Hydrofoil and particle sowing system

Abstract

The embodiment of the invention provides a hydrofoil and a particle sowing system. The hydrofoil is used for being arranged in a liquid flow field, and the first surface and the second surface of the hydrofoil are symmetrically arranged. A pressure maintaining cavity is formed in the hydrofoil; a slot extending in the wingspan direction of the hydrofoil is formed in the front edge of the hydrofoil; the front edge of the hydrofoil faces the incoming flow direction of the liquid flow field; the slot is communicated with the pressure maintaining cavity through a connecting hole channel; the pressure maintaining cavity is provided with a first opening in the first side face of the hydrofoil, and the first opening is used for receiving mixed liquid input from the outside and composed of particles and the liquid. Mixed liquid entering the pressure maintaining cavity passes through the connecting hole channel and is discharged from the slot at the front edge of the hydrofoil, so that the particles are sown in the liquid flow field; wherein the first pressure of the mixed liquid input from the outside is greater than the second pressure of the liquid flow field.

Description

Technical Field

[0001] The present invention relates to the field of fluid dynamics, and particularly to a hydrofoil and a particle seeding system. Background Art

[0002] Particle Image Velocimetry (PIV) is a non-contact fluid velocity measurement technique widely used in water tunnel experiments, especially when studying complex flows, turbulent characteristics, and flow field structures. PIV technology obtains the velocity distribution of the flow field by analyzing the motion of suspended particles in the flow, and is usually used in the field of fluid mechanics research. In water tunnel experiments, particles are used as the velocity measurement medium, and their accurate seeding and uniform distribution directly affect the accuracy and reliability of PIV technology.

[0003] In traditional PIV particle seeding methods, particles are usually evenly scattered into the water flow serving as the flow field and are made to be evenly distributed by stirring. This method is suitable for small-scale water tunnel experiments. In large water tunnels or large water body experiments, the traditional method faces problems of insufficient particle concentration resolution and disturbance of the flow field in the test section. If particles are evenly scattered into the water body and sufficient space is required for the particles to be distributed, then the amount of particles required will be extremely large and almost impossible to achieve. Therefore, how to achieve particle seeding in large water tunnels or relatively large water body experiments, meeting the particle concentration requirements and causing less disturbance to the flow field. Summary of the Invention

[0004] In view of this, embodiments of the present disclosure provide a hydrofoil and a particle seeding system.

[0005] According to a first aspect of embodiments of the present disclosure, a hydrofoil is proposed, characterized in that the hydrofoil is configured to be disposed in a liquid flow field, wherein,

[0006] The first surface and the second surface of the hydrofoil are symmetrically arranged;

[0007] A pressure maintaining cavity is arranged inside the hydrofoil;

[0008] A slot is arranged at the leading edge of the hydrofoil and extends along the span direction of the hydrofoil; wherein, the leading edge of the hydrofoil faces the oncoming flow direction of the liquid flow field;

[0009] The slot communicates with the pressure maintaining cavity through a connecting channel;

[0010] The pressure-holding cavity is provided with a first opening on the first side of the hydrofoil, and the first opening is used to receive the mixed liquid composed of particles and the liquid input from the outside; the mixed liquid entering the pressure-holding cavity is discharged from the slot at the leading edge of the hydrofoil through the connecting channel to spread the particles in the liquid flow field; wherein, the first pressure of the mixed liquid input from the outside is greater than the second pressure of the liquid flow field.

[0011] In some embodiments, the pressure-holding cavity extends along the span direction of the hydrofoil;

[0012] There are N connecting channels, and the N connecting channels are evenly arranged along the span direction of the hydrofoil and communicate with the pressure-holding cavity and the slot respectively, where N is an integer greater than or equal to 1.

[0013] In some embodiments, the sum of the areas of the first cross-sections corresponding to the N connecting channels is smaller than the area of the second cross-section of the slot; wherein, the first cross-section is perpendicular to the flow direction of the mixed liquid in the connecting channel; the second cross-section is perpendicular to the flow direction of the mixed liquid in the slot.

[0014] In some embodiments, the pressure-holding cavity includes a first sub-pressure-holding cavity and a second sub-pressure-holding cavity arranged in sequence along the span direction of the hydrofoil;

[0015] The first end of the first sub-pressure-holding cavity is used to receive the mixed liquid input from the outside;

[0016] The second end of the first sub-pressure-holding cavity and the first end of the second sub-pressure-holding cavity communicate with each other; a switching component is arranged at the connection part between the second end of the first sub-pressure-holding cavity and the first end of the second sub-pressure-holding cavity;

[0017] The switching component is used to conduct or cut off the passage between the first sub-pressure-holding cavity and the second sub-pressure-holding cavity.

[0018] In some embodiments, the inner wall of the first end of the second sub-pressure-holding cavity is provided with threads;

[0019] The switching component includes a bolt that enters the second sub-pressure-holding cavity through the inside of the first sub-pressure-holding cavity and is in threaded cooperation with the inner wall of the first end of the second sub-pressure-holding cavity.

[0020] In some embodiments, the relative thickness of the hydrofoil is 12% to 40%.

[0021] According to the second aspect of the embodiments of the present disclosure, a particle spreading system is provided, which is characterized in that the particle spreading system includes: a water tunnel, a stirring barrel, a gas compression device, and the hydrofoil according to the first aspect;

[0022] The hydrofoil is arranged in the liquid flow field in the water tunnel;

[0023] The mixing barrel is used to mix liquid and particles to obtain a mixture.

[0024] The gas compression device is connected to the mixing barrel and is used to discharge compressed gas into the mixing barrel to pressurize the mixture to a first pressure.

[0025] The mixing barrel is connected to the hydrofoil, and a first opening is provided through the side wall of the hydrofoil to discharge the mixture into a pressure-holding chamber provided inside the hydrofoil.

[0026] In some embodiments, the particle spreading system further includes at least one of the following disposed between the mixing barrel and the hydrofoil:

[0027] A liquid pressure regulating valve for adjusting the pressure of the mixture discharged into the pressure-holding chamber.

[0028] A check valve for blocking the reverse flow of the mixture from the pressure-holding chamber to the mixing barrel.

[0029] A stop valve for shutting off the mixture discharged into the pressure-holding chamber.

[0030] In some embodiments, the water tunnel includes a first side wall and a second side wall disposed opposite to each other.

[0031] A first limiting groove is provided on the inner surface of the first side wall, and the first limiting groove is adapted to the first end of the hydrofoil.

[0032] A second limiting groove is provided on the inner surface of the second side wall, and the second limiting groove is adapted to the second end of the hydrofoil.

[0033] The first side wall and the second side wall respectively clamp the hydrofoil through the first limiting groove and the second limiting groove to fix the hydrofoil in the water tunnel.

[0034] In some embodiments, the first side wall is provided with a through hole communicating with the first opening.

[0035] A pipeline for the flow of the mixed liquid is connected between the mixing barrel and the hydrofoil. Among them, the first end of the pipeline passes through the through hole and is connected to the first opening, and the second end of the pipeline is connected to the mixing barrel.

[0036] In some embodiments, the first side surface is disposed at the first end of the hydrofoil.

[0037] A flexible gasket for sealing the first side surface and the bottom surface of the first limiting groove is provided between the first side surface and the bottom surface of the first limiting groove.

