A parachute turning inducing method applied to a life-saving parachute in a rope sail state

Abstract

The present application belongs to the field of air drop technology, and relates to a rescue parachute turning induction method applied to a rope-sail state, comprising the following steps: 1, obtaining the rope-sail shape under test conditions; 2, establishing a simulation calculation model; 3, determining the boundary conditions of the calculation model; 4, determining the movement frequency and amplitude of the parachute canopy bottom edge; 5, determining the frequency and amplitude of the periodic vibration of the parachute canopy bottom edge, and simulating the movement of the parachute canopy bottom edge under the rope-sail state; 6, calculating the distance between the windward side parachute canopy bottom edge and the leeward side parachute canopy bottom edge under the rope-sail state; 7, determining whether turning occurs; 8, simulating a plurality of frequency and amplitude combinations, evaluating the possibility of turning of the rescue parachute, and counting the frequency and amplitude combination most likely to turn. The present application solves the problem of rescue parachute turning calculation simulation, and provides a turning induction method for the simulation research on the turning mechanism of the rescue parachute and the suppression of the rescue parachute turning.

Description

Technical Field

[0001] This invention belongs to the field of airdrop technology, specifically relating to a parachute flipping induction method applied to the rope sail state, which is used to solve the problem that the simulated parachute flipping cannot be generated in the natural state of the parachute. Background Technology

[0002] When a pilot ejects from their seat, the parachute launches and forms a sail-like rope sail. However, in this state, parachute rollover can occur, where one side of the canopy passes through the opposite side, inflating into a saddle-shaped shape and preventing the parachute from opening properly. This failure to open can cause the pilot to land at excessive speed, potentially resulting in injury or death. To suppress rollover, research has experimentally verified the effectiveness of some rollover suppression structures, but related simulation calculations are still underdeveloped. Currently, there are no dedicated simulation methods for rollover, either domestically or internationally. This is partly because rollover is a low-probability event, influenced by various factors, and its timing is unpredictable. Simulation calculations rely on relatively fixed conditions and cannot estimate rollover induced by sudden triggers, thus failing to simulate rollover under natural conditions. Furthermore, research on rollover has not detailed the flow mechanisms involved, therefore, there are currently no effective simulation methods to guide the simulation of parachute evolution and rollover.

[0003] In order to effectively simulate the parachute flipping process through simulation, it is necessary to apply effective excitation to the parachute based on its flipping state to induce the parachute to flip, and obtain an induction scheme that can induce the flipping, so as to provide technical support for the study of the flipping mechanism and the study of flipping suppression. Summary of the Invention

[0004] Purpose of the invention: To provide a method for inducing parachute flipping in the form of a rope sail, which can guide the simulation of parachute flipping, trigger the parachute to flip, and thus promote the research on the parachute flipping mechanism and flipping suppression.

[0005] Technical Solution: To achieve the above objectives, this invention provides a method for inducing parachute folding in a rope sail configuration, comprising the following steps: Step 1: Obtain the shape of the rope sail under the test conditions based on the video or pictures of the ejection test in which the parachute flipped; Step 2: Establish a simulation calculation model based on the flow field and shape conditions of the life-saving parachute in the ejection test; Step 3: Under the same flow conditions as the catapult test, determine the boundary conditions of the computational model to ensure that the sail shape calculated in the simulation is consistent with the sail shape under the test conditions; Step 4: Analyze the ejection test video or images to determine the frequency and amplitude of the movement of the bottom edge of the parachute canopy; Step 5: Establish the criteria for determining whether a life-saving parachute will overturn; Step 6: Establish the frequency and amplitude of the periodic vibration of the bottom edge of the parachute canopy, and simulate the motion of the bottom edge of the parachute canopy in the rope sail state.

[0006] Step 7: Based on the simulation results from Step 6, calculate the distance between the bottom edge of the canopy on the windward side and the bottom edge of the canopy on the leeward side in the rope sail state.

[0007] Step 8: Based on the criteria for determining whether a life-saving parachute has flipped, compare the results with the calculation results in Step 6 to determine whether a flipping has occurred. Step 9: Change the frequency and amplitude of the periodic vibration of the bottom edge of the parachute canopy, simulate multiple combinations of frequency and amplitude, assess the possibility of the life-saving parachute flipping over, and statistically analyze the most likely combination of frequency and amplitude to flip over.

[0008] Furthermore, the shape of the life-saving parachute rope sail described in step 1 includes the curvature of the rope sail, the relative position of the top of the parachute and the bottom of the parachute rope, and the angle between the rope sail and the incoming current.

