Method for obtaining the dangerous section of a parachute inflation deployment

Abstract

The application discloses a method for obtaining a dangerous section of a parachute during inflation and deployment, which comprises the following steps: deploying a canopy statically, measuring the deployment area of the canopy, and calculating the deployment diameter of the canopy; arranging strain gauges on each of the meridional reinforcing bands of the canopy along the meridional direction; connecting the parachute rope end of the parachute to the rear end of a stabilizer; when the wind speed of a wind tunnel reaches a predetermined value, the stabilizer extends out of a fairing; the parachute is inflated and deployed in the flow field of the wind tunnel; the strain of each strain gauge during the inflation and deployment of the parachute is collected; the maximum strain value on each meridional reinforcing band is selected, and the distance from the strain gauge at the maximum strain value to the top hole of the canopy is calculated according to the distribution position of the strain gauge; the symmetrical meridional reinforcing bands are divided into groups two by two; the sum of the single-side dangerous distances of the two meridional reinforcing bands in each group is calculated, and the maximum value is selected as the dangerous section diameter of the canopy, so as to obtain the dangerous section of the canopy.

Description

Technical Field

[0001] This invention belongs to the field of aviation lifesaving, specifically relating to a method for obtaining the dangerous section of a parachute during inflation and deployment. Background Technology

[0002] Parachutes are aerial stabilization and deceleration devices made of flexible fabric. They have a small packaging volume and efficient stabilization and deceleration performance, and are widely used in pilot rescue, paratrooper airdrops, weapons and supplies delivery, seat bomb stabilization and deceleration, aircraft or other aircraft landings, and parachuting.

[0003] The critical section of a parachute refers to the surface area of ​​the canopy when the parachute is under maximum dynamic load during deployment. Obtaining the critical section allows for the calculation of the maximum stress on the canopy and verification of the canopy strength safety factor. For canopies with variable area characteristics, a variable area device can be installed at the critical section. When the parachute generates maximum dynamic load during deployment, this device is triggered, altering the canopy's deployment area and increasing the parachute's air permeability. This is crucial for improving the parachute's survival envelope.

[0004] Currently, the critical section of a parachute is generally obtained through empirical formulas, simulation calculations, and experimental methods. Among these methods, empirical formulas typically assume the full portion of the canopy to be hemispherical, resulting in significant estimation errors that require further verification. Simulation calculations struggle to perform high-precision microstructural modeling and analysis of the parachute, leading to unreliable calculation results. Experimental methods employ a trial-and-error approach, setting multiple tear zones near the critical section estimated by empirical formulas and observing their opening to determine the critical section. This experimental process is complex and prone to significant errors. Summary of the Invention

[0005] The purpose of this invention is to provide a method for obtaining the dangerous section of a parachute during inflation and deployment. This method can conveniently and accurately obtain the dangerous section of a parachute during inflation and deployment, with a small workload and high accuracy and efficiency.

[0006] The technical solution adopted in this invention is:

[0007] A method for obtaining the hazardous section of a parachute during inflation and deployment involves statically deploying the parachute canopy and measuring the deployed area. And calculate the unfolded diameter of the parasol. Wind tunnel testing was conducted: Strain gauges were first installed along the warp direction on each warp reinforcement strip of the parachute canopy. Each strain gauge was electrically connected to the data acquisition module and the data processing module. Then, the parachute lines were connected to the rear end of the stabilizer bar, which was retractably installed at the rear of the fairing. Initially, the stabilizer bar and parachute were retracted inside the fairing. When the wind tunnel wind speed reached a predetermined value, the stabilizer bar extended out of the fairing, and the parachute inflated and deployed in the wind tunnel flow field. The strain at each strain gauge during the parachute inflation and deployment process was collected. ,in i The serial number of the longitudinal reinforcement belt, j The strain gauges are numbered along the warp direction; the collected data is processed, and the maximum strain value on each warp reinforcement strip is selected. and according to The distance from the strain gauge at the point of maximum strain to the top hole of the canopy is calculated from the distribution location of the strain gauges, i.e., the single-sided danger distance. Divide the symmetrical meridional reinforcement strips into pairs and calculate the unilateral danger distance of the two meridional reinforcement strips in each pair. The sum of these values, and the largest value among them is the diameter of the dangerous section of the canopy. Then, the dangerous section of the umbrella canopy can be calculated. .