[0038] Embodiments of the present disclosure provide a hydrofoil and a particle seeding system. The hydrofoil is configured to be disposed in a liquid flow field, wherein the first surface and the second surface of the hydrofoil are symmetrically arranged; a pressure maintaining cavity is arranged inside the hydrofoil; a slot is arranged at the leading edge of the hydrofoil and extends along the span direction of the hydrofoil; wherein the leading edge of the hydrofoil faces the oncoming flow direction of the liquid flow field; the slot communicates with the pressure maintaining cavity through a connecting channel; the pressure maintaining cavity is provided with a first opening on the first side surface of the hydrofoil, and the first opening is used to receive an externally input mixed liquid composed of particles and the liquid; the mixed liquid entering the pressure maintaining cavity is discharged from the slot at the leading edge of the hydrofoil through the connecting channel to seed the particles in the liquid flow field; wherein the first pressure of the externally input mixed liquid is greater than the second pressure of the liquid flow field. Thus, by discharging the mixed liquid at the leading edge of the hydrofoil, on the one hand, the hydrofoil can reduce the disturbance to the flow field, and on the other hand, discharging the mixed liquid at the leading edge of the hydrofoil where the flow field velocity is small can reduce the direct impact of the particles on the flow field, improve the followability of the particles following the flow field, and improve the distribution uniformity of the particles. Description of the Drawings

[0039] Figure 1 is a schematic three-dimensional structure diagram of a hydrofoil shown according to an embodiment;

[0040] Figure 2 is a schematic side structure diagram of a hydrofoil shown according to an embodiment;

[0041] Figure 3 is a schematic cross-sectional structure diagram of a hydrofoil in the A direction shown according to an embodiment;

[0042] Figure 4 is a schematic cross-sectional structure diagram of a hydrofoil in the B direction shown according to an embodiment;

[0043] Figure 5 is a schematic diagram of particle distribution from a perspective shown according to an embodiment;

[0044] Figure 6 is a schematic diagram of particle distribution from another perspective shown according to an embodiment;

[0045] Figure 7 is a schematic diagram of the pressure of the flow field around the hydrofoil in the particle-free state shown according to an embodiment;

[0046] Figure 8 is a schematic diagram of the pressure of the flow field around the hydrofoil in the particle-containing state shown according to an embodiment;

[0047] Figure 9 is a schematic diagram of a partial enlargement of the cross-section of a hydrofoil shown according to an embodiment;

[0048] Figure 10It is a schematic diagram of the composition structure of a particle spreading system shown according to an embodiment;

[0049] Figure 11 It is a schematic diagram of the working of a water tunnel shown according to an embodiment;

[0050] Figure 12 It is a schematic diagram of the fixing structure of a hydrofoil shown according to an embodiment;

[0051] Figure 13 It is a schematic diagram of the structure of a first side wall shown according to an embodiment;

[0052] Figure 14 It is a schematic diagram of the structure of a second side wall shown according to an embodiment;

[0053] Figure 15 It is a schematic perspective view of the structure of a first side wall shown according to an embodiment. Detailed implementation manners

[0054] To make the technical solutions and beneficial effects of the present invention more obvious and understandable, the following will be described in detail by listing specific embodiments. Among them, the drawings are not necessarily drawn to scale, and local features can be enlarged or reduced to more clearly show the details of the local features; unless otherwise defined, the technical and scientific terms used herein have the same meanings as those in the technical and scientific fields to which this application belongs.

[0055] The embodiments of the present disclosure are not exhaustive, but only schematic of some embodiments, and do not constitute specific limitations on the protection scope of the present disclosure. Without contradiction, each step in an embodiment can be implemented as an independent embodiment, and the steps can be combined arbitrarily. For example, the solution after removing some steps in an embodiment can also be implemented as an independent embodiment, and the order of the steps in an embodiment can be arbitrarily exchanged. Additionally, the optional implementation manners in an embodiment can be combined arbitrarily; furthermore, the embodiments can be combined arbitrarily. For example, parts or all of the steps of different embodiments can be combined arbitrarily, and an embodiment can be combined arbitrarily with the optional implementation manners of other embodiments.

[0056] In each embodiment of the present disclosure, if there is no special explanation and logical conflict, the terms and / or descriptions between the embodiments are consistent and can be cited from each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0057] The terms used in the embodiments of the present disclosure are only for the purpose of describing specific embodiments, and do not constitute a limitation on the present disclosure.

[0058] In the embodiments of the present disclosure, unless otherwise specified, elements expressed in the singular form, such as "a", "an", "the", "above", "said", "aforementioned", "this", etc., may mean "one and only one", or may also mean "one or more", "at least one", etc. For example, when using articles such as "a", "an", "the" in English translation, the noun following the article can be understood as a singular form of expression or a plural form of expression.

[0059] In the embodiments of the present disclosure, "a plurality of" means two or more.

[0060] In some embodiments, terms such as "at least one of (at least one, at least one item, at least one)", "one or more", "a plurality of", "multiple", etc. can be replaced with each other.

[0061] In some embodiments, notations such as "at least one of A and B", "A and / or B", "A in one case, B in another case", "A in one situation, B in another situation", etc. may include the following technical solutions depending on the situation: In some embodiments, A (performing A independently of B); in some embodiments, B (performing B independently of A); in some embodiments, select to perform from A and B (A and B are selectively performed); in some embodiments, A and B (both A and B are performed). The same is true when there are more branches such as A, B, C, etc.

[0062] In some embodiments, notations such as "A or B" may include the following technical solutions depending on the situation: In some embodiments, A (performing A independently of B); in some embodiments, B (performing B independently of A); in some embodiments, select to perform from A and B (A and B are selectively performed). The same is true when there are more branches such as A, B, C, etc.

[0063] In the embodiments of the present disclosure, prefix words such as "first" and "second" are only used to distinguish different described objects, and do not impose restrictions on the position, order, priority, value, or content of the described objects. For the statements of the described objects, refer to the descriptions in the claims or the context of the embodiments. Unnecessary restrictions should not be formed due to the use of prefix words. For example, if the described object is "field", the ordinal numbers before "field" in "first field" and "second field" do not limit the position or order between the "fields". "First" and "second" do not limit whether the "fields" they modify are in the same message, nor do they limit the order of "first field" and "second field". Another example, if the described object is "level", the ordinal numbers before "level" in "first level" and "second level" do not limit the priority between the "levels". Another example, the value of the described object is not restricted by the ordinal number and can be one or more. Taking "first device" as an example, the value of "device" can be one or more. In addition, the objects modified by different prefix words can be the same or different. For example, if the described object is "device", "first device" and "second device" can be the same device or different devices, and their types can be the same or different. Another example, if the described object is "information", "first information" and "second information" can be the same information or different information, and their contents can be the same or different.

[0064] In some embodiments, "including A", "containing A", "for indicating A", "carrying A" can be interpreted as directly carrying A or indirectly indicating A.

[0065] In some embodiments, terms such as "……", "determine……", "in the case of……", "when……", "when……", "if……", "if……" can be mutually replaced.

[0066] In some embodiments, terms such as "greater than", "greater than or equal to", "not less than", "more than", "more than or equal to", "not less than", "higher than", "higher than or equal to", "not lower than", "above", etc. can be mutually replaced, and terms such as "less than", "less than or equal to", "not greater than", "less than", "less than or equal to", "not more than", "lower than", "lower than or equal to", "not higher than", "below", etc. can be mutually replaced.

