Similarity test method and similarity test system for scaled model of cross-medium water inlet and outlet

Abstract

The present invention belongs to the field of cross-medium water ingress and egress test of water ingress and egress scale model, specifically, a similarity test method and a similarity test system of cross-medium water ingress and egress scale model. In the similarity conditions of the water ingress and egress scale model test, the satisfying conditions of fluid mechanics in a hypergravity environment are determined; the cavitation number and gas density coefficient in similar conditions in a hypergravity environment are determined; the Reynolds number in similar conditions in a hypergravity environment is determined; the gas core density in similar conditions in a hypergravity environment is determined; the Weber number in similar conditions in a hypergravity environment is determined; based on the similarity conditions of fluid mechanics, cavitation number and gas density coefficient, Reynolds number, gas core density and Weber number in a hypergravity environment, the similarity criteria and cross-medium similarity law of the water ingress and egress scale model test in a hypergravity environment are obtained. It is used to solve the problems that restrict the development of high-speed cross-medium water ingress and egress scale model tests.

Description

Technical Field

[0001] The present invention belongs to the field of cross-medium water entry and exit test of water entry and exit scale model, and in particular to a similarity test method and a similarity test system of a cross-medium water entry and exit scale model based on a hypergravity environment. Background Art

[0002] At present, the problem that restricts the development of high-speed cross-medium water entry and exit scaled model tests is the similarity criterion of high-speed cross-medium water entry and exit scaled model tests. The existing linear similarity theory is not perfect, and the environmental simulation capabilities of various mesoscale test pools are limited. The Froude number can only be equalized by changing the speed, or the cavitation number can be equalized by reducing pressure. This will also lead to distortions in the cross-medium cavitation development, multi-degree-of-freedom trajectory, and structural mechanics response of the navigation body due to the inability to simultaneously meet other dimensionless similarity criteria of fluid mechanics and structural mechanics.

[0003] Moreover, from the perspectives of economy, timeliness, reliability, effectiveness, etc., the development of each type of existing cross-media water entry and exit equipment generally goes through four stages: "tunnel"-"pool"-"lake"-"sea". That is, first undergo a water tunnel constraint model test to discuss a simplified physical problem, then undergo a quasi-real cross-media physical environment simulation of the water pool free model and water entry test process, then undergo a lake test in limited waters, and finally conduct a 1:1 offshore in-situ test to verify the function of the entire system. The similarity theory and similarity conversion relationship are what effectively link the mutual support relationship between tests of different scales at different stages of cross-media equipment.

[0004] The cross-medium similarity law involves similarity criteria such as Froude number, cavitation number, gas density coefficient, gas core density, Reynolds number (minimum scale ratio), etc. Moreover, the key similarity criteria are different for different tests. Through the hypergravity test environment, while reconciling multiple cross-medium similarity criteria (conflict between cavitation number and air density coefficient, reducing the influence of Weber number), it can provide greater gas core dissolution capacity (wide adjustable range of gas core density number), and provide a longer observation time window for test data collection through specific similarity conversion criteria. Effectively select key similarity criteria and explore new cross-medium similarity laws. Summary of the invention

[0005] The present invention provides a similarity test method of a cross-medium water entry and exit scale model based on a hypergravity environment, so as to solve the problem restricting the development of high-speed cross-medium water entry and exit scale model test.

[0006] The invention provides a similarity test device of a cross-medium water entry and exit scale model based on a hypergravity environment, so as to realize a similarity test method of a cross-medium water entry and exit scale model in a hypergravity environment.

[0007] The present invention is achieved through the following technical solutions:

[0008] A similarity test method for a cross-medium water entry and exit scale model based on a hypergravity environment, the similarity test method comprising

[0009] Determine the satisfying conditions of fluid mechanics in hypergravity environment under similar conditions of water inlet and outlet scale model tests;

[0010] In the similar conditions of the water inlet and outlet scale model test, the cavitation number and gas density coefficient in the similar conditions of the hypergravity environment are determined;

[0011] Determine the Reynolds number in similar conditions in a hypergravity environment under similar conditions in a scaled model test of water entry and exit;

[0012] Determine the density of the gas core in similar conditions of the water inlet and outlet scale model test under similar conditions in the hypergravity environment;

[0013] Determine the Weber number in similar conditions of the water inlet and outlet scale model test in a hypergravity environment;

[0014] Based on the similarity conditions of fluid mechanics, cavitation number and gas density coefficient, Reynolds number, gas core density and Weber number in hypergravity environment, the similarity criteria and cross-medium similarity law of scaled model test of water entry and exit in hypergravity environment are obtained.