[0008] Preferably, the fairing is mounted on the base via a bracket, the parachute rope end is connected to the rear end of the stabilizer bar via a rotor, and the strain gauge data line passes through the stabilizer bar, fairing, bracket, and base in sequence.

[0009] Preferably, the extension of the stabilizer bar is driven by a high-pressure air source, which is connected in sequence to a pressure reducing valve, a solenoid valve, and a fairing via an air pipe.

[0010] Preferably, the high-pressure gas source is a high-pressure nitrogen cylinder.

[0011] Preferably, the unfolded area of ​​the umbrella canopy Including the area of ​​the openings in the umbrella top and canopy structure, and the canopy's unfolded diameter. The calculation formula is: .

[0012] Preferably, the strain gauge is a uniaxial strain gauge, and the length direction of its sensing grid is the meridional direction.

[0013] Preferably, the strain gauge is fixed by adhesive bonding.

[0014] Preferably, the dangerous section of the umbrella canopy The calculation formula is: .

[0015] The beneficial effects of this invention are:

[0016] This method can conveniently and accurately obtain the dangerous section of the parachute during inflation and deployment, with minimal workload and high accuracy and efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a wind tunnel test conducted in an embodiment of the present invention.

[0018] Figure 2 The dangerous section diameter of the umbrella canopy in this embodiment of the invention. A schematic diagram.

[0019] In the diagram: 1-rotor; 2-stabilizing bar; 3-fairing; 4-bracket; 5-data cable; 6-solenoid valve; 7-pressure reducing valve; 8-high-pressure air source; 9-base; 10-air pipe. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] This embodiment discloses a method for obtaining the hazardous section of a parachute during inflation and deployment, which involves statically deploying the parachute canopy and measuring the deployed area of ​​the canopy. And calculate the unfolded diameter of the parasol. Wind tunnel testing was conducted: strain gauges were first installed along the warp direction on each warp reinforcement strip of the canopy. Each strain gauge was electrically connected to the acquisition module and the data processing module, such as... Figure 1 As shown, the parachute lines are then connected to the rear end of the stabilizer bar 2. The stabilizer bar 2 is telescopically mounted at the rear of the fairing 3. Initially, the stabilizer bar 2 and the parachute are housed inside the fairing 3. When the wind tunnel wind speed reaches a predetermined value, the stabilizer bar 2 extends out of the fairing 3, and the parachute inflates and deploys in the wind tunnel flow field. The strain of each strain gauge during the parachute inflation and deployment process is collected. ,in i The serial number of the longitudinal reinforcement belt, j The strain gauges are numbered along the warp direction; the collected data is processed, and the maximum strain value on each warp reinforcement strip is selected. and according to The distance from the strain gauge at the point of maximum strain to the top hole of the canopy is calculated from the distribution location of the strain gauges, i.e., the single-sided danger distance. Divide the symmetrical meridional reinforcement strips into pairs and calculate the unilateral danger distance of the two meridional reinforcement strips in each pair. The sum, such as Figure 2 As shown, the maximum value among them is selected as the diameter of the dangerous section of the umbrella canopy. Then, the dangerous section of the umbrella canopy can be calculated. .

[0022] like Figure 1 As shown, in this embodiment, preferably, the fairing 3 is mounted on the base 9 via the bracket 4, the parachute rope end is connected to the rear end of the stabilizer 2 via the rotor 1, and the strain gauge data line 5 passes through the stabilizer 2, fairing 3, bracket 4 and base 9 in sequence.

