The present disclosure relates generally to gas turbine engine cooling, and more particularly to the cooling of turbine blades in a gas turbine engine (GTE).
GTEs produce power by extracting energy from a flow of hot gas produced by combustion of fuel in a stream of compressed air. In general, turbine engines have an upstream air compressor coupled to a downstream turbine with a combustion chamber (“combustor”) in between. Energy is released when a mixture of compressed air and fuel is burned in the combustor. In a typical turbine engine, one or more fuel injectors direct a liquid or gaseous hydrocarbon fuel into the combustor for combustion. The resulting hot gases are directed over blades of the turbine to spin the turbine and produce mechanical power.
High performance GTEs include cooling passages and cooling fluid to improve reliability and cycle life of individual components within the GTE. For example, in cooling the turbine section, cooling passages are provided within the turbine blades to direct a cooling fluid therethrough. Conventionally, a portion of the compressed air is bled from the air compressor to cool components such as the turbine blades. The amount of air bled from the air compressor, however, is usually limited so that a sufficient amount of compressed air is available for engine combustion to perform useful work.
U.S. Pat. No. 5,603,606 to Glezer et al. (the '606 patent) describes a system for cooling airfoils, such as turbine blades and nozzles, in a GTE. According to the system described in the '606 patent, cooling fluid from the compressor section of the GTE is directed through a cooling path of a turbine blade. The turbine blade includes a plurality of holes or slots, which act as a means for swirling a portion of the cooling fluid through the turbine blade. The cooling fluid flows out of the plurality of holes or slots and into an empty gallery, where the cooling fluid swirls radially along the gallery.
In one aspect, a turbine blade of a gas turbine engine is disclosed. The blade may comprise a first cooling passage and a second cooling passage, where the second cooling passage may be located adjacent a leading edge of the blade. The blade may further comprise at least one slot formed in a partition disposed between the first and second cooling passages, and at least one turbulator disposed within the second passage and downstream of the at least one slot.
In another aspect, a system for cooling a turbine blade of a gas turbine engine is disclosed. The system may include a first cooling path disposed in an interior of the turbine blade and configured to receive a flow of cooling fluid, and a second cooling path disposed in the interior of the turbine blade and configured to receive the flow of cooling fluid. A plurality of passages may form each of the first and second cooling paths, and a plurality of slots may be formed in a partition disposed between two of the plurality of passages forming the first cooling path. The plurality of slots may be configured to guide the flow of cooling fluid through the first cooling path, and at least one turbulator may be disposed downstream of the flow of cooling fluid flowing through the plurality of slots.
In yet another aspect, a method of cooling a turbine blade of a gas turbine engine is disclosed. The method may include flowing a cooling fluid through a plurality of passages and through at least one slot formed in a partition disposed between two of the plurality of passages. The method may further include adding turbulence to at least part of the flow of cooling fluid downstream of the at least one slot, the turbulence being adjacent a leading edge of the turbine blade.
During operation, a cooling fluid, designated by the arrows 14, flows from the compressor section (not shown) to the turbine section 10. Furthermore, each of the combustion chambers (not shown) are radially disposed in a spaced apart relationship with respect to each other, and have a space through which the cooling fluid 14 flows to the turbine section 10. The turbine section 10 further includes a fluid flow channel 16 through which the cooling fluid 14 flows.
The turbine section 10 shown in
As is more clearly shown in
As shown in
A first cooling path 64 positioned within the peripheral wall 50 is interposed the leading edge 42 and the trailing edge 44 of each of the blades 22. The first cooling path 64 includes a first passage 54 extending between the first end 26 and the second end 40 of the turbine blade 22. Further included in the first cooling path 64 is a second passage 56, which extends between the first end 26 and the second end 40 of the turbine blade 22. The second passage 56 is interposed the leading edge 42 and the first passage 54 by a first partition 60, which is connected to the peripheral wall 50 at both the pressure side 46 and the suction side 48 of the turbine blade 22.
As shown in
A turbulator or turbulator element 62 configured to produce a turbulent fluid flow is disposed on the peripheral wall 50 in the second passage 56. In some embodiments, the turbulator element 62 may be formed integrally with the peripheral wall 50. As shown in
In some embodiments, a plurality of turbulator elements 62 may be provided in the second passage 56. For example, a plurality of radially disposed trip strips, like the trip strip shown in
As shown in
In some embodiments, a turbulator element 62 is provided having a turbulator element height D1 depending on the slot height D2. For example, a specified ratio of slot height D2 to turbulator element height D1 may be used to determine the turbulator element 62 to provide in the second passage 56. In one instance, a ratio of the slot height D2 to the turbulator element height D1 may be about 2 to 1, such that the slot height D2 is approximately two times the turbulator element height D1. For example, a turbine blade 22 may be provided having a slot height D2 of about 0.6100 mm (0.024 inches), in which case a corresponding turbulator element 62 may be provided having a turbulator element height D1 of about 0.305 mm (0.012 inches).
The distance D3 between the turbulator element 62 and the slot inlet opening may also depend on both the turbulator element height D1 and the slot height D2. For example, as described above, a larger turbulator element 62 (i.e. a turbulator element 62 having a greater turbulator element height D1) may be provided for a larger slot (i.e. a slot 58 having a greater slot height D2). Additionally or alternatively, the distance D3 may increase proportionately to an increase in slot height D2. For example, a ratio of the distance D3 to the slot height D2 may be less than about 4 to 1, or about 3.5 to 1. Thus, the distance D3 from the slot inlet opening to the turbulator or turbulator element 62 may be less than about four times the slot height D2, or about three and one half times the slot height D2. In one instance, for a turbine blade having a slot 58 with a slot height D2 of about 0.6100 mm (0.024 inches), a corresponding distance D3 may be about 2.16 mm (0.085 inches).
