RU2714529C1 - Device for determining aerodynamic characteristics of a gliding parachute in a wind tunnel - Google Patents

Abstract

FIELD: aviation.

SUBSTANCE: invention relates to aircraft engineering and is intended for measurement of aerodynamic loads acting on gliding parachute (GP) in air flow of wind tunnel (WT) at various angles of attack and sliding. Device comprises a base, a platform mounted thereon, inclined support beams, sling attachment assemblies, top and bottom strain gauges, an angle of attack hinge mechanism, a power pole, wherein the platform is fixed on the power post, between the platform and the sling attachment assemblies, independent measuring units are installed, at least containing lower strain gauges connected to the sling attachment assemblies, and roll and pitch sensors. Platform is fixed on power rack with possibility of movement along guides by means of extension-retract mechanism. Hinged mechanism of angle of attack comprises mechanism for changing distance between inclined support beams. Unlike prototype, slips GP with two throws do not touch elements of device and results of load measurements will not be distorted; lower strain gages with fewer components are used, there are no restrictions for tests of GP with large wing span.

EFFECT: technical result consists in improvement of completeness and information content of obtained data during preparation and during tests, expansion of device capabilities, ensuring performance of tests of a gliding parachute (GP) with one, two and more throws, providing GP tests with increased span, use of scales with fewer components.

11 cl, 3 dwg

Description

The invention relates to aeronautical engineering and is intended for measuring aerodynamic loads acting on a gliding parachute (PP) in the air flow of a wind tunnel (ADT) at various angles of attack and slip.

It is known "Device for measuring the lateral aerodynamic characteristics of a gliding parachute in a wind tunnel" (RF patent No. 2072947). The device selected as an analogue contains two inclined support beams, to the upper part of which longitudinal beams are attached, at the ends of which are placed upper tensi which are attached to the traverse. With the help of short sling ties, the lower edge of the end ribs of the dome of the planning parachute is attached to the traverses, the slings of which are fixed on the lower part of the inclined support beams.

The device works as follows: PP slings are attached to the bottom of the inclined support beams; with the help of auxiliary holding braces, the parachute is inserted into the stream and after it reaches the balancing angle of attack, the auxiliary holding braces are loosened and the inclined support beams are moved so that the traverses are as close as possible to the lower edge of the end ribs of the parachute. Fastening the canopy of the parachute to the traverses with the help of short slings - ties allows you to fix the parachute in the balancing position and, moving the inclined support beams, change the angles of attack and sliding of the canopy of the parachute; the forces and moments measured by the upper tensile weights when the angles of attack and slip deviate from the balancing values are summed up taking into account their orientation.

The described device has the following disadvantages. The device does not contain adjustment mechanisms that allow testing PP of various sizes. There are no weight elements in the attachment points of the slings to the bottom of the inclined support beams, which reduces the information content and the quality of the final results of the experiment.

It is also known a device (RF patent No. 2061629) for measuring the aerodynamic characteristics of a gliding parachute containing a support beam and upper tensile weights, so that on the upper part of the supporting beam upper tensile weights with a frame are mounted, and on the lower part lower tensi weights with a hinge device, to the outer part of which the power slings of the parachute are attached, and the internal part is fastened to the support beam through the lower tensile weights. The disadvantage of this device is that the lower tensile weights show only the total load from the tension forces of the slings in the left and right sides, which does not allow to determine these forces separately during the design and operation of the software.

Also known is a device for measuring the aerodynamic characteristics of a parachute in a wind tunnel (RF patent No. 2655713), selected as a prototype. A device that contains a base, two inclined support beams (with mechanisms for their collapse), a hinged mechanism of the angle of attack, a power rack, upper tensile weights for measuring the loads occurring on the dome, lower tensile weights for measuring the loads occurring in the buckets of the slings, a platform with attachment points main slings PP. In this case, the thimble is understood as a constructive connection in the form of a loop of slings of a parachute intended for connection to a descent object. PP may contain one or more thimbles. The attachment points of the parachute slings are nodes, for example, carabiners, to which the lower tenzweights are connected, or brackets of the fork type, which are reciprocal for the parachute thimble.

The prototype has disadvantages:

- the limited completeness and informativeness of the data obtained during the tests, since the only lower tensi weights are used, and, as a rule, 6-component tensi weights, since when processing the measurement results it is necessary to know the vector of the line tension forces. The use of single lower tensile weights does not provide information about the loads in the attachment points of the slings in the left and right side (thimbles) of the parachute. The difference in the loads in the left and right jacks at zero glide angle can lead to incorrect determination of the aerodynamic characteristics of the parachute and should be eliminated by adjusting the sling system of the parachute before the main tests; It is important to know the loads in the left and right sides of the parachute with asymmetric airflow - in the presence of sliding angles, as well as with asymmetric tightening of the PP control lines.