[0009] Furthermore, the flow field and shape conditions of the ejection test parachute mentioned in step 2 refer to the flow field velocity V, the shape and size of the parachute canopy, the size of the parachute ropes, the material properties of the canopy, and the material properties of the parachute ropes in the ejection test.

[0010] Furthermore, the boundary conditions of the calculation model described in step 3 are determined as follows: Based on the video or photograph of the parachute launch test, and combined with the flow conditions of the parachute launch test, the fixed points of the parachute apex and the bottom of the parachute ropes are determined to obtain the shape of the rope sail under simulated flow conditions. The flow direction of the incoming flow is adjusted, and when the shape of the rope sail is consistent with that of the rope sail in the parachute launch test, the relevant parameters of the incoming flow conditions are fixed.

[0011] Furthermore, the frequency and amplitude of the periodic vibration of the bottom edge of the life-saving parachute canopy mentioned in step 4 refer to the frequency of the periodic motion of the bottom edge of the canopy. f and amplitude A m .

[0012] Furthermore, the judgment criterion mentioned in step 5 is based on the movement trend of the bottom edge of the parachute canopy in the rope sail state. When the distance between the bottom edge of the parachute canopy on the windward side and the bottom edge of the parachute canopy on the leeward side is less than or equal to R, the life-saving parachute will flip. R is a threshold for evaluating the distance between the windward and leeward parachute canopies, which is specifically determined by the results of the flip mechanism analysis.

[0013] Furthermore, the frequency and amplitude of the periodic vibration of the canopy bottom edge established in step 6 are based on the state of the parachute ropes and sails, where a periodic external force F is applied to the bottom edge of one canopy on the windward side to achieve periodic movement of the canopy bottom edge. F by F =F m (2π f ) changes. Among them: F m It is the amplitude of a periodic force. f The frequency of the periodic force. Periodic force. F Under the action, the amplitude of the motion of the bottom edge of the umbrella canopy is A. m The frequency of motion is consistent with the frequency of the applied periodic force.

[0014] Furthermore, the distance between the bottom edge of the windward umbrella canopy and the bottom edge of the leeward umbrella canopy mentioned in step 7 refers to the minimum distance L between the bottom edges of one umbrella canopy on the windward side and the bottom edges of one umbrella canopy on the leeward side in the flow field, calculated based on the simulation calculation results in step 6.

[0015] Furthermore, in step 8, the determination of whether the parachute flips is caused is based on the minimum distance L between the bottom edge of the windward side of the parachute canopy and the bottom edge of the leeward side of the parachute canopy calculated in step 7. If L ≤ R, then it is considered that the life-saving parachute may flip under the vibration state of the bottom edge of the parachute canopy.

[0016] Furthermore, the frequency and amplitude combination of umbrella flipping described in step 9 is repeated in step 6, applying the same parameters to all the bottom edge vibration parameters of the umbrella canopy. A m and f A combined simulation calculation is performed to determine the distance L between the bottom edges of the canopy on the windward and leeward sides. Based on the criterion R, it is determined whether the umbrella has flipped over. Vibration parameters for determining umbrella flipping are also considered. A m and f A database of vibration parameters for umbrella flipping was created. A m1 & f 1, A m2 & f 2, A m3 & f 3… A mN & f N ] , N It is an integer.

[0017] Beneficial effects of the invention: This invention addresses the problem of parachute flipping in simulations by proposing a method to apply vibration to the bottom edge of the parachute canopy, inducing the parachute to flip. This method solves the difficulty of calculating and simulating parachute flipping, providing a method for inducing flipping and verifying the correctness of the conclusions of the mechanism study and the effectiveness of the flipping suppression structure. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 : Schematic diagram of the installation and positioning of the aircraft water drop chamber door on the iron bird stand; Detailed Implementation To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0021] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0023] Example: A method for inducing parachute tumble in a rope sail configuration includes the following steps: Step 1: Obtain the shape of the rope sail under the test conditions through video or pictures of the catapult test. See [link to rope sail shape]. Figure 1 ; Step 2: Establish a simulation calculation model based on the catapult test conditions; Step 3: Determine the boundary conditions of the computational model to ensure that the shape of the sail formed by the simulation model is consistent with the shape of the sail under the test conditions under the same flow conditions as the catapult test. Step 4: Analyze the ejection test video or images to determine the motion pattern of the bottom edge of the parachute canopy; Step 5: Determine the assessment criteria for whether the life-saving parachute will flip over; Step 6: Adjust the relevant parameters of the motion mode, perform simulation, and evaluate the possibility of the life-saving parachute flipping under this state according to the evaluation criteria. Step 7: Repeat step 6 to simulate multiple combinations of motion parameters and assess the possibility of the life-saving parachute flipping. Step 8: Based on the simulation results, calculate the most likely combination of parameters for the umbrella to flip.

