CN113187644B - Active jet structure for improving cavitation flow around hydrofoil - Google Patents
Active jet structure for improving cavitation flow around hydrofoil Download PDFInfo
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- CN113187644B CN113187644B CN202110471877.9A CN202110471877A CN113187644B CN 113187644 B CN113187644 B CN 113187644B CN 202110471877 A CN202110471877 A CN 202110471877A CN 113187644 B CN113187644 B CN 113187644B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03B—MACHINES OR ENGINES FOR LIQUIDS
- F03B3/00—Machines or engines of reaction type; Parts or details peculiar thereto
- F03B3/12—Blades; Blade-carrying rotors
- F03B3/121—Blades, their form or construction
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
- B63B1/16—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces
- B63B1/24—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving additional lift from hydrodynamic forces of hydrofoil type
- B63B1/248—Shape, hydrodynamic features, construction of the foil
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H1/00—Propulsive elements directly acting on water
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03B—MACHINES OR ENGINES FOR LIQUIDS
- F03B11/00—Parts or details not provided for in, or of interest apart from, the preceding groups, e.g. wear-protection couplings, between turbine and generator
- F03B11/04—Parts or details not provided for in, or of interest apart from, the preceding groups, e.g. wear-protection couplings, between turbine and generator for diminishing cavitation or vibration, e.g. balancing
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15D—FLUID DYNAMICS, i.e. METHODS OR MEANS FOR INFLUENCING THE FLOW OF GASES OR LIQUIDS
- F15D1/00—Influencing flow of fluids
- F15D1/002—Influencing flow of fluids by influencing the boundary layer
- F15D1/0025—Influencing flow of fluids by influencing the boundary layer using passive means, i.e. without external energy supply
- F15D1/003—Influencing flow of fluids by influencing the boundary layer using passive means, i.e. without external energy supply comprising surface features, e.g. indentations or protrusions
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15D—FLUID DYNAMICS, i.e. METHODS OR MEANS FOR INFLUENCING THE FLOW OF GASES OR LIQUIDS
- F15D1/00—Influencing flow of fluids
- F15D1/002—Influencing flow of fluids by influencing the boundary layer
- F15D1/0065—Influencing flow of fluids by influencing the boundary layer using active means, e.g. supplying external energy or injecting fluid
- F15D1/008—Influencing flow of fluids by influencing the boundary layer using active means, e.g. supplying external energy or injecting fluid comprising fluid injection or suction means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03B—MACHINES OR ENGINES FOR LIQUIDS
- F03B13/00—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates
- F03B13/12—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy
- F03B13/26—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using tide energy
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/20—Hydro energy
Abstract
The invention discloses an active jet structure for improving cavitation flow around a hydrofoil, which comprises a wing-shaped body, wherein an active jet cavity which is recessed into the wing-shaped body from a suction surface is arranged in the wing-shaped body along the length direction of the wing-shaped body; a rectifying tip which is positioned between the jet inlet and the jet outlet and used for prolonging the flow path of the fluid is convexly arranged in the active jet cavity, and the flow area in the active jet cavity is gradually reduced along the flow direction of the fluid; the active jet flow cavity is internally provided with a rectifying section positioned on a fluid flow path along the extending direction of the wing-shaped body, rectifying holes for fluid to pass through are formed in the rectifying section, and the distance between every two adjacent rectifying holes is gradually increased along the direction away from the jet flow inlet. The invention solves the problems of poor fluid distribution uniformity of the existing active jet structure and poor optimization effect of lift resistance and flow characteristics of the airfoil.
Description
Technical Field
The invention relates to the field of fluid machinery, in particular to an active jet structure for improving cavitation flow around a hydrofoil.
Background
The airfoil profile is a basic structure in the field of fluid machinery, and has wide application in the fields of airfoils, propeller airfoils, wind power generation blade section airfoils, tidal power generation blade airfoils and the like in the field of aviation. With the rapid development of scientific technology and fluid machinery industry, especially with the expansion of application fields, the wide-range use of hydraulic machines such as tidal power generation, marine water jet propellers, underwater vehicles and the like, people no longer meet the dynamic performance provided by the traditional wings, and the requirements on the wing profile performance are higher and higher. Along with the change of the density and viscosity of a fluid medium, the change of a streaming Reynolds number and a Stewarthal number is caused, the front edge of the airfoil is easy to generate a large number of vortex areas, cavitation flow, cloud cavitation and other complex unstable flows when the airfoil runs at a high speed, and cavitation erosion is easily formed when the airfoil runs under the conditions for a long time, the wall surface of a hydraulic machine is damaged, vibration noise is induced, and the performance of the airfoil is seriously influenced.
