CN112682109A - Turbine rotor blade tip leakage flow cooperative inhibition structure - Google Patents
Turbine rotor blade tip leakage flow cooperative inhibition structure Download PDFInfo
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- CN112682109A CN112682109A CN202011388601.6A CN202011388601A CN112682109A CN 112682109 A CN112682109 A CN 112682109A CN 202011388601 A CN202011388601 A CN 202011388601A CN 112682109 A CN112682109 A CN 112682109A
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Abstract
The invention discloses a turbine rotor blade top leakage flow cooperative inhibition structure which comprises a turbine casing and blades in clearance fit with the turbine casing, wherein a suction surface and a pressure surface are respectively formed on two sides of each blade, a blade top groove is formed on a blade top plane of each blade, which is opposite to the turbine casing, the outer side of the top of each blade is provided with an overhanging blade top winglet, the upper surface of each blade top winglet is overlapped with the blade top plane, and an included angle is formed between the side surface of each blade top winglet and the side surface of each blade; and a plurality of self-emission flow holes for reverse jet flow are arranged on the blade top winglet positioned on one side of the pressure surface, and the self-emission flow holes are connected with the side surface and the upper surface of the blade top winglet. The invention organically combines the blade top groove, the winglet and the spontaneous emission hole, thereby greatly improving the inhibition effect on the leakage flow; an external air source is not needed, the passive control method is adopted, complex pipeline connection is omitted, the weight of the engine is reduced, and the efficiency loss of the engine caused by the external air source is also omitted; the whole structure is simple, and the processing and the engineering application are more convenient.
Description
Technical Field
The invention relates to a turbine structure, in particular to a synergistic inhibition structure for leakage flow at the top of a turbine rotor blade.
Background
Axial flow turbines are mechanical components often used in the field of energy conversion and propulsion. The high pressure turbine rotor is the most critical component of the overall turbine. In order to prevent the collision and abrasion of the blade tip and the casing, a certain clearance is reserved between the blade tip of the turbine rotor blade and the turbine casing, the general height of the blade tip clearance accounts for about 1% of the blade grid channel, and the height of the blade tip clearance can also change under different operating states of the turbine. The blade tip clearance is arranged in the whole turbine flow field, the two sides of the blade tip clearance are respectively communicated with the suction surface and the pressure surface of the blade, and the relative thickness of the blade is small, so that fluid on the pressure side can enter the suction side through the clearance under the action of huge pressure difference on the two sides of the clearance to form blade tip clearance leakage flow. After entering one side of the suction surface, the leakage flow rotates towards the middle part of the blade to form leakage vortex in the process of mixing with the main flow. Because the clearance leakage flow flows from the pressure surface to the suction surface in the clearance and does not undergo the expansion in the main flow field of the turbine rotor to push the turbine blade to do work, the working capacity of the single-stage turbine is necessarily reduced due to the existence of the clearance leakage flow. Meanwhile, the flow separation of the clearance leakage flow and the flow mixing with the main flow inevitably bring more secondary flow loss to the turbine, resulting in the reduction of the turbine efficiency. Moreover, the turbine blade operates at the outlet of the combustion chamber where the thermal environment is the most severe, the existence of clearance leakage flow increases the contact area of the tip of the turbine rotor and the high-temperature main flow, which further increases the thermal load of the turbine blade, and therefore, a necessary leakage flow control means is required to reduce the influence of the tip clearance leakage flow. However, the conventional passive control methods such as tip grooves still have a great room for improvement in the leakage flow suppression effect, and some control methods even have adverse effects for different tip structures. Although the structures with the crown tops, such as the sealing labyrinth, have a good effect of inhibiting leakage flow, the problems of high processing difficulty, low mechanical strength and the like exist due to the complex structure of the structure.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a turbine rotor blade tip leakage flow inhibiting structure applying solid blade modification and fluid spontaneous control.
The technical scheme is as follows: the invention discloses a turbine rotor blade top leakage flow cooperative inhibition structure which comprises a turbine casing and blades in clearance fit with the turbine casing, wherein a suction surface and a pressure surface are respectively formed on two sides of each blade, blade top grooves are formed in blade top planes of the blades, which are opposite to the turbine casing, the outer sides of the tops of the blades are provided with overhanging blade top winglets, the upper surfaces of the blade top winglets are overlapped with the blade top planes, and included angles are formed between the side surfaces of the blade top winglets and the side surfaces of the blades; and a plurality of self-emission flow holes for reverse jet flow are formed in the blade top winglet positioned on one side of the pressure surface, and the self-emission flow holes are connected with the side surface and the upper surface of the blade top winglet.
