CN113530612B - Composite blade top groove structure capable of improving turbine gas heat performance - Google Patents
Composite blade top groove structure capable of improving turbine gas heat performance Download PDFInfo
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- CN113530612B CN113530612B CN202110715931.XA CN202110715931A CN113530612B CN 113530612 B CN113530612 B CN 113530612B CN 202110715931 A CN202110715931 A CN 202110715931A CN 113530612 B CN113530612 B CN 113530612B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
- F01D5/12—Blades
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Abstract
The invention relates to a composite blade top groove structure capable of improving the gas heat performance of a turbine, belonging to the field of gas turbines; the composite blade top groove comprises a conventional blade top groove and a blade top groove shoulder wall, and the blade top groove shoulder wall is arranged along the circumferential direction of the blade top; longitudinal ribs, transverse truncated ribs and grid-shaped ribs are arranged in the conventional blade top groove to form a composite blade top groove; the three fins are all vertical to the bottom surface of the groove fixed on the top of the composite blade; the longitudinal ribs are arranged along the middle arc line of the blade top; the 4 transverse intercepting ribs are arranged along the direction vertical to the camber line of the blade top, the camber line of the blade top is divided into 5 sections, and a first transverse intercepting rib, a second transverse intercepting rib, a third transverse intercepting rib and a fourth transverse intercepting rib are sequentially arranged from the front edge to the tail edge; the front edge high heat load area of the composite blade top groove is provided with grid-shaped fins for blocking the washing of the leakage flow of the front edge of the blade top to the surface of the bottom of the groove. The blade top groove structure provided by the invention can obviously reduce the heat load on the surface of the blade top and ensure that the high-pressure gas turbine safely and efficiently operates.
Description
Technical Field
The invention belongs to the field of gas turbines, and particularly relates to a composite blade top groove structure capable of improving the gas heat performance of a turbine.
Background
With the increasing prominence of environmental problems and the adjustment of energy structures, gas turbines are widely applied to the fields of power generation, aerospace industry, chemical industry and mechanical power as thermal power conversion equipment with high thermal efficiency. Currently, increasing the gas temperature at the inlet of a gas turbine is one of the most direct and effective ways to increase the power and thermal efficiency of a gas turbine. The actual gas turbine low aspect ratio high-pressure movable blades in service all adopt a shroud-free design, which directly causes leakage flow loss of a top clearance of the high-pressure turbine stage movable blades and the heat load of the blade tops to be increased remarkably. The thermal barrier coating is easy to fall off when the blade top of the movable blade is washed for a long time under the condition of high-temperature gas leakage flow, and the blade top is ablated more seriously to threaten the service life and the operation safety of the gas turbine.
Since there are large leakage losses of the bucket tip clearance and resulting extremely high thermal loads of the bucket tip, advanced bucket tip designs are required to reduce the tip leakage flow and thermal loads of the bucket tip. Most of the movable blade tips of the actual gas turbines adopt a groove-shaped blade tip structure to inhibit the leakage of the blade tip clearance. In operation of the gas turbine, high-temperature and high-pressure combustion gases migrate from the pressure surface side to the suction surface side under the pressure gradient drive on both sides of the bucket tip. This partial leakage flow accelerates in the narrow tip clearance, resulting in a significant increase in the thermal load on the tip, while the high-speed leakage flow does not coincide with the main flow direction on the suction side and produces strong mixing, resulting in large aerodynamic losses. The conventional blade top groove forms a large chamber between the blade top and the casing, and forms a sealing structure similar to labyrinth seal with the groove shoulder walls on the pressure surface side and the suction surface side, so that the sealing effect of the top of the movable blade is realized. The study showed that: the prior tip groove structure may significantly suppress leakage flow at the bucket tip compared to a flat tip, however, the leakage flow confined to the leading edge groove cavity migrates downstream within the flow direction pressure gradient driven download groove, forming a band-shaped high thermal load region near the tip groove leading edge bottom surface and reattachment line.
The conventional tip groove 3 shown in fig. 1 is adopted by the actual gas turbine bucket 1 at present to suppress the leakage flow of the high-pressure turbine bucket tip clearance 2, and the leakage flow can be obviously weakened relative to the flat blade tip. Fig. 2 shows the structural characteristics of a conventional tip groove 3, which may cause strong impact of leakage flow on the leading edge region 19 of the tip groove, and a vortex formed by the leakage flow migrates in the chord region 20 of the tip groove and the trailing edge region 21 of the tip groove and forms two high heat exchange regions, namely a leading edge high heat load region 8 at the bottom of the tip groove and a band-shaped high heat load region 9 at the bottom of the tip groove, which may pose a great challenge to the safe operation of the gas turbine rotor blade 1, for example, patent 202010262320.X discloses a turbine rotor blade groove-shaped tip structure and a design method thereof. Therefore, the development of a novel blade top groove structure capable of reducing the heat load has very important engineering application value for improving the pneumatic performance of the gas turbine, prolonging the service life and ensuring the safe and effective work of the gas turbine.
As shown in fig. 3, a prior art 202011126947.9 is an interrupted groove blade tip structure with transverse slots for a turbine blade, in which a suction surface side groove wall and a pressure surface side groove wall are arranged on a blade tip, and transverse slots are arranged at a fracture groove wall, and the structure has the advantage that the interrupted groove blade tip can effectively reduce the heat exchange coefficient of a blade tip leading edge region by eliminating a gas reattachment region formed in the groove blade tip of the interrupted region, weaken the intensity of local heat exchange, and improve the cooling characteristic of the blade tip; however, the leakage of the tip clearance cannot be effectively weakened, so that the cavity vortex in the groove cannot be kept all the time, and therefore, the band-shaped high heat exchange area on the surface of the bottom of the groove cannot be eliminated.
