Cavitation dynamics test device

Abstract

The invention discloses a cavitation dynamics test device, and relates to the technical field of cavitation dynamics, and the cavitation dynamics test device is characterized in that a model electric control slide rail is arranged in a water tank, and a to-be-tested motion model is fixed on a slide table of the model electric control slide rail; the air bag filled with air is arranged below the water surface and fixed on the motion path of the motion model to be tested, the air bag is punctured by the air control puncture mechanism to generate free air mass for the cavitation dynamics test, the generated free air mass cannot be condensed in water, the duration time is long, reliable and smooth development of the cavitation dynamics test is ensured, and the test efficiency is improved. The cavitation dynamics test method realized by using the cavitation dynamics test device is simple and convenient to operate, strong in controllability, high in stability and low in cost.

Description

Technical Field

[0001] The present application relates to the technical field of cavitation dynamics, and in particular to a cavitation dynamics test device. Background Art

[0002] When a dry-launched vehicle leaves the tube, the head of the vehicle will interact with the free air mass at the tube mouth to form cavitation attached to the surface of the model. The morphological distribution of the cavitation will change the force characteristics of the vehicle, thereby affecting the vehicle's trajectory in the water, which has an important impact on the hydrodynamic characteristics of the vehicle.

[0003] In order to study the influence of cavitation on the hydrodynamic characteristics of the navigation body, it is necessary to generate free air masses in the laboratory scene for cavitation dynamics test. At present, there are mainly the following ways to generate free air masses for cavitation dynamics test: one is to use the instantaneous high heat of high-voltage electric spark to generate steam, thereby forming free cavitation for cavitation dynamics test. However, the cavitation generated by this method will condense in water again in a very short time, making it difficult to grasp the timing of related tests. At the same time, the instantaneous high voltage will generate electromagnetic interference (including conduction interference and radiation interference), causing distortion to the pressure sensor, inertial group and other signals required for the test. Another way is to use gunpowder ignition to generate cavitation gas. The operation of this method is more complicated and the cost is higher. At the same time, the incomplete combustion of gunpowder will also cause the bubbles to be turbid and difficult to observe. After multiple tests, the water in the water tank is turbid and needs to be replaced or filtered and cleaned by water circulation. Summary of the invention

[0004] In view of the above problems and technical requirements, this application proposes a cavitation dynamics test device. The technical solution of this application is as follows:

[0005] A cavitation dynamics test device, comprising a water tank, a model electric control slide rail, an air bag, an air-controlled piercing mechanism, a motion model to be tested, a main controller and a high-speed observation camera;

[0006] The model electric control slide is fixed inside the water tank, the motion model to be tested is fixed on the slide table of the model electric control slide, the main controller is connected to and controls the motor of the model electric control slide to drive the motion model to be tested to move along the model electric control slide, the water surface inside the water tank covers the entire motion range of the motion model to be tested, and the motor of the model electric control slide is located above the water surface;

[0007] The airbag is arranged below the water surface inside the water tank and fixed on the motion path of the motion model to be tested, and the airbag is filled with gas;

[0008] The needle of the air-controlled pricking mechanism faces the airbag, and the main controller is connected to and controls the air-controlled pricking mechanism to eject or retract the needle. The needle is in a retracted state, does not contact the airbag, and is outside the motion path of the motion model to be tested in a default state. The needle contacts and punctures the airbag in an ejected state.

[0009] The water tank adopts a transparent wall, the high-speed observation camera is arranged outside the water tank and faces the water tank, and the main controller is connected to the high-speed observation camera;

[0010] When the cavitation dynamics test device is used to perform the cavitation dynamics test, the field of view of the high-speed observation camera is adjusted to at least cover the airbag puncture position; the main controller controls the motor of the model electric control slide rail to drive the motion model to be tested to move from the initial position at the start of the test, and after the cylinder start delay t at the start of the test d The air-controlled puncture mechanism ejects the puncture needle and then retracts it to puncture the airbag. When the motion model to be tested reaches the puncture position of the airbag, the gas in the airbag forms a free air mass at the puncture position of the airbag. The test image data of the collision process between the motion model to be tested and the free air mass is obtained through a high-speed observation camera; the cylinder start delay t d It is related to the movement distance L between the initial position of the motion model to be tested and the airbag puncture position and the test requirements.

[0011] A further technical solution is that the test requires the speed v of the motion model to be tested when it collides with the free air mass. m The distance L between the puncture position of the airbag along the motion path of the motion model to be tested and the initial position of the motion model to be tested is not less than the speed of the motion model to be tested from the static state to the speed v m The minimum distance required;

[0012] The cylinder start delay t d =t a +t υ -t c ; where t a The motion model to be tested starts from the initial position and accelerates from rest to the speed v according to the predetermined model acceleration m The time consumption, t υ is the speed υ of the motion model to be tested m Then according to the speed m The time taken to move at a constant speed to the puncture position of the airbag, t c It is the time taken by the main controller to control the pneumatically controlled pricking mechanism to eject the pricking needle once and then retract it.

[0013] A further technical solution is that the cavitation dynamics test device also includes an airbag electric control slide rail, which is fixed inside the water tank and parallel to the model electric control slide rail;

[0014] The airbag is fixed on the slide of the airbag electric control slide rail; the main controller is also connected to and controls the motor of the airbag electric control slide rail to drive the airbag to move along the airbag electric control slide rail to adjust the position of the airbag; the water surface inside the water tank covers the entire sliding range of the airbag, and the motor of the airbag electric control slide rail is located above the water surface.

