided as an alternative to prevent carbon formation as well. The outer race includes an upper-outer surface 50 that sandwiches dome 76 within a retainer ring 52. Studs 54 may be used to hold liner 10, via upper joint 28, with a combustor cap 56 together with an atomizer 58. Studs 54 may also maintain the position of liner 10 during the replacement or inspection of atomizer 58. The resulting assembly allows liner 10 to pivot at upper joint 28 and about point 70 while accommodating thermal relative growth between liner 10 and turbine scroll 12, combustor housing 18 and combustor cap 56.
Igniter 32 may use a grommet 60 in liner 10 to prevent igniter 32 from interfering with any movement of the system. This system helps relieve stress on igniter 32 during movement of either liner 10 or turbine scroll 12.
It should be understood, of course, that the foregoing relates to preferred embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
This invention was made with support from the U.S. Navy under Contract No. N00019-02-C-3002. The Government has certain rights in this invention.
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20040200223 A1 | Oct 2004 | US |