Disclosure of Invention
The technical problem to be solved is as follows:
the invention provides a novel blade top groove structure capable of reducing heat load, aiming at the characteristics that the blade top surface bears extremely high heat load due to leakage flow existing in the blade top gap of a high-pressure turbine of a gas turbine and the conventional blade top groove cannot effectively reduce the blade top heat load.
The technical scheme of the invention is as follows: a composite tip groove structure for improving turbine aerodynamic performance, the composite tip groove structure being located at the tip of a turbine rotor blade and comprising a conventional tip groove and a tip groove shoulder wall, the tip groove shoulder wall being arranged along the circumference of the blade tip; the conventional blade top groove is internally divided into three areas, namely a front edge area, a middle chord area and a tail edge area along a middle camber line; the method is characterized in that: longitudinal ribs, transverse truncated ribs and grid-shaped ribs are arranged in the conventional blade top grooves to form composite blade top grooves; the three fins are all vertical to the bottom surface of the groove fixed on the top of the composite blade;
the longitudinal ribs are arranged along the camber line of the blade top and are positioned in a strip-shaped high-heat-load area in the chord area in the groove of the composite blade top; the 4 transverse intercepting ribs are arranged along the direction vertical to the camber line of the blade top and are arranged vertical to the banded high-heat load area, the camber line of the blade top is divided into 5 sections, and the first transverse intercepting rib, the second transverse intercepting rib, the third transverse intercepting rib and the fourth transverse intercepting rib are arranged from the front edge to the tail edge in sequence;
the front edge high thermal load area of the composite blade top groove is provided with grid-shaped fins for blocking the leakage flow of the front edge of the blade top from scouring the surface of the bottom of the groove.
The further technical scheme of the invention is as follows: one end of each of the 4 transverse intercepting fins is seamlessly connected with the inner wall of the shoulder wall of the blade top groove positioned on the suction surface, and the other end of each transverse intercepting fin is seamlessly connected with the inner wall of the shoulder wall of the blade top groove positioned on the pressure surface; the area enclosed by the first transverse truncated rib, the second transverse truncated rib and the shoulder wall of the blade top groove is a front edge area which is positioned in a high heat load area of the front edge of the composite blade top groove; the area enclosed by the second, third and fourth transverse truncated ribs and the shoulder wall of the blade top groove is a middle chord area; the area enclosed by the fourth transverse truncated rib and the shoulder wall of the blade top groove is a tail edge area.
The further technical scheme of the invention is as follows: the longitudinal rib is positioned on a mean arc line between the second transverse truncated rib and the fourth transverse truncated rib, and two ends of the longitudinal rib are respectively connected with the second transverse truncated rib and the fourth transverse truncated rib in a seamless mode.
The further technical scheme of the invention is as follows: the grid-shaped fins comprise transverse grid truncation fins and longitudinal grid fins; the plurality of transverse grid intercepting ribs are arranged along the arc length direction of the camber line of the blade top, and the plurality of longitudinal grid ribs are arranged along the length direction of the front edge transverse intercepting rib.
The invention further adopts the technical scheme that: the first transverse intercepting rib and the blade top groove shoulder wall form a first front edge area, the intersection point of the arc lines of the suction surface and the pressure surface in the first front edge area is taken as a first boundary point, and the midpoint of the arc line of the suction surface in the first front edge area is taken as a second boundary point; 2 transverse grating truncation ribs and 3 longitudinal grating ribs are arranged in the first front edge area;
one end of each of the 2 transverse grating intercepting ribs is seamlessly connected with the inner wall of the shoulder wall of the blade top groove positioned on the pressure surface, and the two connecting points equally divide the area between the first boundary point and the first transverse intercepting rib; the other end of the blade top groove is in seamless connection with the inner wall of the shoulder wall of the blade top groove positioned on the suction surface, and the two connecting points equally divide the area between the second boundary point and the first transverse intercepting rib;
one end of each of the 3 longitudinal grid fins is seamlessly connected with the inner wall of the shoulder wall of the blade top groove on the suction surface, and the three connecting points equally divide the area between the first dividing point and the second dividing point; the other end is connected with the first transverse truncation rib in a seamless way, and the first transverse truncation rib is equally divided by three connecting points.
The further technical scheme of the invention is as follows: the first transverse intercepting rib, the second transverse intercepting rib and the blade top groove shoulder wall form a second front edge area, and 3 transverse grating intercepting ribs and 3 longitudinal grating ribs are arranged in the second front edge area;
one end of each of the 3 transverse grid truncation ribs is seamlessly connected with the inner wall of the shoulder wall of the blade top groove on the pressure surface, and the three connecting points equally divide the area between the first transverse truncation rib and the second transverse truncation rib; the other end of the blade top groove is in seamless connection with the inner wall of the shoulder wall of the blade top groove positioned on the suction surface, and the three connecting points equally divide the area between the first transverse truncated rib and the second transverse truncated rib;
one end of each of the 3 longitudinal grid fins is connected with the first transverse intercepting fin in a seamless mode, and the first transverse intercepting fin is equally divided by three connecting points; the other end is connected with the second transverse truncation rib in a seamless way, and the second transverse truncation rib is equally divided by the three connecting points.