Further, a spontaneous jet hole is utilized to introduce high-pressure fluid on the pressure side into the gap to form jet flow, the jet flow forms counter flow in the gap and enters a central main flow area of the leakage flow, and a counter flow structure forms a remarkable blocking effect on the main flow. The structural factors of the spontaneous jet hole on the winglet on the pressure surface side comprise a spontaneous jet hole pattern and an equivalent diameter d, an included angle beta between an inlet of the spontaneous jet hole and the side surface of the winglet on the blade top, an included angle alpha between an outlet of the spontaneous jet hole and the upper surface of the winglet on the blade top, and a distance w between the outlet of the spontaneous jet hole and the edge of the winglet on the blade top3And jet hole spacing l. The control effect of the jet holes in the same plane is increased along with the reduction of the hole spacing l, the spontaneous jet holes are arranged at equal intervals, and the ratio of the self-jet hole spacing l to the self-jet hole equivalent diameter d is 4-16. The value of the equivalent diameter d of the reasonable spontaneous jet hole is in positive correlation with the size of the gap h, the equivalent diameter d of the spontaneous jet hole is 0.5-5 times of the height h of the gap formed between the turbine casing and the blade, and the control effect can be improved by adjusting the outlet hole pattern. An included angle beta between an inlet of the spontaneous jet hole and the side surface of the winglet at the top of the blade needs to ensure that the flow resistance is as small as possible on the premise of meeting the jet flow, and the preferred range is 45-135 degrees; an included angle alpha between an outlet of the spontaneous jet hole and the upper surface of the winglet needs to ensure that the jet outflow direction and the local flow direction of the leakage flow are on the same plane, preferably, the spontaneous jet hole is in a circular arc shape, the outlet direction of the spontaneous jet hole is opposite to the movement direction of the leakage flow, and the value range of alpha is 30-75 degrees; distance w between outlet of spontaneous jet hole and edge of winglet on blade top3The height h of the clearance is preferably 2 to 10 times the height h of the clearance formed between the turbine casing and the blade.
Furthermore, the main structural parameter of the blade top groove structure is the groove depth d1And the width w of the shoulder1. The control effect of the groove is increased along with the increase of the depth of the groove, but the control effect is not obviously changed along with the depth after the depth of the groove reaches a certain degree; width w of the shoulder1The strength requirement is also satisfied in relation to the shape of the leaves and the size of the gaps. Preferably, the depth d of the tip groove12.5% -10% of the height of the blade; the two sides of the groove are of convex shoulder structures, and the width w of the convex shoulder1Is 1 to 4 times of the clearance h formed between the turbine casing and the blade.
Further, in order to further improve the inhibition performance, the bottom of the blade tip groove is of a flat groove structure or a stepped groove structure, wherein the stepped groove is of a right-angle step, the step surface of the right-angle step is over against a pressure surface or a suction surface, the depth of the stepped groove can be adjusted, but it is necessary to ensure that the step part has an effect on the vortex which revolves around in the groove, the stepped groove is of a right-angle step, the step surface of the right-angle step is over against the pressure surface or the suction surface, and the step height d of the right-angle step2Is the depth d of the groove of the blade top125% -75% of the total weight of the leaf, but should be selected according to the actual leaf-shaped structure.
Further, the structural factors of the winglet include the distance w by which the winglet overhangs2And the angle gamma between the tip plane and the side and upper surfaces of the tip winglet. Overhang distance w2The larger the winglet, the better the control of leakage flow, but too large can be detrimental to the shape strength; the included angle gamma between the side surface and the upper surface of the winglet on the top of the blade determines the geometrical configuration of the winglet, the smaller the gamma angle is, the better the control effect of the winglet is, but the smaller the gamma angle is, the lower the strength of the winglet is. Meanwhile, the relative position relationship between the winglet and the spontaneous jet hole is also considered. Preferably, the winglet overhangs by a distance w2The included angle gamma between the side surface and the upper surface of the winglet is 25-75 degrees and is 3-15 times of the gap h formed between the turbine casing and the blade.
