Heavy-load rocket sled system section water level water injection depth calculation method and device

Abstract

The invention provides a heavy-load rocket sled system section water level water injection depth calculation method and device, and mainly solves the problem of recovery brake safety of a rocket sled which is large in mass and operates at supersonic speed. According to the heavy-load rocket sled system section water level division water injection depth calculation method, the cross sectional area of a water tank is calculated by adopting the momentum theorem of a continuous medium, and then the draft depth of a water scoop and the water injection depth of the water tank are obtained; on the premise of ensuring the safety of the water scoop structure, the supersonic rocket sled can be safely recovered under a track with a fixed length.

Description

Technical Field

[0001] The invention belongs to the technical field of military product shooting range test, and mainly relates to a braking recovery method for a heavy-load rocket sled system. Background Art

[0002] The rocket sled is an emerging advanced test method in ground simulation tests. It is a full-scale ground test system that connects the ground static test and the flight test. The rocket sled test is basically not limited by the volume and weight of the test piece. The load-bearing weight can range from a few kilograms to tens of tons. The test products can all use 1:1 full-scale products, such as drones, rockets, etc. Compared with laboratory experiments and scaled tests, the mechanical environment that the rocket sled can provide is closer to the actual working conditions, such as the field working environment under the conditions of real speed or acceleration. However, with the continuous increase in the speed of the rocket sled and the continuous increase in the quality of the test products, under the condition of the length limit of the track facilities in the test field, the application of the existing water tank recovery method can no longer meet the needs of on-orbit recovery of the test products and the rocket sled. In addition, since the liquid level change process caused by the operating pressure of the rocket sled is not fully considered, the water bucket structure may be damaged. There is a great test safety risk in the on-orbit recovery process of the rocket sled. Therefore, it is urgent to propose a rocket sled test method that can reliably brake and recover to meet the performance assessment needs of large-mass, supersonic test products. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art and solve the problem of recovery and braking of a large-mass, supersonic rocket sled, the present invention provides a method and device for calculating the water level injection depth of a section of a heavy-loaded rocket sled system.

[0004] A method for calculating the water level injection depth of a section of a heavy-load rocket sled system comprises the following steps:

[0005] S1: Calculate the draft depth of the water bucket of the rocket sled at different speeds;

[0006] According to the momentum theorem of continuous media, calculate the braking force and draft of the water bucket;

[0007] S2: Calculate the water filling depth of the water tank according to the water scoop draft depth obtained in step S1.

[0008] The water filling depth of the water tank is the sum of the draft depth of the water scoop and the distance between the bottom surface of the water scoop and the bottom of the water tank.

[0009] Furthermore, the steps of calculating the draft of the water bucket of the rocket sled at different speed sections are:

[0010] According to the momentum theorem of continuous media, the geometric sum of the change in momentum of the liquid flowing in and out of the two corresponding sections of the pipe per second and the vector sum of the mass force and surface force acting on it is equal to zero, that is:

[0011]

[0012] Define the coordinate axes X, Y and Z: the rocket sled's forward direction is the X axis, the direction perpendicular to the X direction on the orbital plane is the Y axis, and the direction perpendicular to the orbital plane is the Z axis;

[0013] In the formula, is the mass of liquid flowing into the pipe per second;

[0014] is the resultant force of the pipe wall reaction force, where F sx 、F sy 、F sz are the reaction forces on the pipe wall in the X, Y and Z directions respectively;

[0015] is the resultant force of the mass force of the liquid between the inlet and outlet sections of the pipe, where F mx 、F my 、F mz They are the mass forces of the liquid between the outlet and inlet sections of the pipe in the X, Y, and Z directions respectively;

[0016] When moving at high speed, For the convenience of calculation, take

[0017] v is the pulley speed or the flow rate of water entering the bucket, in m / s;

[0018] is the unit vector formed by the cosine function of the direction angle of liquid inflow, where α 入 , β 入 , γ 入 It is the angle formed in the X, Y, and Z directions when the liquid flows in;