[0015] Furthermore, the conditions for determining the fluid mechanics in a hypergravity environment are specifically:

[0016] For fluid dynamics similarity, the Froude number of the water inlet and outlet scale model and the prototype is required to be equal. m =Fr p ,Right now

[0017]

[0018] Among them, g m is the gravitational acceleration of the water inlet and outlet scale model, g p is the prototype gravity acceleration, U m is the launch speed of the scale model in and out of water, U p is the prototype launch speed, L m L is the scale model size of water inlet and outlet, p For prototype size,

[0019] The water inlet and outlet speed of the scaled model needs to meet the following requirements u m is the launch speed of the scaled model in and out of water, β is the scale ratio, U p is the prototype launch speed,

[0020] in, n is the gravitational acceleration ratio, that is, the supergravity coefficient,

[0021] The water inlet and outlet speeds are required to meet the following requirements U m =U p

[0022] When the centrifuge principle is used to achieve a high gravity environment Then U m =U p , the launch speed of the scaled model entering and exiting the water is equal to the launch speed of the prototype, and the Fr numbers of the scaled model entering and exiting the water are equal to those of the prototype; at this time, the requirements of fluid mechanics similarity for the Froude number and the requirements of structural mechanics similarity for the equality of the speed of the scaled model entering and exiting the water and the speed of the prototype are met at the same time.

[0023] Furthermore, the cavitation number coefficient in similar conditions under the hypergravity environment is determined as follows:

[0024] For the cavitation number σ c , from the similarity analysis of the bubbles entering and exiting the water, we can know that

[0025]

[0026] Where P ∞ =P a +γh,P c =P B +P V ,

[0027] Among them, P B is the insoluble gas pressure in the bubble; U is the flow rate; P a is atmospheric pressure; γ is water density; h is water depth; P c is the saturated vapor pressure of the liquid at ambient temperature; P ∞ is the incoming flow pressure; during the initial bubble formation time of the launch or in and out of the water, P B =P ∞ ; But as the navigation body moves in the water, P B Change will occur;

[0028] For the water inlet and outlet scale model σ cm ,

[0029]

[0030] Where ρ is the water density; U m P is the launch speed of the scale model entering and exiting the water; cm P is the saturated vapor pressure of the liquid entering and exiting the water scale model at ambient temperature; ∞mis the inflow pressure of the water inlet and outlet scaled model; β is the scale ratio;

[0031] For the prototype σ cp ,

[0032]

[0033] Where ρ is the water density; U p is the prototype launch speed; P cp is the saturated vapor pressure of the prototype liquid at ambient temperature; P ∞p The incoming flow pressure of the prototype;

[0034] According to the similarity principle, σ cm =σ cp , Substituting equation (2) and equation (3) into equation (4), we get

[0035]

[0036] And P ∞m =P am +γ m h m , substituting into the above formula (5) to obtain P am -P cm =(nβ)(P ap -P cp ),Right now

[0037] P am =(nβ)P ap +P cm -(nβ)P cp (6)

[0038] From formula (6), it can be seen that when the water inlet and outlet scale model test is carried out, the air pressure should be reduced to P am Satisfy formula (6);

[0039] Using the decompression correction equation to conduct water entry and exit tests P am =(nβ)P ap +P cm -(nβ)P cp ,

[0040] In a hypergravity environment, Make

[0041] P am =P ap +P cm -P cp (7)

[0042] For a hypergravity environment under a specific acceleration, the atmospheric pressure ratio that meets the cavitation number requirement becomes P am =Pap , that is, the gravity acceleration of the scaled model when entering and exiting the water is the same as that of the prototype times, the cavitation number can be equalized without reducing pressure.

[0043] Furthermore, the gas density coefficient in similar conditions under the hypergravity environment is specifically determined as follows: the cavitation number can be equal without decompression under the hypergravity environment, that is, the cavitation number P am =P ap At this time, the atmospheric density of the water inlet and outlet scale model test is consistent with the atmospheric density of the prototype test, and the conflict between the cavitation number and the gas density coefficient under conventional gravity disappears.

[0044] Furthermore, the Reynolds number under similar conditions in the hypergravity environment is determined as follows:

[0045] If the scale ratio β between the inlet and outlet water scale model and the prototype satisfies β>β0, the flow states of the inlet and outlet water scale model and the prototype boundary layer are both turbulent;

[0046] If the model velocity is not scaled down in a hypergravity environment, the Reynolds number of the scaled model test for entry and exit into water will increase.