[0067] In some embodiments, a device, etc. can be interpreted as physical or virtual, and its name is not limited to the name recorded in the embodiments. Terms such as "device", "equipment", "device", "circuit", "network element", "node", "function", "unit", "section", "system", "network", "chip", "chip system", "entity", "subject", etc. can be mutually replaced.

[0068] In addition, each element, each row, or each column in the table of the embodiments of the present disclosure can be implemented as an independent embodiment, and any combination of any element, any row, and any column can also be implemented as an independent embodiment.

[0069] A water tunnel is a device for hydrodynamic experiments, which can be used to study phenomena such as boundary layers, wakes, turbulence, cavitation, hydroelasticity, etc., as well as the forces between water flows and test objects. A water tunnel is a water circulation system in which the flow velocity and pressure can be controlled separately. The cross-section of the test section of the water tunnel can be circular, square, or rectangular. There are observation windows (walls) on the upper, lower, front, and rear of the water tunnel.

[0070] PIV particles (which can be simply referred to as particles) are tiny particles used in particle image velocimetry (PIV) experiments. PIV is an optical imaging technique for fluid dynamics research that measures the velocity field of a fluid by tracking the movement of particles in the flow field. PIV particles usually have the following characteristics: 1. Relatively small size. The size of the particles is usually between micrometers and hundreds of micrometers to ensure that they can flow with the fluid without significantly affecting the flow field. 2. High optical properties: PIV particles are usually coated with fluorescent or reflective coatings so that they can produce strong optical signals under laser irradiation, ensuring clear visibility of the particles. 3. Uniform distribution: In order to accurately reflect the characteristics of the flow field, PIV particles should be evenly distributed in the fluid so that the velocity field of the fluid can be derived by analyzing the movement trajectories of the particles. 4. Density similar to that of the fluid: The density of PIV particles needs to be close to that of the experimental fluid to ensure that the particles can follow the fluid movement without deviation or sedimentation. During the experiment, PIV particles are irradiated by a laser beam to capture their instantaneous images. By comparing the images at different time points, the velocity of the particles is calculated, and then the velocity field information of the fluid is obtained. It should be noted that since the fluid types are divided into liquids or gases with large density differences, PIV particles can also be divided into liquid PIV particles and gas PIV particles.

[0071] In traditional water tunnel experiments, most use cavitation buckets with relatively small volume capacities. Particles are usually directly scattered into the water and evenly distributed by stirring to form a flow field containing particles. However, in water tunnel experiments with large flow rates and large water volumes, traditional methods cannot meet the requirements. If particles are mixed into all the water bodies that make up the flow field, a large amount of particles need to be sown, resulting in a significant increase in cost and operation complexity.

[0072] Here, a particle sowing device can be set upstream of the test section of the water tunnel to accurately and evenly sow particles near the laser projection surface while ensuring the minimum impact of this process on the downstream flow field.

[0073] As shown in Figures 1 to 4 the embodiments of the present disclosure propose a hydrofoil 100, which is configured to be disposed in a liquid flow field. Among them,

[0074] the first surface 110 and the second surface 120 of the hydrofoil 100 are symmetrically arranged;

[0075] a pressure maintaining cavity 130 is provided inside the hydrofoil 100;

[0076] a slot 140 extending along the span direction of the hydrofoil 100 is provided at the leading edge of the hydrofoil 100; among them, the leading edge of the hydrofoil 100 faces the flow direction of the liquid flow field;

[0077] the slot 140 is communicated with the pressure maintaining cavity 130 through a connecting channel 150;

[0078] the pressure maintaining cavity 130 is provided with a first opening on the first side surface of the hydrofoil 100, and the first opening is used to receive an externally input mixed liquid composed of particles and the liquid; the mixed liquid entering the pressure maintaining cavity 130 is discharged from the slot 140 at the leading edge of the hydrofoil 100 through the connecting channel 150 to spread the particles in the liquid flow field; among them, the first pressure of the externally input mixed liquid is greater than the second pressure of the liquid flow field.

[0079] Figure 1 is a three-dimensional view of the hydrofoil 100. Figure 2 is a side view of the hydrofoil 100. Figure 3 is Figure 2 a cross-sectional view of the hydrofoil 100 at the position of arrow A shown in Figure 4 is Figure 1 a cross-sectional view at the position of arrow B shown in

[0080] Here, the hydrofoil 100 is used to spread particles in the liquid flow field for particle image velocimetry of the liquid flow field. Among them, the liquid may include water, seawater, etc.

[0081] A mixed liquid with a relatively high particle concentration obtained by mixing the same liquid and particles as the liquid flow field can be used. The mixed liquid can be spread by the hydrofoil 100 upstream of the liquid flow field, so as to generate a liquid flow field with particles distributed downstream of the hydrofoil 100.

[0082] The hydrofoil 100 can be fixed in the liquid flow field, the leading edge of the hydrofoil 100 faces the flow direction of the liquid flow field, and the trailing edge of the hydrofoil 100 points to the flow direction of the liquid flow field.

[0083] Here, the hydrofoil 100 can adopt a symmetric design, that is, the first surface 110 and the second surface 120 are symmetric. In this way, when the liquid in the flow field flows through the hydrofoil 100, the flow consistency when passing through the first surface 110 and the second surface 120 can be improved, thereby reducing the disturbance of the hydrofoil 100 to the flow field.

[0084] The first surface 110 and the second surface 120 are two opposite surfaces on the hydrofoil 100. The first surface 110 and the second surface 120 are the two surfaces through which the flow passes.

[0085] The pressure maintaining cavity 130 can be a cavity provided inside the hydrofoil 100 for accommodating the mixed liquid flowing in from the outside. The pressure maintaining cavity 130 has a relatively large volume relative to the flow rate of the mixed liquid discharged from the connection channel 150, so as to be able to maintain a relatively large pressure of the mixed liquid inside the pressure maintaining cavity 130.

[0086] In a possible implementation, the ratio of the volume of the pressure maintaining cavity 130 to the displacement per unit time of the connection channel 150 is greater than or equal to a predetermined ratio. For example, the ratio of the volume of the pressure maintaining cavity 130 to the displacement per second of the connection channel 150 is greater than or equal to 50. In this way, the pressure maintaining effect of the pressure maintaining cavity 130 can be improved.

[0087] In a possible implementation, the pressure of the mixed liquid inside the pressure maintaining cavity 130 is less than or equal to the first pressure and greater than the second pressure. In this way, affected by the pressure difference, the mixed liquid can be discharged from the pressure maintaining cavity 130 through the connection channel 150 and the slot 140 into the liquid flow field.

[0088] In a possible implementation, the pressure of the mixed liquid inside the pressure maintaining cavity 130 can be adjusted by adjusting the cross-sectional area of the connection channel 150. The cross-sectional area of the connection channel 150 is negatively correlated with the pressure of the mixed liquid inside the pressure maintaining cavity 130.

[0089] The pressure maintaining cavity 130 can receive the mixed liquid with a higher pressure from the first opening on the first side surface of the hydrofoil 100. The mixed liquid reaches the slot 140 through the connection channel 150 and is discharged into the liquid flow field through the slot 140.