[0024] Specifically, step 1 includes: Based on the ejection test video or images of the parachute flipping, extract the shape of the parachute's rope sail, including the sail's curvature, the relative positions of the parachute top and the bottom of the ropes, and the angle between the sail and the oncoming current. See [link to sail shape description]. Figure 1 .

[0025] Specifically, step 2 includes: Based on the life-saving parachute used in the ejection test, a simulation calculation model was constructed according to the shape and size of the parachute canopy, the size of the parachute ropes, the material properties of the canopy, and the material properties of the parachute ropes.

[0026] Specifically, step 3 includes: Determine the anchor points at the apex of the life-saving parachute and the bottom of the parachute lines. Simulate the shape of the rope sail under flow conditions through a parachute launch test. Adjust the flow direction of the incoming flow. When the shape of the rope sail matches that of the rope sail in the parachute launch test, fix the relevant parameters of the incoming flow conditions.

[0027] Specifically, step 4 includes: Observe the video or pictures of the ejection test to determine the frequency of the periodic movement of the bottom edge of the parachute canopy. f .

[0028] Specifically, step 5 includes: Based on the movement trend of the bottom edge of the parachute canopy in the rope sail state, when the distance between the bottom edge of the parachute canopy on the moving side and the bottom edge of the opposite parachute canopy is less than R, the life-saving parachute will flip over.

[0029] Specifically, step 6 includes: Regarding the state of the parachute ropes and sails, a periodic external force F is applied to the bottom edge of the canopy facing the wind, causing periodic movement of the bottom edge of the canopy. F by F = Am (2π f ) changes. Among them: A m It is the amplitude of the periodic external force. f The frequency of the applied external force. This is achieved by applying parameters... A m and f The periodic external force is used to simulate the life-saving parachute. Based on the simulation results, the distance between the bottom edge of the parachute canopy on the moving side and the bottom edge of the opposite parachute canopy is calculated. The evaluation standard R is used to determine whether the parachute flips.

[0030] Specifically, step 7 includes: Based on the simulation results from step 6, adjust the parameters. A m and f , forming an amplitude array [ A m1 , A m2 , A m3 A m A mn The periodic movement frequency of the bottom edge of the parachute canopy during the parachute launch test. f Based on this, at a certain interval Δ f Increase and decrease the frequency to form a frequency array. f 1, f 2, f 3 f f n ], where n is an integer. This is achieved through the amplitude array [ A m1 , A m2 , A m3 A m A mn ] and frequency array [ f 1, f 2, f 3 f f n ],amplitude A m and frequency fThe parameters are combined to form a parameter matrix for simulation calculation. For the parameter combination of the matrix, step 6 is repeated to perform simulation calculation. Based on the simulation calculation results, the distance between the bottom edge of the canopy on the moving side and the bottom edge of the opposite canopy is calculated. The evaluation criterion R is used to determine whether the umbrella flips.

[0031] Specifically, step 8 includes: Based on the calculation results of step 7, select the parameter combinations that may cause umbrella flipping to form a database. A m1 & f 1, A m2 & f 2, A m3 & f 3 A mn & f N ] , N It is an integer.

[0032] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A method for inducing parachute folding in a rope sail configuration, comprising the following steps: Step 1: Obtain the shape of the rope sail under the test conditions based on the video or pictures of the ejection test in which the parachute flipped; Step 2: Establish a simulation calculation model based on the flow field and shape conditions of the life-saving parachute in the ejection test; Step 3: Under the same flow conditions as the catapult test, determine the boundary conditions of the computational model to ensure that the sail shape calculated in the simulation is consistent with the sail shape under the test conditions; Step 4: Analyze the ejection test video or images to determine the movement frequency and amplitude of the bottom edge of the parachute canopy; Step 5: Establish the criteria for determining whether a life-saving parachute will overturn; Step 6: Establish the frequency and amplitude of the periodic vibration of the bottom edge of the parachute canopy, and simulate the motion of the bottom edge of the parachute canopy in the rope sail state; Step 7: Based on the simulation results of Step 6, calculate the distance between the bottom edge of the canopy on the windward side and the bottom edge of the canopy on the leeward side in the rope sail state. Step 8: Based on the criteria for determining whether a life-saving parachute has flipped, compare the results with the calculation results in Step 6 to determine whether a flipping has occurred. Step 9: Change the frequency and amplitude of the periodic vibration of the bottom edge of the parachute canopy, simulate multiple combinations of frequency and amplitude, assess the possibility of the life-saving parachute flipping, and count the most likely combination of frequency and amplitude to flip.

