JPH09269274A - Flutter stop device for wing in wind tunnel test - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flutter stop device moving the center-of-gravity of a wing element instantaneously and positively with simple mechanism at the time of the generation of flutter and fittable also to a thin wing by connecting a mass to a wing body on the rear edge side using a conductor wire such as a steel wire in the state of applying tension to the mass by an elastic body in the direction of pushing it out onto the front edge side. SOLUTION: In a wing 1, damping by aerodynamic force decreases with the increase of aerodynamic force, and vibration increases rapidly to generate flutter. When this initial indication is detected to send a flutter stop signal to a flutter stop device, a switch 30 is closed, and a current of such a grade as to fuse in about 15msec flows to a steer wire 11. Since tension is previously applied to a mass 6 by an elastic body 8, the steel wire 11 expanded and fused becomes unable to withstand the tension and breaks, and the mass 6 jumps out toward the front edge side. Upon reaching the end of the front edge, the mass 6 hits cushioning material 13 so as to be reduced in speed, and an iron plate 7 is attracted to a magnet 12, so that the mass 6 is captured and stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wing flutter stop device in a wind tunnel test of an elastic aircraft model, and more particularly to a wing flutter stop device in a flutter wind tunnel test from a subsonic speed to a supersonic speed range.

[0002]

2. Description of the Related Art In the development process of an aircraft, a flutter test is performed in a wind tunnel to grasp flutter characteristics in a subsonic to supersonic range. Generally, in the flutter test of an aircraft, when flutter occurs, the wing vibrates violently, and the wing material often breaks due to fatigue and excessive amplitude. Therefore, it is necessary to stop the flutter instantly when flutter occurs to protect the wing.

[0003] As a conventional method of stopping flutter, 1) a cylindrical body having a weight added to a wing tip is attached thereto, and movement around the support shaft is restrained by hydraulic pressure before flutter occurs. 2) A method in which a flat plate is inserted into the wind tunnel from the wind tunnel wall in front of the model to reduce the dynamic pressure received by the model from the airflow (JP-A-6-328)
980). The method 1) uses a hydraulic pressure for the restraining force of the mass, complicates the mechanism, and requires an appropriate damping adjustment mechanism because the cylinder rotates around the support axis. In the early stage of the operation of the stop plate, there is a process in which the air flow pressure rises by about 0.3 seconds, and the divergent type flutter has drawbacks such as a small effect.

[0004]

In the flutter test, when a flutter occurs, 50 seconds from the input of the flutter stop signal.
Flutter must be attenuated within milliseconds and reliably stopped within 0.5 seconds. As a method of effectively attenuating flutter, it is known that the center of gravity of the blade element near the tip contributing to flutter may be moved forward from the aerodynamic action point. However, there is no device that can instantaneously and surely move the center of gravity of the blade element and has a simple mechanism and can be attached to a thin blade, and it has been difficult to reliably stop flutter.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and when flutter occurs, the center of gravity of a blade element can be instantaneously and reliably moved by a simple mechanism, and even when a thin blade is used. It is an object to provide a flutter stop device that can be mounted.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a mass is provided at any of the upper, lower, or wing tip of a wing along a flow direction of an air flow, and the mass is elastically moved in a direction for pushing the mass toward a leading edge side. A tension is applied by the body, and the mass is connected to the wing body at the trailing edge side using a conductor wire such as a steel wire while the tension is applied. When a flutter stop signal is input, an electric current is supplied to the conductor wire to instantaneously melt the wire, and the mass is moved to the leading edge side by the tension of the elastic body. When the mass reaches the leading edge side, the mass is captured by a capturing mechanism combining a cushion material, a magnet and an iron plate, or a groove and a claw to prevent the mass from returning to the trailing edge side.

The mass may be provided so as to be movable along a rod provided between the leading edge fixed base and the trailing edge fixed base, and as another means, the leading edge side mass and the trailing edge mass which are integrally connected by a rod are provided. A mass may be configured with the edge-side mass, and the rod may be supported so as to be movable in the airflow direction.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the drawings. 1 and 2 show a wing suspension type embodiment of the flutter stop device of the present invention. FIG. 1 shows an embodiment in which a flutter stop device is incorporated in a suspended body 2 such as an engine nacelle or a fuel tank located on the lower surface of a wing 1 fixed in a wind tunnel, and FIG. 2 is an enlarged view of a main part of the flutter stop device. Is shown. In the flutter stop device of this embodiment, the guide rod 3 is supported between the leading edge side fixed base 5 and the trailing edge side fixed base 4 along the flow direction, and the guide rod 3 incorporates the mass 6 so as to be movable. An iron plate 7 that forms a capturing mechanism together with a cushioning material and a magnet provided on a front edge side fixing base, which will be described later, is fixed to the mass.