[0047] Furthermore, the determination of the gas core density under similar conditions in a hypergravity environment is specifically that the atmospheric pressure does not shrink in a hypergravity environment. Since the amount of gas dissolved in a liquid is proportional to the pressure, the amount of gas allowed to dissolve in water in a hypergravity environment will be greater, and the allowable gas core concentration range during aeration will be wider.

[0048] Furthermore, the Weber number in similar conditions under the hypergravity environment is determined as follows: According to the similarity principle, the prototype and the water entry and exit scale model need to ensure that the Weber number is equal, that is, W em =W ep ;

[0049] In the hypergravity test environment, due to At this time, the minimum allowable scale ratio is changed from the original becomes

[0050] When the surface tension control area is 0.25 <E o <40,

[0051] E for the prototype o The calculation is,

[0052]

[0053] Scale model E for water inlet and outlet o The calculation is,

[0054] R=0.03m, then

[0055] In a hypergravity environment, the effect of surface tension is ignored in the scaled model test of entry and exit into water.

[0056] A similarity test system for a cross-medium water inlet and outlet scale model based on a hypergravity environment, the similarity test system uses the similarity test method for the cross-medium water inlet and outlet scale model based on a hypergravity environment, the similarity test system includes a fluid mechanics calculation module, a cavitation number and gas density coefficient calculation module, a Reynolds number calculation module, a gas core density calculation module and a Weber number calculation module,

[0057] The fluid mechanics calculation module is used to determine the conditions for fluid mechanics in a hypergravity environment under similar conditions to the scaled model test of water entry and exit;

[0058] The cavitation number and gas density coefficient calculation module is used to determine the cavitation number and gas density coefficient under similar conditions in a hypergravity environment under similar conditions of a water inlet and outlet scale model test;

[0059] The Reynolds number calculation module is used to determine the Reynolds number in similar conditions in a hypergravity environment under similar conditions in a water-entry and water-scale model test;

[0060] The gas core density calculation module is used to determine the gas core density under similar conditions in a hypergravity environment under similar conditions in a water-entry and water-scale model test;

[0061] The Weber number calculation module is used to determine the Weber number under similar conditions in a hypergravity environment under similar conditions in a water-entry and water-scale model test;

[0062] The fluid mechanics calculation module, the cavitation number and gas density coefficient calculation module, the Reynolds number calculation module, the gas core density calculation module and the Weber number calculation module all transmit data to the similarity criterion and cross-medium similarity law module, and the similarity criterion and cross-medium similarity law module transmits data to the display module for display.

[0063] An electronic device comprises a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus;

[0064] Memory, used to store computer programs;

[0065] The processor is used to implement the method when executing the program stored in the memory.

[0066] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method described above is implemented.

[0067] The beneficial effects of the present invention are:

[0068] The invention is based on a water entry and exit scaled model, and eliminates the scale contradiction between structural mechanics and fluid mechanics speed in the water entry and exit scaled model; through a hypergravity environment, the test can be carried out under the condition of satisfying the fluid mechanics similarity condition, that is, the Froude number is equal, the launch speed of the model can be equal to the launch speed of the prototype, and the structural mechanics similarity condition that the elastic model E, density ρ, and Poisson's ratio μ of the model and the prototype are equal is satisfied, thereby improving the accuracy of the cross-medium water entry and exit scaled model test.

[0069] The present invention solves the conflict between the simulation of the decompression cavitation number and the simulation of the gas density coefficient. In the hypergravity environment of the present invention, under a specific acceleration, the atmospheric pressure that meets the cavitation number requirements can be made to not need to be scaled down, that is, no decompression is required. At this time, the atmospheric density of the model test is consistent with the atmospheric density of the prototype, which meets the requirements of the test for the gas density coefficient, and the conflict problem between the cavitation number and the gas density coefficient under conventional gravity disappears.

[0070] The invention allows a smaller value of the minimum scale ratio β0. According to the minimum scale effect, the problem of unequal Reynolds numbers between the model and the prototype can be eliminated. In a hypergravity environment, the speed of the model does not need to be scaled down so that the Reynolds number of the model increases, the minimum scale ratio allowed is reduced, and the scale ratio range allowed by the model is expanded.

[0071] The present invention allows a larger amount of gas to be dissolved in water. In a hypergravity environment, the atmospheric pressure does not shrink, which increases the amount of gas allowed to be dissolved in water, and a wider range of gas core concentrations is allowed when gas is added.

