A bionic pistol shrimp cavitating jet nozzle and a design method thereof

Abstract

The application discloses a kind of bionic gun shrimp cavitation jet nozzle, including inlet section, chamber section and outlet section, chamber section and outlet section smooth transition connection;Chamber section includes first curved surface, second curved surface, third curved surface and fourth curved surface that are sequentially smoothly connected.The application also discloses a kind of bionic gun shrimp cavitation jet nozzle design method, including the following steps: constructing the two-dimensional model of gun shrimp large pinch claw profile curve;Dynamic gap formed in the closing process of gun shrimp large pinch claw is mapped to the structure of static nozzle, and the transformation of bionics is carried out, and the gun shrimp large pinch claw profile curve is segmented;Based on two-dimensional model, the structure of bionic cavitation jet nozzle is obtained by discretization mapping method, including inlet section, chamber section and outlet section.The application can generate cavitation bubbles of higher quality, with stable and good cavitation effect of gun shrimp jet high-energy focusing;With the high-frequency output efficiency of nozzle, long-distance cavitation effect is good, and the manufacturing cost is low.

Description

Technical Field

[0001] This invention belongs to the field of jet nozzles, specifically a biomimetic pistol shrimp cavitation jet nozzle and its design method. Background Technology

[0002] In 1897, Barnaby and others discovered that after a period of operation, numerous pits would form on the blade edges of ship propellers, leading to a significant decrease in efficiency. This discovery led to the concept of "cavitation." Researchers have recognized the potential applications of cavitation due to its powerful hydraulic erosion properties, and have widely applied it in industrial cleaning, mining drilling, chemical production, and medical treatment. When using cavitation for cleaning, the high energy concentration resulting from cavitation bubble collapse makes cavitation jets far more effective than high-pressure water jets at the same pressure and velocity. Furthermore, it requires significantly less cleaning time and water consumption than traditional cleaning methods, making it energy-efficient and environmentally friendly. It can also clean fragile items or components, or those with complex structures, deep holes, or narrow crevices.

[0003] A cavitation jet nozzle is a device that generates cavitation bubbles. Its working principle is based on Bernoulli's law: when the pressure of the jet output through the nozzle structure is lower than the saturated vapor pressure, gas nuclei in the liquid continuously expand, generating cavitation bubbles. When these cavitation bubbles reach a high-pressure, low-velocity region, they collapse. Existing devices for generating cavitation jets are mostly combinations of nozzles and pressure pumps, primarily producing clustered cavitation bubbles with cloud-like or fog-like morphology. Essentially, this is a macroscopic effect resulting from the aggregation of numerous tiny cavitation bubbles. This form has poor energy focusing, and energy dissipation over time is quite significant.

[0004] Unlike the clustered cavitation bubbles produced by existing cavitation jet nozzles, pistol shrimp in nature can produce cavitation bubbles with clear morphology, stable state, high energy concentration, and concentrated energy release. Current research on pistol shrimp jet cavitation bubble production, both domestically and internationally, primarily utilizes reverse engineering to model pistol shrimp and conducts experiments with scaled-up models. However, this approach fails to consider the complex curved surface of the pistol shrimp's large claws, hindering subsequent mass production. On the other hand, simplified designs of the pistol shrimp's large claw models are employed to shorten manufacturing cycles and reduce costs. However, these approaches introduce new problems, such as cavitation that damages the claw surface rather than achieving true jet cavitation. Furthermore, none of these experimental studies have resolved the inherent contradiction in pistol shrimp biomimetic motion schemes—the inability to properly match high frequency and high amplitude. In other words, achieving continuous production of high-quality cavitation bubbles while maintaining effective jet cavitation is difficult, representing an inherent deficiency in existing biomimetic pistol shrimp models. Existing models are prone to mechanical deformation, damage, and have a short lifespan; they are also prone to large-scale vibrations and accompanied by a lot of mechanical noise, requiring extremely high structural strength. Summary of the Invention

[0005] Purpose of the invention: In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a biomimetic pike shrimp cavitation jet nozzle with good matching between high frequency and high amplitude and capable of generating cavitation bubbles of good quality. Another purpose of this invention is to provide a design method for a biomimetic pike shrimp cavitation jet nozzle with high frequency output efficiency and low cost.