The working principle is as follows: the invention utilizes a blade top modification structure which inhibits leakage flow by adjusting the flow boundary degree of the leakage flow and comprises a blade top groove and a blade top winglet, and utilizes a blade top structure which guides spontaneous control jet flow to generate, wherein the specific structure is that a spontaneous jet hole is arranged on the blade top winglet at one side of a pressure surface. The synergistic inhibition is characterized in that a groove-winglet structure changes the flow boundary of the leakage flow, increases the flow distance of the leakage flow along the way and reduces the clearance flow area; the spontaneous jet hole is arranged on the pressure side winglet, the increased jet hole is not a space, and high-pressure fluid of the pressure surface of the guide vane is injected into a central main flow area of the gap leakage flow to obviously block the main flow of the leakage flow.
Has the advantages that: compared with the prior art, the invention has the following remarkable characteristics: the invention organically combines the blade top groove, the winglet and the spontaneous emission hole, thereby greatly improving the inhibition effect on the leakage flow; the solid blade modification and the fluid spontaneous control do not need an external air source, and the method belongs to a passive control method, thereby not only saving complex pipeline connection and reducing the weight of an engine, but also saving the efficiency loss of the engine caused by the external air source; the whole structure is relatively simple, and the processing and the engineering application are relatively convenient; the application range is wider, and because the cooperative control scheme is adopted, the control effect on the blade top gaps with different sizes is remarkable.
Drawings
FIG. 1 is a top view of a blade structural configuration of the present invention;
FIG. 2 is a front view of the blade construction of the present invention;
FIG. 3 is a schematic view of a cooperating control blade tip in the direction A-A of FIG. 2;
FIG. 4 is a schematic view of the tip groove configuration of the present invention;
FIG. 5 is a schematic view of the gap leakage flow of the corresponding groove structure of FIG. 4;
FIG. 6 is a graph comparing tip leakage flow rates for a tip recess-tip winglet combination;
FIG. 7 is a graph comparing tip leakage flow rates for a tip groove-tip winglet-self-orifice combination.
Detailed Description
The invention is further illustrated by the following examples and figures.
Referring to fig. 1-3, the turbine rotor tip leakage flow cooperative inhibiting structure designed by applying the solid blade modification and fluid spontaneous control cooperative control principle includes a turbine casing 7 and a blade 1, where the overall height s of the blade 1 is 122mm, a gap h exists between the turbine casing 7 and the blade 1, the height of the gap h is a fixed value, specifically 1% of the blade height, and the gap is located in the entire turbine flow field,the two sides of the blade 1 form a pressure surface 2 and a suction surface 3 in a turbine flow field, and fluid on one side of the pressure surface 2 enters one side of the suction surface 3 through a gap under the action of huge pressure difference on the two sides of the gap to form blade top gap leakage flow. A tip recess 4 is provided in the tip plane of the blade 1 facing the turbine casing 7, wherein the depth d of the tip recess 41Is 5 percent of the height of the blade 1, particularly 6.1mm, two sides of the blade top groove 4 are convex shoulders with the width w of each convex shoulder1Equal to the gap height h, in particular 1.22 mm; the outer side of the top of the blade 1 is provided with an overhanging blade top winglet 5, the upper surface of the blade top winglet 5 is overlapped with a blade top plane, the side surface of the blade top winglet 5 forms an included angle with the side surface of the blade 1, and the included angle gamma between the side surface of the blade top winglet 1 and the upper surface is 65 degrees; a plurality of self-emission flow holes 6 which are arranged at equal intervals are arranged on the blade top winglet 5 positioned on one side of the pressure surface 2, the self-emission flow holes 6 are connected with the side surface and the upper surface of the blade top winglet 5, the self-emission flow holes 6 are arc-shaped, the included angle beta between the inlet of the self-emission flow holes 6 and the side surface of the blade top winglet 5 is 90 degrees, the included angle alpha between the outlet of the self-emission flow holes 6 and the upper surface of the blade top winglet 5 is 60 degrees, and the distance w between the outlet of the self-emission flow holes 6 and the edge of the blade3Is 1.3 times of the gap height h, specifically 1.596 mm.