[0072] The model test of the present invention can ignore the influence of surface tension. In a hypergravity environment, the surface tension reduction ratio required by the Weber number similarity is greatly reduced, so that the influence of surface tension on the development of cross-medium cavitation is greatly reduced. In a hypergravity environment, cavitation is mainly controlled by inertial force, which further reduces the influence of surface tension, so that the influence of surface tension can be ignored in the water inlet and outlet scale model test. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 It is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0074] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0075] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0076] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0077] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0078] The following is a clear and complete description of the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0079] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0080] Embodiment 1

[0081] A similarity test method for a cross-medium water entry and exit scale model based on a hypergravity environment, the similarity test method comprising

[0082] Determine the satisfying conditions of fluid mechanics in hypergravity environment under similar conditions of water inlet and outlet scale model tests;

[0083] In the similar conditions of the water inlet and outlet scale model test, the cavitation number and gas density coefficient in the similar conditions of the hypergravity environment are determined;

[0084] Determine the Reynolds number in similar conditions in a hypergravity environment under similar conditions in a scaled model test of water entry and exit;

[0085] Determine the density of the gas core in similar conditions of the water inlet and outlet scale model test under similar conditions in the hypergravity environment;

[0086] Determine the Weber number in similar conditions of the water inlet and outlet scale model test in a hypergravity environment;

[0087] Based on the similarity conditions of fluid mechanics, cavitation number and gas density coefficient, Reynolds number, gas core density and Weber number in hypergravity environment, the similarity criteria and cross-medium similarity law of scaled model test of water entry and exit in hypergravity environment are obtained.

[0088] Furthermore, the conditions for determining the fluid mechanics in a hypergravity environment are specifically:

[0089] For fluid dynamics similarity, the Froude number of the water inlet and outlet scale model and the prototype is required to be equal. m =Fr p ,Right now

[0090]

[0091] Among them, g m is the gravitational acceleration of the water inlet and outlet scale model, g p is the prototype gravity acceleration, U m is the launch speed of the scale model in and out of water, U p is the prototype launch speed, L m L is the scale model size of water inlet and outlet, p For prototype size,

[0092] The water inlet and outlet speed of the scaled model needs to meet the following requirements U m is the launch speed of the scaled model in and out of water, β is the scale ratio, U p is the prototype launch speed;

[0093] in, n is the gravitational acceleration ratio, that is, the supergravity coefficient,

[0094] Considering that the cross-medium entry and exit navigation body is an elastic body, or when conducting a water entry load reduction test, since the structural material is difficult to design according to the similarity theory, while ensuring that the elastic modulus E, density ρ, and Poisson's ratio μ of the water entry and exit scale model are equal to those of the prototype, the water entry and exit speed is required to meet the following requirements V m =V p

[0095] When the centrifuge principle is used to achieve a supergravity environment, g m > p , that is, n>1, there is a special case Then U m =U p , the launch speed of the scaled model entering and exiting the water is equal to the launch speed of the prototype, and the Fr numbers of the scaled model entering and exiting the water are equal to those of the prototype; at this time, the requirements of fluid mechanics similarity for the Froude number and the requirements of structural mechanics similarity for the equality of the speed of the scaled model entering and exiting the water and the speed of the prototype are met at the same time.

[0096] Furthermore, the cavitation number coefficient in similar conditions under the hypergravity environment is determined as follows:

[0097] For the cavitation number σ c , from the similarity analysis of the bubbles entering and exiting the water, we can know that:

[0098]

[0099] Where: P ∞ =P a +γh,P c =P B +P V ,

[0100] P B is the insoluble gas pressure in the bubble; ρ is the water density; U is the flow rate; P a is atmospheric pressure; γ is water density; h is water depth; P c is the saturated vapor pressure of the liquid at ambient temperature; P ∞ is the incoming flow pressure; during the initial bubble formation time of the launch or in and out of the water, P B =P ∞ ; But as the navigation body moves in the water, P B Change will occur;

[0101] Therefore, when launching underwater, the bubbles in the projectile continuously flow out from the head nozzle, causing the insoluble gas pressure P B Continuously decreasing;

[0102] When entering and exiting the water, the supercavitation bubble changes continuously with the movement of the vehicle, and the P B It also changes accordingly;

[0103] In short, P c It is not a constant but changes with the motion of the vehicle;

[0104] For the water inlet and outlet scale model σ cm ,

[0105]

[0106] Where ρ is the water density; U m P is the launch speed of the scale model entering and exiting the water; cm P is the saturated vapor pressure of the liquid entering and exiting the water scale model at ambient temperature; ∞m is the inflow pressure of the water inlet and outlet scaled model; β is the scale ratio;

[0107] For the prototype σ cp ,

[0108]

[0109] Where ρ is the water density; U p is the prototype launch speed; P cp is the saturated vapor pressure of the prototype liquid at ambient temperature; P ∞p The incoming flow pressure of the prototype;