[0090] Here, the speed of the mixed liquid discharged from the slot 140 can also be adjusted by adjusting the first pressure. By discharging the mixed liquid at a slower speed, the disturbance to the flow field can be reduced, and the uniform distribution of particles can also be ensured. The slot 140 is provided at the leading edge of the hydrofoil 100, and the flow velocity of the liquid in the flowing direction where the slot 140 is not provided at the leading edge position of the hydrofoil 100 is zero. Therefore, injecting particles at this position can reduce the disturbance to the flow field and make the particles discharged from the slot 140 have better followability.

[0091] In a possible implementation,

[0092] In this way, by discharging the mixed liquid at the leading edge of the hydrofoil 100, on the one hand, the hydrofoil 100 can reduce the disturbance to the flow field. On the other hand, discharging the mixed liquid at the leading edge of the hydrofoil 100 where the flow field velocity is relatively small can reduce the direct impact of the particles on the flow field, improve the followability of the particles following the flow field, and improve the distribution uniformity of the particles.

[0093] In some embodiments, the relative thickness of the hydrofoil 100 is 12% to 40%.

[0094] Here, the relative thickness is the percentage ratio of the thickness of the hydrofoil 100 to the chord length of the hydrofoil 100. Among them, the chord length of the hydrofoil 100 is the distance between the leading edge and the trailing edge of the hydrofoil 100.

[0095] The hydrofoil 100 will generate resistance to the flow field. The relative thickness of the hydrofoil 100 is positively correlated with the resistance generated by the hydrofoil 100 to the flow field. Therefore, the relative thickness of the hydrofoil 100 can be set based on the liquid flow velocity of the flow field. For example, if the liquid flow velocity in the flow field is relatively high, then a hydrofoil 100 with a relatively small relative thickness can be used to reduce the interference of the resistance to the flow field; on the contrary, if the liquid flow velocity in the flow field is relatively low, then a hydrofoil 100 with a relatively large relative thickness can be used.

[0096] In a possible implementation, a hydrofoil 100 with a relative thickness of 24% can be used.

[0097] By using hydrofoils 100 with different relative thicknesses, the flexibility of the selection of the hydrofoil 100 can be improved to adapt to different flow fields.

[0098] In some embodiments, as Figure 3 shown, the pressure-holding cavity 130 extends along the span direction of the hydrofoil 100;

[0099] There are N connecting channels 150, and the N connecting channels 150 are uniformly arranged along the span direction of the hydrofoil 100 and are respectively communicated with the pressure-holding cavity 130 and the slot 140, where N is an integer greater than or equal to 1.

[0100] In a possible implementation manner, the pressure-holding cavity 130 can be a cylindrical cavity extending along the span direction of the hydrofoil 100. The cross-sectional shape of the cylindrical cavity can be circular, elliptical, rectangular, etc.

[0101] In a possible implementation manner, the ratio of the volume of the pressure-holding cavity 130 to the total displacement per unit time of the N connecting channels 150 is greater than or equal to a predetermined ratio. For example, the ratio of the volume of the pressure-holding cavity 130 to the total displacement per second of the N connecting channels 150 is greater than or equal to 50. In this way, the pressure-holding effect of the pressure-holding cavity 130 can be improved.

[0102] In a possible implementation, the pressure-holding cavity 130 may penetrate the hydrofoil 100 in the spanwise direction. The pressure-holding cavity 130 may have a first opening provided on the first side surface of the hydrofoil 100, and components such as a sealing cover may be used to seal the second side wall 220 of the hydrofoil 100.

[0103] In a possible implementation, the pressure-holding cavity 130 may have a first opening provided on the first side surface of the hydrofoil 100 and a second opening provided on the second side surface of the hydrofoil 100. Both the first opening and the second opening may be used to receive the mixed liquid to increase the flow rate of the mixed liquid entering the pressure-holding cavity 130.

[0104] In a possible implementation, the length of the pressure-holding cavity 130 in the spanwise direction of the hydrofoil 100 is greater than or equal to the length of the slot 140 in the spanwise direction of the hydrofoil 100.

[0105] In a possible implementation, the pressure-holding cavity 130 is arranged in parallel with the slot 140.

[0106] Here, the N connecting channels 150 are uniformly arranged, that is, the spacing distances between adjacent connecting channels 150 are the same.

[0107] The uniform arrangement of the N connecting channels 150 can enable the mixed liquid entering the slot 140 from the pressure-holding cavity 130 to be evenly distributed into the slot 140. The mixed liquid entering the slot 140 is further mixed, and then the mixed liquid discharged from the slot 140 to the flow field can be evenly distributed. The particles in the mixed liquid are uniformly discharged from the slot 140 along with the mixed liquid and are scattered onto the flow field along the first surface 110 and the second surface 120 of the hydrofoil 100. Due to the symmetric design of the hydrofoil 100, the uniformity of the particles discharged from the trailing edge of the hydrofoil 100 to the flow field can be improved.

[0108] Here, the pressure-holding cavity 130 improves the pressure consistency of the mixed liquid at various positions within the pressure-holding cavity 130. Since the distances of the connecting channels 150 from the first opening are different, the use of the pressure-holding cavity 130 can reduce the pressure difference when the mixed liquid flows into each connecting channel 150, thereby increasing the flow rate of the mixed liquid within the N connecting channels 150, and further improving the uniformity of the mixed liquid entering the slot 140.

[0109] If the slot 140 is not adopted and the mixed liquid is directly discharged from the leading edge of the hydrofoil 100 through the connecting channels 150, since the distribution of the connecting channels 150 is discrete, the discharged particles will be discharged in the form of multiple discrete beam-like particle flows, affecting the uniformity of particle distribution. The slot 140 is continuous at the leading edge of the hydrofoil 100, so the particles can be discharged evenly. If the connecting channels 150 are not adopted and the slot 140 is directly connected to the pressure maintaining cavity 130, then the pressure maintaining cavity 130 will be directly connected to the flow field through the slot 140, resulting in too fast pressure relief of the pressure maintaining cavity 130 and the pressure maintaining cavity 130 being unable to effectively maintain pressure and distribute flow. At the same time, as the particles flow from the first end of the pressure maintaining cavity 130 to the other end of the pressure maintaining cavity 130, under the action of inertia, there will be a movement component of the discharged particles in the span direction of the hydrofoil 100, which will not only affect the flow field but also may cause uneven particle distribution.

[0110] In this way, by arranging N connecting channels 150 with uniform distribution between the pressure maintaining cavity 130 and the slot 140, on the one hand, the pressure maintaining effect of the pressure maintaining cavity 130 can be improved, and on the other hand, the uniformity of the mixed liquid entering the slot 140 can be improved, thereby improving the uniformity of particle distribution in the flow field.

[0111] In some embodiments, the sum of the areas of the first cross-sections corresponding to the N connecting channels 150 is smaller than the area of the second cross-section of the slot 140; wherein, the first cross-section is perpendicular to the flow direction of the mixed liquid in the connecting channels 150; the second cross-section is perpendicular to the flow direction of the mixed liquid in the slot 140.

[0112] Here, the flow rate of the mixed liquid discharged from the pressure maintaining cavity 130 to the slot 140 can be reduced through the connecting channels 150, thereby reducing the situation of too fast pressure relief of the pressure maintaining cavity 130, enabling the pressure maintaining cavity 130 to effectively maintain pressure and distribute flow, and further improving the uniformity of particle distribution.