[0015] A further technical solution is that when the test requirement indicates that the cavitation is stationary, before the cavitation dynamics test begins, the main controller controls the motor of the airbag electric control slide rail to drive the airbag to move to the airbag puncture position, and the airbag remains at the airbag puncture position during the cavitation dynamics test;

[0016] When the test requirements indicate that the cavitation has an initial velocity v b When the cavitation dynamics test starts, the main controller controls the motor of the airbag electronically controlled slide rail to drive the airbag to move to the initial position of the airbag. The initial position of the airbag is located on the motion path of the motion model to be tested, and the distance between the initial position of the airbag along the motion path of the motion model to be tested and the initial position of the motion model to be tested is LS. The distance S is the acceleration of the airbag from rest to the initial speed v according to the predetermined airbag acceleration. b The required distance; When conducting cavitation dynamics test, the main controller will go through the airbag movement delay t at the start of the test g =t a +t υ -t e The motor of the rear control airbag electronically controlled slide rail drives the airbag to move from the initial position of the airbag in a direction away from the motion model to be tested according to the predetermined airbag acceleration; the airbag reaches the initial speed υ after moving a distance S b and reaches the puncture position of the airbag and is punctured by the puncture needle of the air-controlled puncture mechanism; wherein, t a The motion model to be tested starts from the initial position and accelerates from rest to the speed v according to the predetermined model acceleration m The time consumption, t υ is the speed υ of the motion model to be tested m Then according to the speed m The time taken to move at a constant speed to the punctured position of the airbag, t e The airbag accelerates from rest to the initial speed v according to the predetermined airbag acceleration b time consuming.

[0017] Its further technical solution is that the airbag electrically controlled slide rail comprises a first synchronous rail and a second synchronous rail which are spaced apart and arranged in parallel. One radial side of the airbag is fixed to the slider of the first synchronous rail by a fixing rope, and the other radial side of the airbag is fixed to the slider of the second synchronous rail by a fixing rope. The main controller connects the motors of the first synchronous rail and the second synchronous rail to work synchronously to drive the movement of the airbag.

[0018] Its further technical solution is that the fixing rope adopts an elastic fixing rope, and the fixing ropes connected on both sides of the airbag are in a stretched state; after the airbag is punctured by the air-controlled puncture mechanism, the fixing ropes on both sides shrink under the action of elasticity and pull the attached airbag fragments to move to both sides to stay away from the motion path of the motion model to be tested.

[0019] Its further technical solution is that the gas type of the gas filled in the airbag is consistent with the cavitation gas type indicated by the test requirements, the volume of the gas filled in the airbag is consistent with the cavitation size indicated by the test requirements, and the air pressure of the gas filled in the airbag is consistent with the cavitation initial air pressure indicated by the test requirements.

[0020] Its further technical solution is that the air-controlled puncture mechanism includes a quick cylinder, a puncture needle, a solenoid valve, a high-pressure gas cylinder and a ventilation hose. The quick cylinder is fixed to a slider of one of the synchronous rails to move synchronously with the airbag. The cylinder shaft of the quick cylinder moves in the direction of the airbag. The puncture needle is installed on the cylinder shaft of the quick cylinder. When the cylinder shaft retracts, the puncture needle is in a retracted state, and when the cylinder shaft extends, the puncture needle is in an ejected state. The high-pressure gas cylinder is arranged outside the water tank, and the high-pressure gas cylinder is connected to the quick cylinder via a ventilation hose and a solenoid valve is arranged on the ventilation hose. The main controller is connected to and controls the action of the solenoid valve.

[0021] Its further technical solution is that the airbag electric control slide rail and the model electric control slide rail are arranged in the water tank along the vertical direction, the high-pressure gas cylinder and the solenoid valve are arranged on the electric lifting frame outside the water tank, the ventilation hose connected to the high-pressure gas cylinder is introduced from the outside of the water tank through the opening above the water tank into the inside of the water tank to connect to the fast cylinder, and the ventilation hose between the high-pressure gas cylinder and the fast cylinder is arranged according to the shortest path; the main controller is connected to and controls the electric lifting frame, when the fast cylinder moves downward under the drive of the synchronous rail, the main controller controls the electric lifting frame to rise, and when the fast cylinder moves upward under the drive of the synchronous rail, the main controller controls the electric lifting frame to lower.

[0022] Its further technical solution is that the inner diameter of the fast cylinder does not exceed the diameter threshold, the cylinder length reaches the length threshold, and under the predetermined air pressure supply, the movement time of the cylinder shaft of the fast cylinder to the maximum extension state does not exceed the action delay threshold.

[0023] The beneficial technical effects of this application are:

[0024] The present application discloses a cavitation dynamics test device, wherein an inflated air bag is arranged below the water surface and on the motion path of a motion model to be tested, and a pneumatic puncture mechanism is used to puncture the air bag to generate a free air mass for the cavitation dynamics test. The free air mass thus generated will not condense in water and lasts for a long time, thereby ensuring the reliable and smooth implementation of the cavitation dynamics test. The cavitation dynamics test method implemented by the cavitation dynamics test device is simple to operate, has strong controllability, high stability and low cost.