A base end of an elastic body 8 such as a rubber material or a spring is fixed to the suspension body 2 so as to be positioned substantially in the vicinity of the guide rod 3, and the other end is hung on the mass 6, and the mass 6 is fixed on the trailing edge side. The tension of the elastic body 8 is adjusted so that a tension about twice the mass weight acts on the mass 6 at a position where the elastic body 8 contacts the table 4. Also,
As shown in FIG. 2, three to four wire hooking pins 10 are provided on the trailing edge side fixing base 4 via the insulator 9, and two to three wire hooking pins 41 are also provided on the mass side via the insulator 40. Several are provided. Next, the mass 6 is brought close to the trailing edge fixing base 4 while the elastic body 8 is stretched, and as shown in FIG. 2, the wire hooking pins 10 and 41 are connected to the conductor wires having a thickness of 0.1 to 0.2 mm. Steel wire 1
At step 1, both ends are connected in zigzag or alternately, and both ends are connected to the power supply line 42 on the fixed base side.

On the other hand, a magnet 12 and a cushion material 13 which constitute one of the catching mechanisms are provided on the front edge side fixed base 5 of the guide rod 3. The magnet 12 has a square 6
The position is adjusted to such an extent that the iron plate 7 is slightly in contact with the magnet so that the magnet can attract the iron plate when it moves toward the leading edge side fixing base 5.

FIG. 3 shows an electric circuit for evaluating the performance of the flutter stop device having the above configuration. Trailing edge fixing base 4
Both ends of the steel wire 11 attached between the wire hooking pin 10 provided on the wire and the wire hooking pin 41 provided on the mass are connected to an AC power supply 43 via the resistor 32 and the switch 30. A trailing edge side detection switch contact 34 for detecting that the mass 6 is at a position in contact with the trailing edge side fixed base 4;
And a leading edge side detection switch contact 35 for detecting that it is on the leading edge side fixed base, and these switch contacts are connected to a DC power supply 44 via a resistor 36. Further, both ends of the resistor 32 are connected to a pen oscilloscope 45 to record the energizing time of the steel wire, and both ends of the resistor 36 are also connected to the pen oscilloscope 45 to record the moving time of the mass.

The operation of the flutter stop device of this embodiment shown in FIG. 1 will be described with reference to the electric circuit configured as described above. As the aerodynamic force increases, at some point, the wing 1 reduces damping due to the aerodynamic force, and the vibration rapidly increases to generate flutter. An initial sign of the flutter is detected and a flutter stop signal is sent to the flutter stop device.
In the flutter stop device, when a signal is received, the switch 30
However, a current large enough to melt the closed steel wire in about 15 mm seconds flows. Since the mass 6 is previously biased by the elastic body 8 and urged, when the steel wire 11 expands and melts, the steel wire 11 cannot withstand the tension and breaks, and the mass 6 jumps out toward the front edge side. When the mass 6 reaches the end of the leading edge, the mass 6 hits the cushion material 13 and is decelerated, and the iron plate 7 is attracted to the magnet 12 so that the mass is captured and stopped. Therefore, the mass 6 does not return to the trailing edge side by the recoil. As a result, the center of gravity of the blade element instantaneously moves ahead of the aerodynamic action point, and the flutter starts damping when the mass 6 leaves the trailing edge fixed base, and finally the flutter disappears. Further, since the current of the steel wire is automatically cut off at the time of fusing, no special control circuit is required.

In the above operation, the shorter the time from the detection of the initial sign of flutter and the energization of the steel wire to the melting of the steel wire, and the shorter the time until the mass moves to the leading edge side, the flutter stopping function. Means superior. In the present embodiment, the performance of the flutter stop device was evaluated by recording those times on a pen oscilloscope using the circuit shown in FIG.