[0110] According to the similarity principle, σ cm =σ cp , Substituting equation (2) and equation (3) into equation (4), we get:

[0111]

[0112] And P ∞m =P am +γ m h m , substituting into the above formula (5) we get:

[0113] P am -P cm =(nβ)(P ap -P cp ),Right now

[0114] P am =(nβ)P ap +P cm -(nβ)P cp (6)

[0115] From formula (6), it can be seen that when the water inlet and outlet scale model test is carried out, the air pressure should be reduced to P am Satisfy formula (6);

[0116] In the current reduced-pressure pool water inlet and outlet scale model test, the air pressure is reduced to P am =nβ)P ap , the lack of the second and third terms in formula (6) leads to excessive decompression, which will make the bubble layer attached to the navigation body thicker and longer, and thus change the correctness of the water tunnel test of the scaled model of entry and exit; here, formula (6) is called the modified decompression equation.

[0117] Therefore, to ensure σ c The scale test should be carried out under reduced pressure conditions, and the reduced pressure correction equation should be used for the water entry and exit test P am =(nβ)P ap +P cm (nβ)P cp ,

[0118] Obviously, in a supergravity environment, there is a special case: Make

[0119] P am =P ap +P cm -P cp (7)

[0120] The pressure inside the water-inlet and water-outlet scaled model and the prototype bubble is equal to the sum of the intolerant gas partial pressure and the saturated vapor pressure. For the water-inlet and water-outlet scaled model, it is P cm =P Bm +P Vm , for the prototype P cp =P Bp +P Vp , if at the beginning of entering and exiting water, the partial pressure of insoluble gas in the bubbles attached to the scaled model and the prototype is equal, since the movement of the scaled model and the prototype is similar, the deformation and shedding of the bubbles attached in the subsequent movement are also similar, so P Bm =P Bp (represents the partial pressure of insoluble gas in the bubble at a certain moment), and P Vm =P Vp , so we can get P cm =P cp .

[0121] Therefore, for a hypergravity environment under a specific acceleration, the atmospheric pressure ratio that meets the cavitation number requirement becomes: P am =P ap , that is, the gravity acceleration of the scaled model when entering and exiting the water is the same as that of the prototype times, the cavitation number can be equalized without reducing pressure.

[0122] Furthermore, the gas density coefficient under similar conditions in the hypergravity environment is specifically determined as follows: the dynamic pressure affected by the atmospheric density when entering and exiting the water bubble across the medium is p=0.5ρV 2 Determines the speed of cavitation closure, and the dynamic pressure similarity requirement satisfies P m-动压 =(nβ)P ap-动压 , according to the similarity requirement of Froude number in fluid mechanics, V m =V p , then ρ m-空气 =ρ p-空气 ; That is, the atmospheric density of the scaled model test for ingress and egress is consistent with that of the prototype test;

[0123] From the ideal gas state equation p = ρRT, it can be seen that under reduced pressure conditions, according to the reduced pressure correction equation P am =(uβ)P ap +P cm -(nβ)P cp , the atmospheric density under decompression conditions will become nearly nβ times that of the prototype; while in a supergravity environment, the cavitation number can be equal without decompression, that is, the cavitation number P am =P ap At this time, the atmospheric density of the water inlet and outlet scale model test is consistent with the atmospheric density of the prototype test, and the conflict between the cavitation number and the gas density coefficient under conventional gravity disappears.

[0124] Furthermore, the determination of the Reynolds number under similar conditions in a hypergravity environment is specifically as follows: since the Reynolds number and the Froude number in conventional experiments contradict each other, the solution is the same as the similarity analysis of bubble motion on the surface of a pressure-equalizing underwater launch vehicle, and it can be roughly assumed that there is a minimum β0, as long as β>β0.

[0125] The minimum scale effect is used to eliminate the problem of unequal Re between the model and the prototype. The similarity law analysis of the bubble layer motion on the surface of the vehicle during launch under equal pressure exhaust indicates that there is a minimum scale β0.

[0126] If the scale ratio β of the water inlet and outlet scale model and the prototype meets β>β0, the flow states of the water inlet and outlet scale model and the prototype boundary layer are both turbulent, thereby avoiding the contradiction between Re and Fr;

[0127] If the model velocity is not scaled down in a hypergravity environment, the Reynolds number of the scaled model test for entry and exit will increase, that is, the value of the minimum allowable scale ratio β0 will be smaller, and the scale ratio range allowed by the model will be wider.