2. The method for inducing parachute folding in a rope sail configuration according to claim 1, characterized in that... The shape of the life-saving parachute rope sail described in step 1 includes the curvature of the rope sail, the relative position of the top of the parachute and the bottom of the rope, and the angle between the rope sail and the incoming current.

3. The method for inducing parachute folding in a rope sail configuration according to claim 1, characterized in that... The flow field and shape conditions of the life-saving parachute mentioned in step 2 refer to the flow field velocity V, the shape and size of the parachute canopy, the size of the parachute ropes, the material properties of the canopy, and the material properties of the parachute ropes in the ejection test.

4. A method for inducing parachute folding in a rope sail configuration according to claim 1, characterized in that... The boundary conditions of the calculation model described in step 3 are determined as follows: Based on the video or photograph of the parachute launch test, and combined with the flow conditions of the parachute launch test, the fixed points of the parachute apex and the bottom of the parachute ropes are determined to obtain the shape of the rope sail under the simulated flow state. The flow direction of the incoming flow is adjusted, and when the shape of the rope sail is consistent with that of the rope sail in the parachute launch test, the relevant parameters of the incoming flow conditions are fixed.

5. A method for inducing parachute folding in a rope sail configuration according to claim 1, characterized in that... The frequency and amplitude of the periodic vibration of the bottom edge of the life-saving parachute canopy mentioned in step 4 refer to the frequency of the periodic motion of the bottom edge of the canopy. f and amplitude A m .

6. A method for inducing parachute folding in a rope sail configuration according to claim 1, characterized in that... The judgment criteria mentioned in step 5 are based on the movement trend of the bottom edge of the parachute canopy in the state of the rope sail. When the distance between the bottom edge of the parachute canopy on the windward side and the bottom edge of the parachute canopy on the leeward side is less than or equal to R, the life-saving parachute will flip over. R is a threshold for evaluating the distance between the parachute canopy on the windward side and the parachute canopy on the leeward side, which is specifically determined by the analysis results of the flip-over mechanism.

7. A method for inducing parachute folding in a rope sail configuration according to claim 1, characterized in that... The frequency and amplitude of the periodic vibration of the canopy bottom edge established in step 6 are based on the state of the parachute ropes and sails, where a periodic external force F is applied to the bottom edge of one canopy on the windward side to achieve periodic movement of the canopy bottom edge. F by F = F m (2π f ) changes; among which: F m It is the amplitude of a periodic force. f The frequency of the periodic force. Periodic force. F Under the action, the amplitude of the motion of the bottom edge of the umbrella canopy is A. m The frequency of motion is consistent with the frequency of the applied periodic force.

8. A method for inducing parachute folding in a rope sail configuration according to claim 1, characterized in that... The distance between the bottom edge of the canopy on the windward side and the bottom edge of the canopy on the leeward side mentioned in step 7 refers to the minimum distance L between the bottom edges of one canopy on the windward side and the bottom edges of one canopy on the leeward side in the flow field, calculated based on the simulation results in step 6.

9. A method for inducing parachute folding in a rope sail configuration according to claim 1, characterized in that... In step 8, to determine whether the parachute has flipped, the minimum distance L between the bottom edge of the windward side of the parachute canopy and the bottom edge of the leeward side of the parachute canopy, calculated in step 7, is compared with the determination criterion R in step 5. If L ≤ R, then it is considered that the life-saving parachute may flip under the vibration state of the bottom edge of the parachute canopy.

10. A method for inducing parachute folding in a rope sail configuration according to claim 1, characterized in that... The frequency and amplitude combination of umbrella flipping described in step 9 is repeated in step 6, and the vibration parameters of the bottom edge of all umbrella canopies are adjusted accordingly. A m and f A combined simulation calculation is performed to calculate the distance L between the bottom edges of the canopy on the windward and leeward sides. Based on the criterion R, it is determined whether the umbrella has flipped over. Vibration parameters for determining umbrella flipping are also considered. A m and f A database of vibration parameters for umbrella flipping was created. A m1 & f 1, A m2 & f 2, A m3 & f 3… A mN & f N ] , N It is an integer.

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