AU2020104197A4

AU2020104197A4 - Flange-groove combined blade tip clearance leakage vortex cavitation suppressor

Info

Publication number: AU2020104197A4
Application number: AU2020104197A
Authority: AU
Inventors: Huaiyu CHENG; Bin Ji; Xinping LONG
Original assignee: Wuhan University WHU
Current assignee: Wuhan University WHU
Priority date: 2020-01-15
Filing date: 2020-12-21
Publication date: 2021-03-04
Anticipated expiration: 2028-12-21
Also published as: CN111255730A; CN111255730B

Abstract

Disclosed is a flange-groove combined blade tip clearance leakage vortex cavitation suppressor, relating to the field of fluid machinery. The flange-groove combined blade tip 5 clearance leakage vortex cavitation suppressor is mounted on an end surface of a blade, and includes a plurality of flanges arranged at intervals and a connecting fin connected to each flange. A groove is formed among two adjacent flanges and the connecting fin. The flange and the chord length of the end surface of the blade form an angle of 30 to 90 degrees. The width of the flange is 0.005 to 0.2 time the chord length of the end surface of the blade. One end of each J flange is flush with the edge of a pressure surface of the blade, and the other end of each flange is semicircular and extends out of the edge of a suction surface of the blade. An envelope line of the semicircular end of each flange is an equidistant amplification line of the outer contour of the end surface of the blade. The distance between each envelope line and the outer contour of the end surface of the blade is 0.005 to 0.1 time the chord length of the end surface of the blade. 5 The flange-groove combined blade tip clearance leakage vortex cavitation suppressor has a leakage vortex suppression effect within a large clearance range and can adapt to a straight or bent blade end surface. 10 DRAWINGS 200 \10 100 100 FIG. 2 FIG. 2 Page 1 of 3

Description

DRAWINGS

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FIG. 2

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FLANGE-GROOVE COMBINED BLADE TIP CLEARANCE LEAKAGE VORTEX CAVITATION SUPPRESSOR

TECHNICAL FIELD The present disclosure relates to the field of fluid mechanical devices, and in particular, to a flange-groove combined blade tip clearance leakage vortex cavitation suppressor.

BACKGROUND Axial hydraulic machinery is very important hydraulic machinery, which has been widely D used in large scale water transfer, drainage and irrigation, ship propulsion, cascade hydropower stations, and ocean energy development, etc., and plays a great role in national life. In a rotor passage of the axial-flow hydraulic machinery, there is inevitably a clearance between a rotating rotor part and a fixing part (a pump shell or a runner chamber) on an outer edge, which forms a complex vortex structure near a blade tip, that is, blade tip clearance leakage flow. Due to the low pressure at the vortex center, it usually induces cavitation at the vortex center, thereby forming blade tip clearance leakage vortex cavitation. This is a key factor that causes flow field vibration and noise near the blade tip of the hydraulic machinery, which may significantly worsen the performance of the hydraulic machinery, such as reducing the head and efficiency of a pump, reducing the energy output of a hydroturbine, and limiting the thrust characteristics of a J propeller, and even may seriously harm the safe operation of the hydraulic machinery. Therefore, researchers have carried out a large number of investigations in order to control the blade tip clearance leakage vortex cavitation, and preliminarily proposed some ideas and methods with certain positive effects. Generally, these methods may be divided into two categories: active control and passive control. Active control methods mainly regulate and control operating parameters of control parts according to flow conditions to achieve a purpose of suppressing leakage vortex cavitation, such as using an active vortex generator (actively regulating an attack angle of the vortex generator, etc.), and using active air ejection control (actively regulating the flow rate of introduced air, etc.). The active control methods may generally achieve relatively ideal effects within relatively large ranges of working conditions. o However, they have the main disadvantages that such methods are usually complex in structure and need to be maintained carefully, so they are difficult to be widely used in practical projects under severe conditions. Passive control methods are on the contrary. They are typically relatively simple in structure and can operate reliably under severe situations. However, because such methods are usually designed and finalized with respect to specific working conditions during designing, it is difficult to achieve ideal cavitation suppression effects with respect to off-design working conditions. The passive leakage vortex cavitation control methods are relatively potential control methods due to their simple structures and reliable operations. However, the existing passive tip leakage vortex cavitation control methods can only achieve a significant control effect with respect to the working conditions of small clearances, but cannot meet the control requirements under the situations of different clearance sizes, especially large clearances. Therefore, it is necessary to provide a blade tip leakage vortex control method, which can achieve a significant positive effect within a relatively large clearance range.