[0128] Furthermore, the determination of the density of gas nuclei under similar conditions in a hypergravity environment is specifically that the characteristics of gas nuclei entrained in water under a hypergravity environment are similar to those under conventional gravity, and the atmospheric pressure does not shrink under hypergravity conditions. Since the amount of gas dissolved in liquid is proportional to the pressure, the amount of gas allowed to dissolve in water under a hypergravity environment will be greater, and the allowable range of gas nuclei concentration during aeration will be wider.

[0129] Furthermore, the Weber number in similar conditions under the hypergravity environment is determined as follows: According to the similarity principle, the prototype and the water entry and exit scale model need to ensure that the Weber number is equal, that is, W em =W ep ;

[0130] Then we can get: The relationship between the surface tension of the test and the prototype is obtained as follows:

[0131]

[0132] That is, the surface tension and the scale ratio are scaled in a quadratic relationship. From the surface tension coefficient of water of 0.072N / m, it can be seen that when β=1 / 20, the scale ratio requirement cannot be met. According to the existing fluorocarbon surfactants that are known to reduce the surface tension of water, the maximum surface tension coefficient S of water can be reduced to 0.015N / m (the critical concentration of carbon surfactants added to water is 3‰), that is It shows that when adding surfactant to change the surface tension of water, the minimum scale ratio can only reach 1 / 2. This scale ratio cannot meet the requirements of model tests, so it is necessary to consider the influence of surface tension on the development of bubbles in and out of water.

[0133] In the test environment of super gravity, since V m =V p , then the original β that the surface tension of water and the prototype surface tension in the water inlet and outlet scale model test must satisfy under normal gravity 2 The relationship becomes a β relationship, which is At this time, the requirements for the surface tension ratio of the water inlet and outlet scale model test are greatly reduced. At the same time, under the influence of the existing surfactant, the minimum scale ratio allowed is reduced from the original becomes

[0134] To further discuss the effect of surface tension on the development of bubbles in and out of water, another similarity criterion is introduced: Characterize the relationship between bubble buoyancy and surface tension.

[0135] When the surface tension control area is 0.25 <E o<40, when it exceeds this area, the cavitation is mainly controlled by inertial force, at this time E o The value is large, and the cavitation bubble is spherical cap-shaped;

[0136] E for the prototype o The calculation is,

[0137]

[0138] Scale model E for water inlet and outlet o The calculation is,

[0139] R=0.03m, then

[0140] Therefore, in a hypergravity environment, the effect of surface tension is ignored in the scaled model test of entry and exit into water.

[0141] Embodiment 2

[0142] A similarity test system for a cross-medium water inlet and outlet scale model based on a hypergravity environment, the similarity test system uses the similarity test method for the cross-medium water inlet and outlet scale model based on a hypergravity environment, the similarity test system includes a fluid mechanics calculation module, a cavitation number and gas density coefficient calculation module, a Reynolds number calculation module, a gas core density calculation module and a Weber number calculation module,

[0143] The fluid mechanics calculation module is used to determine the conditions for fluid mechanics in a hypergravity environment under similar conditions to the scaled model test of water entry and exit;

[0144] The cavitation number and gas density coefficient calculation module is used to determine the cavitation number and gas density coefficient under similar conditions in a hypergravity environment under similar conditions of a water inlet and outlet scale model test;

[0145] The Reynolds number calculation module is used to determine the Reynolds number in similar conditions in a hypergravity environment under similar conditions in a water-entry and water-scale model test;

[0146] The gas core density calculation module is used to determine the gas core density under similar conditions in a hypergravity environment under similar conditions in a water-entry and water-scale model test;

[0147] The Weber number calculation module is used to determine the Weber number under similar conditions in a hypergravity environment under similar conditions in a water-entry and water-scale model test;

[0148] The fluid mechanics calculation module, the cavitation number and gas density coefficient calculation module, the Reynolds number calculation module, the gas core density calculation module and the Weber number calculation module all transmit data to the similarity criterion and cross-medium similarity law module, and the similarity criterion and cross-medium similarity law module transmits data to the display module for display.

[0149] As can be seen from the above, the embodiment of the present invention calculates the Froude number and velocity, cavitation number and gas density coefficient, Reynolds number, gas core density and Weber number through the similarity test system of the cross-medium water-entry and water-reduction model in the hypergravity environment to effectively select key similarity criteria for the water-entry and water-reduction model experiment, and explores a new cross-medium similarity law. The experimental results show that the system improves the accuracy of the cross-medium water-entry and water-reduction model test, expands the scale ratio range allowed by the model, and the gas core concentration range allowed when aerating is wider.

[0150] Embodiment 3

[0151] An embodiment of the present invention provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the memory is used to store software programs and modules, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory. The memory and the processor are connected via a bus. Specifically, the processor implements any step in the first embodiment above by running the computer program stored in the memory.