[0025] By replacing the airbag, the size, initial pressure and gas type of the formed cavitation can be controlled, with high flexibility and strong controllability. In addition, the position of the airbag can be adjusted quickly and accurately by using the airbag electric control slide rail, which can simplify the debugging process of different cavitation dynamics tests. Moreover, the airbag electric control slide rail can be used to drive the airbag to move, which can generate free air masses with initial velocity, so that the device can not only perform cavitation dynamics tests on static cavitation, but also on moving cavitation, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a device structure diagram of a cavitation dynamics test device according to one embodiment of the present application.

[0027] Figure 2 It is a partial structural diagram of a cavitation dynamics test device according to one embodiment of the present application.

[0028] Figure 3 It is a schematic diagram of the structure of the air-controlled piercing mechanism and the airbag according to one embodiment of the present application.

[0029] Figure 4 This is a schematic diagram of the structure of a cavitation dynamics test device of one embodiment of the present application without a water tank.

[0030] Figure 5 It is a partial structural front view of the airbag, the airbag electric control slide rail and the air-controlled piercing mechanism in a cavitation dynamics test device according to one embodiment of the present application.

[0031] Figure 6 It is a partial structural front view of the airbag, the airbag electric control slide rail and the air-controlled piercing mechanism in a cavitation dynamics test device according to one embodiment of the present application.

[0032] Figure 7 The figure is a motion diagram of an embodiment of a cavitation dynamics test apparatus of the present application for generating stationary cavitations to conduct a cavitation dynamics test.

[0033] Figure 8 This is a motion schematic diagram of another embodiment of a cavitation dynamics test using the cavitation dynamics test device of the present application to generate cavitations with an initial velocity for a cavitation dynamics test. DETAILED DESCRIPTION

[0034] The specific implementation of the present application is further described below in conjunction with the accompanying drawings.

[0035] This application discloses a cavitation dynamics test device, which can generate free air masses to conduct cavitation dynamics tests. Please refer to Figure 1 The structure diagram and Figure 2As shown in the partial structural diagram, the cavitation dynamics test device includes a water tank 1, a model electric-controlled slide rail 2, an air bag 3, an air-controlled piercing mechanism 4, a motion model to be tested 5, a main controller and a high-speed observation camera, which are not shown in the figure.

[0036] The water tank 1 is filled with water or other liquids, and the cavitation dynamics test is carried out inside the water tank 1. The transparent wall of the water tank 1 is convenient for observing the cavitation dynamics test phenomenon from the outside, and also convenient for the high-speed observation camera outside the water tank 1 to capture the test image data of the cavitation dynamics test. The water tank 1 can be partially transparent, or Figure 1 and Figure 2 As shown, all walls of the water tank 1 are transparent, so that it is convenient to observe the cavitation dynamics test phenomenon from all angles and obtain relevant test image data. A typical practice is that the water tank 1 is composed of an aluminum alloy frame and acrylic walls. The size of the water tank 1 is determined according to actual needs. The high-speed observation camera is arranged outside the water tank 1 and faces the water tank 1, and the main controller is connected to the high-speed observation camera.

[0037] The model electric-controlled slide 2 is fixed inside the water tank 1, and the motion model 5 to be tested is fixed on the slide of the model electric-controlled slide 2. The main controller connects and controls the motor of the model electric-controlled slide 2 to drive the motion model 5 to be tested to move along the model electric-controlled slide 2. The length of the model electric-controlled slide 2 is determined according to the requirements of the motion range of the motion model 5 to be tested. For example, under normal circumstances, the length of the model electric-controlled slide 2 is required to be at least 3m, so as to ensure the motion range of the motion model 5 to be tested. The water surface inside the water tank 1 covers the entire motion range of the motion model 5 to be tested, so that the motion model 5 to be tested is always underwater during the sliding process. The motor of the model electric-controlled slide 2 is located above the water surface to ensure the safety of the device.

[0038] Theoretically, the model electric control slide rail 2 can be arranged in any direction, but in practice, for the convenience of operation, the typical practice is to arrange the model electric control slide rail 2 in the vertical direction, and the motion model 5 to be tested moves up and down in the vertical direction. In this way, the upper opening of the water tank 1 does not need to be sealed, and the area occupied by the water tank 1 is relatively smaller, as long as the height meets the requirements of the motion range of the motion model 5 to be tested.

[0039] The airbag 3 is arranged below the water surface inside the water tank 1 and fixed on the motion path of the motion model 5 to be tested, and the airbag 3 is filled with gas. The gas inside the airbag 3 will form the free air mass required for the cavitation dynamics test and then form cavitation attached to the motion model 5 to be tested. Therefore, the volume of the airbag 3 and the state parameters of the gas filled in the airbag 3 match the test requirements, including: the gas type of the gas filled in the airbag 3 is consistent with the cavitation gas type indicated by the test requirements. The volume of the gas filled in the airbag 3 is consistent with the cavitation size indicated by the test requirements. The air pressure of the gas filled in the airbag 3 is consistent with the initial air pressure of the cavitation indicated by the test requirements. After determining the volume of the gas filled in the airbag 3, adjusting the size of the airbag 3 can change the air pressure of the gas filled in the airbag 3. In different cavitation dynamics tests, the corresponding airbags 3 can be arranged according to the test requirements to form the required cavitation, which is highly flexible and controllable.