[0019] is the unit vector formed by the cosine function of the direction angle of liquid outflow, where α 出 , β 出 , γ 出 It is the angle formed in the X, Y, and Z directions when the liquid flows out;

[0020] According to the momentum theorem:

[0021] Assume that water is a non-viscous, incompressible liquid, and there is no friction between the water flow and the inner wall of the bucket. The water inlet direction of the bucket is consistent with the sliding direction of the pulley, that is, α 入 =0, and α 出 =θ, then the braking force is:

[0022] F=ρAv 2 (1-R v cosθ);

[0023] Where v = v 入 ; R v R is the ratio of the outlet flow rate to the inlet flow rate of the water bucket. v =v 出 / v 入 ; ρ is the density of water, unit is kg / m 3 ; A is the cross-sectional area of ​​the water flow at the pipe inlet, unit: m 2 ;

[0024] Since the water flows fast and in a short time in the bucket, it is assumed that the water flow speed at the inlet and outlet is the same, that is, R v =1.

[0025] Furthermore, a water brake device designed by using the calculation method of water injection depth of the section water level of the heavy-load rocket sled system includes a water tank and a plurality of partitions; the plurality of partitions divide the water tank into N sections; Tank i There are i sections of water tank, 1≤i≤N; the length of each section of the water tank is 60m; the method in step S2 is used to calculate the water filling depth of the first section of the water tank and the water filling depths of the remaining water tanks respectively.

[0026] Furthermore, the water filling depth of the first water tank is calculated as follows:

[0027] F 1 =ρA 1 v 1 2 (1-R v cosθ); where F 1 is the braking force at the entrance of the first water tank; v 1 is the speed of the water bucket at the entrance of the first section of the flume;

[0028] Among them, F 1 It is one-fourth of the maximum allowable braking force of the water bucket; the maximum allowable braking force of the water bucket is the theoretical maximum braking force of the water bucket, which is a known quantity; v 1 Obtained through measurement, it is a known quantity;

[0029] By F 1 =ρA 1 v 1 2(1-R v cosθ) to obtain A 1 , A 1 is the cross-sectional area of ​​the first section of the flume;

[0030] Thus, the draft depth of the water bucket in the first water tank is obtained; and then the water filling depth of the first water tank is obtained;

[0031] Since the rocket skid water scoop is suddenly subjected to a large braking force at the entrance of the first water trough, the static water will have an instantaneous large impact on the water scoop structure, so the maximum braking force borne by the water scoop at the entrance of the first water trough shall not exceed one quarter of the maximum allowable braking force of the water scoop.

[0032] Furthermore, the calculation steps of the water filling depth of the j-th water tank are:

[0033] Calculate the velocity of the water scoop at the outlet of the j-1th section of the flume:

[0034] The aerodynamic simulation calculates the aerodynamic resistance and friction resistance of the water bucket in the j-1th section, 2≤j≤N; the mass of the rocket sled system is a known quantity; the mass of the rocket sled system includes the mass of the rocket sled, the water bucket and the test object, and the acceleration at the entrance of the j-1th section of the water tank is calculated according to Newton's second law; the time t starts from 0, the interval is 0.001s, and the movement speed of the water bucket at each time is iteratively calculated, and then the corresponding displacement at each time is obtained. When the displacement is equal to 60m, the corresponding speed is the movement speed of the water bucket at the outlet of the j-1th section of the water tank, and also the movement speed of the water bucket at the entrance of the jth section of the water tank;

[0035] Calculate the braking force on the water bucket at the entrance of the j-th water tank:

[0036] The braking force borne by the water scoop at the entrance of the j-th section of the water trough shall not be greater than 1.5 times the braking force borne by the water scoop at the entrance of the j-1-th section of the water trough. The braking force borne by the water scoop at the entrance of the j-th section of the water trough is calculated;

[0037] If the braking force borne at the entrance of the j-th water flume is greater than or equal to the maximum allowable braking force of the water scoop, then the braking force borne by the water scoop at the entrance of the j-th water flume is the maximum allowable braking force of the water scoop;

[0038] If the braking force borne at the entrance of the j-th section of the water trough is less than the maximum allowable braking force of the water scoop, the braking force borne by the water scoop at the entrance of the j-th section of the water trough shall be 1.5 times the braking force borne at the entrance of the j-1-th section of the water trough.