In order to research the effect of the groove-winglet-spontaneous jet flow blade top structure on blade top leakage flow, a plane blade grid is selected as a basic blade shape, a numerical calculation method is adopted, and the influence of the groove-winglet-spontaneous jet flow blade top structure on blade tip leakage flow is simulated under the working condition of a typical engine turbine rotor. The settings were as follows: numerical simulation is carried out on a cascade flow field with a blade tip constructed by a synergistic inhibition method under a typical high-temperature high-pressure working condition through an RANS method. The geometry setup included models, where model Base1 indicated no clearance between the turbine case and the blade, model Base2 indicated the blade was a flat top blade, and model Base3 was a flat top blade with grooves; models A0, A1, A2, A3, B0, B1, B2 and B3 all adopt a groove-winglet-spontaneous jet structure, and the width w of the winglet at the top of each model A0, A1, A2 and A32The width w of the winglet of the models B0, B1, B2, B3 is 1.85 times the height h of the gap, in particular 2.257mm2Is 3.7 times of the gap height hThe diameter is 4.514mm, the equivalent diameter d of the spontaneous jet holes in each model is a fixed value, specifically 1.22mm, and the ratio of the spacing l between the spontaneous jet holes to the equivalent diameter d is detailed in the following table 1.
TABLE 1 model geometry setup
It should be noted that other parameters in the above models, such as the tip groove depth d, are described1Width w of shoulder1Distance w between outlet of self-emission hole 6 and edge of winglet 53The values of the included angle γ between the side surface and the upper surface of the winglet 1 on the leaf top, the included angle β between the inlet of the self-emission flow hole 6 and the side surface of the winglet 5 on the leaf top, the included angle α between the outlet of the self-emission flow hole 6 and the upper surface of the winglet 5 on the leaf top, and the like are fixed and are not used as parameters which change during lateral comparison.
FIG. 6 shows groove-winglet combined tip leakage flow, where it can be seen that with the width w of the tip winglet2Increasing, the tip leakage flow rate gradually decreased, indicating an increased control of leakage flow by increasing width, while the leakage flow rate for model Base3 was lower than for model Base2, indicating an increased control of leakage flow by the groove versus structure. Fig. 7 shows the groove-winglet-spontaneous jet combined tip leakage flow, where it can be seen that models a0 and B0 without spontaneous jet holes are adopted, the tip leakage flow is higher than other models with spontaneous jet holes, which indicates that the setting of spontaneous jet holes can further increase the blocking effect on the main flow of leakage flow, and secondly, as the ratio of hole pitch l to equivalent diameter d decreases, the leakage flow decreases, and the ratio of hole pitch l to equivalent diameter d decreases, which indicates that the distance between adjacent holes on the structure decreases, at this time, the density of spontaneous jet holes on the whole structure increases continuously, so the leakage flow decreases as the density of spontaneous jet holes increases.
In order to research the control effect of the stepped grooves on the gap flow, clarify the mechanism of the blade top grooves for controlling the gap flow, analyze the influence of the stepped grooves on the gap leakage flow, and adopt5 types of tip structures were used, shown in FIG. 4, of type (a): flat top (Type-A); type (b): the depth of the groove is 2.5% of the leaf height (Type-B); type (c): the depth of the groove is 5% of the leaf height (Type-C); type (d): adopting right-angle steps, wherein the step surfaces of the right-angle steps are just opposite to the pressure surface (Type-D) and the Type (e): adopt the right angle ladder, the ladder face of right angle ladder just is to suction surface (Type-E). Referring to FIG. 5, the tip clearance leakage flow for five flute configurations is shown, with the clearance leakage flow decreasing with increasing flute depth, illustrating flute depth d1The increase of (b) increases the control effect of the leakage flow, and secondly, after the groove is provided with the step structure, the step structure can keep a certain effect of controlling the leakage flow, but the leakage flow value of the type (d) is higher than that of the type (b), but the leakage flow value of the type (e) is lower than that of the type (c), and the analysis result shows that the complexity of the flow structure in the groove is increased due to the step structure at the bottom of the groove. Compared with a conventional groove, the number of main vortexes in the stepped groove is changed from one to two, the swirling directions of the two vortexes are the same, and for the step flow of the type (d), the vortex structure at the rear part of the stepped groove is smaller, the strength of the stepped groove is smaller, and the leakage flow control effect is poorer; and the groove depth of the step structure of the type (e) close to the suction surface is larger, and the formed vortex is close to the groove with the large depth of the type (c), so that a better control effect can be achieved.