[0040] The needle of the air-controlled pricking mechanism 4 is directed toward the airbag 3. The main controller is connected to and controls the air-controlled pricking mechanism to eject or retract the needle. In the default state, the needle is in a retracted state, does not contact the airbag 3 and is outside the motion path of the motion model to be tested. In the ejected state, the needle contacts and punctures the airbag 3.

[0041] In one embodiment, please refer to Figure 3 The structure diagram of the pneumatically controlled puncture mechanism 4 shown in FIG. 4 includes a fast cylinder 41, a puncture needle 42, a solenoid valve 43, a high-pressure gas cylinder 44 and a ventilation hose 45. The cylinder shaft of the fast cylinder 41 moves in the direction of the airbag 3, and the puncture needle 42 is mounted on the cylinder shaft of the fast cylinder 41. When the cylinder shaft of the fast cylinder 41 retracts, the puncture needle 42 is in a retracted state, and when the cylinder shaft of the fast cylinder 41 extends, the puncture needle 42 is in an ejected state. The fast cylinder 41 and the puncture needle 42 are both arranged inside the water tank 1, and the high-pressure gas cylinder 44 is arranged outside the water tank 1. The high-pressure gas cylinder 44 is connected to the fast cylinder 41 via the ventilation hose 45 to supply air to the fast cylinder 41. The solenoid valve 43 is arranged on the ventilation hose 45, and the solenoid valve 43 is also located outside the water tank 1. The main controller connects and controls the action of the solenoid valve 43 to control the on and off of the air supply to the fast cylinder 41. In actual implementation, the solenoid valve 43 is implemented by a two-position five-way valve. In addition, a barometer 46 may be provided on the ventilation hose 45 , and the main controller is connected to the barometer 46 to monitor the real-time air pressure in the ventilation hose 45 , thereby ensuring the stability of air supply to the fast cylinder 41 .

[0042] The steps of conducting a cavitation dynamics test using the cavitation dynamics test device of the present application include:

[0043] Step 1: The controller controls the motor of the model electric control slide rail 2 to drive the motion model 5 to be tested to move to the initial position and keep it still.

[0044] Step 2, according to the test requirements, determine the airbag puncture position, which is also the position where the airbag 3 is punctured by the air-controlled puncture mechanism 4. The gas in the airbag 3 forms a free air mass at the airbag puncture position, and collides with the moving motion model 5 to be tested to form a cavitation bubble attached to the motion model 5 to be tested. The field of view of the high-speed observation camera is adjusted to at least cover the airbag puncture position, so that the collision process between the motion model 5 to be tested and the free air mass can be captured.

[0045] When conducting the cavitation dynamics test, the motion model 5 to be tested is required to pass through the cavitation at a specific speed, so the airbag puncture position must be located on the motion path of the motion model 5 to be tested. Secondly, the motion model 5 to be tested is stationary at the initial position. After the cavitation dynamics test starts, the motion model 5 to be tested needs to accelerate from stationary to the required specific speed, so it is also necessary to ensure that the motion model 5 to be tested has accelerated to the required speed when it moves to the airbag puncture position.

[0046] Based on the above two points, after fixing the initial position of the motion model 5 to be tested, the predetermined model acceleration used when the model electric control slide rail 2 drives the motion model 5 to be tested to accelerate is predetermined, and the speed v when the motion model 5 to be tested collides with the free air mass indicated by the test requirements is determined. m , the airbag puncture position can be determined. The airbag puncture position is located on the motion path of the motion model 5 to be tested, and the distance between the motion path of the motion model to be tested and the initial position of the motion model 5 to be tested is L, and the distance L is not less than the speed v of the motion model 5 to be tested accelerating from a static state to a speed v according to the predetermined model acceleration. m Minimum distance required.

[0047] Step 3, determine the initial position of the airbag according to the puncture position of the airbag, and fix the airbag 3 at the initial position of the airbag. As described above, when the initial position of the motion model 5 to be tested and the predetermined model acceleration remain unchanged, when the test requirements are different, the puncture position of the airbag will be different, and the corresponding initial position of the airbag will also be different. Therefore, in order to be able to quickly and effectively adjust the initial position of the airbag under different test requirements, in one embodiment, the cavitation dynamics test device also includes an airbag electric control slide rail, which is fixed inside the water tank 1 and parallel to the model electric control slide rail 2. The airbag 3 is fixed on the slide of the airbag electric control slide rail. The main controller is also connected to and controls the motor of the airbag electric control slide rail to drive the airbag 3 to move along the airbag electric control slide rail to quickly and effectively adjust the position of the airbag. The water surface inside the water tank 1 covers the entire sliding range of the airbag 3, ensuring that the airbag 3 is always below the water surface, and the motor of the airbag electric control slide rail is located above the water surface to ensure the safety of the device.

[0048] On this basis, the airbag electronic control slide adopts a synchronous double-track structure, please refer to Figure 4 The structure diagram after removing the water tank 1 and Figure 5 and Figure 6 As shown in the partial front view, the airbag electric control slide rail includes a first synchronous rail 61 and a second synchronous rail 62 which are arranged in parallel at intervals. One radial side of the airbag 3 is fixed to the slider of the first synchronous rail 61 by a fixing rope 71, and the other side of the airbag 3 is fixed to the slider of the second synchronous rail 62 by a fixing rope 72. The motors of the main controller connected to the first synchronous rail 61 and the second synchronous rail 62 work synchronously to drive the airbag 3 to move. By adjusting the arrangement position of the first synchronous rail 61 and the second synchronous rail 62, and adjusting the length of the fixing ropes 71 and 72 on both sides of the airbag 3, the airbag 3 can be located on the motion path of the motion model 5 to be tested. When the position of the airbag 3 needs to be adjusted, the motors of the first synchronous rail 61 and the second synchronous rail 62 work synchronously, and both sides drive the airbag 3 to move to different positions along the motion path of the motion model 5 to be tested, and it can be ensured that the airbag 3 is always located on the motion path of the motion model 5 to be tested during the movement, so that the position of the airbag 3 can be quickly adjusted, simplifying the debugging process.