[0113] In some embodiments, as Figure 3 and Figure 4 shown, the pressure maintaining cavity 130 includes a first sub-pressure maintaining cavity 131 and a second sub-pressure maintaining cavity 132 arranged in sequence along the span direction of the hydrofoil 100;

[0114] The first end of the first sub-pressure maintaining cavity 131 is used to receive the mixed liquid input from the outside;

[0115] The second end of the first sub-pressure maintaining cavity 131 and the first end of the second sub-pressure maintaining cavity 132 are interconnected; a on-off component is arranged at the connection part between the second end of the first sub-pressure maintaining cavity 131 and the first end of the second sub-pressure maintaining cavity 132;

[0116] The on-off component is used to conduct or cut off the passage between the first sub-pressure maintaining cavity 131 and the second sub-pressure maintaining cavity 132.

[0117] In a possible implementation manner, the pressure maintaining cavity 130 may include two or more sub-pressure maintaining cavities 130. The first sub-pressure maintaining cavity 131 and the second sub-pressure maintaining cavity 132 may be two adjacent sub-pressure maintaining cavities 130.

[0118] Specifically, as Figure 3 shown, the first sub-pressure maintaining cavity 131 and the second sub-pressure maintaining cavity 132 are arranged along the span direction of the hydrofoil 100. The externally input mixed liquid can flow into the first sub-pressure maintaining cavity 131 and then flow from the first sub-pressure maintaining cavity 131 to the second sub-pressure maintaining cavity 132.

[0119] The first sub-pressure maintaining cavity 131 and the second sub-pressure maintaining cavity 132 are respectively used to provide the mixed liquid to different regions of the slot 140. As Figure 3 shown, the first sub-pressure maintaining cavity 131 is used to discharge the mixed liquid to the first segment 141 of the slot 140, and the second sub-pressure maintaining cavity 132 is used to discharge the mixed liquid to the second segment 142 of the slot 140. Whether to inject the mixed liquid into the second sub-pressure maintaining cavity 132 can be controlled through the on-off component, and further whether the second sub-pressure maintaining cavity 132 discharges the mixed liquid to the second segment 142 of the slot 140 can be controlled to control the area of the particle-covered flow field.

[0120] Figure 5 and Figure 6 are respectively the distribution situations of the particles in the flow field observed at different viewing angles when the on-off component cuts off the injection of the mixed liquid into the second sub-pressure maintaining cavity 132.

[0121] Figure 7 and Figure 8 are respectively the flow pressure conditions of the first segment and the second segment of the slot 140 in the flow direction of the flow field liquid when the on-off component cuts off the injection of the mixed liquid into the second sub-pressure maintaining cavity 132.

[0122] By setting the first sub-pressure maintaining cavity 131 and the second sub-pressure maintaining cavity 132 and using the on-off component to control whether to inject the mixed liquid into the second sub-pressure maintaining cavity 132, the control of the particle-covered flow field area can be realized, the flexibility of particle spreading can be improved, and the adaptability to different scenarios can be improved.

[0123] In some embodiments, the inner wall of the first end of the second sub-pressure maintaining cavity 132 is provided with a thread;

[0124] The on-off component includes a bolt that enters the second sub-pressure maintaining cavity 132 through the inside of the first sub-pressure maintaining cavity 131 and is in threaded fit with the inner wall of the first end of the second sub-pressure maintaining cavity 132.

[0125] Specifically, as Figure 9 shown ( Figure 9 being Figure 3 an enlarged view of region X), the cross-sections of the first sub-pressure-holding cavity 131 and the second sub-pressure-holding cavity 132 can be circular, and the inner diameter of the first sub-pressure-holding cavity 131 can be greater than or equal to the inner diameter of the second sub-pressure-holding cavity 132. A bolt can pass through the first sub-pressure-holding cavity 131 to reach the second sub-pressure-holding cavity 132, and the bolt thread can be threadedly engaged with the inner wall of the first end of the second sub-pressure-holding cavity 132. The sealing of the first end of the second sub-pressure-holding cavity 132 can be achieved based on the threaded engagement.

[0126] In a possible implementation, the bolt can include a nut. When the inner diameter of the first sub-pressure-holding cavity 131 is greater than the inner diameter of the second sub-pressure-holding cavity 132, a step will be generated between the second end of the first sub-pressure-holding cavity 131 and the first end of the second sub-pressure-holding cavity 132 due to the internal diameter difference. The sealing of the first end of the second sub-pressure-holding cavity 132 is achieved based on the tight fit between the nut and this step.

[0127] As Figure 10 shown, an embodiment of the present disclosure provides a particle spraying system, which includes: a water tunnel 200, a stirring barrel 300, a gas compression device 400, and a hydrofoil 100;

[0128] The hydrofoil 100 is disposed in the liquid flow field in the water tunnel 200;

[0129] The stirring barrel 300 is used to mix a liquid and particles to obtain a mixed liquid;

[0130] The gas compression device 400 is connected to the stirring barrel 300 and is used to discharge compressed gas into the stirring barrel 300 to pressurize the mixed liquid to a first pressure;

[0131] The stirring barrel 300 is connected to the hydrofoil 100, and the mixed liquid is discharged into the pressure-holding cavity 130 disposed inside the hydrofoil 100 through a first opening provided on the side wall of the hydrofoil 100.

[0132] Here, the implementation manner of the hydrofoil 100 is as described in any of the above embodiments, and will not be elaborated herein.

[0133] The water tunnel 200 is a hydrodynamic experimental device for allowing a liquid flow to pass through. The water tunnel 200 can be a water circulation system in which the flow rate and pressure can be controlled separately.

[0134] In a possible implementation, the cross-section of the water tunnel 200 section can be circular, square, rectangular, etc.

[0135] The hydrofoil 100 can be fixed within the water tunnel 200. For example, the hydrofoil 100 can be fixed at the upstream position of the liquid flow field within the water tunnel 200 so that the hydrofoil 100 can disperse particles at the upstream position of the liquid flow field.

[0136] The mixing barrel 300 can include a pressure barrel and a stirrer. The liquid and particles are mixed within the pressure barrel to obtain a mixed liquid. The mixing barrel 300 can be powered by an electric motor to rotate the stirrer at a high speed, thereby improving the mixing efficiency. The pressure barrel can be configured to withstand high pressure and is used for stirring under the first pressure.

[0137] The gas compression device 400 can generate pressurized gas (such as air, nitrogen, etc.) and input the pressurized gas into the mixing barrel 300. The gas compression device 400 can compress the input gas into pressurized (such as high-pressure) gas by mechanical means (such as piston compression). The gas compression device 400 and the mixing barrel 300 can be connected through a high-pressure gas pipe.

[0138] In a possible implementation, a gas pressure regulating valve 800 (such as a gas pressure reducing valve) can also be included between the gas compression device 400 and the mixing barrel 300 to regulate the pressure of the compressed gas input into the mixing barrel 300. This is to improve the stability of the input gas pressure and further improve the stability of the mixed liquid discharged by the hydrofoil 100.

[0139] Exemplarily, as Figure 10 shown, the gas compression device 400 is connected to the mixing barrel 300 through a gas hose. The gas hose can be connected to the top of the mixing barrel 300 to introduce the compressed gas above the liquid level of the mixed liquid to pressurize the mixed liquid. The mixing barrel 300 can include an electric stirrer and a control device. The electric stirrer includes a stirring blade located below the liquid level of the mixed liquid. The mixing barrel 300 can be provided with a liquid addition port for adding liquid and particles into the mixing barrel 300. After the stirring blade rotates, it can continuously stir the mixed liquid within the mixing barrel 300 to ensure uniform mixing of the particles and the liquid and prevent the particles from settling or floating.

