Tuna longline fishing gear model test device and test method

Abstract

The present invention discloses a tuna longline fishing gear model test device and test method, the device comprises: two parallel X-direction tracks, which are horizontally erected above the test water tank and parallel to the water flow direction of the water tank; two parallel Y-direction tracks, with both ends sliding on the two X-direction tracks respectively; a sensor platform is slidably arranged on one of the Y-direction tracks, and at least two sensor platforms are slidably arranged on the other Y-direction track; a force sensor is connected to the bottom of each sensor platform through a vertical fixing rod; the bottom of the force sensor is fixedly connected to the end of the longline fishing gear model. The system can test the resistance, underwater shape and depth of the longline fishing gear under different shortening rates, different attack angles and different water flow speeds.

Description

Technical Field

[0001] The invention relates to the field of fishing gear mechanics, and in particular to a tuna longline fishing gear model test device and a test method. Background Art

[0002] Tuna longline fishing gear is one of the main methods of fishing for tuna, especially bigeye tuna, yellowfin tuna and albacore tuna. As the international fishery organizations have increasingly stringent regulations on bycatch, that is, to reduce the accidental capture of seabirds, sea turtles and marine mammals, it is necessary to study the depth and underwater deployment shape of longline fishing gear. Therefore, the quality of its hydrodynamic performance directly affects the catch and fishing efficiency, and also affects the accidental capture of bycatch. At present, the test methods for the hydrodynamic characteristics of longline fishing gear mainly include numerical simulation methods, offshore measurement methods and tank test methods. The offshore measurement method can only measure the depth of longline fishing gear, but cannot obtain the underwater deployment shape of longline fishing gear. The numerical simulation method needs to be verified based on the results of the measured hook depth and the longline fishing gear model experiment. Therefore, according to the operating characteristics of longline fishing gear, the tank model experiment method is more ideal. In order to evaluate the hydrodynamic performance of longline fishing gear and design new longline fishing gear, a small-scale longline fishing gear model was made according to the longline fishing gear model test criteria, and the underwater deployment shape and depth of the model were observed and measured according to the model similarity criteria, and then converted into the values ​​of the actual fishing gear according to the model test criteria. The tank longline fishing gear model test can accurately obtain the resistance, underwater deployment shape and depth of the longline fishing gear, and can reasonably evaluate the hydrodynamic performance of the longline fishing gear, providing a scientific basis for the eco-friendly fishing of longline fishing gear.

[0003] At present, for the model experiment of tuna longline fishing gear, two guards are usually used, one guard is connected to one end of the tuna longline fishing gear model, and the other guard is connected to the other end of the tuna longline fishing gear model. Then the shortening rate of the longline fishing gear model is adjusted by controlling the distance between the two guards. The water tank is generally equipped with a mobile trolley, under which two guards are installed. The two guards can only move horizontally along the cross section of the trolley. The water flow direction of the water tank is perpendicular to the cross section of the trolley. At this time, the angle of attack of the water flow and the longline fishing gear model is 90 degrees. Therefore, the current water tank equipment can only measure the hydrodynamic performance of the longline fishing gear model under different shortening rates when the angle of attack is 90 degrees.

[0004] According to the existing equipment in the water tank, it is impossible to measure the longline fishing gear model under different shortening rates and different attack angles. The existing sword is too large. In the test, when the water flows through, the sword's frontal area is too large, which easily generates vortices and affects the accuracy of the experimental results. Summary of the invention

[0005] In view of the above-mentioned defects of the prior art, the present invention provides a tuna longline fishing gear model test device and test method, which can test the resistance, underwater shape and depth of longline fishing gear at different flow rates under different shortening angles.

[0006] To achieve the above-mentioned purpose, the present invention provides a tuna longline fishing gear model test device, which comprises:

[0007] Two parallel X-direction rails are horizontally erected above the test water tank and parallel to the water flow direction of the water tank;

[0008] Two parallel Y-direction tracks, both ends of which slide on the two X-direction tracks respectively; a sensor platform is slidably arranged on one of the Y-direction tracks, and at least two sensor platforms are slidably arranged on the other Y-direction track;

[0009] A force sensor is connected to the bottom of each sensor platform through a vertical fixing rod; the bottom of the force sensor is fixedly connected to the end of the longline fishing gear model.