[0039] Furthermore, the method for correcting the liquid level depth of the first section of the water tank at the entrance of the rocket sled water scoop is: carry out gas-liquid two-phase flow calculation on the rocket sled, obtain the height of the influence of air pressure on the liquid level, add the height of the influence of air pressure on the liquid level and the water injection depth, and obtain the liquid level depth correction of the water tank at the entrance of the water brake.

[0040] Furthermore, the theoretical maximum braking force of the water bucket is obtained through static analysis, and the maximum allowable braking force of the water bucket is calculated using the safety factor based on strength theory. The safety factor is 1.7, that is, the maximum allowable braking force is the theoretical maximum braking force of the water bucket divided by the safety factor.

[0041] Compared with the existing rocket sled on-orbit recovery method, the advantages of the present invention are:

[0042] 1. The advantages of the present invention are that it proposes a long-range braking recovery test method for a heavy-load rocket sled system section water level, which can meet the requirements of on-orbit recovery of a large-mass, supersonic test rocket sled test object;

[0043] 2. The present invention also has the advantage that the segment water level long-distance brake recovery test method takes into account the influence of the earth's gravity during the water brake deployment process, and realizes the on-orbit recovery of the rocket sled under complex conditions of the stepped water surface;

[0044] 3. The advantage of the present invention is that the segment water level long-distance brake recovery test method takes into account the liquid level changes caused by the operating pressure of the rocket sled during the water brake deployment process, thereby improving the safety of the rocket sled's water brake process. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a schematic diagram of the working principle of the water bucket;

[0046] Figure 2 This is a schematic diagram of the on-site layout of a large aspect ratio rocket supersonic gliding rocket sled test;

[0047] Among them, 1-test radar; 2-aerial observation platform; 3-deceleration water brake; 4-interception sandbag; 5-electronic tester; 6-photoelectric theodolite; 7-high-speed motion tracking system; 8-high-speed camera; 9-dynamic power grid. DETAILED DESCRIPTION

[0048] A method for calculating the water level injection depth of a section of a heavy-load rocket sled system comprises the following steps:

[0049] S1: Calculate the draft depth of the water bucket of the rocket sled at different speeds;

[0050] According to the momentum theorem of continuous media, the geometric sum of the change in momentum of the liquid flowing in and out of the two corresponding sections of the pipe per second and the vector sum of the mass force and surface force acting on it is equal to zero, that is:

[0051]

[0052] Define the coordinate axes X, Y and Z: the rocket sled's forward direction is the X axis, the direction perpendicular to the X direction on the orbital plane is the Y axis, and the direction perpendicular to the orbital plane is the Z axis;

[0053] In the formula, is the mass of liquid flowing into the pipe per second;

[0054] is the resultant force of the pipe wall reaction force, where F sx 、F sy 、F sz are the reaction forces on the pipe wall in the X, Y and Z directions respectively;

[0055] is the resultant force of the mass force of the liquid between the inlet and outlet sections of the pipe, where F mx 、F my 、F mz They are the mass forces of the liquid between the outlet and inlet sections of the pipe in the X, Y, and Z directions respectively;

[0056] When moving at high speed, For the convenience of calculation, take

[0057] v is the pulley speed or the flow rate of water entering the bucket, in m / s;

[0058] is the unit vector formed by the cosine function of the direction angle of liquid inflow, where α 入 , β 入 , γ 入 It is the angle formed in the X, Y, and Z directions when the liquid flows in;