- the design and functional potential of the device is limited, since it is not possible to test the most common PPs with two jacks (and not just the PP version with 4 jacks): in this case, the main slings or control lines will touch the structural elements of the device (hinged mechanism of the angle of attack and other elements), which is unacceptable, since the results of measuring the loads are distorted due to an uncontrolled decrease in the measured forces;

- there is no constructive ability to test the PP with a large wingspan due to the limited stroke of the camber mechanism of the inclined support beams. And with an increase in the stroke of the camber mechanism, the angles of deviation of the inclined support beams from the vertical increase, in this regard, the maximum possible length of the lines decreases, and the PP with a large wingspan, as a rule, have long lines.

The present invention aims to solve the following problems:

- increasing the completeness and informativeness of the data obtained during the preparation of tests and during testing;

- expanding the functionality of the device;

- providing the ability to test PP with one, two or more thimbles;

- providing the ability to test software with increased scope.

The resulting technical result of the invention includes:

- increasing information content by increasing the amount of experimentally obtained data from each measuring unit installed for each sling attachment unit;

- simplification of the design due to the use of simpler tensile weights contained in the measuring unit, for example, as single-component ones;

- expanding experimental capabilities, including the possibility of testing PP with an increased scope, providing the ability to measure the magnitude and direction of individual loads from the lines in the left and right sides of the PP and to control their symmetry for the most common PPs with two attachment points for the slings.

The technical result is achieved by the fact that the proposed device for determining the aerodynamic characteristics of a gliding parachute in a wind tunnel contains a base with a platform mounted on it, inclined support beams, attachment points for slings, upper and lower tensile weights, an articulated angle of attack angle, and a power rack, and the platform is mounted on the power rack, between the platform and the attachment points of the slings installed independent from each other measuring units, at least containing the lower tenzovy, connected e with the attachment points of the slings, and roll angle and pitch sensors.

The technical result is also achieved by the fact that the roll and pitch angle sensors are installed in the axes of the roll and pitch hinges, which are connected to the tensile weights on one side and to the platform on the other.

The technical result is also achieved by the fact that to ensure testing of various PP structures, the number of sling attachment points and, accordingly, the number of measuring units is a multiple of two.

The technical result is also achieved by the fact that to determine the loads in the attachment points of the slings, the lower tenzovy can be one-component.

The technical result is also achieved by the fact that the platform is mounted on a power rack with the ability to move along the guides using the extension-cleaning mechanism, to ensure that the main slings or control lines of the device’s structural elements (hinged angle of attack and other elements) are not touched and that the results of load measurements not distorted due to an uncontrolled decrease in the measured forces.

The technical result is also achieved by the fact that to increase the wingspan of the PP, the hinged mechanism of the angle of attack contains a mechanism for changing the distance between the inclined support beams.

The technical result is also achieved by the fact that to ensure reliable testing of PP with an increased scope of the dome, the mechanism for changing the distance between the inclined support beams is equipped with interchangeable spacers of various lengths for installation between the inclined support beams.

The technical result is also achieved by the fact that the mechanism for changing the distance between the inclined support beams can be made telescopic with clamps, for example, with collet-type clamps.

The technical result is also achieved by the fact that the mechanism of the extension-cleaning platform and its fixation contains a drive moving the platform. The drive can be made mechanical, electrical or hydraulic.

List of figures:

FIG. 1 Scheme of the proposed device (side view)

FIG. 2 Scheme of the proposed device (view of the flow of ADT)

FIG. 3 Hinged angle of attack in the form of telescopic tubes

The proposed device (for example, a design with two attachment points of the slings, Fig. 1) contains two inclined support beams 1, which are connected via a hinge mechanism of the angle of attack 2 to the power stand 3, to which the platform 4 with the pitch and roll joints 5, 6 is attached. In the axes of the hinges 5, 6, the sensors of these angles 7, 8 are installed. The one of the lower hinges 9 is attached to the upper hinges, and the attachment points 10 of the main lines 11 and control lines 12 of the dome 13 are attached to them.

Measuring blocks 14 gives information about the magnitude and direction of forces from the slings 11 and 12. The number of lower tensile weights 9 in the measuring blocks 14 corresponds to and is equal to the number of attachment points of the slings 10 PP. The platform 4 is connected to the power rack 3 using the extension-cleaning mechanism 15. The attachment points of the parachute lines 10 and the platform 4 are positioned relative to the power rack 3 against the ADT flow by an amount sufficient for the main lines 11 and control lines 12 of the hinge mechanism of the angle of attack 2 not to touch The position of the platform 4 relative to the power rack 3 can be adjusted using the extension-cleaning mechanism 15. The extension-cleaning mechanism 15 for transmitting the movement of the platform along the guides 16 is made by a worm gear (on of 1 and 2 are not shown). The drive can also be made electric, hydraulic or manual. In the latter case, holes with constant pitch are made in the guides 16 of the platform and, accordingly, on the platform 4 to ensure that the position of the discretely moved platform is fixed using a rod installed in the holes (not shown). The drive for the extension-cleaning mechanism 15 is self-braking, which ensures the fixation of the set position of the platform regardless of the loads applied by the parachute.

On the platform 4, the attachment points of the 10 PP slings can be located with both two and 4 or more kosushi of the PP slings on a different transverse base (for this, special seats are provided in the platform 4).