[0140] A liquid level indicator is provided on the side wall of the pressure barrel of the mixing barrel 300, and the liquid level within the barrel can be read at any time. The mixing barrel 300 can also be provided with a pressure gauge for real-time monitoring of the pressure of the pressure barrel.

[0141] The mixing barrel 300 can be connected to the hydrofoil 100 through a pipeline. The pipeline is used to connect the liquid outlet of the mixing barrel 300 and the first opening of the hydrofoil 100.

[0142] In a possible implementation, the pipeline can be implemented using a metal bellows. The metal bellows can provide elastic deformation when subjected to external forces, temperature changes, or pressure changes, absorb vibrations, compensate for displacements, or serve as a seal.

[0143] As Figure 10 shown, the particle dispensing system may further include an optical illumination device (such as a laser) and an image capturing device (such as a high-speed camera). The optical illumination device is used to irradiate the particles in the liquid flow field (such as projecting laser light through a laser). The image capturing device is used to obtain images of the particles in the liquid flow field, so as to calculate the motion parameters (speed, moving direction, etc.) of the particles by comparing the images at different time points, and further obtain the velocity field information of the fluid in the flow field, etc.

[0144] Here, as Figure 11 shown, the water tunnel 200 may be provided with transparent side walls for the optical illumination device to irradiate the flow field and for the image capturing device to obtain particle images. For example, the side walls of the water tunnel 200 may be made of a transparent material (such as glass, acrylic, etc.).

[0145] In this way, the liquid and particles are stirred in the stirring barrel 300 to obtain a mixed liquid, and then the compressed gas of the gas compression device 400 pressurizes the mixed liquid, and the pressurized mixed liquid is input into the hydrofoil 100 in the water tunnel 200. Combining with the dispensing structure of the hydrofoil 100, the dispensing of particles in the flow field is realized. By discharging the mixed liquid at the leading edge of the hydrofoil 100, on the one hand, the hydrofoil 100 can reduce the disturbance to the flow field, and on the other hand, discharging the mixed liquid at the leading edge of the hydrofoil 100 where the flow field velocity is small can reduce the direct impact of the particles on the flow field, improve the followability of the particles to follow the flow field, and improve the distribution uniformity of the particles.

[0146] In some embodiments, the particle dispensing system further includes at least one of the following disposed between the stirring barrel 300 and the hydrofoil 100:

[0147] A liquid pressure regulating valve 500 for adjusting the pressure of the mixed liquid discharged into the pressure maintaining chamber 130;

[0148] A check valve 600 for blocking the reverse flow of the mixed liquid from the pressure maintaining chamber 130 to the stirring barrel 300;

[0149] A shut-off valve 700 for shutting off the mixed liquid discharged into the pressure maintaining chamber 130.

[0150] The liquid pressure regulating valve 500 is used to adjust the pressure of the mixed liquid input into the pressure maintaining chamber 130 so that the mixed liquid input into the pressure maintaining chamber 130 can maintain a first pressure, thereby improving the smoothness of the input mixed liquid and further improving the stability of the mixed liquid discharged by the hydrofoil 100.

[0151] The shut-off valve 700 is used to shut off the mixed liquid discharged into the pressure maintaining chamber 130 to realize the on-off control of particle dispensing.

[0152] The check valve 600 is used to prevent the backflow of the mixed liquid in the pressure-holding cavity 130 into the mixing barrel 300, so as to reduce the influence on the concentration of the mixed liquid in the mixing drum, and further improve the uniformity of particle spreading.

[0153] In some embodiments, as Figures 11 to 14 shown, the water tunnel 200 includes a first side wall 210 and a second side wall 220 which are oppositely arranged,

[0154] a first limiting groove 211 is arranged on the inner surface of the first side wall 210, and the first limiting groove 211 is adapted to the first end of the hydrofoil 100,

[0155] a second limiting groove 221 is arranged on the inner surface of the second side wall 220, and the second limiting groove 221 is adapted to the second end of the hydrofoil 100,

[0156] the first side wall 210 and the second side wall 220 respectively clamp the hydrofoil 100 through the first limiting groove 211 and the second limiting groove 221, and fix the hydrofoil 100 in the water tunnel 200.

[0157] Here, the first side wall 210 and the second side wall 220 can be flat or curved surfaces, which are not limited herein.

[0158] The first limiting groove 211 and the second limiting groove 221 are set based on the cross-sectional shape of the hydrofoil 100 to realize the matching between the first limiting groove 211 and the first end of the hydrofoil 100 and the matching between the second limiting groove 221 and the second end of the hydrofoil 100.

[0159] Through the limiting groove, the hydrofoil 100 in the flow field can be fixed, the movement of the hydrofoil 100 can be reduced, and the stability of the flow field and the stability of particle spreading can be improved.

[0160] In a possible implementation manner, a first fixing through hole 213 and a second fixing through hole 222 can be respectively arranged at the bottom of the first limiting groove 211 and the bottom of the second limiting groove 221. A first limiting hole 170 can be arranged on the side wall of the first end of the hydrofoil 100 corresponding to the first fixing through hole 213; a second limiting hole 180 can be arranged on the side wall of the second end of the hydrofoil 100 corresponding to the second fixing through hole 222. A first limiting pin (such as a limiting bolt) can pass through the first fixing through hole 213 and enter the first limiting hole 170 to further fix the hydrofoil 100. A second limiting pin (such as a limiting bolt) can pass through the second fixing through hole 222 and enter the second limiting hole 180 to further fix the hydrofoil 100. The first limiting pin can be fixed in cooperation with the first limiting hole 170 through a thread. The second limiting pin can be fixed in cooperation with the second limiting hole 180 through a thread.

[0161] In a possible implementation, a sealing member (such as raw tape) can be provided on the side wall of the first limit pin to achieve sealing with the first fixing through hole 213. A sealing member (such as raw tape) can be provided on the side wall of the second limit pin to achieve sealing with the second fixing through hole 222.

[0162] In some embodiments, such as Figure 15 the first side wall 210 is provided with a through hole 212 communicating with the first opening,

[0163] a pipeline for the flow of the mixed liquid is connected between the mixing barrel 300 and the hydrofoil 100, wherein, the first end of the pipeline passes through the through hole 212 and is connected to the first opening, and the second end of the pipeline is connected to the mixing barrel 300.

[0164] Specifically, during the installation process of the hydrofoil 100, the hydrofoil 100 can be first fixed in the water tunnel 200 by clamping the hydrofoil 100 with the first side wall 210 and the second side wall 220. The pipeline can pass through the through hole 212 and be connected to the first opening. In this way, the connection of the pipeline through the through hole 212 to the first opening can improve the installation convenience.

[0165] In a possible implementation, the pipeline can be hermetically connected to the first opening by screw fit.

[0166] In some embodiments, the first side surface is disposed at the first end of the hydrofoil 100,

[0167] a flexible gasket for sealing the first side surface and the bottom surface of the first limit groove 211 is provided between the first side surface and the bottom surface of the first limit groove 211.

