1. Technical Field
The present invention relates to chemical milling and, in particular, to a method for chemical milling an apparatus with a flow passage based on flow area of the flow passage.
2. Background Information
Apparatus with flow passages may be utilized for various applications such as, for example, components for gas turbine engines. Gas turbine engine components may be manufactured using both casting and machining processes. A gas turbine engine duct blocker, for example, may be cast and subsequently machined to provide the duct blocker with a predetermined geometry. A typical machining process, however, may be time consuming, relatively expensive and leave the duct blocker with discontinuous surfaces.
According to a first aspect of the invention, a method for manufacturing an apparatus with a flow passage includes providing a preform apparatus with a preform flow passage. Flow area of the preform flow passage is determined to provide determined flow area data. The determined flow area data is compared to reference flow area data to provide flow area comparison data. The preform apparatus is chemical milled based on the flow area comparison data.
According to a second aspect of the invention, a method for manufacturing a gas turbine engine component with a flow passage includes forming a preform engine component with a preform flow passage. Flow area of the preform flow passage is determined, and compared to reference flow area. A chemical milling time is determined based on the comparison between the determined flow area and the reference flow area, and the preform engine component is chemical milled for the chemical milling time.
The foregoing features and the operation of the invention will become more apparent in light of the following description and the accompanying drawings.
The present invention includes a method for manufacturing an apparatus that includes a flow passage with a predetermined flow area. The method includes providing a preform apparatus that includes a preform flow passage. The preform apparatus and the preform flow passage may respectively have substantially the same geometrical configuration as the apparatus and the flow passage, however, for example, with one or more different dimensions. Flow area of the preform flow passage therefore is determined, and compared to a reference flow area that is indicative of the predetermined flow area. Based on this comparison, the preform apparatus is chemical milled to provide a milled apparatus that includes a milled flow passage with a milled flow area that is substantially equal to the reference flow area and, thus, the predetermined flow area.
Apparatuses with flow passages may be utilized for various applications such as, for example, components for gas turbine engines.
The duct blocker rotor 14 includes an inner rotor platform 18, an outer rotor platform 20, a plurality of first vane segments 22 (e.g., leading edge vane segments), and a plurality of first flow apertures 24. The first vane segments 22 extend radially from the inner rotor platform 18 to the outer rotor platform 20. Each first vane segment 22 extends axially from a first vane edge 26 (e.g., a vane leading edge) to a first vane endwall 28. Each first flow aperture 24 extends circumferentially between respective adjacent first vane segments 22, and axially through the duct blocker rotor 14.
The duct blocker stator 16 includes an inner stator platform 30, an outer stator platform 32, a plurality of second vane segments 34 (e.g., trailing edge vane segments), and a plurality of second flow apertures 36. The second vane segments 34 extend radially between the inner stator platform 30 and the outer stator platform 32. Each second vane segment 34 extends axially from a second vane endwall 38 to a second vane edge 40 (e.g., a vane trailing edge). Each second flow aperture 36 extends circumferentially between respective adjacent second vane segments 34, and axially through the duct blocker stator 16.
The inner rotor platform 18 is arranged axially adjacent to the inner stator platform 30. The outer rotor platform 20 is arranged axially adjacent to the outer stator platform 32.
During engine operation, the duct blocker rotor 14 rotates relative to the duct blocker stator 16. More particularly, the first vane segments 22 move circumferentially relative to the second vane segments 34 to regulate how much fluid may flow from the first flow apertures 24 to the second flow apertures 36. The first vane segments 22 may move, for example, between the first configuration (e.g., the open configuration) illustrated in
In the first configuration (e.g., the open configuration) illustrated in
In the second configuration (e.g., the closed configuration) illustrated in
In step 420, one or more dimensions of the preform duct blocker 110 are measured. Referring to
In step 430, the dimensional data is processed to determine flow area of the preform flow passage for a configuration where, for example, the preform duct blocker 110 is arranged in a second configuration (e.g., a closed configuration). The flow area may be determined, for example, by calculating an average flow area of the preform sub-flow passages 144, and multiplying the average flow area by the total number (N) of preform sub-flow passages 144 included in the preform duct blocker 110.
Total Flow Area=N×Avg. Flow Area (Eq. 1)
The average flow area may be calculated with, for example, the following expressions:
The Avg. Passage Height may be calculated by subtracting an average value (R1) of the inner duct radiuses 158 from an average value (R2) of the outer duct radiuses 160. The Avg. Passage Width may be calculated for the second (e.g., closed) configuration, for example, with the following expression:
Avg. Passage Width=[π×(R1+R2)−W1−W2]÷N (Eq. 4)
where W1 is an average value of the first preform vane segment widths 146, and W2 is an average value of the second preform vane segment widths 148. The Avg. Fillet Radius is the average value of the fillet radiuses 162.
In step 440, determined flow area data is compared to (e.g., subtracted from) reference flow area data to provide flow area comparison data. The determined flow area data is indicative of the flow area of the preform flow passage determined in step 430. The reference flow area data is indicative of the second flow area of the flow passage illustrated in
In step 450, the flow area comparison data is processed to determine a chemical milling time. The chemical milling time is indicative of a quantity of time that the preform duct blocker 110 may be subjected to a chemical milling solution to increase its flow area, for example, to the second flow area set forth by the reference flow area data.
In step 460, the preform duct blocker 110 is chemical milled and, more particularly, subjected to (e.g., submersed in) a chemical milling solution for at least a portion of the chemical milling time. The chemical milling solution substantially uniformly removes material from exposed surfaces of the preform duct blocker 110, and may increase the flow area of the preform flow passage to the second flow area set forth by the reference flow area data. The chemical milling may also provide the preform duct blocker 110 with relatively smooth and continuous surfaces, and may remove alpha case where, for example, the preform duct blocker is constructed from titanium or titanium alloy.
Referring to
In some embodiments, steps 420, 430, 440, 450 and 460 may be repeated one or more times on the milled preform duct blocker before step 470, for example, to ensure the flow area of the milled flow passage is substantially equal to the second flow area set forth by the reference flow area data.
In some embodiments, one or more portions of the preform duct blocker may be masked before step 460.
In some embodiments, one or more post chemical milling processes may be performed on the milled preform duct blocker 110. Examples of post chemical milling processes may include machining, additional chemical milling processes, etc.
In some embodiments, the Avg. Fillet Area may alternatively be calculated by multiplying the Avg. Fillet Radius by a predetermined correction factor.
One of ordinary skill in the art will appreciate that the steps of the disclosed method may be performed automatically, for example, under the control of a processing device that executes program instructions. However, it is also contemplated that the steps may be performed by discrete devices.
While various embodiments of the present invention have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Accordingly, the present invention is not to be restricted except in light of the attached claims and their equivalents.
This invention was made with government support under Contract No. N00019-02-C-3003 awarded by the United States Navy. The government may have certain rights in the invention.