[0010] A further improvement of the present invention is that the bottom end of the vertical fixing rod and the force sensor are located below the water surface of the water tank.

[0011] A further improvement of the present invention is that the cross section of the vertical fixing rod is streamlined.

[0012] A further improvement of the present invention is that the vertical fixing rod is a telescopic rod.

[0013] A further improvement of the present invention is that the force sensor is a three-force balance.

[0014] An embodiment of the present invention further provides a tuna longline fishing gear model test method, which is implemented using the above-mentioned tuna longline fishing gear model test device, and the two ends of the longline fishing gear model are respectively hung under two force sensors. For a predetermined angle of attack and shortening rate, the positions of the two force sensors connected to the ends of the longline fishing gear model are adjusted during the test so that the angle between the connecting line of the two force sensors and the water flow direction is equal to the angle of attack, and the distance between the two force sensors makes the shortening rate of the longline fishing gear model equal to the predetermined shortening rate.

[0015] The device and method provided by the present invention have the following technical effects: the resistance, underwater shape and depth of longline fishing gear can be tested under different shortening rates, different attack angles and different water flow velocities.

[0016] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a top view schematic diagram of a tuna longline fishing gear model test device;

[0018] Figure 2 It is a schematic diagram of the side surface of the model test device for tuna longline fishing gear with the tracks hidden;

[0019] Figure 3 It is a schematic diagram of the test process of the tuna longline fishing gear model test device. DETAILED DESCRIPTION

[0020] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0021] It should be noted that the illustrations provided in the following embodiments are only used to illustrate the basic concept of the present invention in a schematic manner, and thus the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0022] While some exemplary embodiments of the present invention have been described for the purpose of illustration, it should be understood that the present invention may be implemented in other ways not specifically shown in the drawings.

[0023] like Figure 1 , 2 As shown, an embodiment of the present invention provides a tuna longline fishing gear model test device and test method, which includes: two parallel X-direction tracks 1, two parallel Y-direction tracks 2 and three sensor platforms 3.

[0024] Among them, two parallel X-direction tracks 1 are horizontally erected above the test water tank and are parallel to the water flow direction of the water tank. In this embodiment, tracks are provided at both ends of the water tank, and the two ends of the X-direction track 1 are respectively erected on the tracks at both ends of the water tank. In this embodiment, the two X-direction tracks 1 are made of I-beams.

[0025] Both ends of the Y-direction track 2 slide on the two X-direction tracks 1. One sensor platform 3 is slidably arranged on one of the Y-direction tracks 2, and two sensor platforms 3 are slidably arranged on the other Y-direction track 2.

[0026] A force sensor 6 is connected to the bottom of each sensor platform 3 through a vertical fixing rod 4. The bottom of the force sensor 6 is fixedly connected to the two ends of the longline fishing gear model. Each sensor platform 3 is equipped with a gear rack travel mechanism or a screw slide rail drive mechanism so as to travel on the Y-direction track 2.

[0027] In the present application, the force sensor 6 is a three-force balance, which can detect the forces on three axes at the same time. The reason for configuring three force sensors 6 is that when the two ends of the longline fishing gear model are respectively mounted on the force sensors 6 located under the two Y-direction tracks 2, the attack angle of the longline fishing gear model is 90>α≥0. When the two ends of the longline fishing gear model are respectively mounted on the force sensors 6 under the same Y-direction track 2, the attack angle of the longline fishing gear model is 90°.

[0028] In the present application, the vertical fixing rod 4 is a telescopic rod and is provided with a plurality of equally spaced positioning buckles to adjust the length of the vertical fixing rod 4. In the application process, the lengths of the vertical fixing rods 4 are equal, so that the force sensors 6 are at the same height.

[0029] During the test, the bottom end of the vertical fixing rod 4 and the force sensor 6 are located below the water surface of the water tank. In order to reduce the self-resistance and reduce the generation of vortices to make the flow state more stable, the cross section of each vertical fixing rod 4 is streamlined.