In the prior art, in order to optimize the lift-drag characteristic and the flow characteristic of the airfoil, an active jet orifice is usually arranged at the front edge of the airfoil, and the active jet is used for inhibiting laminar flow shunting at the front edge of the airfoil, so that the lift-drag characteristic and the flow characteristic of the airfoil are improved. Although the existing active jet technology can achieve a certain optimization effect, the existing active jet opening is simple in structure and only has a single jet passage, so that the distribution uniformity of fluid injected from the jet opening is poor, and the optimization effect on the lift resistance and the flow characteristic of the airfoil is not good, thus urgent solution is needed.
Disclosure of Invention
To avoid and overcome the technical problems of the prior art, the present invention provides an active jet structure that improves cavitation flow around a hydrofoil. The invention ensures that the active jet flow is more uniformly distributed after leaving the jet flow outlet, reduces the area of a vortex area, inhibits the flow separation capability of the suction surface of the wing profile, and ensures that a separation point is closer to the tail edge of the wing profile so as to obviously improve the lift coefficient.
In order to achieve the purpose, the invention provides the following technical scheme:
an active jet structure for improving cavitation flow around a hydrofoil comprises a hydrofoil body, wherein an active jet cavity which is recessed into the hydrofoil body from a suction surface is formed in the hydrofoil body along the length direction, an opening of the active jet cavity on the suction surface is a jet outlet, a jet inlet which penetrates through the wing end on one side of the hydrofoil body is formed in the active jet cavity along the length direction, and the jet inlet is communicated with an active jet source; a rectifying tip which is positioned between the jet inlet and the jet outlet and used for prolonging the flow path of the fluid is convexly arranged in the active jet cavity, and the flow area in the active jet cavity is gradually reduced along the flow direction of the fluid;
the active jet flow cavity is provided with a rectifying section which is positioned on a fluid flow path and cuts off the path along the extending direction of the wing-shaped body, rectifying holes for fluid to pass through are formed in the rectifying section, and the distance between every two adjacent rectifying holes is gradually increased along the direction away from the jet flow inlet.
As a further scheme of the invention: the rectifying tip extends from the suction surface of the airfoil body to the active jet cavity along the incoming flow direction of the airfoil; the rectifying tip divides the active jet flow cavity into a pre-compression cavity, a transition compression cavity and a jet flow compression cavity which are sequentially arranged along the fluid flow direction, a gap between the end part of the rectifying tip and the active jet flow cavity is the transition compression cavity, the pre-compression cavity is communicated with the jet flow inlet, and the jet flow outlet of the jet flow compression cavity faces the same direction as the fluid flow direction on the surface of the suction surface.
As a still further scheme of the invention: the rectifying section is a rectifying tube, the shape of the rectifying tube is matched with that of the jet inlet, and the rectifying tube is inserted into the pre-compression cavity along the jet inlet and is fixed.
As a still further scheme of the invention: the chord length of the airfoil body is taken as L, the distance between the rectifying tube and the front edge of the airfoil is 0.3L, the height of the jet flow outlet is 0.002L-0.008L, and the distance between the jet flow outlet and the front edge of the airfoil is 0.2L-0.4L.
As a still further scheme of the invention: and a flow passage partition plate is arranged in the jet flow compression cavity and divides the jet flow compression cavity into at least two flow passages along the length expanding direction.
As a still further scheme of the invention: the chord length of the airfoil body is taken as L, the width of the jet flow outlet is 0.8L, the width of the flow channel partition plate is 0.1L, the number of the flow channel partition plates is two, and the jet flow outlet is uniformly divided into three flow channels with the width of 0.2L.
As a still further scheme of the invention: the active jet cavity is a curved cavity, and the cross section of the active jet cavity is in a hook jade shape.
As a still further scheme of the invention: the total hole area of the rectifying hole is smaller than the area of the jet inlet.