[0168] Generally, the hydrofoil 100 and the first side wall 210 can be made of rigid materials. Therefore, the contact surface between the first side surface and the bottom surface of the first limit groove 211 is a contact surface of rigid materials and cannot achieve sealing. When there is a leakage of the mixed liquid between the pipeline and the first opening, the leaked mixed liquid may flow along the first side surface and the bottom surface of the first limit groove 211 into the liquid flow field, thus affecting the uniformity of particle scattering. Therefore, a flexible gasket can be provided between the first side surface and the bottom surface of the first limit groove 211 to improve the sealing degree between the first side surface and the bottom surface of the first limit groove 211 and reduce the influence of the leaked mixed liquid on particle scattering.

[0169] In a possible implementation, the flexible gasket can be made of materials such as rubber and silica gel.

[0170] In a possible implementation, a flexible gasket can also be provided between the second side surface at the second end of the flying wing and the bottom surface of the first limit groove 211.

[0171] A specific example is provided below in combination with any of the above embodiments:

[0172] The schematic diagram of the particle scattering system is as Figures 10 to 15 shown, including: a gas compression device 400; a gas pressure regulating valve 800; a stirring tank 300; a liquid pressure regulating valve 500; a one-way valve; a stop valve 700; a hydrofoil 100, a water tunnel 200; an optical lighting device; an image capturing device; a power supply (such as 220V mains power).

[0173] 1. Gas compression device 400: Such as an air compressor. The gas compression device 400 works through a connected compression tank and can maintain the pressure in the compression tank within a certain range after being powered on. During the experiment, this range can be set to be higher than the total pressure in the water tunnel 200 to ensure that the particles can smoothly enter the flow field of the water tunnel 200.

[0174] 2. Gas pressure regulating valve 800: Such as a gas pressure reducing valve. The gas pressure regulating valve 800 can stably supply pressure to the downstream when the incoming air source pressure is unstable. By setting the supply pressure downstream of the pressure reducing valve to a fixed value higher than the total pressure in the water tunnel 200, the particles can be pressed into the flow field of the water tunnel 200 at a stable flow rate.

[0175] 3. Stirring tank 300: Such as an electric stirring pressure tank. The gas pressure regulating valve 800 is connected to the top opening of the stirring tank 300 through a gas hose, aiming to introduce the stable air pressure supplied by the gas pressure regulating valve 800 into the top of the pressure tank, so as to pump the high-concentration particle mixture liquid in the tank into the water tunnel 200. The stirring tank 300 includes an electric stirrer motor and a control device for controlling the rotation speed of the stirring blade. Water and particles are added to the stirring tank 300. After the stirring blade rotates, it can continuously stir the particle liquid in the stirring tank 300 to ensure uniform mixing of the particles and water and prevent the particles from settling or floating. A water level indicator is provided on the side wall of the pressure tank for reading the water level in the tank at any time. The stirring tank 300 is also provided with a pressure gauge for real-time monitoring of the pressure in the tank. The other end of the metal bellows connecting the outlet pipe of the pressure tank is inserted into the bottom of the tank.

[0176] 4. Liquid pressure regulating valve 500: Such as a liquid pressure reducing valve. The liquid pressure regulating valve 500 is installed downstream of the stirring tank 300, and the flow rate of the particle mixture flowing into the water tunnel 200 can be quickly controlled by adjusting the valve, so as to achieve stable and controllable particle concentration.

[0177] 5. One-way valve, installed downstream of the liquid pressure regulating valve 500, allowing fluid to flow unidirectionally. When the upstream pressure is greater than the downstream pressure, the valve opens; when the downstream pressure is greater than the upstream pressure, the valve closes, thus preventing the water in the water tunnel 200 from flowing back to the stirring tank 300.

[0178] 6. A globe valve 700 is installed downstream of the check valve, and this valve can quickly close the flow channel. When particles are not being sprinkled, this valve can be closed.

[0179] 7. The hydrofoil 100 is used to sprinkle particles into the water tunnel 200.

[0180] The hydrofoil 100 is fixed on the two side wall surfaces of the water tunnel 200. The particles first enter the flow distribution and pressure maintaining cavity 130 of the hollow hydrofoil 100, and then are evenly distributed into the slot 140 on the oncoming flow surface, so as to realize the uniform sprinkling of particles on the specified plane of the water tunnel 200.

[0181] The hydrofoil 100 and the two side wall surfaces (the first side wall 210 and the second side wall 220) can be fixed by screws.

[0182] A rubber can be arranged between the first side surface of the hydrofoil 100 and the first side wall 210 to play a waterproof role and prevent the particle mixture from overflowing from the gap between the two.

[0183] A pressure maintaining cavity 130 is arranged inside the hydrofoil 100. The pressure maintaining cavity 130 includes a first sub-pressure maintaining cavity 131 and a second sub-pressure maintaining cavity 132, and the two are connected by a screw switch. When the isolation screw is tightened, for the first sub-pressure maintaining cavity 131 and the second sub-pressure maintaining cavity 132, the particle mixture only enters the first sub-pressure maintaining cavity 131 and is sprinkled into the water tunnel 200 on the corresponding side of the first sub-pressure maintaining cavity 131. At this time, the particles only cover half of the laser section of the water tunnel 200. When the isolation screw is removed, for the first sub-pressure maintaining cavity 131 and the second sub-pressure maintaining cavity 132, the particle mixture fills both cavities and is pressed into the flow field through the slot 140 on the oncoming flow surface of the entire hydrofoil 100 for uniform sprinkling.

[0184] Slot 140 is arranged on the oncoming flow surface of the structure of the hydrofoil 100, and particles are evenly and stably sprinkled into the flow field of the water tunnel 200 through this slot 140;

[0185] A connecting pore 150 is arranged between the slot 140 and the pressure maintaining cavity 130. The function of this connecting pore 150 is to realize flow distribution and pressure maintaining to ensure that the pressure at each point in the flow distribution and pressure maintaining cavity 130 is equal. The total cross-sectional area of the connecting pore 150 is smaller than the area of the slot 140. Therefore, the pressure near the inlet and far from the inlet in the flow distribution and pressure maintaining cavity 130 is almost the same, so that the pressure difference between the inlet and outlet of each small hole is consistent. Since the pressure at each part in the slot 140 is equal to the total pressure of the water tunnel 200, it is ensured that the flow rate of the particle mixture at each part on the slot 140 of the hydrofoil 100 is equal, realizing the uniform sprinkling of particles.

[0186] The first side wall 210 and the second side wall 220 are two independent wall surface components of the water tunnel 200 used to fix the main body of the hydrofoil 100.

[0187] Exemplarily, the span of the hydrofoil 100 is set to 32 cm (longer than the test section size of the water tunnel 200, which is 30 cm, with 1 cm left at each end for fixing to the wall surface of the water tunnel 200). The chord length of the hydrofoil 100 is 8 cm. The diameter of the flow distribution pressure maintaining cavity 130 is 13 mm. The PIV particle discharge holes are evenly distributed, with a total of 60 holes, the hole diameter is 1.5 mm, the hole depth is 4 mm, and the hole pitch is 5 mm. The width of the PIV particle discharge groove is 2 mm, and the depth is 15 mm.