The invention further adopts the technical scheme that: the heights of the longitudinal ribs, the transverse cut ribs and the grid-shaped ribs are all equal to the height H of the shoulder wall of the groove at the blade top 0 And are equal.
The further technical scheme of the invention is as follows: the widths of the longitudinal ribs and the transverse truncated ribs and the width W of the shoulder wall of the groove at the blade top 0 Are equal.
The invention further adopts the technical scheme that: the width of the grating truncation ribs and the longitudinal grating ribs is the width W of the shoulder wall of the groove at the blade top 0 0.5 times of the total weight of the powder.
Advantageous effects
The invention has the beneficial effects that: the invention arranges the fins along the camber line of the blade top groove and the direction vertical to the camber line, inhibits the leakage flow of the blade top gap from the pressure surface side to the suction surface side and the migration of the vortex system in the cavity of the blade top groove to the downstream, and arranges the transverse grating intercepting fins and the longitudinal grating fins in the front edge area of the blade top groove to block the washing of the leakage flow of the blade top front edge to the bottom surface of the groove. The specific analysis is as follows:
firstly, dividing a conventional blade top groove into three regions according to the interaction of leakage flow in the groove and a vortex structure, wherein the leakage characteristics of the three regions are different due to different widths of the blade top groove along the leakage direction; then, ribs are arranged along the camber line of the blade top, so that leakage flow is inhibited from being flushed towards the surface of the bottom of the groove under the extrusion of a scraping vortex near a casing above the groove, and the surface of the bottom of the groove is protected; then, arranging intercepting ribs along the vertical direction of the mean camber line of the blade top so as to intercept a strong vortex system which migrates from upstream to downstream along the mean camber line direction in the groove cavity, thereby realizing the protection of the groove surface of the downstream blade top; finally, a high thermal load area exists for the front edge of the bottom of the blade top groove, and transverse grid intercepting ribs and longitudinal grid ribs are arranged in the front edge area of the blade top groove. The fin is arranged along the pitch arc of the blade top groove to block high-temperature leakage flow scouring towards the bottom surface of the blade top groove, so that on one hand, the leakage flow migrating from the pressure surface side to the suction surface side can be inhibited, on the other hand, the direct scouring of the high-temperature leakage flow to the bottom surface of the blade top groove is weakened, and the blade top is protected. The intercepting rib blocks a chamber vortex which moves from upstream to downstream in the cavity of the groove of the blade top along the direction of a mean camber line, and can weaken the scouring of the chamber vortex on the surface of the bottom of the groove of the blade top. The transverse and longitudinal grid ribs in the region of the leading edge of the blade tip groove block the erosion of the surface of the bottom of the groove by the leakage flow of the leading edge of the blade tip.
1. In the invention, 4 transverse truncated ribs are adopted to divide the camber line at the top of the blade into 5 sections equally to form 5 areas. According to numerical simulation research, the tip grooves in the leading edge region along the chord length from the leading edge to the camber line by 20 percent are mainly influenced by the impact of the leading edge leakage flow to generate a leading edge high heat load region at the bottom of the tip grooves, and the leading edge region along the chord length from the camber line by 20 percent to 40 percent is mainly subjected to vortex washing of a cavity formed after the impact of the leading edge leakage flow to generate a banded high heat conforming region. In addition, the mid-chord groove bottom surface along 40% -80% chord length of the mid-camber line is mainly washed by the cavity vortex and the transverse leakage flow to form a belt-shaped high heat conforming area. At the mid-chord groove bottom surface along 80% -100% chord length of the mean camber line, the thermal load is small in this region due to the small width of the groove chamber and the small volume of the chamber, which results in leakage flow not being able to directly wash to the bottom surface. In view of this, the present invention arranges 4 ribs along the tip groove mean arc to divide the groove chamber five equal parts along the mean arc.
2. The invention adopts a structure that the connecting points at the two ends of the transverse grating truncation rib and the longitudinal grating rib equally divide the connecting area. When the transverse grating truncation ribs and the longitudinal grating ribs of the blade top groove front edge area are arranged, the process difficulty of processing and manufacturing is considered, the invention adopts the connection points of the transverse grating truncation ribs and the longitudinal grating ribs as an equal-division structure, on one hand, the manufacturing difficulty is reduced, on the other hand, high-temperature gas absorbed from the suction surface side and leakage flow exist at the front edge of the blade top groove of the gas turbine in actual operation, and are mixed to form a cavity vortex to migrate downstream, and therefore, the adoption of the structure not only inhibits the leakage flow migrating from the pressure surface side to the suction surface side, but also inhibits the high-temperature gas absorbed from the suction surface side of the front edge of the blade top.