[0152] It should be understood that in the embodiments of the present invention, the processor referred to may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0153] The memory may include a read-only memory, a flash memory, and a random access memory, and provides instructions and data to the processor. A part or all of the memory may also include a nonvolatile random access memory.

[0154] As can be seen from the above, the electronic device provided in the embodiment of the present invention can realize various data calculations of the similarity test method of the water entry and exit scale model as described in Example 1 by running a computer program, obtain effective and key similarity criteria for various similarity conditions of similarity tests in a hypergravity environment, and explore new cross-media similarity laws.

[0155] It should be understood that if the above-mentioned integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The above-mentioned computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the above-mentioned computer program includes computer program code, and the above-mentioned computer program code can be in source code form, object code form, executable file or some intermediate form. The above-mentioned computer-readable medium may include: any entity or device capable of carrying the above-mentioned computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the above-mentioned computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction.

[0156] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0157] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the above-mentioned device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0158] It should be noted that the methods and detailed examples provided in the above embodiments can be combined with the devices and equipment provided in the embodiments, and references can be made to each other, and no further details will be given.

[0159] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0160] In the embodiments provided by the present invention, it should be understood that the disclosed apparatus / terminal equipment and method can be implemented in other ways. For example, the apparatus / equipment embodiments described above are only illustrative, for example, the division of the above modules or units is only a logical function division, and in actual implementation, other division methods can be used, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0161] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A similarity test method for a cross-medium water inlet and outlet scale model based on a hypergravity environment, characterized in that: The similar test methods include Determine the satisfying conditions of fluid mechanics in hypergravity environment under similar conditions of water inlet and outlet scale model tests; In the similar conditions of the water inlet and outlet scale model test, the cavitation number and gas density coefficient in the similar conditions of the hypergravity environment are determined; Determine the Reynolds number in similar conditions in a hypergravity environment under similar conditions in a scaled model test of water entry and exit; Determine the density of the gas core in similar conditions of the water inlet and outlet scale model test under similar conditions in the hypergravity environment; Determine the Weber number in similar conditions of the water inlet and outlet scale model test in a hypergravity environment; Based on the similarity conditions of fluid mechanics, cavitation number and gas density coefficient, Reynolds number, gas core density and Weber number in hypergravity environment, the similarity criterion and cross-medium similarity law of water inlet and outlet scale model test in hypergravity environment are obtained. The conditions for determining fluid mechanics in a hypergravity environment are specifically: For fluid dynamics similarity, the Froude number of the water inlet and outlet scale model and the prototype is required to be equal. m =Fr p ,Right now In the formula, g m is the gravitational acceleration of the water inlet and outlet scale model, g p is the prototype gravity acceleration, U m is the launch speed of the scale model in and out of water, U p is the prototype launch speed, L m L is the scale model size of water inlet and outlet, p For prototype size, The water inlet and outlet speed of the scaled model needs to meet the following requirements β is the scale ratio, in, n is the gravitational acceleration ratio, that is, the supergravity coefficient, The water inlet and outlet speeds are required to meet the following requirements U m =U p , When the centrifuge principle is used to achieve a high gravity environment Then U m =U p , the launch speed of the scaled model entering and exiting the water is equal to the launch speed of the prototype, and the Fr numbers of the scaled model entering and exiting the water are equal to those of the prototype; at the same time, the requirements of fluid mechanics similarity for the Froude number and the requirements of structural mechanics similarity for the model speed and the prototype speed to be equal are met.

2. According to claim 1, a similarity test method for a cross-medium water inlet and outlet scale model based on a hypergravity environment, characterized in that: The specific method for determining the cavitation number coefficient in similar conditions under a hypergravity environment is: For the cavitation number σ c , from the similarity analysis of the bubbles entering and exiting the water, we can know that Where P ∞ =P a +γh,P c =P B +P V , Among them, P B is the insoluble gas pressure in the bubble; U is the flow rate; P a is atmospheric pressure; γ is water density; h is water depth; P c is the saturated vapor pressure of the liquid at ambient temperature; P ∞ is the incoming flow pressure; during the initial bubble formation time of the launch or in and out of the water, P B =P ∞ ; But as the navigation body moves in the water, P B Change will occur; For the water inlet and outlet scale model σ cm , Among them, P cm P is the saturated vapor pressure of the liquid entering and exiting the water scale model at ambient temperature; ∞m is the inflow pressure of the water inlet and outlet scale model; For the prototype σ cp , Where ρ is the water density; P cp is the saturated vapor pressure of the prototype liquid at ambient temperature; P ∞p The incoming flow pressure of the prototype; According to the similarity principle, σ cm =σ cp , Substituting equation (2) and equation (3) into equation (4), we get And P ∞m =P am +γ m h m , substituting into the above formula (5) we get: P am -P cm =(nβ)(P ap -P cp ), ie P am =(nβ)P ap +P cm -(nβ)P cp (6) Among them, γ m h is the water density of the water inlet and outlet scale model, m The water depth of the scale model for ingress and egress; From formula (6), it can be seen that when the water inlet and outlet scale model test is carried out, the air pressure should be reduced to P am Satisfy formula (6); Using the decompression correction equation to conduct water entry and exit tests P am =(nβ)P ap +P cm -(nβ)P cp , In a hypergravity environment, So that, P am =P ap +P cm -P cp (7) For a hypergravity environment under a specific acceleration, the atmospheric pressure ratio that meets the cavitation number requirement becomes P am =P ap , that is, the gravity acceleration of the scaled model when entering and exiting the water is the same as that of the prototype times, the cavitation number can be equalized without reducing pressure.