[0049] In another embodiment, the fixing ropes 71 and 72 on both sides of the airbag 3 are elastic fixing ropes, and the fixing ropes connected on both sides of the airbag 3 are in a stretched state. Then, after the airbag 3 is punctured by the air-controlled piercing mechanism 4, the fixing ropes 71 and 72 on both sides shrink under the elastic effect and pull the attached airbag fragments to move to both sides to stay away from the motion path of the motion model 5 to be tested, thereby preventing the airbag fragments from affecting the motion process of the motion model 5 to be tested.

[0050] The air-controlled puncture mechanism 4 needs to puncture the airbag at the airbag puncture position. Since the airbag puncture position varies under different test requirements, it is necessary not only to adjust the position of the airbag according to the test requirements, but also to adjust the position of the air-controlled puncture mechanism 4 according to the test requirements, mainly to adjust the position of the fast cylinder 41 located inside the water tank 1 and the puncture needle 42 fixed thereon. Similarly, for the convenience of adjustment, in one embodiment, the fast cylinder 41 is fixed on a slider of one of the synchronization rails to move synchronously with the airbag 3, such as Figure 4-Figure 6 Taking the fast cylinder 41 fixed on the second synchronization rail 62 as an example, the fast cylinder 41 is arranged horizontally, so that the needle 42 fixed thereon can be inserted and retracted horizontally. In addition, since the airbag 3 is a floating body, when it is pulled by the fixed rope in the water, it will float up as a whole and the position will be higher. When the size of the airbag is different, the floating height of the airbag 3 will also be different. Therefore, the installation position of the fast cylinder 41 on the synchronization rail is higher than the fixed position of the airbag on the synchronization rail, for example Figure 4-Figure 6 The middle fast cylinder 41 is fixed above the fixed rope 72. In addition, the position of the airbag 3 needs to be adjusted by the slider of the other side synchronization rail where the fast cylinder 41 is not installed, so that the airbag 3 is aligned with the needle 42. Since the airbag 3 is subjected to the upward buoyancy as a floating body, the slider of the other side synchronization rail needs to be adjusted downward, so Figure 4-Figure 6 In the embodiment, the slider of the second synchronization rail 61 is located below the slider of the second synchronization rail 62.

[0051] There are usually two test requirements for cavitation dynamics testing. In these two methods, the methods for determining the initial position of the airbag according to the puncture position of the airbag are different:

[0052] (1) The first test requirement of cavitation dynamics test: the free air mass is generated at rest. At the moment of free air mass generation, the motion model 5 to be tested moves at a specific speed v m It passes through the static free air mass to form a static cavity attached to the motion model 5 to be tested.

[0053] In this case, when the test requirements indicate that the cavitation is stationary, the airbag puncture position is the airbag initial position. Before the cavitation dynamics test begins, the main controller controls the motor of the airbag electric control slide to drive the airbag 3 to the airbag puncture position. Figure 7 As shown, the airbag 3 is located on the motion path of the motion model 5 to be tested, and the distance between the airbag 3 and the initial position of the motion model 5 to be tested along the motion path of the motion model 5 to be tested is L. It should be noted that the distance between the airbag 3 and the initial position of the motion model 5 to be tested referred to in this application is the distance between the lower end of the airbag 3 and the upper end of the motion model 5 to be tested.

[0054] (2) The second test requirement of cavitation dynamics test: the free air mass itself has a certain initial velocity, and the motion model 5 to be tested moves at a specific speed v m Passing through the free air mass with an initial velocity, a cavitation bubble with an initial velocity attached to the motion model 5 to be tested is formed.

[0055] In this case, when the test requirements indicate that the cavitation bubble has an initial velocity v b When , the initial position of the airbag is located on the motion path of the motion model 5 to be tested, and is a position closer to the initial position of the motion model 5 to be tested than the punctured position of the airbag. And the distance between the initial position of the airbag along the motion path of the motion model to be tested and the initial position of the motion model to be tested is LS, then the distance between the initial position of the airbag along the motion path of the motion model to be tested and the punctured position of the airbag is S, please refer to Figure 8 The distance S is the distance at which the airbag 3 accelerates from rest to the initial speed v according to the predetermined airbag acceleration. b The required distance and the predetermined airbag acceleration adopted by the airbag 3 are known quantities.

[0056] Step 4: At the start of the test, the main controller controls the motor of the model electric control slide rail 2 to drive the motion model 5 to be tested to start moving from the initial position. The motion model 5 to be tested starts to move uniformly from the static state according to the predetermined model acceleration from the initial position until it accelerates to the speed indicated by the test requirement.m Then, according to the speed m Uniform motion.

[0057] Under the above two different cavitation dynamics test requirements, the control of the airbag position during the cavitation dynamics test is also different, which are introduced as follows:

[0058] (1) When the test requirements indicate that the cavitation is stationary, during the cavitation dynamics test, the position of the airbag 3 is kept unchanged at the airbag puncture position.