3. The heights of the longitudinal ribs, the transverse truncated ribs, the grating truncated ribs and the longitudinal grating ribs are all equal to the height of the shoulder wall of the groove on the blade top. I.e. H 1 ＝H 2 ＝H 3 ＝H 4 ＝H 0 This is because the tip clearance height is extremely small, typically 0.5% of the blade height, typically a minimum clearance height to ensure optimum aerodynamic performance. The fins are higher than the shoulder wall of the groove at the top of the blade, so that the fins are easily scratched and rubbed with the casing, and the blades are damaged. The height of the fins is less than the height of the shoulder wall of the tip groove, which results in an increase in leakage flow, and therefore the height of the fins of the present invention is equal to the height of the shoulder wall of the tip groove. In addition, the longitudinal ribs and the transverse cutoff ribs are subjected to the leakage flow of the tip clearance and the strong washing of the chamber vortex, while taking into account the complexity of the design, their width is set to be equal to the width of the tip groove shoulder wall, i.e. to withstand the major aerodynamic thermal load. However, the grid cut-off ribs, longitudinal grid ribs, are mainly concentrated in the leading edge region of the tip groove, the main function of which is to block the leading edge leakage flow and the strong scouring effect of the high-temperature combustion gas ingested on the suction side on the bottom surface of the tip groove, aiming at producing a grid by arranging the ribs to form a plurality of small chambersThe sealing effect is expected to be smaller in the widths of the grating truncation ribs and the longitudinal grating ribs, and meanwhile, in consideration of the design and processing difficulty, the grating truncation ribs and the longitudinal grating ribs are arranged to be 0.5 times of the widths of the shoulder walls of the blade top grooves.
As shown in fig. 6 (b), the longitudinal ribs and the transverse truncated ribs arranged along the band-shaped high heat load region can make the band-shaped high heat load region at the bottom of the tip groove disappear, and the transverse grid truncated ribs at the leading edge region of the tip groove and the longitudinal grid ribs at the leading edge region of the tip groove make the leading edge high heat load region at the bottom of the tip groove disappear.
FIG. 7 is a graph comparing the heat transfer coefficient profiles of prior art and inventive composite tip grooves, the comparison showing that the inventive tip grooves significantly reduce the thermal loading of the tip.
The novel blade top groove structure capable of reducing the heat load can obviously reduce the heat load of the surface of the blade top and ensure that a high-pressure gas turbine can safely and efficiently operate. The novel blade top groove structure has universal applicability to reducing blade top clearance leakage flow and blade top heat load of movable blades in high-pressure gas turbines at present.
Drawings
FIG. 1 is a meridional cross-sectional view of a background art high pressure turbine stage with tip grooves;
FIG. 2 is a schematic view of a prior art bucket tip with conventional grooves and winglets;
FIG. 3 is a schematic view of a prior art discontinuous groove tip with a transverse slot;
FIG. 4 is a meridional cross-sectional view of a high pressure turbine stage with composite tip grooves according to the present invention;
FIG. 5 is a top view of the composite tip pocket construction of the present invention;
FIG. 6 (a) is a leakage flow and vortex system structure in a conventional tip pocket at different chord length locations, and FIG. 6 (b) is a leakage flow and vortex system structure in a composite tip pocket at different chord length locations;
FIG. 7 is a graph comparing heat transfer coefficient profiles for prior art and inventive composite tip grooves; (a) Is the heat transfer coefficient profile within the conventional tip flute, and (b) is the heat transfer coefficient profile of the tip flute of the present invention.
Description of reference numerals: 1-gas turbine rotor blade, 2-tip clearance, 3-conventional tip groove, 4-rim seal, 5-gas turbine stator blade, 6-tip groove shoulder wall, 7-tip leading edge, 8-leading edge high thermal load zone at tip groove bottom, 9-banded high thermal load zone at tip groove bottom, 10-tip groove mean camber line, 11-composite tip groove, 12-longitudinal rib disposed along banded high thermal load zone, 13-transverse rib, 14-transverse grid rib of tip groove leading edge zone, 15-longitudinal grid rib of tip groove leading edge zone, 16-tip leading edge suction side shoulder wall, 17-groove bottom surface of tip leading edge, 18-tip leading edge pressure side shoulder wall, 19-tip groove leading edge zone, 20-chord zone in tip groove, 21-tip groove trailing edge zone, 22-tip suction side vortex, 23-tip casing, 24-tip clearance scraping vortex, 25-tip pressure side vortex, 26-pressure side vortex, 27-tip groove leading edge zone, 27-tip groove leading edge pressure side vortex, 27-longitudinal grid rib, and 14-tip groove leading edge suction side vortex 4 29-longitudinal grid rib width W of leading edge region of tip groove 4 30-longitudinal grid rib height H of the leading edge region of the tip groove 3 31-width W of transverse grid truncated rib in leading edge region of tip groove 3 32-transversely cutting the width W of the rib 2 33-transversely cutting the width H of the fins 2 34-height H of longitudinal ribs arranged along the high thermal load zone of the strip 1 35-width of longitudinal ribs W arranged along the high thermal load zone of the strip 1 36-width W of tip groove shoulder wall 0 37-height of shoulder wall of concave groove on blade tip 0 38-tip groove trailing edge cavity vortex, 39-transverse slot.
Detailed Description
The embodiments described below with reference to the accompanying drawings are illustrative and intended to explain the present invention and should not be construed as limiting the present invention.
The invention discloses a composite blade top groove structure 11 capable of improving the thermal performance of a turbine, wherein the composite blade top groove structure 11 is characterized in that a transverse intercepting rib 13 and a longitudinal rib 12 arranged along a strip-shaped high-thermal-load area on the surface of the bottom of a conventional blade top groove 3 are arranged at the bottom of the conventional blade top groove, and a transverse grid intercepting rib 14 in the front edge area of the blade top groove and a longitudinal grid rib 15 in the front edge area of the blade top groove are introduced to form grid-shaped rib arrangement in the front edge area of the groove. The leading edge high thermal load zone 8 at the tip groove bottom and the band-shaped high thermal load zone 9 at the tip groove bottom were obtained by experiment or numerical simulation under given conditions. The transverse cutoff ribs 13 are arranged along the vertical banded high heat load zone while the longitudinal ribs 12 are arranged along the banded high heat load zone.