As a still further scheme of the invention: the active jet cavity is composed of a first curved surface, a second curved surface, a third curved surface, a fourth curved surface, a fifth curved surface, a sixth curved surface and a seventh curved surface which are connected in sequence, wherein a gap between the first curved surface and the seventh curved surface is a jet outlet.
As a still further scheme of the invention: the section curve of the first curved surface is a cubic curve,
wherein: a is more than or equal to 7 and less than or equal to 6 below zero; b is more than or equal to 6 and less than or equal to 7; c is more than or equal to-2 and less than or equal to-1; d is more than or equal to 0 and less than or equal to 1;
the section curve of the second curved surface is a cubic curve,
wherein: e is more than or equal to-920 and less than or equal to-900; f is more than or equal to 1200 and less than or equal to 1220; -530. ltoreq. g.ltoreq.520; h is not less than 75 and not more than 80;
the section curve of the third curved surface is a cubic curve,
wherein: i is more than or equal to 45 below zero and less than or equal to 40 below zero; j is more than or equal to-45 and less than or equal to-40; k is more than or equal to-15 and less than or equal to-20; l is more than or equal to-2 and less than or equal to-1;
the section curve of the fourth curved surface is a cubic curve,
wherein: m is more than or equal to-155 and less than or equal to-145; n is more than or equal to 140 and less than or equal to 145; o is more than or equal to-50 and less than or equal to-40; p is more than or equal to 4 and less than or equal to 5;
the section curve of the fifth curved surface is a cubic curve,
wherein: q is more than or equal to 20 and less than or equal to 25; r is more than or equal to-25 and less than or equal to-20; s is more than or equal to 8 and less than or equal to 10; t is more than or equal to-2 and less than or equal to-1;
wherein the boundary conditions are as follows:
x 1 ＝3.10 y 1 ＝0.75
x 5 ＝2.65 y 5 ＝0.29
x 1 ＝x 2 ＝2.36 y 1 ＝y 2 ＝0.53
x 2 ＝x 3 ＝2.17 y 2 ＝y 3 ＝0.19
x 3 ＝x 4 ＝2.99 y 3 ＝y 4 ＝-0.45
x 4 ＝x 5 ＝3.58 y 4 ＝y 5 ＝0
the section curve of the sixth curved surface is an arc curve, the chord length of the airfoil body is taken as L, and the radius of the arc curve of the sixth curved surface is 0.007L;
the cross-sectional curve of the seventh curved surface is a cubic curve, and the flow area of the jet flow outlet between the seventh curved surface and the first curved surface is linearly reduced by 1.2 times along the flow direction of the fluid.
Compared with the prior art, the invention has the beneficial effects that:
1. the rectifying tip is creatively arranged in the traditional active jet flow cavity in a protruding mode to enable the rectifying tip to transversely stretch between the jet flow inlet and the jet flow outlet, so that a straight flow track of fluid from the jet flow inlet to the jet flow outlet is changed into an arc-shaped flow track running around the rectifying tip, the flowing distance of the fluid is prolonged in a limited active jet flow cavity space, meanwhile, through separation of the rectifying tip, the overflowing area flowing to the active jet flow cavity along the fluid is gradually reduced, after the active jet flow source jets the fluid with a certain speed into the active jet flow cavity, the fluid is continuously compressed in the cavity, and the uniformity of the speed of the jetted fluid is improved; because the flow distance of the fluid in the limited space is prolonged, the flow time is also prolonged, sufficient compression and diffusion time is obtained in the active jet flow cavity, the fluid is distributed more uniformly after leaving the jet flow outlet, the area of a vortex area at the upstream of the jet flow outlet is reduced, the vortex area at the downstream of the jet flow outlet is moved downwards, the flow separation capacity of the suction surface of the wing profile is inhibited, a separation point is closer to the tail edge of the wing profile, and compared with a common active jet flow structure, the negative pressure area is larger, the cavitation phenomenon is prevented, and the lift coefficient of the wing profile is obviously improved; the setting of rectification section and its surface rectification hole has evenly compensated the streamline of airfoil suction surface, makes its distribution even, has further improved the lift coefficient of airfoil, has carried out energy compensation to the suction surface.