[0006] Technical solution: The biomimetic pistol shrimp cavitation jet nozzle of the present invention includes an inlet section, a chamber section and an outlet section, with the chamber section and the outlet section smoothly connected; the chamber section includes a first curved surface, a second curved surface, a third curved surface and a fourth curved surface that are smoothly connected in sequence.

[0007] Preferably, the ratio of the minimum diameter of the outlet section, the length of the outlet section, the maximum diameter of the chamber section, the length of the chamber section, the length of the inlet section, and the diameter of the inlet section is 1:8:5:7:3:4.

[0008] Furthermore, the entrance section is cylindrical.

[0009] Furthermore, when the minimum diameter of the outlet section is 1 mm, the diameter of the first curved surface is 9.3 mm and the central angle is 27°; the diameter of the second curved surface is 9.4 mm and the central angle is 25°; the diameter of the third curved surface is 3.2 mm and the central angle is 55°; and the diameter of the fourth curved surface is 4.5 mm and the central angle is 38°.

[0010] The present invention discloses a design method for a biomimetic pistol shrimp cavitation jet nozzle, comprising the following steps:

[0011] Step 1: Construct a two-dimensional model of the cross-sectional curved surface of the pistol shrimp's large claw;

[0012] Step 2: Map the dynamic gap formed during the closing of the pistol shrimp's large claw to the structure of a static nozzle, carry out biomimetic transformation, and segment the cross-sectional curve of the pistol shrimp's large claw.

[0013] Step 3: Based on the two-dimensional model in Step 1, the structure of the biomimetic cavitation jet nozzle is obtained through the discretization mapping method, including the inlet section, the chamber section and the outlet section.

[0014] Combining the characteristic of pistol shrimp in nature that it can generate high-quality cavitation bubbles compared to existing cavitation nozzles, and utilizing the unique dynamic claw curve of pistol shrimp to generate cavitation bubbles, a discretization mapping method is used to transform it into a static nozzle structure. At the same time, the structure is optimized by using ANSYS CFD two-dimensional cavitation jet simulation, and finally a biomimetic pistol shrimp cavitation jet nozzle of the present invention is obtained, which realizes high-quality and high-efficiency output of cavitation bubbles.

[0015] Furthermore, in step one, the original data of the pistol shrimp's large claw profile curve is the contour points formed by the gap between the plunger and the sac cavity on the cross-sectional plane along the long axis of the flow channel when the claw is closed. The contour points are imported into CAD software to complete the point mapping and replication of the pistol shrimp's large claw profile curve model.

[0016] Furthermore, in step two, the cross-sectional curves of the large claw of the pistol shrimp are the rotation curves of the inlet segment, the chamber segment, and the outlet segment.

[0017] Furthermore, in step three, the discretization mapping method, through ANSYS CFD simulation experiments, follows the principle of controlling variables. While maintaining the same mesh generation method, simulation condition settings, and multiple feature dimensions, only one feature dimension parameter is changed in a single simulation experiment. The ANSYS CFD simulation conditions are set as follows: two-phase flow model, Mixture; cavitation model, Schnerr-Sauer; viscous model, RNG ke; outlet pressure, standard atmospheric pressure, i.e., 101325 Pa; solution method, SIMPLEC, second-order upwind discretization, pressure-based transient solution; time step, 10... -4 s.

[0018] Furthermore, the ratio of the minimum diameter of the outlet section, the length of the outlet section, the length of the chamber section, the length of the inlet section, and the diameter of the inlet section is 1:8:7:3:4.

[0019] Furthermore, the fluid is pumped and pressurized in the inlet section, then accelerated in the chamber section, and finally jetted into the liquid environment through the outlet section.