In a gas turbine in actual service, the conventional tip groove 3 structure has a limited effect of suppressing tip leakage flow, and three regions with different leakage characteristics, namely, a large groove chamber region close to the leading edge, are present in the tip groove, an angular vortex is formed at each of shoulder walls on the pressure surface side and the suction surface side of the region, the two angular vortex influence regions are the same in size, and the leakage flow is extruded towards the bottom surface of the tip groove by a scraping vortex near a casing above the tip groove, so that a band-shaped high heat load region is formed on the bottom surface of the tip groove. Specifically, the surface of the bottom of the tip forms a leading edge high heat load zone 8 at the bottom of the tip groove and a band-shaped high heat load zone 9 at the bottom of the tip groove under the strong scouring of the leading edge impingement flow and the reattachment flow at the middle cavity of the groove. The groove width of the intermediate chord length is reduced as compared with the groove near the leading edge, so that the angular vortex at the suction surface side shoulder wall of this region is suppressed and the band-like high heat load region formed by the impact of the leakage flow is shifted toward the suction surface side. Near the trailing edge, the groove width decreases significantly such that the leakage flow cannot impinge on the groove bottom surface and flow directly to the suction side, where the pressure and suction side corner vortices merge to form a large return vortex in the groove.
According to the experimental and numerical research, the following results are found: the tip clearance leakage flow migrates under the combined action of the pressure gradient from the pressure surface side toward the suction surface side and the pressure gradient from the leading edge toward the downstream. At the same time, the mainstream high-temperature gas is also taken in from the suction surface side shoulder wall 16 of the leading edge of the blade tip. In order to suppress the tip clearance leakage flow generated under the action of the driving pressure difference to the maximum extent and reduce the increase of the conventional groove bottom surface heat load caused by the leakage flow, the present invention arranges the cutoff rib 14 and the longitudinal rib 15 arranged along the band-shaped high heat load region of the groove bottom surface at the bottom of the conventional tip groove 3 with respect to the difference of the flow structure of the leakage flow of the tip groove leading edge region 19, the tip groove mid-chord region 20, and the tip groove trailing edge region 2, and can significantly reduce the scouring of the reattachment leakage flow to the groove bottom surface and at the same time can limit the development of the vortex system from the upstream to the downstream. In addition, the novel composite tip groove structure 12 of the present invention introduces the transverse grid truncated ribs 14 of the tip groove leading edge region and the longitudinal grid ribs 15 of the tip groove leading edge region into the tip groove leading edge region 19 to form a grid-like rib arrangement in the groove leading edge region, significantly suppressing the erosion of the leakage flow to the bottom surface of the tip groove leading edge, while attenuating the ingestion of the mainstream high temperature gas from the tip leading edge suction surface side shoulder wall 16.
Example (b):
referring to fig. 4 and 5, the composite tip groove structure for improving the thermal performance of the turbine is positioned at the top of a turbine rotor blade and comprises a conventional tip groove 3 and a tip groove shoulder wall 6, wherein the tip groove shoulder wall 6 is arranged along the circumferential direction of the blade top; the conventional blade top groove 3 is divided into three regions, namely a front edge region, a middle chord region and a tail edge region along a middle camber line; longitudinal ribs, transverse truncated ribs and grid-shaped ribs are arranged in the conventional blade top groove 3 to form a composite blade top groove; the three fins are all vertical to the bottom surface of the groove fixed on the top of the composite blade;
the longitudinal ribs are arranged along the pitch arc of the blade top and are positioned in a strip-shaped high-heat-load area of the middle chord area of the groove of the composite blade top; the 4 transverse intercepting ribs are arranged along the direction perpendicular to the camber line of the blade top and are arranged perpendicular to the strip-shaped high-heat-load area, the camber line of the blade top is divided into 5 sections, and the first transverse intercepting rib, the second transverse intercepting rib and the fourth transverse intercepting rib are sequentially arranged from the front edge to the tail edge; one end of each of the 4 transverse intercepting fins is seamlessly connected with the inner wall of the shoulder wall of the blade top groove positioned on the suction surface, and the other end of each transverse intercepting fin is seamlessly connected with the inner wall of the shoulder wall of the blade top groove positioned on the pressure surface; the area enclosed by the first transverse truncated rib, the second transverse truncated rib and the shoulder wall of the blade top groove is a front edge area which is positioned in a front edge high thermal load area of the composite blade top groove; the area enclosed by the second, third and fourth transverse truncated ribs and the shoulder wall of the blade top groove is a middle chord area; the area enclosed by the fourth transverse truncated rib and the shoulder wall of the blade top groove is a tail edge area. The longitudinal rib is positioned on a mean arc line between the second transverse truncated rib and the fourth transverse truncated rib, and two ends of the longitudinal rib are respectively connected with the second transverse truncated rib and the fourth transverse truncated rib in a seamless mode.