2. The rectifying tip extends into the active jet cavity from the airfoil suction surface, the active jet cavity is artificially divided into a pre-compression cavity for inflow, a jet compression cavity for outflow and a transition compression cavity for transition between the jet compression cavity and the pre-compression cavity; due to the separation of the rectifying tip and the matching of the rectifying tip and the cavity wall, the fluid is continuously compressed through each cavity along the flow direction of the fluid and is finally uniformly diffused and ejected.
3. According to the invention, the rectifier tube with the size matched with the size of the jet inlet is inserted into the active jet cavity, and the fluid is distributed and compressed before entering the active jet cavity, so that the fluid is uniformly distributed after entering the active jet cavity, and the subsequent streaming phenomenon is prevented; and by designing the total area of the rectifying holes to be smaller than the area of the jet inlet, the fluid can be pre-compressed before entering the active jet cavity, so that the fluid flows uniformly.
4. The invention divides the jet flow outlet into a plurality of flow channels by arranging the flow channel division plate in the jet flow compression cavity, improves the uniformity of fluid ejection, plays a role in compressing the flow channel flow area due to the thickness of the flow channel division plate, and continuously compresses the fluid in the process of fluid ejection.
5. The invention optimizes the parameters by carrying out specific parametric setting on the active jet cavity, thereby being more convenient for processing.
Drawings
FIG. 1 is a cross-sectional view of an airfoil of the present invention taken along the chord length.
FIG. 2 is a three-dimensional schematic view of an airfoil of the present invention.
FIG. 3 is a three-dimensional schematic view of the present invention with the tip of one side of the airfoil removed.
FIG. 4 is a cross-sectional view of the active jet chamber.
FIG. 5 is a cross-sectional view of the active jet chamber after insertion into a rectifier tube.
Fig. 6 is a schematic structural diagram of a rectifier tube.
Fig. 7 is a sectional view of a rectifier tube.
FIG. 8 is a top view of an airfoil of the present invention.
FIG. 9 is a vortex distribution diagram for an airfoil suction surface without an active jet structure.
FIG. 10 is a vortex profile for an airfoil suction surface with a conventional active jet configuration.
FIG. 11 is a profile of airfoil suction surface vortices with the active jet structure of the present invention.
FIG. 12 is a vortex distribution diagram for an airfoil suction surface having an active jet structure of the present invention with a rectifier tube inserted therein.
FIG. 13 is a simulated view of airfoil streamlines with a common active jet configuration.
FIG. 14 is a schematic view of an airfoil streamline simulation with the active jet structure of the present invention.
FIG. 15 is a schematic view of an airfoil streamline simulation having an active jet structure of the present invention with a rectifying tube inserted therein.
In the figure: 10. an airfoil body; 101. a suction surface; 20. a motive jet chamber; 201. a flow passage partition plate; 202. a rectifying tip; 203. a rectifier tube; 2031. a jet hole; 2041. a first curved surface; 2042. a second curved surface; 2043. a third curved surface; 2044. a fourth curved surface; 2045. a fifth curved surface; 2046. a sixth curved surface; 2047. a seventh curved surface; u, a pre-compression chamber; v, a transitional compression cavity; w, jet compression chamber.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1 to 15, in an embodiment of the present invention, an active jet structure for improving cavitation flow around a hydrofoil includes an airfoil body 10, and the present invention takes an NACA0015 airfoil as an example, and the structure of the present invention can be applied to various airfoils. As shown in fig. 1, 2 and 3, the chord length of the airfoil body 10 is L, the airfoil span length is 0.8L, and an active jet cavity 20 recessed from the suction surface 101 into the airfoil body 10 is formed in the airfoil body 10 along the span length direction. The length of the active jet cavity 20 along the extending direction of the wing profile is also 0.8L, the wing ends on two sides of the wing profile are provided with thin walls, two ends of the active jet cavity 20 are sealed, and the thickness of the thin walls is ignored.
The fluid in the invention is divided into two parts, one part is active jet flow injected into the active jet flow cavity by the active jet flow source, and the other part is fluid flowing through the surface of the wing profile; except for the fact that the fluid is definitely indicated to come from the surface of the airfoil, the fluid in the invention refers to active jet flow which is emitted into an active jet flow cavity by an active jet flow source.
The active jet cavity 20 is a smooth curved surface; the suction surface 101 extends into the active jet cavity 20 along the direction of the wing-shaped incoming flow to form an arc-shaped rectifying tip 202, and the rectifying tip 202 extends into the active jet cavity 20 to make the active jet cavity 20 in a hook-jade shape.