J SUMMARY The objective of the present disclosure is to provide a flange-groove combined blade tip clearance leakage vortex cavitation suppressor, which can achieve a significant tip vortex suppression effect within a large clearance range and can adapt to a straight end surface or a bent end surface of a blade. The embodiments of the present disclosure are implemented as follows: The embodiments of the present disclosure provide a flange-groove combined blade tip clearance leakage vortex cavitation suppressor, mounted on an end surface of a blade, and including a plurality of strip-shaped flanges arranged at intervals and a connecting fin connected to each flange. A groove is formed among two adjacent flanges and the connecting fin. Each J flange and the chord length of the end surface of the blade form an angle of 30 to 90 degrees. The width of the flange is 0.005 to 0.2 time the chord length of the end surface of the blade. One end of each flange is flush with the edge of a pressure surface of the blade. The other end of each flange extends out of the edge of a suction surface of the blade, and the cross section of an end part of the other end is semicircular. An envelope line of the end part of the semicircular end of each flange is an equidistant amplification line of the outer contour of the end surface of the blade. The distance between the envelope line and the outer contour of the end surface of the blade is 0.005 to 0.1 time the chord length of the end surface of the blade. In some alternative implementation solutions, the width of the flange is 0.5 to 20 mm. In some alternative implementation solutions, the radius of the flange is 0.5 time the width thereof. In some alternative implementation solutions, the distance between the envelope line and the outer contour of the end surface of the blade is 0.5 to 10 mm. In some alternative implementation solutions, the width of the groove is 0.005 to 0.2 time the chord length of the blade. In some alternative implementation solutions, the width of groove is 0.5 to 20 mm.

In some alternative implementation solutions, at least one mounting hole is formed in the connecting fin and/or the flanges. In some alternative implementation solutions, the flanges and the connecting fin are made of at least one of nylon, aluminium alloy, and steel. The present disclosure has the beneficial effects that: the flange-groove combined blade tip clearance leakage vortex cavitation suppressor provided by the present embodiment is mounted on an end surface of a blade, and includes a plurality of strip-shaped flanges arranged at intervals and a connecting fin connected to each flange. A groove is formed among two adjacent flanges and the connecting fin. Each flange and the chord length of the end surface of the blade J form an angle of 30 to 90 degrees. The width of the flange is 0.005 to 0.2 time the chord length of the end surface of the blade. One end of each flange is flush with the edge of a pressure surface of the blade. The other end of each flange extends out of the edge of a suction surface of the blade, and the cross section of an end part of the other end is semicircular. An envelope line of the end part of the semicircular end of each flange is an equidistant amplification line of the outer contour of the end surface of the blade. The distance between the envelope line and the outer contour of the end surface of the blade is 0.005 to 0.1 time the chord length of the end surface of the blade. The flange-groove combined blade tip clearance leakage vortex cavitation suppressor provided by the present embodiment can achieve a significant tip vortex suppression effect within a large clearance range and can adapt to a straight end surface or a bent end surface J of the blade.

BRIEF DESCRIPTION OF THE DRAWINGS To describe the technical solutions in the embodiments of the present disclosure more clearly, the following briefly introduces the accompanying drawings required for describing the embodiments of the present disclosure. It should be understood that the following accompanying drawings only show some embodiments of the present disclosure, thus should not be considered as limitation to a scope. Persons of ordinary skill in the art may still derive other relevant accompanying drawings from these accompanying drawings without creative efforts. FIG. 1 is a schematic structural diagram of a flange-groove combined blade tip clearance leakage vortex cavitation suppressor provided by Embodiment 1 of the present disclosure mounted on a straight end surface of a blade from a first view angle. FIG. 2 is a schematic structural diagram of the flange-groove combined blade tip clearance leakage vortex cavitation suppressor provided by Embodiment 1 of the present disclosure mounted on a straight end surface of the blade from a second view angle.