[0059] (2) When the test requirements indicate that the cavitation has an initial velocity v b When conducting cavitation dynamics test, the main controller starts the test after the airbag movement delay t g =t a +t υ -t e The motor of the rear control airbag electric control slide rail drives the airbag 3 to move from the airbag initial position in a direction away from the motion model to be measured according to a predetermined airbag acceleration.

[0060] Among them, t a The motion model to be tested starts from the initial position and accelerates from rest to the speed v according to the predetermined model acceleration m The time consumption, t υ is the speed υ of the motion model to be tested m Then according to the speed m The time taken to move at a constant speed to the punctured position of the airbag, t e The airbag accelerates from rest to the initial speed v according to the predetermined airbag acceleration b time consuming.

[0061] Since the distance S between the initial position of the airbag and the punctured position of the airbag is the distance between the initial position of the airbag and the punctured position, the airbag accelerates to the initial speed v b The required distance, so the airbag 3 starts from the initial position of the airbag and moves at a uniform acceleration according to the predetermined airbag acceleration to reach the initial speed v b And reach the airbag puncture position.

[0062] Step 5: After the cylinder start delay time t at the test start time d The air-controlled puncture mechanism 4 is then controlled to eject the puncture needle and then retract it to puncture the airbag 3 .

[0063] Cylinder start delay t d It is related to the moving distance L between the initial position of the motion model 5 to be tested and the punctured position of the airbag and the test requirements. Specifically, regardless of whether the test requirements indicate that the cavitation is stationary or has an initial velocity, the cylinder start delay is t d =t a +t υ -tc Among them, t a The motion model to be tested starts from the initial position and accelerates from rest to the speed v according to the predetermined model acceleration m The time consumption, t υ is the speed υ of the motion model to be tested m Then according to the speed m The time taken to move at a constant speed to the punctured position of the airbag, t c It is the time taken by the main controller to control the pneumatically controlled pricking mechanism to eject the pricking needle once and then retract it.

[0064] When the test requirements indicate that the cavitation is stationary, such as Figure 7 As shown, at the start of the test, after the cylinder start delay t d The air-controlled pricking mechanism 4 is then controlled to eject the pricking needle and then retract it. The time taken for the main controller to control the air-controlled pricking mechanism to execute an action of ejecting the pricking needle and then retracting it is t c , the gas in the airbag 3 forms a free air mass at the puncture position of the airbag. At this time, the motion model 5 to be tested also moves to the puncture position of the airbag. Therefore, at the moment when the static free air mass is generated, the motion model 5 to be tested moves at a specific speed v m Pass through this stationary free air mass.

[0065] When the test requirements indicate that the cavitation has an initial velocity v b When Figure 8 As shown, at the start of the test, after the airbag movement delay t g The motor of the rear airbag electric control slide rail drives the airbag 3 to move at a uniform acceleration. The airbag 3 accelerates at t e After reaching the initial speed v b And move a distance S to reach the airbag puncture position. On the other hand, after the cylinder start delay t at the test start time d The air-controlled pricking mechanism 4 is then controlled to eject the pricking needle and then retract it. The time taken for the main controller to control the air-controlled pricking mechanism to execute an action of ejecting the pricking needle and then retracting it is t c , the airbag 3 is punctured by the air-controlled puncture mechanism 4 just when it reaches the airbag puncture position. At this time, the motion model 5 to be tested also moves to the airbag puncture position, so that at the initial speed v b At the moment when the free air mass is generated, the motion model 5 to be tested is moving at a specific speed v m Passing through the b of free air masses.

[0066] The time t taken by the main controller to control the air-controlled pricking mechanism to execute an action of ejecting the pricking needle and then retracting it is cIt is related to many factors, including the control delay of the main controller to the solenoid valve, the air supply delay after the solenoid valve is opened, and the action delay of the fast cylinder. In order to ensure the real-time action, this time consumption should be reduced as much as possible. c In one embodiment, the design is done from the following aspects:

[0067] (a) The main controller is connected to the control solenoid valve 43 through the PLC input and output module. The main controller and the PLC input and output module are combined using the EtherCAT bus. The communication control cycle is less than 1ms, ensuring the real-time control of the solenoid valve by the main controller.

[0068] (b) The ventilation hose 45 between the high-pressure gas cylinder 44 and the fast gas cylinder 41 is arranged along the shortest path, so that the ventilation hose 45 is shortened as much as possible to minimize the air supply delay caused by the ventilation hose 45. In actual measurement, this part can be within 20ms.

[0069] However, as mentioned above, the puncture position of the airbag is different in different tests, and the position of the corresponding fast cylinder 41 also needs to be adjusted. On the basis of using the shortest possible ventilation hose 45, in order to ensure that the high-pressure gas cylinder 44 can still be stably connected to the fast cylinder 41 during the position adjustment of the fast cylinder 41, the bubble dynamics test device also includes an electric lifting frame 8, and the high-pressure gas cylinder 44 and the solenoid valve 43 are arranged on the electric lifting frame 8 outside the water tank 1. The airbag electric control slide rail and the model electric control slide rail are both arranged in the water tank 1 along the vertical direction. The ventilation hose 45 connected to the high-pressure gas cylinder 44 is introduced from the outside of the water tank 1 through the upper opening of the water tank 1 into the inside of the water tank 1 to connect with the fast cylinder 41. The main controller connects and controls the electric lifting frame 8. When the fast cylinder 41 moves downward under the drive of the synchronous rail, the main controller controls the electric lifting frame 8 to rise, and when the fast cylinder moves upward under the drive of the synchronous rail, the main controller controls the electric lifting frame 8 to lower. That is, the electric lifting frame 8 keeps following the quick cylinder 41 , thereby ensuring that the ventilation hose 45 can always meet the distance between the quick cylinder 41 and the high-pressure gas cylinder 44 .