Due to the separation of the fairing tip 202, the flow path of the fluid in the active fluidic chamber 20 changes from a straight to an arcuate shape, the flow path is lengthened, and the presence of the fairing tip 202 causes the flow area of the active fluidic chamber 20 to gradually decrease in the direction of the fluid flow.
The opening of the active jet cavity 20 on the suction surface 101 of the airfoil body 10 is the jet outlet.
After the rectifying tip 202 extends into the active jet flow cavity 20, the active jet flow cavity 20 is divided into a pre-compression cavity u, a transition compression cavity v and a jet flow compression cavity w which are sequentially arranged along the fluid flow direction, a gap between the rectifying tip 202 and the active jet flow cavity 20 is the transition compression cavity v, the jet flow compression cavity w is the tail section of the active jet flow cavity 20 and is connected with the suction surface 101, and fluid is finally ejected from a jet flow outlet of the jet flow compression cavity w.
An opening is formed in the thin wall of the closed active jet cavity 20 at one side wing end of the wing section body 10, the opening is communicated with the pre-compression cavity u, the opening is a jet inlet, the jet inlet is communicated with an active jet source, the active jet source provides active jet with a certain jet speed from the jet inlet into the active jet cavity 20, and the incoming flow speed of the suction surface of the wing section is V 1 The jet velocity of the active jet source is V 2 ，0.3V 2 ≤V 1 ≤1.5V 2 。
The shape of the jet inlet is not limited, and a circular jet inlet is preferred; the rectifying tube 203 is inserted into the jet inlet, and the end of the rectifying tube 203 away from the jet inlet is abutted against the wall of the active jet cavity 20, and then the rectifying tube 203 is fixed by any means, for example, welding or riveting. The jet hole 2031 is provided on the tube body of the rectifier tube 203, the jet hole 2031 is arranged at intervals along the length direction of the rectifier tube 203, and the distance between each adjacent jet hole 2031 gradually increases along the direction away from the jet inlet. Since the rectifier 203 is located in the flow path of the fluid, the fluid must pass through the jet hole 2031 of the rectifier 203 before entering the pre-compression chamber u after entering the jet inlet.
In order to optimize the structure, the distance between the axis of the rectifying pipe 203 and the front edge of the airfoil is kept at 0.3L, the height of the jet outlet is kept at 0.002L-0.008L and the distance between the jet outlet and the front edge of the airfoil is kept at 0.2L-0.4L by taking the chord length L of the airfoil body 10 as reference.
However, the rectifying pipe 203 is not the only option, and the same function as the rectifying pipe 203 can be achieved by inserting and fixing a rectifying plate into the jet inlet so that the rectifying plate spans between the pre-compression chamber u and the transitional compression chamber v, and forming rectifying holes at intervals on the plate body, and keeping the distance between each adjacent rectifying holes gradually larger in the direction away from the jet inlet.
In order to ensure the fluid compression function, the total area of the holes on the rectifier tube 203 or the rectifier plate is smaller than the area of the jet inlet; the thickness of the rectifying tube 203 or the rectifying plate is 0.01L, and the surface aperture is 0.0125L.
In order to further improve the compression and rectification performance of the jet flow compression cavity w, a runner partition plate 201 is arranged in the jet flow compression cavity w to partition the jet flow compression cavity w into a plurality of runners. Taking the chord length of the airfoil body 10 as L, the width of the jet outlet along the extension of the airfoil body 10 is 0.8L, at this time, two flow channel partition plates 201 are preferably arranged, and the width of each flow channel partition plate is 0.1L, so that the jet outlet of the jet compression cavity w is uniformly partitioned into three 0.2L flow channels.
The active jet cavity 20 is specifically composed of a first curved surface 2041, a second curved surface 2042, a third curved surface 2043, a fourth curved surface 2044, a fifth curved surface 2045, a sixth curved surface 2046 and a seventh curved surface 2047 which are connected in sequence, and a gap between the first curved surface 2041 and the seventh curved surface 2047 is a jet outlet of the jet compression cavity w, which will be described in detail below.