Interchangeable spacers 17 are located between the inclined support beams 1 on the hinged mechanism of the angle of attack 2. Their length is selected according to the swing of the tested parachute. The hinged mechanism of the angle of attack 2 can be performed without interchangeable spacers 17, in the form of telescopic pipes (Fig. 3). The outer pipe 18 is a large diameter pipe mounted in bearings 19 connected to the base 20, connected in the plane of symmetry to the power rack 3, clamps 21, for example, collets, are installed at the ends of the outer pipe 18. At the ends, two inner pipes 22 are inserted into the outer pipe 18 using a spline or key connection to prevent turning. At the ends of the inner tubes 22, inclined support beams 1 are installed. The distance between the inner tubes 22 and between the inclined support beams 1 can vary in accordance with the required span of the PP.

The invention works as follows.

Before the start of the experiment, one-component lower tensile weights 9 and pitch and roll angle sensors 7, 8 are calibrated. Next, the thimbles of the main parachute slings 11 are connected to the attachment points of the slings 10 on platform 4, and the ADT is started. In test launches after filling the dome 13, the necessary distance between the inclined beams 1 is determined, it is changed using interchangeable spacers 17 or by moving the inner pipes 22 of the hinged mechanism of the angle of attack 2 and fixing them with latches 21. Using the extension-cleaning mechanism 15, the position of the platform 4 is determined, exclusive contact control lines 12 and the main lines 11 of the hinged mechanism of the angle of attack 2 and the collapse mechanism of the inclined support beams 23.

After that, at a given ADT flow rate, the sling system of the main slings 11 and the control slings 12 are adjusted using the data of the measuring units 14 on the loads in the left and right attachment points of the slings 10 of the lower ten-weight weights 9 and achieving equal forces and the same indications of the angle sensors 7, 8 in on both sides of the platform 4. After adjusting the slings, the canopy 13 of the parachute is fixed in the balancing position using remote-controlled clamps (not shown) and, according to the readings of the angle sensors 7, 8 and the lower tensile weights 9, are checked correctly fixation spine: their readings before and after fixation should match. In the event of a mismatch between the angles and the loads, the dome 13 of the PP is unlocked and fixed again until a positive result is achieved. Further, according to the program, by changing the angles of attack and sliding of the device, the loads and the orientation of the forces of the lower tenders 9 of the measuring units 14 are recorded. After the test program is completed, measurements of the loads on the upper 24 and lower tensises 9 in both sides are taken into account taking into account the readings of the pitch and roll angle sensors 7 , 8 measuring units 14.

The set of essential features of the proposed technical solution ensures the fulfillment of tasks and the achievement of the required technical result.

The invention is implemented in design and tested to determine the aerodynamic characteristics of the gliding parachute in the TsAGI wind tunnel.

The list of positions:

Inclined support beam 1

Hinge angle 2

Power stand 3

Platform 4

Pitch Hinge 5

Roll hinge 6

Pitch Angle Sensor 7

Roll angle sensor 8

Ten lower weights 9

Sling mount 10

Basic slings 11

Control lines 12

Parachute dome 13

Measuring unit 14

Platform extension-cleaning mechanism 15

Guides 16

Interchangeable spacer 17

Outer pipe 18

Bearing 19

Base 20

Latch 21

Inner pipe 22

The mechanism of the collapse of the inclined support beams 23

Top Ten Weights 24

Longitudinal beam 25

Traverse 26

Straps 27

Parachute sling attachment device 28

Claims (11)

1. A device for determining the aerodynamic characteristics of a gliding parachute in a wind tunnel, containing a base, a platform mounted on it, inclined support beams, attachment points of slings, upper and lower tensi weights, a hinged mechanism of the angle of attack, a power stand, characterized in that the platform is mounted on a power the stand, between the platform and the attachment points of the slings, measuring units independent of each other are installed, at least containing the lower tensile weights connected to the attachment points of the slings, and angle sensors in roll and pitch. 2. The device according to claim 1, characterized in that the roll and pitch angle sensors are installed in the axes of the roll and pitch hinges, which are connected to the tensile weights on one side and to the platform on the other. 3. The device according to claim 1, characterized in that the number of attachment points of the slings and, accordingly, the number of measuring units are multiples of two. 4. The device according to p. 1, characterized in that the lower tensi are one-component. 5. The device according to p. 1, characterized in that the platform is mounted on a power rack with the ability to move along the guides using the extension-cleaning mechanism. 6. The device according to claim 1, characterized in that the hinged mechanism of the angle of attack contains a mechanism for changing the distance between the inclined support beams. 7. The device according to p. 6, characterized in that the mechanism for changing the distance between the inclined support beams is equipped with interchangeable spacers of various lengths for installation between the inclined support beams. 8. The device according to p. 6, characterized in that the mechanism for changing the distance between the inclined support beams is made telescopic with clamps. 9. The device according to p. 8, characterized in that the collet type latches. 10. The device according to p. 5, characterized in that the mechanism of the extension-cleaning platform and its fixation contains a drive moving the platform. 11. The device according to p. 10, characterized in that the drive is mechanical, electrical or hydraulic.

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