In FIG. 3, when the switch 30 is closed due to the occurrence of flutter, a current flows through the steel wire 11, the steel wire is melted and cut, and the current is automatically extinguished. Resistance 32
The voltage is changed at both ends by the power supply time, and a steel wire power supply time waveform 33 is recorded on the pen oscilloscope. When the steel wire is melted and the mass 6 starts to move forward due to the tension of the elastic body 8, the contact of the switch 34 is closed and the mass 6 is moved to the front edge magnet 1.
When complemented by 2, the contact of the switch 35 opens. As a result, a voltage change represented by a mass movement time waveform 37 as shown in FIG. 4 appears at both ends of the resistor 36. The pulse-like waveform of the steel wire energization time waveform 33 is the melting and cutting time of the steel wire, and the high potential time zone of the mass movement time waveform 37 is the time during which the mass is moving.

According to this embodiment, as can be seen from FIG. 4, the steel wire is cut in 13.2 milliseconds from the start of energization to the steel wire, the mass 6 leaves the trailing edge fixing base 4, and 266 millimeters from energization. In a second, the mass 6 has reached the leading edge fixed base. This means that the time required to escape from the flutter is reduced to 1/5 to 1/10 compared to the conventional method in which a stop plate is inserted into the wind tunnel, and the method of the present invention is extremely useful for stopping flutter. You can see that.

FIGS. 5 to 7 show another embodiment of the flutter stop device of the present invention. In this embodiment, a flutter stop device is provided at the wing tip. Rod support 14 at wing tip
And a rod 15 movable in the airflow direction via the supporting portion is disposed, and a leading edge mass 16 and a trailing edge mass 17 are respectively attached so that the masses are located at both ends of the rod. A tension is applied by an elastic body 18 in a direction in which the elastic body 18 protrudes to the edge side.

FIGS. 6 and 7 are detailed views of the rod support portion 14. FIG. The linear bearing 38 is fixed to the wing 1 by the rod support portion 14, an insulating ring 19 made of an insulating material is attached to the leading edge side, and 5 to 7 wire hooking pins 20 are provided in the circumferential direction of the insulating ring 19. An insulating ring 21 and a wire pin 22 are also provided on the front edge side mass 16 of the rod 15, and are connected to the rod 15 via a collar 39. Further, in order to prevent the heads of the wire pins 20, 22 from being exposed to the airflow, the insulating ring 21 is manufactured to be smaller in diameter by about 5 mm than the front edge side mass 16, and the portion where the wire pins 20, 22 are provided. Is formed as a groove recessed from the surface of the leading edge side mass.
After connecting the pins 20 and 22 with the steel wire 23 while pulling the rod 15 toward the trailing edge, the groove is thinned with a thin adhesive tape 2.
4 and cover in a cantilevered state (see FIGS. 6 and 7).

A trailing edge mass 17 provided with a through hole 25 of the elastic body 18 is attached to the trailing edge side of the rod 15, and a trapping groove 26 is provided in the mass 17. One end of the elastic body 18 is fixed to the rod support portion 14, is folded back through the through hole 25 of the rear edge mass, and the other end is fixed to the rod support portion, so that the rear edge mass is moved to the rod support portion side, that is, the front edge side. The tension is urged to be pulled. On the other hand, the catching claw 27, the deceleration cushion material 28, the cushion support 29
Are provided at two positions every 180 degrees. Other configurations of the present embodiment and a circuit configuration for evaluating the same are the same as those of the above-described embodiment, and thus detailed description will be omitted.

The flutter stopping device of the present embodiment is configured as described above. A flutter test is performed in the wind tunnel in the state shown in FIG. 5 or FIG. A large current flows, the steel wire melts, and the rod 15 jumps forward due to the tension of the elastic body 18. As a result, as shown in FIG. 7, the leading edge tapered surface 46 of the trailing edge mass 17 is
8 and the catching claw 27 is moved to the rear edge
7 and are captured by fitting. Accordingly, the rod 27 does not return due to the recoil, and the trailing edge mass 17 is reliably captured by the rod support portion 14 to maintain a stopped state, and simultaneously with the occurrence of flutter, the center of gravity of the blade element is moved forward from the aerodynamic action point. And flutter can be stopped instantaneously.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various design changes are possible. For example, in the embodiment,
The fixed side and the mass are fixed with a steel wire and the steel wire is blown. However, the present invention is not limited to the steel wire, and any conductor wire having a high tension and capable of instantaneously blowing with a high current may be used.
Further, the capturing mechanism shown in FIG. 1 may be employed in the flutter stopping device shown in FIG. 5, and the capturing mechanism shown in FIG. 5 may be employed in the flutter stopping device shown in FIG. Further, it is also possible to provide a cushioning material, a magnet or a catching claw on the movable side and provide an iron plate or a catching groove on the fixed side in these capturing mechanisms.