The active jet cavity 20 is cut along the chord length direction of the airfoil body 10, the section curve of the first curved surface 2041 is a cubic curve,
-7≤a≤-6；6≤b≤7；-2≤c≤-1；0≤d≤1；
the cross-sectional curve of the second curved surface 2042 is a cubic curve,
e is more than or equal to-920 and less than or equal to-900; f is more than or equal to 1200 and less than or equal to 1220; -530. ltoreq. g.ltoreq.520; h is not less than 75 and not more than 80; the cross-sectional curve of the third curved surface 2043 is a cubic curve,
-45≤i≤-40；-45≤j≤-40；-15≤k≤-20；-2≤l≤-1；
the cross-sectional curve of the fourth curved surface 2044 is a cubic curve,
-155≤m≤-145；140≤n≤145；-50≤o≤-40；4≤p≤5；
the cross-sectional curve of the fifth curved surface 2045 is a cubic curve,
20≤q≤25；-25≤r≤-20；8≤s≤10；-2≤t≤-1；
wherein the boundary conditions are as follows:
x 1 ＝3.10y 1 ＝0.75
x 5 ＝2.65y 5 ＝0.29
x 1 ＝x 2 ＝2.36y 1 ＝y 2 ＝0.53
x 2 ＝x 3 ＝2.17y 2 ＝y 3 ＝0.19
x 3 ＝x 4 ＝2.99y 3 ＝y 4 ＝-0.45
x 4 ＝x 5 ＝3.58y 4 ＝y 5 ＝0
the section curve of the sixth curved surface 2046 is an arc curve, the chord length of the airfoil body 10 is taken as L, the radius of the arc curve of the sixth curved surface is 0.007L, and the arc is a semicircular arc.
The cross-sectional curve of the seventh curved surface 2047 is a cubic curve, and the flow area of the jet flow outlet between the seventh curved surface 2047 and the first curved surface 2041 linearly decreases by 1.2 times in the fluid flow direction. The flow area S of the tail end of a single flow channel of the jet flow outlet along the flow direction of the fluid 1 Is 0.04mm 2 -0.16mm 2 The flow area of the initial end of a single flow passage is S 2 Is 2.5S 1 -4S 1 。
Since the flow area is determined in a linear relationship and the first curved surface 2041 is also known, the cross-sectional curve of the seventh curved surface 2047 can be obtained from the cross-sectional curve of the first curved surface 2041.
FIGS. 9-12 are vortex profiles for airfoil suction surfaces;
as shown in FIG. 9, the suction surface of a conventional airfoil has a large number of vortices.
As shown in FIG. 10, in an airfoil having a conventional active jet configuration, the wake area of the airfoil suction surface is reduced, but a large number of wake areas are still present at the jet exit of the airfoil suction surface.
As shown in fig. 11, compared with the conventional jet structure, the airfoil with the active jet structure of the present invention has the advantages that the vortex area at the upstream of the jet outlet of the airfoil suction surface is scattered, the area is significantly reduced, the vortex area at the jet outlet is also significantly reduced, the vortex area at the downstream of the jet outlet moves down as a whole, which means that the separation point moves down, the jet significantly inhibits the flow separation capability of the airfoil suction surface, so that the separation point is closer to the trailing edge of the airfoil, and compared with the conventional active jet structure, the airfoil with the active jet structure has a larger negative pressure area, thereby significantly improving the lift coefficient of the airfoil.
As shown in fig. 12, in the airfoil with the active jet structure of the present invention, a rectifier tube is further inserted into the active jet cavity, so that with the help of the rectifier tube, the downward moving amplitude of the vortex region at the downstream of the jet outlet is larger, the reduction amplitude of the area of the vortex region at the upstream of the jet outlet is larger, and the overall lift coefficient is improved more.
FIGS. 13-15 are streamline simulated views of airfoil surfaces;
as shown in fig. 13, in the suction surface of the airfoil of the conventional active jet structure, the jet is accumulated at the position far away from the jet inlet and flows around from the position far away from the jet inlet, and only a small amount of fluid is present on the suction surface near the jet inlet to compensate the energy of the suction surface of the airfoil, which is caused by the fact that the fluid cannot be sufficiently diffused in the active jet structure.
As shown in fig. 14, in the airfoil with the active jet structure of the present invention, the streamlines of the suction surface are uniformly distributed along the extending direction of the airfoil, the vortex is effectively suppressed, and the jet obviously suppresses the flow separation capability of the suction surface of the airfoil, so that the separation point is closer to the trailing edge of the downstream of the suction surface of the airfoil, and the lift coefficient is improved.