The front edge high thermal load area of the composite blade top groove is provided with grid-shaped fins for blocking the leakage flow of the front edge of the blade top from scouring the surface of the bottom of the groove. The grid-shaped fins comprise transverse grid truncated fins and longitudinal grid fins; the plurality of transverse grid intercepting ribs are arranged along the arc length direction of the camber line of the blade top, and the plurality of longitudinal grid ribs are arranged along the length direction of the front edge transverse intercepting rib.
The first transverse truncated rib and the blade top groove shoulder wall form a first front edge area, the intersection point of the suction surface arc line and the pressure surface arc line in the first front edge area is taken as a first boundary point, and the midpoint of the suction surface arc line in the first front edge area is taken as a second boundary point; 2 transverse grating truncation ribs and 3 longitudinal grating ribs are arranged in the first front edge area; one end of each of the 2 transverse grating intercepting ribs is seamlessly connected with the inner wall of the shoulder wall of the blade top groove positioned on the pressure surface, and the two connecting points equally divide the area between the first boundary point and the first transverse intercepting rib; the other end of the blade top groove is in seamless connection with the inner wall of the shoulder wall of the blade top groove positioned on the suction surface, and the two connecting points equally divide the area between the second boundary point and the first transverse intercepting rib; one end of each of the 3 longitudinal grid fins is seamlessly connected with the inner wall of the shoulder wall of the blade top groove on the suction surface, and the three connecting points equally divide the area between the first dividing point and the second dividing point; the other end is connected with the first transverse truncation rib in a seamless mode, and the first transverse truncation rib is equally divided by the three connecting points.
The first transverse intercepting rib, the second transverse intercepting rib and the blade top groove shoulder wall form a second front edge area, and 3 transverse grating intercepting ribs and 3 longitudinal grating ribs are arranged in the second front edge area; one end of each of the 3 transverse grating intercepting fins is seamlessly connected with the inner wall of the shoulder wall of the blade top groove positioned on the pressure surface, and the three connecting points equally divide the area between the first transverse intercepting fin and the second transverse intercepting fin; the other end of the blade top groove is in seamless connection with the inner wall of the shoulder wall of the blade top groove positioned on the suction surface, and the three connecting points equally divide the area between the first transverse truncated rib and the second transverse truncated rib; one end of each of the 3 longitudinal grid fins is connected with the first transverse intercepting fin in a seamless mode, and the first transverse intercepting fin is equally divided by three connecting points; the other end is connected with the second transverse truncation rib in a seamless way, and the second transverse truncation rib is equally divided by the three connecting points.
Referring to fig. 6 (a), in the conventional tip groove near the leading edge and the intermediate chord length, there are a suction side shoulder angle vortex 22 and a tip scraping vortex 24 and a pressure side shoulder angle vortex 25, and the leakage flow is swept from the pressure side toward the tip groove bottom surface by these three vortices to form a band-shaped high heat load region 9. The width of the tip groove near the trailing edge is reduced, the pressure side shoulder angle vortices 25 in the tip groove merge with the suction side shoulder angle vortices 22 to form return vortices 38, and the band-shaped high thermal load region 9 of the tip groove bottom surface near the trailing edge disappears.
Referring to fig. 6 (b), the novel tip groove structure of the present invention incorporates longitudinal ribs 12 and transverse truncated ribs 13 disposed along the banded high thermal load zone within the conventional groove, as well as transverse grid truncated ribs 14 at the leading edge region of the tip groove and longitudinal grid ribs 15 at the leading edge region of the tip groove. Specifically, the truncated rib height H along the vertical banded high thermal load zone in the composite tip flute 11 configuration 2 33 and a rib height 34H arranged along the high thermal load zone of the strip 1 Height 28H of transverse grid truncated ribs along leading edge region of tip groove 4 And a longitudinal grid rib height 30H of the leading edge region of the tip groove 3 (30) Are all equal to the height H of the shoulder wall of the groove of the blade top 0 37 equal, i.e. H 1 ＝H 2 ＝H 3 ＝H 4 ＝H 0 (ii) a Width of truncated rib 32W arranged along vertical strip-shaped high heat load area 2 And a rib width 35W arranged along the band-shaped high thermal load region 1 Height 37W of groove shoulder wall of blade top 0 Are equal, i.e. W 1 ＝W 2 ＝W 0 (ii) a Transverse grid truncation rib width 31W along tip groove leading edge region 3 And longitudinal grid rib of leading edge region of tip grooveSheet width 29W 4 30 is the height W of the shoulder wall of the groove on the blade top 0 0.5 times of 37, i.e. W 3 ＝W 4 ＝0.5W 0 。
In the implementation of the invention, modeling and simulation are firstly carried out through given blade cascade geometry and flow conditions, and then the longitudinal ribs 12 and the transverse truncated ribs 13 arranged along a strip-shaped high-heat-load area are determined according to the blade top gap flow structure in the conventional blade top groove and the heat load distribution characteristics of the bottom surface of the blade top groove, and meanwhile, the transverse grid truncated ribs 14 of the leading edge area 19 of the blade top groove and the longitudinal grid ribs 15 of the leading edge area of the blade top groove are introduced. The longitudinal ribs 12 and the transverse ribs 13 arranged along the strip-shaped high thermal load zone make it possible to eliminate the strip-shaped high thermal load zone 9 at the bottom of the tip groove, and the transverse grid ribs 14 and the longitudinal grid ribs 15 in the leading edge region 19 of the tip groove make it possible to eliminate the leading edge high thermal load zone 8 at the bottom of the tip groove. Truncated rib height 33H along vertical banded high thermal load zone in composite tip groove 11 configuration 2 And a rib height 34H disposed along the high thermal load zone of the strip 1 Transverse grid truncated rib height 28H along the leading edge region of the tip groove 4 And a longitudinal grid rib height 30H of the leading edge region of the tip groove 3 Are all equal to the height 37H of the shoulder wall of the groove of the blade top 0 Equal, i.e. H 1 ＝H 2 ＝H 3 ＝H 4 ＝H 0 (ii) a Width of cutoff rib 32W arranged along vertical strip-shaped high thermal load zone 2 And a rib width 35W arranged along the band-shaped high thermal load region 1 Height 37W of the shoulder wall of the groove on the blade top 0 Etc. are W 1 ＝W 2 ＝W 0 (ii) a Transverse grid truncated rib width 31W along the leading edge region of the tip groove 3 And longitudinal grid rib width 29W of the leading edge region of the tip groove 4 The height of the shoulder wall of the groove at the top of the blade is 37W 0 0.5 times of (W) 3 ＝W 4 ＝0.5W 0 。
