MULTI-CHAMBER AIRFOIL COOLING INSERT FOR TURBINE VANE

Abstract: An airfoil-shaped combustion turbine vane has a single, unitary insert 22 which is divided by a plurality of radially ex­ tending ribs 38, 40, and 42 into a forward chamber 30, and suc­ cessively rearward chambers 32, 34, and 36, with throttling means 48 being provided at the inlet to the rearward chambers while the airflow 46 to the forward chamber is not restricted, with the forward chamber being at a higher pressure than the rearward chambers so that the impingement jets through the impingement ports 56 are at a higher velocity than the impinge­ ment jets through the impingement ports 58 and 60 from the lower pressure rearward chambers.

Description: MULTI-CHAMBER AIRFOIL COOLING INSERT FOR TURBINE VANE This invention relates to a combustion turbine and in particular to an airfoil-shaped, hollow turbine vane having a leading edge wall. Such turbine airfoil vanes provided with an insert, with the arrangement as a whole providing for air cooling of the vanes. It is known that different stages of the stator vanes require different levels of cooling. The vane structure is of a character and in a stage calling for a low or a moderate level of cooling, which level of cooling can be carried out by the use of impingement jets directed against the interior walls of the vane. Even with those vanes which do not require a high level of cooling, the degree of cooling required at different locations on the vane may differ, with the leading edge region of the vane typically having a relatively higher heat load while downstream and toward the trailing edge of the vane the heat load may be significantly lower. An object is to provide a vane and insert structure in which a vane having a single internal cavity is provided with a single, unitary, hollow insert provided with a chamber arrangement and jet impingement ports all tailored to relate the impingement cooling of the walls to the external heat load. According to the present invention, a combustion turbine comprises an airfoil-shaped, hollow, turbine vane having a leading edge wall, a trailing edge portion with an exit air slot therein, and pressure and suction sidewalls defining a single internal cavity in communication with said exit air slot, a single1 unitary, air-cooling, hollow insert, of substantially complementary airfoil shape in cross section, located in said cavity and extending in a chordwise direction for substantially the entire extent of said cavity, a plurality of radially extending partition means in said insert dividing the interior thereof into a forward chamber in the leading edge portion of said vane, and at least two separate, successively rearward chambers in communication with each other, a plurality of impingement ports in the insert walls of all of said chambers, one radial end portion of said chambers being in communication with a source of cooling air, means for throttling the flow into said rearward chambers in which said forward chamber is at a relatively higher pressure than said rearward chambers so that the impingement jets through said ports of said forward chamber against said interior vane walls of said leading edge portion are at the significantly higher velocity than the impingement jets exiting the ports of said rearward chambers. Conveniently, the insert is provided with a plurality of radially extending partition means to divide the interior thereof into a single forward chamber in the leading edge portion of the vane, and at least two separate, successively rearward chambers in at least partial communication with each other, a plurality of impingement ports in the walls of all of said chambers, one radial end portion of all the chambers being in communication with a source of cooling air, and with means for throttling the flow into the rearward chambers so that the forward chamber is a relatively higher pressure than said rearward chambers and so the impingement jets through the ports of said forward chamber against said interior vane walls of said leading edge portion are at a significantly higher velocity than the impingement jets exiting the ports of the rearward chambers. The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a chordwise sectional view through the vane and insert as would appear from a section taken along the line I-I of Figure 2; and Figure 2 is a view partly in elevation and partly in section of the vane and insert, and corresponding to a view taken along the line II-II of Figure 1. Figure 1 shows a hollow vane having a single internal cavity defined by the leading edge section, a concave sidewall 14, a convex sidewall 16, the downstream portions of these opposite sidewalls defining a trailing edge portion 18 provided with a slot 20 therein. The general direction of the hot gas past the vane is as indicated by the dash line arrow in Figure 1. The single, unitary, air-cooling, hollow insert 22 has an airfoil shape in cross section which is complementary to the vane airfoil shape, and extends in a chordwise direction for substantially the entire extent of the vane cavity. While the insert does have the overall shape of an airfoil, it may be seen in Figure 1 that at the leading edge portion 24 the insert is bulged somewhat, a similar bulged arrangement being provided at the trailing edge portion 26. The intermediate portion 28 has walls which are basically uniformly spaced from the vane walls throughout the intermediate extent between the front and rear bulges. The unitary insert 22 has its interior divided into a forward chamber 30 and successively rearward chambers 32, 34, and. 36, by the radially extending partition means 38, 40, and 42, which also perform a structural tying function. The radially inner ends of all of the chambers are closed while the radially outer ends of the chambers are in communication with a source of cooling air. As may be best understood from Figure 2, the radially outer end 44 is completely open so that cooling air flows directly into the forward chamber 30 as indicated by the arrow 46 in Figure 2. While the rearward chambers 32, 34,- and 36 are also in communication with the source of cooling air, the flow into these chambers is throttled by means of a radial extension 48 of the insert comprising opposite walls 50 capped by plate 52 which prevents the direct admission of the cooling air into the rearward chambers in the fashion in which the forward chambers receives its air, the cooling air being throttled into the rearward chambers by the provision of the holes 54 in the walls 50. The throttling results in the rearward chambers being at a lower pressure than the forward chamber 30. Referring to both figures, all of the chambers are provided with impingement ports in their sidewalls. Those ports provided in the forward chamber sidewalls are identified by the numeral 56 as best seen in Figure 1. The impingement ports in the convex sidewall of the insert for the rearward chambers are designated 58 while those in the concave wall are designate 60. All of the impingement ports are in rows which extend substantially radially. The rows of ports 56 of the forward chamber are more widely spaced from each other than the rows of ports from the rearward chambers on the convex side, and most of the concave side with the exception of the spacing of the rows of ports of the concave side of the first low-pressure chamber 32. The three rearward chambers are open to each other through the provision of a series of ports 62 in both of the partitions or ribs 40 and 42. The rearward chambers are also in open communication with each other at the radially outer portion of the chambers by virtue of the partitions 40 and 42 stopping short of the space 64 at the radially outer ends of the chambers. The insert has dimples 66 embossed outwardly in its leading edge portion and similar dimples 68 in its trailing edge portion to properly space the insert walls from the vane walls. With the arrangement as shown and described, the forward chamber 30 is maintained at a higher pressure than the rearward chambers 32, 34, and 36, so that the cooling jets issuing from the forward chamber are projected at a higher velocity than those exiting through the ports of the rearward chambers so that the higher velocity jets are projected at the higher heat load leading edge and forward convex surface areas of the vane, while the jets issuing from the lower pressure rearward chambers are projected at a lower velocity for cooling the relatively lower heat load regions of the airfoil vane. The relatively closer spaced rows of ports throughout the midchord region is to obtain more uniform cooling than would be obtained with widelyspaced high velocity jets. Typical pressures at which the chambers can be maintained may be in order of, for example, 160 psig (1102 E+03PA) for the forward chamber, 155 psig (1068 E+03Pa) for the rearward chambers, with the pressures in the spaces between the insert and the opposing vane walls being 150 psig (1033 E+03Pa).