FIG. 3 shows a clearance leakage vortex cavitation condition of a blade 200 not mounted with the flange-groove combined blade tip clearance leakage vortex cavitation suppressor provided by Embodiment 1 under the clearance of 2 mm. FIG. 4 shows a clearance leakage vortex cavitation condition of a blade 200 mounted with the flange-groove combined blade tip clearance leakage vortex cavitation suppressor provided by Embodiment 1 under the clearance of 2 mm. FIG. 5 shows a clearance leakage vortex cavitation condition of a blade 200 not mounted with the flange-groove combined blade tip clearance leakage vortex cavitation suppressor provided by Embodiment 1 under the clearance of 7 mm. J FIG. 6 shows a clearance leakage vortex cavitation condition of a blade 200 mounted with the flange-groove combined blade tip clearance leakage vortex cavitation suppressor provided by Embodiment 1 under the clearance of 7 mm. FIG. 7 shows a clearance leakage vortex cavitation condition of a blade 200 not mounted with the flange-groove combined blade tip clearance leakage vortex cavitation suppressor provided by Embodiment 1 under the clearance of 20 mm. FIG. 8 shows a clearance leakage vortex cavitation condition of a blade 200 mounted with the flange-groove combined blade tip clearance leakage vortex cavitation suppressor provided by Embodiment 1 under the clearance of 20 mm. FIG. 9 is a schematic structural diagram of a flange-groove combined blade tip clearance J leakage vortex cavitation suppressor provided by Embodiment 2 of the present disclosure mounted on a bent end surface of a blade. In the drawings: 100-flange; 110-connecting fin; 111-mounting hole; 120-groove; 200-blade.