[0070] (c) The inner diameter of the fast cylinder 41 does not exceed the diameter threshold, and the cylinder length reaches the length threshold, that is, the fast cylinder 41 selects a model with a smaller cross-sectional area and a longer length, so that under the same air pressure, the fast cylinder 41 can obtain a higher movement speed, so that the fast cylinder 41, under the predetermined air pressure supply, the movement time of the cylinder axis of the fast cylinder 41 to the maximum extension state does not exceed the action delay threshold. The faster the action speed of the fast cylinder 41, the shorter the time from inflation to puncturing the airbag, so the dispersion at this moment will also be smaller, which can ensure the real-time nature of cavitation generation. In one example, the inner diameter of the fast cylinder 41 is 10mm and the cylinder length is 200mm. Under the air supply of 500kpa, the movement time of the fast cylinder 41 to the maximum extension state is less than 30ms.

[0071] After the above design, the time taken by the main controller to control the pneumatically controlled pricking mechanism to eject the pricking needle and then retract it can be reduced as much as possible. c , and the time t c It can be determined by fitting in advance. Generally, the time taken for the fast cylinder 41 to extend the cylinder shaft plus the time taken for the cylinder shaft to retract plus the reserved amount is taken as the time taken t c , and in actual control, for example, in one example, the time taken for the fast cylinder 41 to extend the cylinder shaft and the time taken for the cylinder shaft to retract are both 50ms, and the reserve amount is 10ms, then the time taken is t c In addition, the air-controlled pricking mechanism 4 quickly retracts the pricking needle away from the motion path of the motion model 5 to be tested after each ejection, so as to prevent the pricking needle from affecting the motion process of the motion model 5 to be tested. Generally, the time taken for the fast cylinder 41 to extend the cylinder axis plus the reserved amount is taken as the waiting time. After the fast cylinder 41 is controlled to extend the cylinder axis, the fast cylinder 41 is controlled to retract after the waiting time. In the above example, the waiting time is 60ms.

[0072] The above is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.

Claims

1. A cavitation dynamics test device, characterized in that: The cavitation dynamics test device comprises a water tank, a model electric-controlled slide rail, an air bag, an air-controlled piercing mechanism, a motion model to be tested, a main controller and a high-speed observation camera; The model electric-controlled slide is fixed inside the water tank, the motion model to be tested is fixed on the slide of the model electric-controlled slide, the main controller is connected to and controls the motor of the model electric-controlled slide to drive the motion model to be tested to move along the model electric-controlled slide, the water surface inside the water tank covers the entire motion range of the motion model to be tested, and the motor of the model electric-controlled slide is located above the water surface; The airbag is arranged below the water surface inside the water tank and fixed on the motion path of the motion model to be tested, and the airbag is filled with gas; The needle of the air-controlled pricking mechanism faces the airbag, and the main controller is connected to and controls the air-controlled pricking mechanism to eject or retract the needle. The needle is in a retracted state, does not contact the airbag, and is outside the motion path of the motion model to be tested in a default state. The needle contacts and punctures the airbag in an ejected state. The water tank adopts a transparent wall surface, the high-speed observation camera is arranged outside the water tank and faces the water tank, and the main controller is connected to the high-speed observation camera; When the cavitation dynamics test device is used to perform the cavitation dynamics test, the field of view of the high-speed observation camera is adjusted to at least cover the airbag puncture position; the main controller controls the motor of the model electric control slide rail to drive the motion model to be tested to move from the initial position at the test start time, and after the cylinder start delay t at the test start time, the motion model to be tested is moved from the initial position to the initial position. d Then the pneumatically controlled puncture mechanism is controlled to eject the puncture needle and then retract it to puncture the airbag. When the motion model to be tested reaches the puncture position of the airbag, the gas in the airbag forms a free air mass at the puncture position of the airbag. The test image data of the collision process between the motion model to be tested and the free air mass is obtained by the high-speed observation camera. The cylinder start delay t d It is related to the movement distance L between the initial position of the motion model to be tested and the airbag puncture position and the test requirements.

2. The cavitation dynamics test device according to claim 1, characterized in that: The test requirement indicates the velocity v of the motion model to be tested when it collides with the free air mass. m The distance L between the puncture position of the airbag along the motion path of the motion model to be tested and the initial position of the motion model to be tested is not less than the distance L between the motion model to be tested and the initial position of the motion model to be tested. m The minimum distance required; The cylinder start delay t d =t a +t v -t c ; where t a The motion model to be tested starts from the initial position and accelerates from rest to speed v according to the predetermined model acceleration m The time consumption, t v is the speed v that the motion model to be tested accelerates to m Then according to the speed v m The time taken to move at a constant speed to the punctured position of the airbag, t c It is the time taken for the main controller to control the pneumatically controlled pricking mechanism to execute an action of ejecting the pricking needle and then retracting it.