[0021]

As described above, according to the present invention, when a flutter signal is received, the center of gravity of the blade element near the tip, which contributes the mass to the flutter, is instantaneously and surely moved forward from the aerodynamic action point. And flutter can be stopped instantaneously. And because it has a mass trapping mechanism,
The mass can be reliably captured on the leading edge side by a simple mechanism, and the mass does not return to the trailing edge side due to recoil. Therefore, the flutter stopping device of the present invention has good responsiveness to flutter, and can reduce the flutter stopping time to 1/5 to 1/10 compared to the conventional method of inserting a stop plate into the wind tunnel. Also, the divergent flutter can be stopped without fail, which provides a special effect.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a state in which a flutter stop device according to an embodiment of the present invention is provided on a suspended body of a wing.

FIG. 2 is a perspective view of a main part of the flutter stop device according to the embodiment of the present invention.

FIG. 3 is a performance evaluation circuit of the flutter stop device of the embodiment.

FIG. 4 is a pen oscilloscope recording waveform showing a steel wire energizing time and a mass moving time of the flutter stop device according to the embodiment of the present invention.

FIG. 5 is a schematic front view showing a state in which a flutter stop device according to another embodiment of the present invention is provided at a wing tip.

FIG. 6 is a cross-sectional view of a main part in a state where the mass is on the trailing edge side.

FIG. 7 is a cross-sectional view of an essential part in a state where the mass has moved to the front edge side.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Wing 2 Suspended body 3 Guide rod 4 Trailing edge side fixed stand 5 Leading edge side fixed stand 6 Mass 7 Iron plate 8, 18 Elastic body 9, 39 Insulator 10, 20, 22, 4
DESCRIPTION OF SYMBOLS 1 Wire hanging pin 11, 23 Steel wire 12 Magnet 13, 28 Cushion material 14 Rod support part 15 Rod 16 Front edge mass 17 Trailing edge mass 19, 21 Insulation ring 24 Adhesive tape 25 Through hole 26 Capture groove 27 Capture claw 29 Cushion support Tools 30, 34, 35
Switch 32, 36 Resistance 33 Steel wire conduction time waveform 37 Mass movement time waveform 38 Linear bearing 42 Power line 43 AC power 44 DC power 45 Oscillograph 46 Tapered surface

Claims (6)

[Claims] 1. A mass which is movable in the flow direction of an air flow is provided on an arbitrary cross section of a wing, on a lower surface, or on a wing tip, and the mass and the wing are connected by a conductor wire in a state where the mass is urged in a direction protruding to a leading edge side. A flutter stopping device for a blade in a wind tunnel test, wherein the mass is moved forward by coupling the conductor wires when fluttering occurs to cut off the conductor wires. 2. The flutter stop device according to claim 1, wherein the mass is provided so as to be movable along a rod provided between the front edge side fixed base and the rear edge side fixed base. 3. The flutter stop according to claim 1, wherein the mass comprises a leading edge side mass and a trailing edge side mass which are integrally connected by a rod, and the rod is supported so as to be movable in a flow direction of the air flow. apparatus. 4. The flutter stopping device according to claim 1, further comprising a catching mechanism for catching the mass and stopping at a leading edge stop position when the mass moves to the leading edge. 5. The catching mechanism comprises a cushion member for decelerating the mass to a leading edge stop position, a magnetic material, and a magnet for attracting the magnetic material to catch the mass at the leading edge stop position. The flutter stop device as described. 6. The catching mechanism according to claim 6, wherein the catching mechanism comprises a cushioning member for decelerating the mass to a leading edge stop position, a catching claw, and a catching groove for engaging the catching claw at the leading edge side stopping position to catch the mass. Item 6. The flutter stopping device according to Item 4.