[0020] Starting with the decomposition of the cavitation process of a pike shrimp jet, this study focuses on the dynamic gap formed by the moving and stationary claws during the instantaneous closure of the pike shrimp to generate a cavitation jet. This gap is a crucial geometric feature that transforms a conventional water jet into a cavitation jet. Given the similarity between this dynamic gap and the internal structure of a cavitation jet nozzle, a biomimetic method of discretization mapping is employed to map this geometric feature to the internal structure of an existing nozzle, thus constructing a biomimetic pike shrimp cavitation jet nozzle with high-energy-accumulating geometry.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0022] 1. It can generate high-quality cavitation bubbles and has a stable and good cavitation effect with high-energy focusing of pistol shrimp jets;

[0023] 2. It has the high-frequency output efficiency of the nozzle, good cavitation effect over long distance, and low manufacturing cost;

[0024] 3. Under the conditions of an inlet pressure of 20 MPa, an outlet diameter of 4 mm, an expansion angle section length-to-diameter ratio of 8:1, and other simulation settings and mesh generation methods being the same, the simulation comparison experiment shows that the cavitation performance of the obtained jet nozzle is approximately 70% higher than that of the existing angular nozzle, with the gas phase area improved by about 70% in the two-dimensional cavitation simulation. Attached Figure Description

[0025] Figure 1 This is a design flowchart of the present invention;

[0026] Figure 2 This is the cross-sectional curve of the large claw of the pistol shrimp of the present invention;

[0027] Figure 3 This is a schematic diagram of the structure of the present invention;

[0028] Figure 4 This is an exploded view of chamber section 2 of the present invention;

[0029] Figure 5 This is a CFD simulation gas phase cloud image of the biomimetic cavitation jet nozzle of the present invention, in which the d:L0 value changes from 1:5 to 1:9, at a certain time.

[0030] Figure 6 The data points 1-5 are the CFD simulation cavitation area curves corresponding to the biomimetic cavitation jet nozzle of this invention, where the d:L0 value changes from 1:5 to 1:9.

[0031] Figure 7 These are the CFD simulation cavitation area curves corresponding to data points 6-20, which are biomimetic cavitation jet nozzles of different sizes and characteristics of the present invention. Detailed Implementation

[0032] like Figure 1 The design method of a biomimetic pistol shrimp cavitation jet nozzle includes the following steps:

[0033] Step 1: Initial 2D modeling of the cross-sectional curve of the pistol shrimp's large claw:

[0034] The original curve data of the biomimetic pistol shrimp cavitation jet nozzle was drawn using reverse modeling technology, such as... Figure 2 As shown, the contour points on the cross-sectional plane along the long axis of the flow channel in the chelate closed state are formed by the gap between the plunger (upper curve) and the bladder (lower curve). The contour point image is then imported into CAD software to complete the point mapping and replication of the nozzle's two-dimensional curve model.

[0035] Step 2, biomimetic transformation design of the pistol shrimp cavitation jet nozzle:

[0036] The biomimetic cavitation jet nozzle transformation design process does not involve rotating the right portion of the curve of the pistol shrimp's large claw profile obtained in step one around a fixed axis. Instead, when mapping the dynamic gap formed during the closure of the pistol shrimp's large claw into a static nozzle structure, the curve is divided into three parts. The basic rotation curves of the three parts of the biomimetic pistol shrimp cavitation jet nozzle include the basic rotation curve of the inlet section 1, the basic rotation curve of the chamber section 2, and the basic rotation curve of the outlet section 3. This also reflects the unique biomimetic method of discretizing and mapping simple continuous motion mechanisms in this invention.