[0023] like Figure 1 As shown, in this embodiment, preferably, the extension of the stabilizer bar 2 is driven by a high-pressure gas source 8, which is connected in sequence to a pressure reducing valve 7, a solenoid valve 8, and a rectifier 3 via a gas pipe 10. Preferably, the high-pressure gas source 8 is a high-pressure nitrogen cylinder.

[0024] In this embodiment, preferably, the unfolded area of ​​the umbrella canopy Including the area of ​​the openings in the umbrella top and canopy structure, and the canopy's unfolded diameter. The calculation formula is: .

[0025] In this embodiment, preferably, the strain gauge is a uniaxial strain gauge, with its sensing grid length direction being the meridional direction. Preferably, the strain gauge is fixed by adhesive bonding.

[0026] like Figure 1 As shown, in this embodiment, preferably, the dangerous section of the umbrella canopy... The calculation formula is: .

[0027] This method can conveniently and accurately obtain the dangerous section of the parachute during inflation and deployment, with minimal workload and high accuracy and efficiency.

[0028] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A method for obtaining the hazardous section of a parachute during inflation and deployment, characterized in that: The parachute canopy was statically unfolded, and the unfolded area was measured. And calculate the unfolded diameter of the parasol. Wind tunnel testing was conducted: Strain gauges were first installed along the warp direction on each warp reinforcement strip of the parachute canopy. Each strain gauge was electrically connected to the data acquisition module and the data processing module. Then, the parachute lines were connected to the rear end of the stabilizer bar, which was retractably installed at the rear of the fairing. Initially, the stabilizer bar and parachute were retracted inside the fairing. When the wind tunnel wind speed reached a predetermined value, the stabilizer bar extended out of the fairing, and the parachute inflated and deployed in the wind tunnel flow field. The strain at each strain gauge during the parachute inflation and deployment process was collected. ,in i For the serial number of the meridional reinforcement belt, j The strain gauges are numbered along the warp direction; the collected data is processed, and the maximum strain value on each warp reinforcement strip is selected. and according to The distance from the strain gauge at the point of maximum strain to the top hole of the canopy is calculated from the distribution location of the strain gauges, i.e., the single-sided danger distance. Divide the symmetrical meridional reinforcement strips into pairs and calculate the unilateral danger distance of the two meridional reinforcement strips in each pair. The sum of these values, and the largest value among them is the diameter of the dangerous section of the canopy. Then, the dangerous section of the umbrella canopy can be calculated. .

2. The method for obtaining the dangerous section of a parachute during inflation and deployment as described in claim 1, characterized in that: The fairing is mounted on the base via a bracket, and the parachute ropes are connected to the rear end of the stabilizer bar via a rotor. The strain gauge data lines pass through the stabilizer bar, fairing, bracket, and base in sequence.

3. The method for obtaining the dangerous section of a parachute during inflation and deployment as described in claim 1, characterized in that: The extension of the stabilizer bar is driven by a high-pressure air source, which is connected to a pressure reducing valve, a solenoid valve, and a fairing in sequence via an air pipe.

4. The method for obtaining the dangerous section of a parachute during inflation and deployment as described in claim 3, characterized in that: The high-pressure gas source uses a high-pressure nitrogen cylinder.

5. The method for obtaining the dangerous section of a parachute during inflation and deployment as described in claim 1, characterized in that: Umbrella canopy unfolding area Including the area of ​​the openings in the umbrella top and canopy structure, and the canopy's unfolded diameter. The calculation formula is: .

6. The method for obtaining the dangerous section of a parachute during inflation and deployment as described in claim 1, characterized in that: The strain gauge is a uniaxial strain gauge, and its sensing grid length direction is the meridional direction.

7. The method for obtaining the dangerous section of a parachute during inflation and deployment as described in claim 1, characterized in that: The strain gauges are fixed by adhesive bonding.

8. The method for obtaining the dangerous section of a parachute during inflation and deployment as described in claim 1, characterized in that: Dangerous sections of umbrella canopy The calculation formula is: .

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