As shown in fig. 15, in the airfoil having the active jet structure of the present invention, after the rectifying tube is inserted, the partial vortex region at the downstream of the jet outlet is further eliminated, so that the lift coefficient of the airfoil is further improved.
Numerical simulation tests are respectively carried out on an NACA0015 common airfoil profile, an NACA0015 airfoil profile comprising a common jet flow structure, an NACA0015 airfoil profile comprising the jet flow structure of the invention and an NACA0015 airfoil profile comprising a rectifying tube inserted in the jet flow structure of the invention according to an attack angle of 8 degrees, an incoming flow speed of 10m/s and an active jet flow source jet flow speed of 5m/s, and lift drag coefficient results of four schemes are shown in the following table:
the lift coefficient of the airfoil can be greatly improved while the resistance coefficient of the common active jet structure is greatly reduced, and the lift coefficient of the airfoil is greatly improved after the original common active jet structure is replaced by the active jet structure, so that the energy loss of the airfoil suction surface is effectively compensated. After the rectifier tube is inserted into the active jet structure, the lift coefficient is improved again, and the resistance coefficient is maintained stable.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered as the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.
Claims (8)
1. The active jet flow structure for improving the cavitation flow around the hydrofoil is characterized by comprising a wing section body (10), wherein an active jet flow cavity (20) which is recessed into the wing section body (10) from a suction surface (101) is formed in the wing section body (10) along the extending direction, an opening of the active jet flow cavity (20) on the suction surface (101) is a jet flow outlet, a jet flow inlet penetrating through the wing end on one side of the wing section body (10) is formed in the active jet flow cavity (20) along the extending direction, and the jet flow inlet is communicated with an active jet flow source; a rectifying tip (202) which is positioned between the jet inlet and the jet outlet and used for prolonging the flow path of the active jet is convexly arranged in the active jet cavity (20), and the flow area in the active jet cavity (20) is gradually reduced along the flow direction of the active jet;
a rectifying section which is positioned on the fluid flow path and cuts off the path is arranged in the active jet cavity (20) along the extending direction of the airfoil body (10), rectifying holes for the fluid to pass through are formed in the rectifying section, and the distance between every two adjacent rectifying holes is gradually increased along the direction away from the jet inlet;
the active jet cavity (20) is composed of a first curved surface (2041), a second curved surface (2042), a third curved surface (2043), a fourth curved surface (2044), a fifth curved surface (2045), a sixth curved surface (2046) and a seventh curved surface (2047) which are connected in sequence, wherein a gap between the first curved surface (2041) and the seventh curved surface (2047) is a jet outlet;
the section curve of the first curved surface (2041) is a cubic curve,
wherein: a is more than or equal to minus 7 and less than or equal to minus 6; b is more than or equal to 6 and less than or equal to 7; c is more than or equal to-2 and less than or equal to-1; d is more than or equal to 0 and less than or equal to 1;
the section curve of the second curved surface (2042) is a cubic curve,
wherein: e is more than or equal to-920 and less than or equal to-900; f is more than or equal to 1200 and less than or equal to 1220; -530. ltoreq. g.ltoreq.520; h is not less than 75 and not more than 80;
the section curve of the third curved surface (2043) is a cubic curve,
wherein: i is more than or equal to minus 45 and less than or equal to minus 40; j is more than or equal to-45 and less than or equal to-40; k is more than or equal to-15 and less than or equal to-20; l is more than or equal to-2 and less than or equal to-1;
the section curve of the fourth curved surface (2044) is a cubic curve,
wherein: m is more than or equal to-155 and less than or equal to-145; n is more than or equal to 140 and less than or equal to 145; o is more than or equal to-50 and less than or equal to-40; p is more than or equal to 4 and less than or equal to 5;
the section curve of the fifth curved surface (2045) is a cubic curve,
wherein: q is more than or equal to 20 and less than or equal to 25; r is more than or equal to-25 and less than or equal to-20; s is more than or equal to 8 and less than or equal to 10; t is more than or equal to-2 and less than or equal to-1;
wherein the boundary conditions are as follows:
x 1 ＝x 2 ＝2.36y 1 ＝y 2 ＝0.53
x 2 ＝x 3 ＝2.17y 2 ＝y 3 ＝0.19
x 3 ＝x 4 ＝2.99y 3 ＝y 4 ＝-0.45
x 4 ＝x 5 ＝3.58y 4 ＝y 5 ＝0
the section curve of the sixth curved surface (2046) is an arc curve, the chord length of the airfoil body (10) is taken as L, and the radius of the arc curve of the sixth curved surface is 0.007L;
the section curve of the seventh curved surface (2047) is a cubic curve, and the flow area of the jet outlet between the seventh curved surface (2047) and the first curved surface (2041) is linearly reduced by 1.2 times along the fluid flow direction.