[0188] The above designs are all optimized based on the numerical calculation results of computational fluid dynamics (CFD), and the numerical results are as Figures 6 to 8 shown. After the particles are extruded from the PIV particle discharge groove at the leading edge of the hydrofoil 100, they are evenly distributed downward along the wall surface of the hydrofoil 100, and have a relatively small impact on the flow field.

[0189] The geometric dimensions of the flow distribution pressure maintaining cavity 130, the PIV particle discharge holes and the discharge groove of the hydrofoil 100 are optimized. If the flow distribution pressure maintaining cavity 130 is too small, the pressure maintaining function will decline, resulting in uneven pressure along the span of the hydrofoil 100, thus causing uneven distribution of the PIV particle flow rate; if it is too large, the flow-facing area of the hydrofoil 100 is too large, which may have an adverse impact on the flow in the test section.

[0190] If the pure slot 140 discharge method is adopted, the flow distribution pressure maintaining cavity 130 will be directly connected to the flow field of the water tunnel 200 through the slot 140, resulting in too fast pressure relief along the span of the hydrofoil 100, and it is impossible to effectively maintain pressure and distribute the flow rate. At the same time, the particles will flow out along the span of the channel under the action of inertia, which will not only affect the flow field, but may also cause no particle distribution at the position close to the wall surface of the water tunnel 200.

[0191] If the pure hole discharge method is adopted, the particles will not be evenly distributed on the laser surface, and its discharge method usually presents as discharging in the form of multiple discrete beam-like particle flows. In addition, the longer hole channels are difficult to machine. If the diameter of the particle discharge hole is too large, the pressure relief will be too fast; if the diameter is too small, the jet intensity will be too large, which may interfere with the flow field, and at the same time, the particles cannot be evenly distributed on the wall surface of the hydrofoil 100.

[0192] The selection of the size of the slot 140 will also affect the particle seeding effect. The PIV particle discharge groove is set at the leading edge of the hydrofoil 100 because the flow velocity at this position is zero, which is helpful for good particle followability. This position can also make the particle mixture extruded at an extremely slow speed, which neither affects the flow field nor can ensure uniform distribution.

[0193] It should be understood that the above embodiments are all exemplary and do not cover all possible implementation manners included in the claims. Without departing from the scope of the present disclosure, various deformations and changes can be made on the basis of the above embodiments. Similarly, various technical features of the above embodiments can be arbitrarily combined to form additional embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments only represent several implementation manners of the present invention and do not limit the protection scope of the present invention patent.

Claims

1. A hydrofoil, characterized in that: The hydrofoil is used to be arranged in a liquid flow field, wherein: The first surface and the second surface of the hydrofoil are symmetrically arranged; A pressure-maintaining chamber is provided inside the hydrofoil; The leading edge of the hydrofoil is provided with a slot extending along the span direction of the hydrofoil; wherein the leading edge of the hydrofoil faces the incoming flow direction of the liquid flow field; The slot is connected to the pressure-maintaining cavity through a connecting channel; The pressure-maintaining chamber is provided with a first opening on the first side of the hydrofoil, and the first opening is used to receive a mixed liquid consisting of particles and the liquid input from the outside; the mixed liquid entering the pressure-maintaining chamber passes through the connecting channel and is discharged from the slot at the leading edge of the hydrofoil to spread the particles in the liquid flow field; wherein the first pressure of the mixed liquid input from the outside is greater than the second pressure of the liquid flow field.

2. The hydrofoil according to claim 1, characterized in that: The pressure-maintaining cavity extends along the span direction of the hydrofoil; There are N connecting channels, and the N connecting channels are evenly arranged along the span direction of the hydrofoil, respectively connecting the pressure-maintaining cavity and the slot, wherein N is an integer greater than or equal to 1.

3. The hydrofoil according to claim 2, characterized in that: The sum of the areas of the first cross-sections corresponding to the N connecting channels is smaller than the area of ​​the second cross-section of the slot; wherein the first cross-section is perpendicular to the flow direction of the mixed liquid in the connecting channel; and the second cross-section is perpendicular to the flow direction of the mixed liquid in the slot.

4. The hydrofoil according to claim 1, characterized in that: The pressure-maintaining chamber comprises a first sub-pressure-maintaining chamber and a second sub-pressure-maintaining chamber which are sequentially arranged along the span direction of the hydrofoil; The first end of the first sub-pressure-maintaining chamber is used to receive the mixed liquid input from the outside; The second end of the first sub-pressure-maintaining chamber and the first end of the second sub-pressure-maintaining chamber are connected to each other; a connecting part between the second end of the first sub-pressure-maintaining chamber and the first end of the second sub-pressure-maintaining chamber is provided with a switching component; The on-off component is used to open or close the passage between the first sub-pressure maintaining chamber and the second sub-pressure maintaining chamber.

5. The hydrofoil according to claim 4, characterized in that: The inner wall of the first end of the second sub-pressure-maintaining chamber is provided with threads; The on-off component includes a bolt that enters the second sub-pressure maintaining chamber through the interior of the first sub-pressure maintaining chamber and is threadedly engaged with the inner wall of the first end of the second sub-pressure maintaining chamber.

6. The hydrofoil according to any one of claims 1 to 5, characterized in that: The relative thickness of the hydrofoil is between 12% and 40%.

7. A particle spreading system, characterized in that: The particle spreading system comprises: a water hole, a stirring barrel, a gas compression device and a hydrofoil according to any one of claims 1 to 6; The hydrofoil is arranged in the liquid flow field in the water tunnel; The stirring barrel is used to mix the liquid and particles to obtain a mixed liquid; The gas compression device is connected to the stirring barrel and is used to discharge compressed gas into the stirring barrel to pressurize the mixed liquid to a first pressure; The stirring barrel is connected to the hydrofoil, and a first opening is provided on the side wall of the hydrofoil to discharge the mixed liquid into a pressure-maintaining cavity provided inside the hydrofoil.

8. The particle spreading system according to claim 7, characterized in that: The particle spreading system further includes at least one of the following items disposed between the mixing barrel and the hydrofoil: A liquid pressure regulating valve, used for adjusting the pressure of the mixed liquid discharged into the pressure-maintaining chamber; A check valve, used to cut off the mixed liquid from flowing back from the pressure-maintaining chamber to the mixing barrel; The stop valve is used to shut off the mixed liquid discharged into the pressure-maintaining chamber.

9. The particle spreading system according to claim 7 or 8, characterized in that: The water hole comprises a first side wall and a second side wall which are arranged opposite to each other. The inner surface of the first side wall is provided with a first limiting groove, and the first limiting groove is adapted to the first end of the hydrofoil. The inner surface of the second side wall is provided with a second limiting groove, and the second limiting groove is adapted to the second end of the hydrofoil. The first side wall and the second side wall clamp the hydrofoil through the first limiting groove and the second limiting groove respectively, so as to fix the hydrofoil in the water hole.

10. The particle spreading system according to claim 9, characterized in that: The first side wall is provided with a through hole communicating with the first opening, A pipeline for the mixed liquid to flow is connected between the stirring barrel and the hydrofoil, wherein a first end of the pipeline passes through the through hole and is connected to the first opening, and a second end of the pipeline is connected to the stirring barrel.

11. The particle spreading system according to claim 9, characterized in that: The first side surface is arranged at a first end of the hydrofoil, A flexible gasket is arranged between the first side surface and the bottom surface of the first limiting groove to seal the first side surface and the bottom surface of the first limiting groove.

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