The technical principle of the invention is as follows:
referring to FIG. 1, in a gas turbine, conventional bucket tip grooves 3 are employed to reduce leakage of the bucket tip gap 2. As shown in fig. 6 (a), the conventional tip groove 3 and the casing 23 form a sealing structure similar to a labyrinth seal, and leakage flow enters the tip clearance to form a strong suction surface side shoulder angle vortex 22, a tip scraping vortex 24 and a pressure surface side shoulder angle vortex 25 in a chamber between the tip groove and the casing. The leakage flow scours the surface of the bottom of the groove at the top of the blade to form a high heat load area 8 at the front edge of the bottom of the groove at the top of the blade and a high heat load area 9 at the band-shaped bottom of the groove at the top of the blade, thus threatening the operation safety and the service life of the top of the blade. Numerical simulation studies show that: the high heat load region is present only in the tip groove leading edge region 19 and the tip groove mid-chord region 20, while the tip groove trailing edge region 21 is less heat loaded. As can be seen from fig. 6 (a), the leakage vortex forms a tip scraping vortex 24 under the combined action of the tip clearance 2 and the casing 23, resulting in a leakage flow washing towards the groove bottom surface, resulting in a high thermal load region. The invention proposes longitudinal ribs 12 and transverse truncated ribs 13 arranged along a band-shaped high thermal load zone at the bottom surface of the conventional tip groove 3, while transverse grid truncated ribs 14 leading into the tip groove leading edge area 19 and longitudinal grid ribs 15 leading into the tip groove leading edge area. On one hand, the leakage flow of the blade top gap is weakened, the scouring of the leakage flow to the bottom surface 17 of the groove of the blade top front edge is weakened, and meanwhile, the transverse intercepting rib 13 inhibits the chamber vortex in the blade top groove from migrating from the front edge to the tail edge; on the other hand, the grating structure formed by the transverse grating intercepting ribs 14 of the blade tip groove leading edge area 19 and the longitudinal grating ribs 15 of the blade tip groove leading edge area can block the leakage flow of the blade tip leading edge from washing the bottom surface of the groove, and finally reduce the thermal load of the blade tip.
The composite blade tip groove 11 of the present invention significantly reduces the erosion of the blade tip surface by the blade tip leakage flow and reduces the thermal load of the blade tip by the longitudinal ribs 12 and the transverse cutoff ribs 13 arranged along the band-shaped high thermal load region on the bottom surface of the conventional blade tip groove 3, and the transverse grid cutoff ribs 14 of the blade tip groove leading edge region 19 and the longitudinal grid ribs 15 of the blade tip groove leading edge region are introduced at the same time.
The results of numerical simulations have preliminarily demonstrated that the novel tip pocket (11) of the present invention is capable of significantly reducing the thermal loading of the tip (as shown in fig. 7).
The applicant searches for related patents for reducing the thermal load of the blade top at home and abroad, and shows that a novel blade top groove structure similar to the structural characteristic of the invention is not found.
Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and that those skilled in the art may make variations, modifications, substitutions and alterations within the scope of the present invention without departing from the spirit and scope of the present invention.
Claims (8)
1. A composite tip groove structure for improving turbine thermal performance, the composite tip groove structure located at the tip of a turbine rotor blade, comprising a conventional tip groove and a tip groove shoulder wall, the tip groove shoulder wall being disposed circumferentially of the blade tip; the conventional blade top groove is internally divided into three areas, namely a front edge area, a middle chord area and a tail edge area along a middle camber line; the method is characterized in that: longitudinal ribs, transverse truncated ribs and grid-shaped ribs are arranged in the conventional blade top groove to form a composite blade top groove; the three fins are all vertical to the bottom surface of the groove fixed on the top of the composite blade;
the longitudinal ribs are arranged along the camber line of the blade top and are positioned in a strip-shaped high-heat-load area in the chord area in the groove of the composite blade top; the 4 transverse intercepting ribs are arranged along the direction vertical to the camber line of the blade top and are arranged vertical to the banded high-heat load area, the camber line of the blade top is divided into 5 sections, and the first transverse intercepting rib, the second transverse intercepting rib, the third transverse intercepting rib and the fourth transverse intercepting rib are arranged from the front edge to the tail edge in sequence;
the front edge high thermal load area of the composite blade top groove is provided with grid-shaped fins for blocking the leakage flow of the front edge of the blade top from scouring the surface of the bottom of the groove;
one end of each of the 4 transverse intercepting fins is seamlessly connected with the inner wall of the blade top groove shoulder wall positioned on the suction surface, and the other end of each transverse intercepting fin is seamlessly connected with the inner wall of the blade top groove shoulder wall positioned on the pressure surface; the area enclosed by the first transverse truncated rib, the second transverse truncated rib and the shoulder wall of the blade top groove is a front edge area which is positioned in a front edge high thermal load area of the composite blade top groove; the area enclosed by the second, third and fourth transverse truncated ribs and the shoulder wall of the blade top groove is a middle chord area; the area enclosed by the fourth transverse truncated rib and the shoulder wall of the blade top groove is a tail edge area.