2. The active jet structure for improving cavitation flow around a hydrofoil according to claim 1, characterized in that the fairing tip (202) extends from the suction surface (101) of the airfoil body (10) into the active jet cavity (20) along the incoming flow direction of the fluid on the surface of the suction surface (101); the rectifying tip (202) divides the active jet cavity (20) into a pre-compression cavity (u), a transition compression cavity (v) and a jet compression cavity (w) which are sequentially arranged along the flow direction of the active jet, a gap between the end part of the rectifying tip (202) and the active jet cavity (20) is the transition compression cavity (v), the pre-compression cavity (u) is communicated with the jet inlet, and the jet outlet of the jet compression cavity (w) faces the same direction as the flow direction of the fluid on the surface of the suction surface (101).
3. The active jet structure for improving cavitation flow around hydrofoil according to claim 2 characterized in that the rectifying section is a rectifying tube (203), and the rectifying tube (203) is matched with the shape of the jet inlet, inserted into the pre-compression chamber (u) along the jet inlet and fixed.
4. The active jet structure for improving cavitation flow around hydrofoil according to the claim 3 is characterized in that, with the chord length of the airfoil body (10) as L, the distance between the rectifying tube (203) and the front edge of the airfoil is 0.3L, the height of the jet outlet is 0.002L-0.008L, and the distance between the jet outlet and the front edge of the airfoil is 0.2L-0.4L.
5. The active jet structure for improving cavitation flow around hydrofoil according to any one of claims 2 to 4, characterized in that a flow channel partition plate (201) is arranged in the jet compression chamber (w) to divide the jet compression chamber (w) into at least two flow channels along the extending direction.
6. The active jet structure for improving the cavitation flow around the hydrofoil according to the claim 5 is characterized in that, the chord length of the airfoil body (10) is L, the width of the jet outlet is 0.8L, the width of the flow channel separation plate (201) is 0.1L, and the flow channel separation plate (201) is divided into two in total, so as to uniformly separate the jet outlet into three flow channels with the width of 0.2L.
7. The active jet structure for improving cavitation flow around hydrofoil according to any one of claims 1 to 4, characterized in that the active jet cavity (20) is a curved cavity with a cross section in a hook-jade shape.
8. The active jet structure for improving cavitation flow around hydrofoil according to any of claims 1 to 4, characterized in that the total area of the orifices of the rectifying hole is smaller than the area of the jet inlet.
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| CN205891234U (en) * | 2016-08-02 | 2017-01-18 | 西北工业大学 | A unite efflux controlling means for helicopter rotor blade |
| CN106593786A (en) * | 2017-02-15 | 2017-04-26 | 西北工业大学 | Reverse co-flow jet controlling method and device used for wind turbine blade pneumatic braking |
| CN110685976A (en) * | 2019-09-12 | 2020-01-14 | 武汉大学 | Suction jet device for blade boundary layer |
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| US9239039B2 (en) * | 2008-10-27 | 2016-01-19 | General Electric Company | Active circulation control of aerodynamic structures |
| CN111322198A (en) * | 2020-03-10 | 2020-06-23 | 上海理工大学 | Wind turbine wing section for improving pneumatic performance through jet flow |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN205891234U (en) * | 2016-08-02 | 2017-01-18 | 西北工业大学 | A unite efflux controlling means for helicopter rotor blade |
| CN106593786A (en) * | 2017-02-15 | 2017-04-26 | 西北工业大学 | Reverse co-flow jet controlling method and device used for wind turbine blade pneumatic braking |
| CN110685976A (en) * | 2019-09-12 | 2020-01-14 | 武汉大学 | Suction jet device for blade boundary layer |
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