[0037] Step 3: Structural optimization of the biomimetic pistol shrimp cavitation jet nozzle based on ANSYS:

[0038] The structure of the biomimetic cavitation jet nozzle is based on the pistol shrimp's large claw model. Through a discretization mapping method, it is transformed and designed to obtain the nozzle structure with multiple characteristic dimensions in step two, such as... Figures 3-4 As shown, it comprises three parts: inlet section 1, chamber section 2, and outlet section 3. Inlet section 1 is the area where fluid is pumped in by a water pump. Chamber section 2 is the area where the fluid pumped in from inlet section 1 is accelerated. Outlet section 3 is the area where the fluid entering from inlet section 1, accelerated in chamber section 2, interacts with the submerged liquid environment, and ultimately generates cavitation bubbles. Chamber section 2 includes a first curved surface 21, a second curved surface 22, a third curved surface 23, and a fourth curved surface 24 that are smoothly connected in sequence. The discretization mapping method also includes a method for determining the proportion of size parameters when the nozzle cavitation effect is optimal. This involves using ANSYS CFD series simulation experiments, following the principle of controlled variables, and keeping the mesh generation method, simulation conditions, and multiple feature dimensions the same. In a single simulation experiment, only the parameters of one feature dimension are changed. The simulation experiments are conducted using existing ANSYS CFD software, with the following experimental conditions: two-phase flow model (Mixture); cavitation model (Schnerr-Sauer); viscous model (RNG ke); outlet pressure (ambient pressure, i.e., one atmosphere, 101325 Pa); solution method (SIMPLEC, second-order upwind discretization, pressure-based transient solution); time step (10). -4 s.

[0039] Taking the investigation of the influence of the d:L0 value on the cavitation effect as an example, this paper demonstrates the process of simulating and optimizing the structure of a biomimetic pistol shrimp cavitation jet nozzle: First, ensure that the characteristic dimensions d = 4 mm, d:L1 = 1:2.5, d:D2 = 1:4.5, and D2:L2 = 1:0.5 are the same. Then, change the value of d:L0 to 1:5, 1:6, 1:7, 1:8, and 1:9 respectively, and perform five CFD two-dimensional transient simulations. Figure 4It can be seen that the air-carrying area of ​​the biomimetic pistol shrimp cavitation jet nozzle changes continuously with time. When d:L0 = 1:5, that is, when the diameter-to-length ratio is the largest, the air-carrying area is the smallest compared to the others. Figure 5 (First from the left).

[0040] Discarding the simulation convergence time period of 0-0.02s, a cavitation stabilization time period of 0.02-0.10s was selected. The sum of the simulated cavitation areas of the biomimetic pistol shrimp cavitation jet nozzles was statistically analyzed, corresponding to data points 1-5 in Table 1. Based on this, plotting... Figure 5 The simulated cavitation area curves corresponding to data points 1-5 are shown. Compared to d:L0 = 1:5, the simulated cavitation area of ​​the biomimetic pistol shrimp cavitation jet nozzle increases by approximately 260% when d:L0 = 1:9. Furthermore, the smaller the 3 / 4 diameter-to-length ratio of the outlet section of the pistol shrimp cavitation jet nozzle, the better the cavitation effect. Based on experience in the optimized design of bellows nozzles from relevant literature, and considering the processing limitations of the diameter-to-length ratio orifice, d:L0 = 1:8 is selected as the optimal characteristic dimension for cavitation.

[0041] Table 1: Simulated cavitation area corresponding to data points 1-5 within the same time period

[0042]

[0043] Similarly, the selection of other characteristic dimensions for the simulated pistol shrimp cavitation nozzle can follow the simulation optimization process of d:L0, taking d = 4mm, d:L0 = 1:4.5, d:D2 = 1:6.5, D2:L2 = 1:0.5, d:L1 = 1:5, 1:6, 1:7, 1:8, 1:9, which correspond to respectively Figure 6 Data points 6-10; take d = 4mm, d:L0 = 1:4, d:L1 = 1:3.5, D2 = 10mm, d:D2 = 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, which correspond to respectively Figure 6 Data points 11-15. Taking d = 4mm, d:L0 = 1:3.5, d:L1 = 1:3, D2 = 10mm, D2:L2 = 1:0.25, 1:0.5, 1:0.75, 1:1, 1:1.25, respectively, corresponding to... Figure 6 Data points 16-20 in the dataset.