As shown in
As mentioned above with respect to
The aforementioned description is of the first stage turbine assembly 12; however, it should be known that the construction could be typical of the remainder of the turbine stages within the turbine section 10 where cooling may be employed.
The described system may be applicable to turbine blades of a GTE. Additionally, although the system has been described with respect to turbine blades in the first stage turbine assembly, the system may be applied to any turbine blade in any stage of the turbine section of a GTE. Furthermore, although the above-mentioned cooling system has been described for cooling a turbine blade, the system may be adapted to any airfoil, for example a first stage nozzle and shroud assembly. Additionally, the cooling system may be applied to any localized structure subject to heat that involves air flows and hot fluid temperatures. Moreover, the described cooling system may be applied in a variety of industries, for example, heat exchange, energy, aerospace, or defense.
The following operation will be directed to the first stage turbine assembly 12; however, the cooling operation of other airfoils and stages (turbine blades or nozzles) could be similar.
A portion of the compressed fluid from the compressor section of the GTE is bled from the compressor section and forms the cooling fluid 14 used to cool the first stage turbine blades 22. The compressed fluid exits the compressor section, flows through a combustor discharge plenum and enters into a portion of the fluid flow channel 16 as cooling fluid 14. The flow of cooling fluid 14 is used to cool and prevent ingestion of hot gases into the internal components of the GTE. For example, the air bled from the compressor section flows into a compressor discharge plenum, through spaces between a plurality of combustion chambers, and into the fluid flow channel 16 (
As shown in
The cooling fluid 14 flows through the slots 58 and over the turbulator element 62 creating a turbulent swirling flow that travels at least partially along the arcuate portion 96 of the second passage 56 in a radial direction, as shown in
A portion of the cooling fluid 14 may also exit the plurality of apertures 102, cooling a skin of the peripheral wall 50 in contact with combustion gases on the suction side 48 prior to mixing with the combustion gases. The remainder of the cooling fluid 14 in the first cooling path 64 exits the first cooling path outlet opening 74 in the trailing edge 44 to also mix with the combustion gases.
A second portion of the cooling fluid 14, after having passed through the cooling fluid inlet opening 34 (
Current swirl-cooling technology may be prone to manufacturing challenges due to a small slot height D2 (
The above-described system provides more efficient use of the cooling air bled from the compressor section of a GTE in order to facilitate increased component life and efficiency of the GTE. The swirling and turbulence of the cooling fluid 14 contributes to the efficiency of the cooling fluid 14 flow as the cooling fluid 14 passes through the turbine blade 22. Increasing the slot height D2 and providing a turbulator element 62 downstream of the slot 58 may decrease pressure losses, which may in turn improve cooling effectiveness downstream of the slot 58. Furthermore, efficiency is facilitated within the internal portion of the turbine blade 22 along the leading edge 42, downstream of the turbulator element 62.
Specifically, the swirling action caused by the arrangement of slots 58 in the first partition 60 and the turbulator element 62 in the second passage 56, the arcuate configuration of the arcuate portion 96 of the second passage 56, along with the flow of cooling fluid 14 through the angled passage 194, cause the cooling fluid 14 to generate a vortex flow in the second passage 56. The vortex flow caused by the slots 58 and turbulator element 62 leads to high local turbulence (vortices) along the arcuate portion 96 adjacent the leading edge 42 of the turbine blade 22. Turbulent flow, as opposed to laminar flow, has more energy for cooling components such as turbine blades 22. The portion of the cooling fluid 14 entering the angled passage 194 between the first passage 54 and the second passage 56 adds to the vortex flow by directing the cooling fluid 14 generally radially outward from the second passage 56 into the first horizontal passage 68. The cooling fluid 14 takes on a screw-type flow from the end 72 of the second passage 56 toward the first horizontal passage 68, which adds to the cooling efficiency in order to better cool the turbine blade 22.
The above-described system enables use of slot having a greater height, and thus easier and less costly to manufacture, without suffering from undesirable reductions in cooling performance, by use of a turbulator element. The turbulator element compensates for a reduced swirl cooling fluid velocity through the slot due to a larger slot height, and also increases the back-flow margin for blade tip film-cooling. As mentioned above, the size, specifically the height, of the turbulator element provided may depend on the slot height. Using a predetermined desired ratio of slot height to turbulator element height, for example a ratio of 2 to 1, may allow for improved cooling performance, while avoiding the manufacturing challenges associated with smaller slots. For example, where a turbulator element is provided as a single radial trip-strip, improvement in cooling may be achieved. Additionally, the above-described system may reduce the tendency of core die wear due to the increased slot height, thereby maintaining turbine blade manufacturing tolerances and increasing turbine blade core die life. Due to a decreased metal temperature of the turbine blade, the blade life may be extended, in some instances by three times. Improved cooling and extended blade life may thus be achieved with minimal core changes to the internal flow passages of the turbine blade by incorporation of a turbulator element downstream of the slots between first and second flow passages.
As noted above, in some embodiments the turbulator or turbulator element may be provided as at least one convex protrusion, or a plurality of convex protrusions, disposed on the peripheral wall in the second chamber. In some embodiments, the protrusions may be formed integrally with the peripheral wall. In yet other embodiments, as also noted above, the turbulator element may be provided as at least one concave cavity, or dimple, or a plurality of concave dimples, formed in the peripheral wall of the second chamber. A plurality of protrusions and/or dimples may be provided as the turbulator or turbulator element where, for example, a radially disposed trip strip may cause excessive pressure loss in the second chamber. Protrusions and/or dimples may provide a desired turbulent flow without causing too great of a reduction in pressure.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed turbine cooling system. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed system and method. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.