3. According to claim 2, a similarity test method for a cross-medium water inlet and outlet scale model based on a hypergravity environment, characterized in that: The specific method for determining the gas density coefficient under similar conditions in a supergravity environment is: In a hypergravity environment, the cavitation number can be equalized without decompression, that is, the cavitation number P am =P ap At this time, the atmospheric density of the water inlet and outlet scale model test is consistent with the atmospheric density of the prototype test, and the conflict between the cavitation number and the gas density coefficient under conventional gravity disappears.

4. According to claim 1, a similarity test method for a cross-medium water inlet and outlet scale model based on a hypergravity environment, characterized in that: The Reynolds number in similar conditions under the hypergravity environment is specifically determined as follows: If the scale ratio β between the inlet and outlet water scale model and the prototype satisfies β>β0, the flow states of the boundary layer of the inlet and outlet water scale model and the prototype are both turbulent; If the model velocity is not scaled down in a hypergravity environment, the Reynolds number of the scaled model test for entry and exit into water will increase.

5. According to claim 1, a similarity test method for a cross-medium water inlet and outlet scale model based on a hypergravity environment, characterized in that: The method for determining the gas core density under similar conditions in a hypergravity environment is as follows: in a hypergravity environment, the atmospheric pressure does not shrink. Since the amount of gas dissolved in a liquid is proportional to the pressure, the amount of gas allowed to dissolve in water in a hypergravity environment will be greater, and the allowable gas core concentration range during aeration will be wider.

6. The similarity test method of a cross-medium water inlet and outlet scale model based on a hypergravity environment according to claim 1 is characterized in that: The Weber number in similar conditions under the hypergravity environment is specifically determined as follows: According to the similarity principle, the prototype and the water entry and exit scale model need to ensure that the Weber number is equal, that is, W em =W ep ; In the hypergravity test environment, due to At this time, the minimum allowable scale ratio is changed from the original becomes When the surface tension control area is 0.25 <E o <40, E for the prototype o The calculation is, Scale model E for water inlet and outlet o The calculation is, R=0.03m, then In a hypergravity environment, the effect of surface tension is ignored in the scaled model test of entry and exit into water.

7. A similarity test system of a cross-medium water inlet and outlet scale model based on a hypergravity environment, characterized in that: The similarity test system uses the similarity test method of the cross-medium water inlet and outlet scale model based on the hypergravity environment as claimed in claim 1, and the similarity test system includes The fluid mechanics calculation module is used to determine the conditions for fluid mechanics in a hypergravity environment under similar conditions to the scaled model test of water entry and exit; The cavitation number and gas density coefficient calculation module is used to determine the cavitation number and gas density coefficient under similar conditions in the hypergravity environment under similar conditions in the water scale model test; Reynolds number calculation module, used to determine the Reynolds number in similar conditions in the hypergravity environment under similar conditions in the water scale model test; The gas core density calculation module is used to determine the gas core density in similar conditions of the water inlet and outlet scale model test under similar conditions in the hypergravity environment; Weber number calculation module, used to determine the Weber number in similar conditions of the water-entry and water-scale model test under similar conditions in the hypergravity environment; The fluid mechanics calculation module, the cavitation number and gas density coefficient calculation module, the Reynolds number calculation module, the gas core density calculation module and the Weber number calculation module all transmit data to the similarity criterion and cross-medium similarity law module, and the similarity criterion and cross-medium similarity law module transmits data to the display module for display.

8. An electronic device, characterized in that: It includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus; Memory, used to store computer programs; A processor, for implementing any of the methods described in claims 1-6 when executing a program stored in a memory.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

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