3. The cavitation dynamics test device according to claim 1, characterized in that: The cavitation dynamics test device also includes an airbag electric control slide rail, which is fixed inside the water tank and parallel to the model electric control slide rail; The airbag is fixed on the slide of the airbag electric control slide rail; the main controller is also connected to and controls the motor of the airbag electric control slide rail to drive the airbag to move along the airbag electric control slide rail to adjust the position of the airbag; the water surface inside the water tank covers the entire sliding range of the airbag, and the motor of the airbag electric control slide rail is located above the water surface.

4. The cavitation dynamics test device according to claim 3, characterized in that: When the test requirement indicates that the cavitation is stationary, before the cavitation dynamics test begins, the main controller controls the motor of the airbag electric control slide rail to drive the airbag to move to the airbag puncture position, and the airbag remains at the airbag puncture position during the cavitation dynamics test; When the test requirements indicate that the cavitation bubble has an initial velocity v b When the cavitation dynamics test starts, the main controller controls the motor of the airbag electric control slide to drive the airbag to move to the initial position of the airbag. The initial position of the airbag is located on the motion path of the motion model to be tested, and the distance between the initial position of the airbag along the motion path of the motion model to be tested and the initial position of the motion model to be tested is LS. The distance S is the acceleration of the airbag from rest to the initial speed v according to the predetermined airbag acceleration. b When conducting a cavitation dynamics test, the main controller starts the test after the airbag movement delay t g =t a +t v -t e Then, the motor of the airbag electric control slide rail is controlled to drive the airbag to move from the initial position of the airbag in a direction away from the motion model to be tested according to the predetermined airbag acceleration; the airbag reaches the initial speed v after moving the distance S. b and reaches the airbag puncture position and is punctured by the puncture needle of the air-controlled puncture mechanism; wherein, t a The motion model to be tested starts from the initial position and accelerates from rest to speed v according to the predetermined model acceleration m The time consumption, t v is the speed v that the motion model to be tested accelerates to m Then according to the speed v m The time taken to move at a constant speed to the punctured position of the airbag, t e The airbag accelerates from rest to the initial speed v according to the predetermined airbag acceleration b time consuming.

5. The cavitation dynamics test device according to claim 3, characterized in that: The airbag electrically controlled slide rail comprises a first synchronous rail and a second synchronous rail which are spaced apart and arranged in parallel. One radial side of the airbag is fixed to a slider of the first synchronous rail by a fixing rope, and the other side of the airbag is fixed to a slider of the second synchronous rail by a fixing rope. The motors of the main controller connected to the first synchronous rail and the second synchronous rail work synchronously to drive the airbag to move.

6. The cavitation dynamics test device according to claim 5, characterized in that: The fixing rope is an elastic fixing rope, and the fixing ropes connected on both sides of the airbag are in a stretched state; after the airbag is punctured by the air-controlled puncture mechanism, the fixing ropes on both sides shrink under the elastic action and pull the attached airbag fragments to move to both sides to stay away from the motion path of the motion model to be tested.

7. The cavitation dynamics test device according to claim 1, characterized in that: The gas type of the gas filled in the airbag is consistent with the cavitation gas type indicated by the test requirements, the volume of the gas filled in the airbag is consistent with the cavitation size indicated by the test requirements, and the gas pressure of the gas filled in the airbag is consistent with the cavitation initial gas pressure indicated by the test requirements.

8. The cavitation dynamics test device according to claim 5, characterized in that: The pneumatically controlled puncture mechanism comprises a quick cylinder, a puncture needle, a solenoid valve, a high-pressure gas cylinder and a ventilation hose. The quick cylinder is fixed to a slider of one of the synchronous rails to move synchronously with the airbag. The cylinder shaft of the quick cylinder moves in a direction toward the airbag. The puncture needle is mounted on the cylinder shaft of the quick cylinder. When the cylinder shaft retracts, the puncture needle is in a retracted state, and when the cylinder shaft extends, the puncture needle is in an ejected state. The high-pressure gas cylinder is arranged outside the water tank, and the high-pressure gas cylinder is connected to the quick cylinder via a ventilation hose, and the solenoid valve is arranged on the ventilation hose. The main controller is connected to and controls the action of the solenoid valve.

9. The cavitation dynamics test device according to claim 8, characterized in that: The airbag electric control slide rail and the model electric control slide rail are both arranged in the water tank along the vertical direction, the high-pressure gas cylinder and the solenoid valve are arranged on the electric lifting frame outside the water tank, the ventilation hose connected to the high-pressure gas cylinder is introduced from the outside of the water tank through the opening above the water tank to the inside of the water tank to connect to the fast cylinder, and the ventilation hose between the high-pressure gas cylinder and the fast cylinder is arranged according to the shortest path; the main controller is connected to and controls the electric lifting frame, when the fast cylinder moves downward under the drive of the synchronous rail, the main controller controls the electric lifting frame to rise, and when the fast cylinder moves upward under the drive of the synchronous rail, the main controller controls the electric lifting frame to lower.

10. The cavitation dynamics test device according to claim 8, characterized in that: The inner diameter of the fast cylinder does not exceed the diameter threshold, and the cylinder length reaches the length threshold. Under the predetermined air pressure supply, the movement time taken for the cylinder shaft of the fast cylinder to reach the maximum extension state does not exceed the action delay threshold.

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