[0030] like Figure 1 , Figure 2 , Figure 3 As shown, an embodiment of the present invention further provides a tuna longline fishing gear model test method, which is implemented using the above-mentioned tuna longline fishing gear model test device. In this method, the two ends of the longline fishing gear model are respectively hung under two force sensors. For a predetermined angle of attack and shortening rate, the positions of the two force sensors connected to the ends of the longline fishing gear model are adjusted during the test so that the angle between the connecting line of the two force sensors and the water flow direction is equal to the angle of attack, and the distance between the two force sensors is such that the shortening rate of the longline fishing gear model is equal to the predetermined shortening rate.

[0031] Specifically, during the test:

[0032] 1. Design the experimental conditions, where the shortening rate of the longline fishing gear model 5 is set to h, the water flow velocity of the water tank is set to i, and the attack angle α is set to j. h The distance L between the two end points of the longline fishing gear model 5 is h The total length of the longline fishing gear model is S, and the shortening rate is K h =L h / S. For the adjustment of the shortening rate, the distance L between the two end points of the longline fishing gear model 5 is adjusted. hIn this embodiment, this function can be achieved by adjusting the spacing between the Y-direction tracks 2 and the position of the sensor platform 3 .

[0033] 2. For the control of the angle of attack α, D j =L h ×sin(α j ), D j F is the distance that the force sensor 6b moves from one side of the water tank to the other side of the water tank. j =L h ×(1-cos(α j )), F j It is the distance that the Y-direction track 2 equipped with the force sensor 6b moves toward another Y-direction track.

[0034] 3. Install the longline fishing gear model, fix one end of the longline fishing gear model 5 on the force sensor 6b, and the other end on the force sensor 6c. The force sensor 6b and the force sensor 6c are on the same horizontal plane.

[0035] 4. During the experiment, first determine the shortening rate K h Then at a certain shortening rate K h Under the working condition, adjust the distance D j and F j , so that the angle of attack of the longline fishing gear model 5 is α j Under this attack angle condition, by adjusting the water velocity V, the hydrodynamic performance parameters of the longline fishing gear model at different water velocity are obtained. Then the attack angle α is adjusted to obtain the hydrodynamic performance parameters of the longline fishing gear model at different water velocity at different attack angles. For the case where the attack angle is 90 degrees, the end point of the longline fishing gear under the force sensor 6b is fixed under the force sensor 6a, and the hydrodynamic performance parameters of the longline fishing gear at different water velocity at the attack angle of 90 degrees can be obtained.

[0036] 5. Adjust the shortening rate K h+1 , repeat step 4 to obtain the hydrodynamic performance parameters of the longline fishing gear model 5 at different shortening rates, different attack angles and different water flow velocities.

[0037] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A tuna longline fishing gear model test device, characterized in that include: Two parallel X-direction rails are horizontally erected above the test water tank and parallel to the water flow direction of the water tank; Two parallel Y-direction tracks, both ends of which slide on the two X-direction tracks respectively; a sensor platform is slidably arranged on one of the Y-direction tracks, and at least two sensor platforms are slidably arranged on the other Y-direction track; A force sensor is connected to the bottom of each sensor platform through a vertical fixing rod; the bottom of the force sensor is fixedly connected to the end of the longline fishing gear model.

2. A tuna longline fishing gear model test device according to claim 1, characterized in that: The bottom end of the vertical fixing rod and the force sensor are located below the water surface of the water tank.

3. The tuna longline fishing gear model test device according to claim 2, characterized in that: The cross section of the vertical fixing rod is streamlined.

4. The tuna longline fishing gear model test device according to claim 1, characterized in that: The vertical fixing rod is a telescopic rod.

5. The tuna longline fishing gear model test device according to claim 1, characterized in that: The force sensor is a three-force balance.

6. A tuna longline fishing gear model test method, implemented using the tuna longline fishing gear model test device according to any one of claims 1 to 5, characterized in that: The two ends of the longline fishing gear model are hung under two force sensors respectively. For the predetermined angle of attack and shortening rate, the positions of the two force sensors connected to the ends of the longline fishing gear model are adjusted during the test so that the angle between the connecting line of the two force sensors and the water flow direction is equal to the angle of attack, and the distance between the two force sensors is such that the shortening rate of the longline fishing gear model is equal to the predetermined shortening rate.

Images