DETAILED DESCRIPTION To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the following clearly and completely describes the technical solutions in the embodiments of the present disclosure with reference to the accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are part rather than all of the embodiments of the present disclosure. Typically, the components of the embodiments of the present disclosure, which are described and shown in the accompanying drawings herein, may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the accompanying drawings is not intended to limit the scope of protection of the present disclosure, but only represents the selected embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present disclosure without creative efforts fall within the scope of protection of the present disclosure. It should be noted that: similar numerals and letters represent similar items in the following accompanying drawings. Therefore, once a certain item is defined in one accompanying drawing, it is unnecessary to further define and explain the certain item in subsequent accompanying drawings. In the descriptions of the present disclosure, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", 9 "vertical", "horizontal", "inner", "outer", and the like are based on the orientations or positional relationships shown in the accompanying drawings, or the customary placement orientations or positional relationships when the product of the present disclosure is used, are only intended to facilitate the descriptions of the present disclosure and simplify the descriptions, rather than indicating or implying that the apparatuses or elements must have specific orientations or must be constructed and operated in specific orientations, and thus may not be interpreted as limitation to the present disclosure. In addition, terms "first", "second", "third", and the like are only used for distinguishing descriptions, and cannot be understood as indicating or implying relative importance. In addition, terms "horizontal", "vertical", "overhung", and the like do not mean that the 9 parts are required to be absolutely horizontal or overhung, but may be slightly tilted. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", rather than meaning that the structure must be completely horizontal, but may be slightly tilted. In the descriptions of the present disclosure, it should be noted that, unless otherwise specified and defined explicitly, terms "arranged", "mounted", "interconnected", and "connected" are to be interpreted broadly, for example, may befixedly connected, or detachably connected, or integrally connected, may be mechanically connected, or electrically connected, may be directly connected, or indirectly connected through an intermediate medium, or internally communicated between two elements. A person of ordinary skill in the art may understand specific meanings of these terms in the present disclosure in specific situations. In the present disclosure, unless otherwise explicitly specified and defined, a first feature "above" or "below" of a second feature may include that the first feature is in direct contact the second features, or may include that the first and second features are not in direct contact, but in contact through other features therebetween. In addition, the first feature "above", "over", and "on" the second feature, includes that the first feature is directly above and obliquely above the second feature, or only means that the horizontal height of the first feature is higher than that of the second feature. The first feature "under", "below", and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or only means that the horizontal height of the first feature is lower than that of the second feature. The characteristics and performance of the flange-groove combined blade tip clearance leakage vortex cavitation suppressor of the present disclosure are further described below with reference to embodiments. Embodiment 1 As shown in FIG. 1 and FIG. 2, the embodiment of the present disclosure provides a flange-groove combined blade tip clearance leakage vortex cavitation suppressor, mounted on J an end surface of a blade 200. The chord length C of the end surface of the blade 200 is 100 mm. The flange-groove combined blade tip clearance leakage vortex cavitation suppressor includes a connecting fin 110 which extends in a straight line direction and 16 strip-shaped flanges 100 which are arranged at intervals and are separately connected to the connecting fin 110. A groove 120 is formed among two adjacent flanges 100 and the connecting fin 110. The connecting fin 110 extends in the chord length direction of the end surface of the blade 200. The included angle P between each flange 100 and the chord length of the end surface of the blade 200 is 45 degrees. One end of each flange 100 is flush with the edge of a pressure surface of the blade 200. The other end of each flange 100 extends out of the edge of a suction surface of the blade 200, and the cross section of an end part of the other end is semicircular, where the width WI of the J flange 100 is 10 mm (0.1 time the chord length of the end surface of the blade 200). The radius R of a semicircular end part of the flange 100 is 5 mm. An envelope line of the semicircular end part of each flange 100 is an equidistant amplification line of the outer contour of the end surface of the blade 200. The distance H between the envelope line and the outer contour of the end surface of the blade 200 is 5 mm (0.05 time the chord length of the blade 200). The width W2 of the groove 120 is 10 mm (0.1 time the chord length of the end surface of the blade 200). A mounting hole 111 is formed in each of the two ends of the connecting fin110. The flanges 100 and the connecting fin 110 are all made of aluminium alloy. The flange-groove combined blade tip clearance leakage vortex cavitation suppressor provided by the present embodiment consists of the connecting fin 110 and the 16 flanges 100 which connected to the connecting fin 110 at intervals in a length direction. 30 grooves 120 which are respectively located on the two sides of the connecting fin 110 are formed among two adjacent flanges 100 and the connecting fin 110. During use, the flange-groove combined blade tip clearance leakage vortex cavitation suppressor is mounted on the end surface of the blade 200 through the fit of the mounting holes 111 formed in the connecting fin 110 and nuts, so that one end of each flange 100 is flush with the edge of the outer contour of a pressure surface of the blade 200. The semicircular end part at the other end protrudes from the outer contour of the suction surface of the blade 200, and the envelope line of the semicircular end part of each flange 100 is made the equidistant amplification line of the outer contour of the end surface of the blade 200. The distance H between the envelope line and the outer contour of the end surface of the blade 200 is 5 mm, which can effectively prevent the fusion of a leakage vortex and a separation vortex at the end part of blade 200, so as to suppress the tip clearance leakage vortex cavitation of the blade 200, thereby significantly increasing throttle loss in cases of different clearances, preventing the movement of tip leakage flow of the blade 200 from the pressure surface to the suction surface, and weakening the intensity of the tip clearance leakage J vortex cavitation of the blade 200. The flange-groove combined blade tip clearance leakage vortex cavitation suppressor is placed in a cavitation water tunnel of Ecole Polytechnique Federale De Lausanne in Switzerland for observing before and after being mounted on the blade 200 under a small clearance (2mm), an intermediate clearance (7mm), and a large clearance (20mm) respectively, and the results are shown in FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, and FIG. 8. The FIG. 3 shows a clearance leakage vortex cavitation condition of the blade 200 not mounted with the flange-groove combined blade tip clearance leakage vortex cavitation suppressor under a small clearance. FIG. 4 shows a clearance leakage vortex cavitation condition of the blade 200 mounted with the flange-groove combined blade tip clearance leakage vortex cavitation suppressor under the J small clearance. FIG. 5 shows a clearance leakage vortex cavitation condition of the blade 200 not mounted with the flange-groove combined blade tip clearance leakage vortex cavitation suppressor under an intermediate clearance. FIG. 6 shows a clearance leakage vortex cavitation condition of the blade 200 mounted with the flange-groove combined blade tip clearance leakage vortex cavitation suppressor under the intermediate clearance. FIG. 7 shows a clearance leakage vortex cavitation condition of the blade 200 not mounted with the flange-groove combined blade tip clearance leakage vortex cavitation suppressor under a large clearance. FIG. 8 shows a clearance leakage vortex cavitation condition of a blade 200 mounted with the flange-groove combined blade tip clearance leakage vortex cavitation suppressor under the large clearance. Comparing FIG. 3 with FIG. 4, FIG. 5 with FIG. 6, and FIG. 7 with FIG. 8, it can be seen that the tip clearance leakage vortex cavitation of the blade 200 under the working conditions of large, medium, and small clearances are significantly suppressed after the flange-groove combined blade tip clearance leakage vortex cavitation suppressor provided by the present embodiment is additionally mounted. In addition, the changes of the lift and drag characteristics of the blade 200 before and after the flange-groove combined blade tip clearance leakage vortex cavitation suppressor is mounted under various working conditions are also tested. Results show that the influence on the lift and drag characteristics of the blade 200 caused by additionally mounting the flange-groove combined blade tip clearance leakage vortex cavitation suppressor is quite limited, which shows that the blade tip clearance cavitation effect of the blade 200 may be greatly improved without affecting the hydraulic performance thereof by additionally mounting the flange-groove combined blade tip clearance leakage vortex cavitation suppressor of the present embodiment. Embodiment 2 As shown in FIG. 9, the present embodiment provides a flange-groove combined blade tip clearance leakage vortex cavitation suppressor, which has a structure approximately the same as 9 that of the flange-trench compound tip clearance leakage vortex cavitation suppressor provided in Embodiment 1. The difference is that, in the present embodiment, a connecting fin 110 is arc-shaped, and the number of flanges 100 connected to the connecting fin 110 is 18. The flange-groove combined blade tip clearance leakage vortex cavitation suppressor is mounted on an end surface of a bent blade. In some alternative embodiments, the number of the flanges 100 connected to the connecting fin 110 may also be 5 to 10, 10 to 15, 15 to 20, or more than 20. In some alternative embodiments, one, two, three, or more than three mounting holes 111 may also be formed in flanges 100; or one, two, three or more than three mounting holes 111 are formed in flanges 100 and a connecting fin 110. In some alternative embodiments, mounting holes 111 may also not be 9 formed. When the flange-groove combined blade tip clearance leakage vortex cavitation suppressor needs to be used, the connecting fin 110 and the flanges 100 are bonded to an end surface of the blade 200 by using glue. In some alternative embodiments, the flanges 100 and the connecting fin 110 may also be made of the materials, such as nylon, copper, and steel. The embodiments described above are part rather than all of the embodiments of the present disclosure. The detailed description of the embodiments of the present disclosure is not intended to limit the scope of protection of the present disclosure, but only represents selected embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present disclosure without creative efforts fall within the scope of protection of the present disclosure.