[0044] The resulting biomimetic pistol shrimp cavitation jet nozzle works by initially pressurizing the fluid through the inlet section 1, then accelerating it through the chamber section 2, and finally ejecting the jet into the submerged liquid environment through the outlet section 3. The nozzle structure has multiple characteristic dimensions, including inlet diameter D2, inlet length L2, chamber inlet diameter D1, chamber length L1, outlet diameter d, and outlet length L0. The ratio of these dimensions when the cavitation effect is optimal is d:L0:L1:L2:D2 = 1:8:7:3:4.

[0045] When d = 1 mm, the diameter of the first surface 21 is 9.3 mm and the central angle is 27°; the diameter of the second surface 22 is 9.4 mm and the central angle is 25°; the diameter of the third surface 23 is 3.2 mm and the central angle is 55°; and the diameter of the fourth surface 24 is 4.5 mm and the central angle is 38°.

Claims

1. A design method for a biomimetic pistol shrimp cavitation jet nozzle, characterized in that, Includes the following steps: Step 1: Construct a two-dimensional model of the cross-sectional curve of the pistol shrimp's large claw; Step 2: Map the dynamic gap formed during the closing of the pistol shrimp's large claw to the structure of the static nozzle, carry out biomimetic transformation, and segment the cross-sectional curve of the pistol shrimp's large claw. Step 3: Based on the two-dimensional model in Step 1, the structure of the biomimetic cavitation jet nozzle is obtained by discretization mapping method, including inlet section (1), chamber section (2) and outlet section (3). In step two, the cross-sectional curves of the large claw of the pistol shrimp are the rotation curves of the inlet segment (1), the chamber segment (2), and the outlet segment (3). In step three, the discretization mapping method is to use ANSYS CFD simulation experiments, following the principle of controlling variables, and on the premise that the mesh generation method, simulation condition settings and multiple feature dimensions are the same, only the parameter of one feature dimension is changed in a single simulation experiment.

2. The design method of a biomimetic pistol shrimp cavitation jet nozzle according to claim 1, characterized in that: In step one, the original data of the pistol shrimp's large claw profile curve is the contour points formed by the gap between the plunger and the sac cavity on the cross-sectional plane along the long axis of the flow channel when the claw is closed. The contour points are imported into CAD software to complete the point mapping and replication of the pistol shrimp's large claw profile curve model.

3. The design method of a biomimetic pistol shrimp cavitation jet nozzle according to claim 1, characterized in that: The conditions for the ANSYS CFD simulation experiments were set as follows: two-phase flow model, Mixture; cavitation model, Schnerr-Sauer; viscous model, RNG ke; outlet pressure, standard atmosphere; solution method, SIMPLEC, second-order upwind discretization, pressure-based transient solution; time step, 10. -4 s.

4. The design method of a biomimetic pistol shrimp cavitation jet nozzle according to claim 1, characterized in that: In step three, the ratio of the minimum diameter of the outlet section (3), the length of the outlet section (3), the length of the chamber section (2), the length of the inlet section (1), and the diameter of the inlet section (1) is 1:8:7:3:

4.

5. The design method of a biomimetic pistol shrimp cavitation jet nozzle according to claim 1, characterized in that: The inlet section (1) pressurizes the fluid, which is then accelerated through the chamber section (2) and finally jetted into the liquid environment through the outlet section (3).

6. A biomimetic pistol shrimp cavitation jet nozzle obtained by the design method described in claim 1, characterized in that: It includes an inlet section (1), a chamber section (2) and an outlet section (3), with the chamber section (2) and the outlet section (3) smoothly connected; the chamber section (2) includes a first curved surface (21), a second curved surface (22), a third curved surface (23) and a fourth curved surface (24) that are smoothly connected in sequence.

7. The biomimetic pistol shrimp cavitation jet nozzle according to claim 6, characterized in that: The ratio of the minimum diameter of the outlet section (3), the length of the outlet section (3), the maximum diameter of the chamber section (2), the length of the chamber section (2), the length of the inlet section (1), and the diameter of the inlet section (1) is 1:8:5:7:3:

4.

8. The biomimetic pistol shrimp cavitation jet nozzle according to claim 6, characterized in that: The inlet section (1) is cylindrical.

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