[0059] is the unit vector formed by the cosine function of the direction angle of liquid outflow, where α 出 , β 出 , γ 出 It is the angle formed in the X, Y, and Z directions when the liquid flows out;

[0060] According to the momentum theorem:

[0061] Assume that water is a non-viscous, incompressible liquid, and there is no friction between the water flow and the inner wall of the bucket. The water inlet direction of the bucket is consistent with the sliding direction of the pulley, that is, α 入 =0, and α 出 =θ, then the braking force is:

[0062] F=ρAv 2 (1-R v cosθ);

[0063] Where v = v 入 ; R v R is the ratio of the outlet flow rate to the inlet flow rate of the water bucket. v =v 出 / v 入 ; ρ is the density of water, unit is kg / m 3 ; A is the cross-sectional area of ​​the water flow at the pipe inlet, unit: m 2 ;

[0064] In practical engineering applications, especially at high speeds, it is difficult to obtain accurate R v Since the water flows fast and in a short time in the bucket, it is assumed in the engineering calculation that the water flow speed at the inlet and outlet is the same, that is, R v =1;

[0065] S2: Calculate the water filling depth of the water tank;

[0066] According to the draft depth of the rocket skid scoop at different speeds obtained by S1, calculate the water filling depth of the water tank;

[0067] The water filling depth of the water tank is the sum of the draft of the water scoop and the distance between the bottom surface of the water scoop and the bottom of the water tank;

[0068] A water brake device designed by applying a method for calculating the water level injection depth of a heavy-load rocket sled system section comprises a water tank and a plurality of partitions; the plurality of partitions divide the water tank into N sections; i is the i-section water tank, 1≤i≤N; the length of each section of the water tank is 60m;

[0069] Since the rocket sled track is an absolutely horizontal straight line in space during construction, during the water brake deployment process, the static water is affected by the earth's gravity and there is a height difference between the water levels at both ends of the water tank. The end of the water tank with a high liquid level is the inlet end of the rocket sled water bucket, and the end of the water tank with a low liquid level is the outlet end of the rocket sled water bucket.

[0070] The calculation steps for the water filling depth of the first section of the water tank are:

[0071] F 1 =ρA 1 v 1 2 (1-R v cosθ); where F 1 is the braking force at the entrance of the first water tank; v 1 is the speed of the water bucket at the entrance of the first section of the flume;

[0072] Among them, F 1 It is one-fourth of the maximum allowable braking force of the water bucket; the maximum allowable braking force of the water bucket is the theoretical maximum braking force of the water bucket, which is a known quantity; v 1 Obtained through measurement, it is a known quantity;

[0073] By F 1 =ρA 1 v 1 2 (1-R v cosθ) to obtain A 1 , A 1 is the cross-sectional area of ​​the first section of the flume;

[0074] Thus, the draft depth of the water bucket in the first water tank is obtained; and then the water filling depth of the first water tank is obtained;

[0075] Since the rocket skid water scoop suddenly bears a large braking force at the entrance of the first water trough, the static water will have an instantaneous large impact on the water scoop structure, so the braking force borne by the water scoop at the entrance of the first water trough should not be greater than one-fourth of the maximum allowable braking force of the water scoop;

[0076] The maximum braking force of the water bucket theoretical design is obtained through static analysis. The maximum allowable braking force of the water bucket is calculated using the safety factor according to the strength theory. The safety factor is 1.7, that is, the maximum allowable braking force = the maximum braking force of the water bucket theoretical design\the safety factor used; this can increase the safety factor of system operation;

[0077] The calculation steps for the water filling depth of the j-th water tank are:

[0078] Calculate the velocity of the water scoop at the outlet of the j-1th section of the flume:

[0079] The aerodynamic simulation calculates the aerodynamic resistance and friction resistance of the water bucket in the j-1th section, 2≤j≤N; the mass of the rocket sled system is a known quantity; the mass of the rocket sled system includes the mass of the rocket sled, the water bucket and the test object, and the acceleration at the entrance of the j-1th section of the water tank is calculated according to Newton's second law; the time t starts from 0, the interval is 0.001s, and the movement speed of the water bucket at each time is iteratively calculated, and then the corresponding displacement at each time is obtained. When the displacement is equal to 60m, the corresponding speed is the movement speed of the water bucket at the outlet of the j-1th section of the water tank, and also the movement speed of the water bucket at the entrance of the jth section of the water tank;

[0080] Calculate the braking force on the water bucket at the entrance of the j-th water tank:

[0081] The braking force borne by the water scoop at the entrance of the j-th section of the water trough shall not be greater than 1.5 times the braking force borne by the water scoop at the entrance of the j-1-th section of the water trough. The braking force borne by the water scoop at the entrance of the j-th section of the water trough is calculated;

[0082] If the braking force borne at the entrance of the j-th water flume is greater than or equal to the maximum allowable braking force of the water scoop, then the braking force borne by the water scoop at the entrance of the j-th water flume is the maximum allowable braking force of the water scoop;

[0083] If the braking force at the entrance of the j-th water flume is less than the maximum allowable braking force of the water scoop, the braking force at the entrance of the j-th water flume is 1.5 times the braking force at the entrance of the j-1-th water flume.

[0084] Correction of the liquid level depth of the first section of the water tank at the entrance of the rocket sled water bucket: Carry out gas-liquid two-phase flow calculation on the rocket sled to obtain the height of the influence of air pressure on the liquid level, add the height of the influence of air pressure on the liquid level and the water injection depth, and get the correction of the liquid level depth of the water tank at the entrance of the water brake; the liquid level changes caused by the operating pressure of the rocket sled. For the rocket sled running in the supersonic stage, the incoming gas will form a high-pressure area at the head of the test object. This part of the pressure will cause the water brake liquid level to fluctuate, and the fluctuation of the liquid level directly affects the draft of the water bucket, and ultimately affects the safety of the in-orbit recovery of the rocket sled and the test object. By carrying out gas-liquid two-phase flow calculation, the rocket sled water bucket can provide maximum braking force while ensuring safety, so that the speed of the sled body can be reduced as quickly as possible.

[0085] The problem to be solved by the present invention is to provide a segmented water level derivative long-range braking recovery test method for a heavy-loaded supersonic gliding rocket sled test, which is used for the on-orbit recovery of a heavy-loaded supersonic gliding rocket sled to achieve complete recovery of the test object.

[0086] A heavy-load rocket sled system section water level long-range braking recovery test method includes the following contents:

[0087] 1) During the on-orbit recovery process of a heavy-loaded supersonic gliding rocket sled, it must first rely on aerodynamic resistance and friction resistance to decelerate the glide. Only when the speed drops to a safe range where the water scoop can withstand the braking force, can it be recovered on-orbit through water brakes. The braking force that the water scoop can withstand is determined by its structural design.

[0088] 2) The static water pre-placed in the water tank in the track is picked up by the combined water scoop, and the running speed of the rocket sled system is reduced by using the principle of momentum conversion until the rocket sled stops on the track, thereby realizing the complete recovery of the test object on track.

[0089] 3) Design the maximum braking force according to the water scoop theory, consider the safety factor during use, and calculate the draft of the water scoop at different speed ranges according to the following calculation process.

[0090] like Figure 1 As shown, when the fluid changes direction through the pipe, a force acts on the pipe wall.