Claims (8)
1. The utility model provides a turbine rotor blade tip leakage flow suppresses structure in coordination, includes turbine casing (7) and with turbine casing (7) clearance fit's blade (1), the both sides of blade (1) form suction surface (3) and pressure surface (2) respectively, its characterized in that: a blade top groove (4) is formed in a blade top plane of the blade (1) opposite to the turbine casing (7), an outward extending blade top winglet (5) is arranged on the outer side of the top of the blade (1), the upper surface of the blade top winglet (5) is overlapped with the blade top plane, and an included angle is formed between the side surface of the blade top winglet (5) and the side surface of the blade (1); the blade top winglet (5) positioned on one side of the pressure surface (2) is provided with a plurality of spontaneous jet holes (6) used for reverse jet, and the spontaneous jet holes (6) are connected with the side surface and the upper surface of the blade top winglet (5).
2. The turbine rotor tip leakage flow synergistic containment structure of claim 1, wherein: the self-jet holes (6) are arranged at equal intervals, the equivalent diameter d of the self-jet holes (6) is 0.5-5 times of the height h of a gap formed between the turbine casing (7) and the blade (1), and the ratio of the distance l between the self-jet holes (6) to the equivalent diameter d of the self-jet holes (6) is 4-16.
3. The turbine rotor tip leakage flow synergistic containment structure of claim 2, wherein: the side included angle beta of the inlet of the spontaneous jet hole (6) and the winglet (5) on the top of the leaf is 45-135 degrees, the included angle alpha of the outlet of the spontaneous jet hole (6) and the upper surface of the winglet (5) on the top of the leaf is 30-75 degrees, the spontaneous jet hole (6) is in an arc shape, and the outlet direction of the spontaneous jet hole (6) is opposite to the movement direction of leakage flow.
4. The turbine rotor tip leakage flow synergistic containment structure of claim 2, wherein: the distance w between the outlet of the self-emission flow hole (6) and the edge of the winglet (5)3Is 2 to 10 times of the height h of the gap formed between the turbine casing (7) and the blade (1).
5. The turbine rotor tip leakage flow synergistic containment structure of claim 1, wherein: the depth d of the blade tip groove (4)12.5-10% of the height of the blade (1), convex shoulders at two sides of the blade top groove (4), and the width w of the convex shoulders1Is 1 to 4 times of the height h of the gap formed between the turbine casing (7) and the blade (1).
6. The turbine rotor tip leakage flow synergistic suppression structure according to claim 1 or 5, characterized in that: the bottom of the blade top groove (4) is of a flat groove structure or a stepped groove structure.
7. The turbine rotor tip leakage flow synergistic containment structure of claim 6, wherein: what is needed isThe stepped groove adopts right-angled steps, the step surface of the right-angled steps is just opposite to the pressure surface (2) or the suction surface (3), and the step height d of the right-angled steps2The depth d of the blade top groove (4)125 to 75 percent of the total weight of the composition.
8. The turbine rotor tip leakage flow synergistic containment structure of claim 1, wherein: the distance w by which the tip winglet (5) extends outward2The height h of a gap formed between the turbine casing (7) and the blade (1) is 3-15 times, and the included angle gamma between the side surface and the upper surface of the winglet (1) at the top of the blade is 25-75 degrees.
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| CN202011388601.6A CN112682109A (en) | 2020-12-02 | 2020-12-02 | Turbine rotor blade tip leakage flow cooperative inhibition structure |
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| CN202011388601.6A CN112682109A (en) | 2020-12-02 | 2020-12-02 | Turbine rotor blade tip leakage flow cooperative inhibition structure |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115977999A (en) * | 2023-01-12 | 2023-04-18 | 山东科技大学 | Subsonic compressor, rotor blade and flow stability expansion control method |
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| CN105179022A (en) * | 2015-09-30 | 2015-12-23 | 北京大学 | Turbine blade of blade top rib wing structure |
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| WO2019088992A1 (en) * | 2017-10-31 | 2019-05-09 | Siemens Aktiengesellschaft | Turbine blade with tip trench |
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2020
- 2020-12-02 CN CN202011388601.6A patent/CN112682109A/en active Pending
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| CN105179022A (en) * | 2015-09-30 | 2015-12-23 | 北京大学 | Turbine blade of blade top rib wing structure |
| CN205225343U (en) * | 2015-11-25 | 2016-05-11 | 燕山大学 | Improved generation apex structure based on compound thought of controlling passively |
| WO2019088992A1 (en) * | 2017-10-31 | 2019-05-09 | Siemens Aktiengesellschaft | Turbine blade with tip trench |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115977999A (en) * | 2023-01-12 | 2023-04-18 | 山东科技大学 | Subsonic compressor, rotor blade and flow stability expansion control method |
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