Patent Application
20070187461
The present invention relates to gas turbine engine repair tools, and, more particularly, to a dam for use with inert gas to shield a portion of an impeller during a weld repair process.
A gas turbine engine may be used to power various types of vehicles and systems. A particular type of gas turbine engine that may be used to power an aircraft is a turbofan gas turbine engine. A turbofan gas turbine engine may include, for example, a fan section, a compressor section, a combustor section, a turbine section, and an exhaust section. The fan section is positioned at the front of the engine, and includes a fan that induces air from the surrounding environment into the engine and accelerates a fraction of this air toward the compressor section. The remaining fraction of induced air is accelerated into and through a bypass plenum, and out the exhaust section.
The compressor section is configured to raise the pressure of the air to a relatively high level. In particular, the compressor section includes an impeller that has a plurality of vanes extending therefrom that accelerate and compress the air. The compressed air then exits the compressor section, and is energized by the combustor section and flowed into the turbine section to cause rotationally mounted turbine vanes to rotate and generate energy.
Over time, certain components of the engine may become worn and may need to be replaced or repaired. For example, impeller vanes may become deformed or damaged due to prolonged exposure to high temperature air and continuous bombardment by particles during engine operation. Impeller vane repairs often employ welding processes, such as, for example, laser welding, tungsten inert gas welding, or plasma arc welding, where a power source is used to melt a filler material, and a sufficient amount of the melted material is deposited onto a desired area of the impeller. After the material cools and hardens, the area is machined into a desired configuration.
When the filler material is in a molten state, it is preferably isolated from contact with oxygen. Oxygen may oxidize or contaminate the filler material and cause it to become relatively brittle or weak. To prevent such contamination, the impeller is typically bathed in a noble gas, such as argon. The gas, which is typically heavier than air, is generally supplied through a weld head, spread through a metal screen either coupled or adjacent thereto, and poured directly onto the impeller.
Although the above-mentioned technique for bathing the impeller is adequate, it suffers from certain drawbacks. Specifically, because the impeller does not include portions that form enclosed cavities, the gas continuously spills off of the impeller and thus, needs to be continually supplied. As a result, a large amount of gas is used. Additionally, the gas may not sufficiently bathe certain portions of the impeller, and, consequently, the impeller may not be entirely covered in the gas. Thus, the likelihood of the filler material becoming oxidized increases.
Hence, there is a need for a dam that reduces the amount of gas used in a welding process. Additionally, it is desirable that the dam allow a repair area of the impeller to be entirely covered by the gas to reduce the likelihood that the filler material will become oxidized.
A dam is provided for localizing gas around an outer periphery of an impeller. In one embodiment, by way of example only, the dam includes a skirt, a flange, and a fastener. The skirt includes an inner section, an outer section, and an outer peripheral edge. The inner section is configured to be placed under the impeller, and the outer section extends radially outwardly of the impeller outer periphery to the skirt outer peripheral edge. The flange extends substantially perpendicular from the skirt outer section edge. The fastener is coupled to the skirt and configured to couple the dam to the impeller.
In another embodiment, by way of example only, the dam includes an annular skirt, an annular flange, and a fastener. The annular skirt includes an inner section, an outer section, and an outer peripheral edge, where the inner section is configured to be placed under the impeller, and the outer section extends radially outwardly of the impeller outer periphery to the annular skirt outer peripheral edge. The annular flange extends substantially perpendicular from the skirt outer section. The fastener is coupled to the annular skirt and configured to couple the dam to the impeller.
Other independent features and advantages of the preferred mask will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
The following detailed description of the invention is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description of the invention.
Turning now to the description, and with reference first to
The high-pressure compressed air then enters the combustor and turbine module 130, where a ring of fuel nozzles 114 (only one illustrated) injects a steady stream of fuel. The injected fuel is ignited by a burner (not shown), which significantly increases the energy of the high-pressure compressed air. This high-energy compressed air then flows first into a high pressure turbine 115 and then a low pressure turbine 116, causing rotationally mounted turbine blades 118 on each turbine 115, 116 to turn and generate energy. The energy generated in the turbines 115, 116 is used to power other portions of the engine 100, such as the fan module 110 and the compressor module 120. The air exiting the combustor and turbine module 130 then leaves the engine 100 via the exhaust module 140. The energy remaining in the exhaust air aids the thrust generated by the air flowing through the bypass 112.
With reference now to
The high pressure section 160 includes a high pressure diffuser case 210, a shroud 215, and a high pressure impeller 220. The high pressure diffuser case 210 couples the low pressure section 150 to the high pressure section 160 and directs the air exhausted from the fourth stage 155d of the low pressure section 150 at an appropriate angle into the high pressure impeller 220. The shroud 215 is mounted to the diffuser case 210 and surrounds a portion of the high pressure impeller 220.
Turning now to
As mentioned briefly above, the impeller 220 may need to undergo a weld repair process. In such case, a dam 270, shown mounted to the impeller 220 in
With reference to both
The flange 280 cooperates with the skirt 275 to pool the gases around the impeller outer peripheral edge 255. In this regard, the flange 280 is formed on the outer peripheral portion 315 of the skirt 275 and extends substantially perpendicular therefrom. Preferably, the flange 280 has a length that is equal to or greater than an axial length from the vane bottom edge 265 to the vane corner 260; however, it will be appreciated that the flange 280 may have any other suitable length. The flange 280 may extend around the circumference of the skirt 275, or alternatively may include one or more notches 285 formed therein through which one or more of the fasteners 283 may extend. It will be appreciated that although the flange 280 is shown as extending from the outer peripheral edge of the skirt 275, the flange 280 may alternatively extend from any other section of the outer peripheral portion 315 of the skirt 275.
The fasteners 283 are coupled to the skirt 275 and are configured to rotate relative thereto. It will be appreciated that the fasteners 283 may be any one of numerous conventional devices suitable for coupling the dam 270 to the impeller 220. For example, as shown in
In another exemplary embodiment, shown in
Returning to
The above-described dam 270 reduces the amount of noble gas used in a welding process and allows the impeller 220 to be substantially bathed in gas. Consequently, the likelihood of the filler material becoming oxidized is decreased. As a result, the repaired impeller 220 is structurally robust, and frequency of repair is decreased.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