[0091] According to the momentum theorem of continuous media, the geometric sum of the change in momentum of the liquid flowing in and out of the two corresponding sections of the pipe per second and the vector sum of the mass force and surface force acting on it is equal to zero, that is,

[0092]

[0093] in,

[0094] In the formula, is the mass of liquid flowing into the pipe per second; is the resultant force of the pipe wall reaction force, where F sx 、F sy 、F sz are the reaction forces on the pipe wall in the X, Y and Z directions respectively; is the resultant force of the mass force of the liquid between the outlet and inlet sections of the pipe, where F mx 、F my 、F mz They are the mass forces of the liquid between the outlet and inlet sections of the pipeline in the three directions of X, Y, and Z (the forward direction is the x-axis, the direction perpendicular to the x-direction on the orbital plane is the y-direction, and the direction perpendicular to the orbital plane is the z-direction); when moving at high speed, For the convenience of calculation, take is the unit vector formed by the cosine function of the direction angle of liquid inflow, where α 入 , β 入 , γ 入 It is the angle formed in the X, Y, and Z directions when the liquid flows in; is the unit vector formed by the cosine function of the direction angle of liquid outflow, where α 出 , β 出 , γ 出 It is the angle formed in the X, Y, and Z directions when the liquid flows out.

[0095] but

[0096]

[0097] Assume that water is a non-viscous, incompressible liquid, and there is no friction between the water flow and the inner wall of the bucket. The water inlet direction of the bucket is consistent with the sliding direction of the pulley, that is, α 入 =0, and α 出 =θ, then the braking force is

[0098] F=ρAv 2 (1-R v cosθ)

[0099] Where: v = v 入 is the pulley speed or the flow rate of water entering the bucket, in m / s; R v =v 出 / v 入 is the ratio of the water scoop outlet flow rate to the inlet flow rate; ρ is the water density, unit kg / m 3 ; A is the cross-sectional area of ​​the water flow at the pipe inlet, unit: m 2 .

[0100] In practical engineering applications, especially at high speeds, it is difficult to obtain accurate R v Considering that the water flows fast and in a short time in the bucket, it is generally assumed in engineering calculations that the water flow speed at the inlet and outlet is the same, that is, R v =1.

[0101] 4) The rocket sled track is an absolutely horizontal straight line in space when it is built. Therefore, when the water brake is laid out, due to the influence of the earth's gravity, there is a height difference between the two ends of the water brake at a certain distance. The change in the draft depth of the water bucket during the braking process affects the braking effectiveness during the rocket sled recovery process. To ensure the safety of the water bucket structure, the braking force difference before and after the partition must not be less than 1.5 times, but in order to fully improve the braking efficiency of the water bucket, it is recommended that the braking force difference before and after the partition should not be greater than 2 times.

[0102] 5) Consider the liquid level changes caused by the rocket sled's operating pressure. For a rocket sled operating at transonic speed, the incoming gas will form a high-pressure area at the head of the test object. This part of the pressure will cause the water brake liquid level to fluctuate, and the fluctuation of the liquid level will directly affect the draft of the water bucket, and ultimately affect the safety of the rocket sled and the test object in orbit recovery.

[0103] By carrying out gas-liquid two-phase flow calculation on the rocket sled system, the water area is initialized at the liquid level of the water tank, and the air domain is initialized for the external flow field. Unsteady-state aerodynamic calculation is used to simulate the pressure field changes during the operation of the rocket sled. Real-time data exchange is carried out between the pressure field and the water area, and the liquid level fluctuation is calculated to provide data support for the draft evaluation of the brake bucket.

[0104] In the test of a supersonic gliding rocket sled of a large aspect ratio rocket, the specific implementation method of the complete on-orbit recovery of the rocket sled and the test object is as follows:

[0105] Step 1: Design and manufacture the rocket sled (including the water scoop) according to the test requirements, and select the booster engine.

[0106] Step 2: Conduct rocket sled test recovery plan design.

[0107] a) The angle of the water bucket pipe is designed to be 60°, and the theoretical maximum braking force is calculated to be 44t. Based on usage experience and considering a safety factor of 1.7, the maximum allowable braking force is 25.8t.