2. The composite tip groove structure for improving thermal performance of a turbine as claimed in claim 1, wherein: the longitudinal rib is positioned on a mean arc line between the second transverse truncated rib and the fourth transverse truncated rib, and two ends of the longitudinal rib are respectively connected with the second transverse truncated rib and the fourth transverse truncated rib in a seamless mode.
3. The composite tip pocket structure for enhancing thermal performance of a turbine as claimed in claim 1, wherein: the grid-shaped fins comprise transverse grid truncation fins and longitudinal grid fins; the plurality of transverse grid intercepting ribs are arranged along the arc length direction of the camber line of the blade top, and the plurality of longitudinal grid ribs are arranged along the length direction of the front edge transverse intercepting rib.
4. The composite tip pocket structure for enhancing thermal performance of a turbine as defined in claim 3, wherein: the first transverse truncated rib and the blade top groove shoulder wall form a first front edge area, the intersection point of the suction surface arc line and the pressure surface arc line in the first front edge area is taken as a first boundary point, and the midpoint of the suction surface arc line in the first front edge area is taken as a second boundary point; 2 transverse grid truncation ribs and 3 longitudinal grid ribs are arranged in the first front edge area;
one end of each of the 2 transverse grating intercepting ribs is seamlessly connected with the inner wall of the shoulder wall of the blade top groove positioned on the pressure surface, and the two connecting points equally divide the area between the first boundary point and the first transverse intercepting rib; the other end of the blade top groove is in seamless connection with the inner wall of the shoulder wall of the blade top groove positioned on the suction surface, and the two connecting points equally divide the area between the second boundary point and the first transverse intercepting rib;
one end of each of the 3 longitudinal grid fins is seamlessly connected with the inner wall of the shoulder wall of the blade top groove on the suction surface, and the three connecting points equally divide the area between the first boundary point and the second boundary point; the other end is connected with the first transverse truncation rib in a seamless way, and the first transverse truncation rib is equally divided by three connecting points.
5. The composite tip pocket structure for enhancing thermal performance of a turbine as defined in claim 3, wherein: the first transverse intercepting rib, the second transverse intercepting rib and the blade top groove shoulder wall form a second front edge area, and 3 transverse grating intercepting ribs and 3 longitudinal grating ribs are arranged in the second front edge area;
one end of each of the 3 transverse grid truncation ribs is seamlessly connected with the inner wall of the shoulder wall of the blade top groove on the pressure surface, and the three connecting points equally divide the area between the first transverse truncation rib and the second transverse truncation rib; the other end of the blade top groove is in seamless connection with the inner wall of the shoulder wall of the blade top groove positioned on the suction surface, and the three connecting points equally divide the area between the first transverse intercepting rib and the second transverse intercepting rib;
one end of each of the 3 longitudinal grid fins is seamlessly connected with the first transverse truncated fin, and the first transverse truncated fin is equally divided by the three connecting points; the other end is connected with the second transverse truncation rib in a seamless mode, and the second transverse truncation rib is equally divided by the three connecting points.
6. The composite tip pocket structure for enhancing thermal performance of a turbine as claimed in claim 1, wherein: the heights of the longitudinal ribs, the transverse truncated ribs and the grid-shaped ribs are all equal to the height H of the shoulder wall of the groove at the top of the blade 0 Are equal.
7. The composite tip pocket structure for enhancing thermal performance of a turbine as claimed in claim 1, wherein: the width of the longitudinal rib and the transverse truncated rib and the width W of the shoulder wall of the groove at the blade top 0 Are equal.
8. The composite tip pocket structure for enhancing thermal performance of a turbine as defined in claim 4, wherein: the widths of the grid truncation ribs and the longitudinal grid ribs are the width W of the shoulder wall of the groove at the blade top 0 0.5 times of the total weight of the powder.
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| US5997251A (en) * | 1997-11-17 | 1999-12-07 | General Electric Company | Ribbed turbine blade tip |
| US8083484B2 (en) * | 2008-12-26 | 2011-12-27 | General Electric Company | Turbine rotor blade tips that discourage cross-flow |
| JP6159151B2 (en) * | 2013-05-24 | 2017-07-05 | 三菱日立パワーシステムズ株式会社 | Turbine blade |
| US10443405B2 (en) * | 2017-05-10 | 2019-10-15 | General Electric Company | Rotor blade tip |
| CN110566284A (en) * | 2019-10-09 | 2019-12-13 | 西北工业大学 | Groove blade top structure with partition ribs |
| CN112240229A (en) * | 2020-10-20 | 2021-01-19 | 西北工业大学 | A high-efficient cooling structure for turbine power blade top |
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