Claims: CLAIMS: 1. A combustion turbine comprising an airfoilshaped, hollow, turbine vane having a leading edge wall, a trailing edge portion with an exit air slot therein, and pressure and suction sidewalls defining a single internal cavity in communication with said exit air slot, a single, unitary, air-cooling, hollow insert, of substantially complementary airfoil shape in cross section, located in said cavity and extending in a chordwise direction for substantially the entire extent of said cavity, a plurality of radially extending partition means in said insert dividing the interior thereof into a forward chamber in the leading edge portion of said vane, and at least two separate, successively rearward chambers in communication with each other, a plurality of impingement ports in the insert walls of all of said chambers, one radial end portion of said chambers being in communication with a source of cooling air, means for throttling the flow into said rearward chambers in which said forward chamber is at a relatively higher pressure than said rearward chambers so that the impingement jets through said ports of said forward chamber against said interior vane walls of said leading edge portion are at the significantly higher velocity than the impingement jets exiting the ports of said rearward chambers. 2. A turbine as claimed in claim 1 wherein said impingement ports in said forward chamber are more widely spaced than the majority of the impingement ports in said rearward chambers. 3. A turbine as claimed in claim 1 or 2 wherein said throttling means includes a radially outwardly extend ing portion of the insert at the radially outer ends of said rearward chambers, and a plurality of throttling holes in said portion of said insert. 4. A turbine as claimed in any one of claims 1 to 3 wherein said rearward chambers comprise at least three chambers. 5. A turbine as claimed in any one of claims 1 to 4 wherein said partition means comprises rigidly extending ribs, the first rib separating said forward chamber from the first successively rear chamber being imperforate, and successive rearward second ribs having openings therein. 6. A combustion turbine as claimed in 5 wherein said second ribs extend radially outwardly less than said first rib so that said rearward chambers are in open communication with each other in their radially outer portions. 7. A combustion turbine, including an airfoilshaped, hollow, turbine vane, constructed and adapted for use, substantially as hereinbefore described and illustrated with reference to the accompanying drawings.

Inventors: NORTH, WILLIAM EDWARD, SZEWCZUK, THOMAS M.
Applicants: WESTINGHOUSE ELECTRIC CORPORATION
Application year: 1985
Main classification: F01D5
IPC codes: F01D5, F01D9