[0108] b) Considering the liquid level changes caused by the operating pressure of the rocket sled, the gas-liquid two-phase flow calculation was carried out with a calculated speed of 254m / s. The analysis results show that under the action of static pressure, the near-end liquid level fluctuates by less than 1cm, and there is no obvious fluctuation in the rear liquid level.

[0109] c) Due to the influence of the earth's gravity, it was found during the actual layout of the water level that the water level dropped by about 1.5 mm every 15 m from north to south along the track. The water level change caused by this was considered to be linear in the trajectory design.

[0110] d) To ensure effective braking during the recovery of the rocket sled, water baffles are arranged every 15 m in combination with the test site conditions to ensure the water draft of the water scoop as much as possible. The water brake arrangement is shown in Table 1.

[0111] Table 1 Water brake layout

[0112]

[0113]

[0114] Step 3: Arrange water brakes according to the recovery plan.

[0115] Step 4: Assemble the test article and the rocket sled on site and install the booster engine.

[0116] Step 5: Deploy ground test equipment according to test requirements.

[0117] Step 6: When the test conditions are met, the booster engine is ignited and launched.

[0118] Step 7: The rocket sled is stopped on the track by means of water brakes, and the test object is recovered intact.

Claims

1. A method for calculating the water level injection depth of a heavy-load rocket sled system section, characterized in that: The steps include: S1: Calculate the draft of the water bucket of the rocket sled at different speed ranges; According to the momentum theorem of continuous media, calculate the braking force and draft of the water bucket; S2: Calculate the water filling depth of the water tank according to the draft of the water bucket obtained in step S1; The water filling depth of the water tank is the sum of the draft depth of the water scoop and the distance between the bottom surface of the water scoop and the bottom of the water tank.

2. A method for calculating the water level injection depth of a section of a heavy-load rocket sled system according to claim 1, wherein the step of calculating the draft depth of the water scoop of the rocket sled at different speed sections is as follows: According to the momentum theorem of continuous media, the geometric sum of the change in momentum of the liquid flowing in and out of the two corresponding sections of the pipe per second and the vector sum of the mass force and surface force acting on it is equal to zero, that is: Define the coordinate axes X, Y and Z: the rocket sled's forward direction is the X axis, the direction perpendicular to the X direction on the orbital plane is the Y axis, and the direction perpendicular to the orbital plane is the Z axis; In the formula, m is the mass of liquid flowing into the pipe per second; is the resultant force of the pipe wall reaction, where F sx 、F sy 、F sz are the reaction forces on the pipe wall in the X, Y and Z directions respectively; is the resultant force of the mass force of the liquid between the outlet and inlet sections of the pipe, where F mx 、F my 、F mz They are the mass forces of the liquid between the outlet and inlet sections of the pipe in the X, Y, and Z directions respectively; When moving at high speed, For the convenience of calculation, take v is the pulley speed or the flow rate of water entering the bucket, in m / s; is the unit vector formed by the cosine function of the direction angle of liquid inflow, where α 入 , β 入 , γ 入 It is the angle formed in the X, Y, and Z directions when the liquid flows in; is the unit vector formed by the cosine function of the direction angle of liquid outflow, where α 出 , β 出 , γ 出 It is the angle formed in the X, Y, and Z directions when the liquid flows out; According to the momentum theorem: Assume that water is a non-viscous, incompressible liquid, and there is no friction between the water flow and the inner wall of the bucket. The water inlet direction of the bucket is consistent with the sliding direction of the pulley, that is, α 入 =0, and α 出 =θ, then the braking force is: F=ρAv 2 (1-R v cosθ); in, v=v 入 ; R v R is the ratio of the outlet flow rate to the inlet flow rate of the water bucket. v =v 出 / v 入 ; ρ is the density of water, unit is kg / m 3 ; A is the cross-sectional area of ​​the water flow at the pipe inlet, unit: m 2 ; Because the water flows fast and in a short time in the bucket, it is assumed that the water flow speed at the inlet and outlet is the same, that is, R v =1; the volume of the water tank is a known quantity, and the draft of the water scoop is obtained through the cross-sectional area A of the water flow at the water inlet of the pipe;.