Claims

Claims WHAT IS CLAIMED IS:

1. A flange-groove combined blade tip clearance leakage vortex cavitation suppressor, mounted on an end surface of a blade, and comprising a plurality of strip-shaped flanges arranged at intervals and a connecting fin connected to each of the flanges; a groove is formed among two adjacent flanges and the connecting fin; each of the flanges and the chord length of the end surface of the blade form an angle of 30 to 90 degrees; the width of the flange is 0.005 to 0.2 time the chord length of the end surface of the blade; one end of each of the flanges is flush with the edge of a pressure surface of the blade; the other end of each of the flanges extends out of J the edge of a suction surface of the blade, and the cross section of an end part of the other end is semicircular; an envelope line of the end part of the semicircular end of each of the flanges is an equidistant amplification line of the outer contour of the end surface of the blade; the distance between the envelope line and the outer contour of the end surface of the blade is 0.005 to 0.1 time the chord length of the end surface of the blade.

2. The flange-groove combined blade tip clearance leakage vortex cavitation suppressor according to claim 1, wherein the width of the flange is 0.5 to 20 mm;

wherein the radius of an end part of the flange is 0.5 time the width thereof;

wherein the distance between the envelope line and the outer contour of the end surface of the blade is 0.5 to 10 mm.

J

3. The flange-groove combined blade tip clearance leakage vortex cavitation suppressor according to claim 1, wherein the width of the groove is 0.005 to 0.2 time the chord length of the blade;

wherein the width of the groove is 0.5 to 20 mm.

4. The flange-groove combined blade tip clearance leakage vortex cavitation suppressor according to claim 1, wherein at least one mounting hole is formed in the connecting fin and/or the flanges.

5. The flange-groove combined blade tip clearance leakage vortex cavitation suppressor according to claim 1, wherein the manufacturing material of the flanges and the connecting fin comprises at least one of nylon, aluminium alloy, and steel.