3. A water brake device designed by using the method for calculating the water level injection depth of a heavy-load rocket sled system section according to claim 1, characterized in that: The tank comprises a water tank and a plurality of partitions; the plurality of partitions divide the water tank into N sections; i is the i-th water tank, 1≤i≤N; the length of each water tank is 60m; a heavy-load rocket sled system section water level filling depth calculation method is used to calculate the filling depth of the first water tank and the filling depth of the remaining water tanks respectively.

4. The water brake device according to claim 3, wherein the step of calculating the water filling depth of the first water tank is: F1=ρA1v1 2 (1-R v cosθ); where F1 is the braking force at the entrance of the first water tank; v1 is the speed of the water bucket at the entrance of the first water tank; Where F1 is one-fourth of the maximum allowable braking force of the water bucket; the maximum allowable braking force of the water bucket is the theoretically designed maximum braking force of the water bucket, which is a known quantity; v1 is obtained through measurement and is a known quantity; Through F1 = ρA1v1 2 (1-R v cosθ) to obtain A1, where A1 is the cross-sectional area of ​​the first section of the water tank; Thus, the draft depth of the water scoop in the first section of the water tank is obtained; and then the water filling depth of the first section of the water tank is obtained.

5. The water brake device according to claim 3, wherein the step of calculating the water filling depth of the j-th water tank is: Calculate the velocity of the water scoop at the outlet of the j-1th section of the flume: The aerodynamic simulation calculates the aerodynamic resistance and friction resistance of the water bucket in the j-1th section, 2≤j≤N; the mass of the rocket sled system is a known quantity; the mass of the rocket sled system includes the mass of the rocket sled, the water bucket and the test object, and the acceleration at the entrance of the j-1th section of the water tank is calculated according to Newton's second law; the time t starts from 0, the interval is 0.001s, and the movement speed of the water bucket at each time is iteratively calculated, and then the corresponding displacement at each time is obtained. When the displacement is equal to 60m, the corresponding speed is the movement speed of the water bucket at the outlet of the j-1th section of the water tank, and also the movement speed of the water bucket at the entrance of the jth section of the water tank; Calculate the braking force on the water bucket at the entrance of the j-th water tank: The braking force borne by the water scoop at the entrance of the j-th section of the water trough shall not be greater than 1.5 times the braking force borne by the water scoop at the entrance of the j-1-th section of the water trough. The braking force borne by the water scoop at the entrance of the j-th section of the water trough is calculated; If the braking force borne at the entrance of the j-th water flume is greater than or equal to the maximum allowable braking force of the water scoop, then the braking force borne by the water scoop at the entrance of the j-th water flume is the maximum allowable braking force of the water scoop; If the braking force borne at the entrance of the j-th section of the water trough is less than the maximum allowable braking force of the water scoop, the braking force borne by the water scoop at the entrance of the j-th section of the water trough shall be 1.5 times the braking force borne at the entrance of the j-1-th section of the water trough.

6. The water brake device according to claim 3 is characterized in that the method for correcting the liquid level depth of the first section of the water tank at the inlet of the rocket sled water scoop is: performing gas-liquid two-phase flow calculation on the rocket sled to obtain the height of the influence of the air pressure on the liquid level, adding the height of the influence of the air pressure on the liquid level to the water injection depth, and obtaining the correction of the liquid level depth of the water tank at the inlet of the water brake.

7. The water brake device according to claim 3 is characterized in that the maximum allowable braking force is obtained by obtaining the theoretical design of the water bucket through static analysis, and the maximum allowable braking force of the water bucket is calculated using a safety factor based on strength theory, and the safety factor is 1.7, that is, the maximum allowable braking force is the theoretical design maximum braking force of the water bucket divided by the safety factor.

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