CN111024356B - Device and method for measuring stress after eddy current caused by small-sized bulges on surface - Google Patents
Device and method for measuring stress after eddy current caused by small-sized bulges on surface Download PDFInfo
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- CN111024356B CN111024356B CN201911167033.4A CN201911167033A CN111024356B CN 111024356 B CN111024356 B CN 111024356B CN 201911167033 A CN201911167033 A CN 201911167033A CN 111024356 B CN111024356 B CN 111024356B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
- G01M9/02—Wind tunnels
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
- G01M9/06—Measuring arrangements specially adapted for aerodynamic testing
- G01M9/062—Wind tunnel balances; Holding devices combined with measuring arrangements
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Abstract
The invention discloses a measuring device and a measuring method for stress after eddy current is caused by small bulges on the surface, wherein the measuring structure comprises the following components: the device comprises a first flat plate, a second flat plate, a horizontal balance, a vertical balance, a bracket, a convex structure and a watertight cylinder with an opening at the top; the bracket is fixed in the watertight cylinder through the horizontal balance; the convex structure is arranged on the bracket; the first flat plate and the second flat plate are symmetrically arranged at two ends of the top opening of the watertight cylinder; the watertight cylinder is filled with liquid, and the horizontal balance is located below the liquid level of the liquid. The invention obtains the stress process of the local small-sized bulge in a non-contact local stress measurement mode.
Description
Technical Field
The invention belongs to the technical field of test measurement, and particularly relates to a device and a method for measuring stress after eddy current is caused by small protrusions on the surface.
Background
The flow change caused by the small-sized protrusions on the surface in test measurement is difficult to measure because the magnitude of the stress action of the flow change is small and is small relative to the whole stress of a test piece. If the local projections are measured separately, it is difficult to ensure that the local flow is not disrupted and the measurement data is contaminated.
By adopting the existing test technology, the local flow is difficult to be simultaneously ensured not to be disturbed, and the stress of the convex part is measured. Therefore, it is difficult to study the influence of the change of the size and shape of the small protrusions on the flow. The influence degree of surface damage cannot be defined, and the rule that the characteristic scale of the damage influences the flow field is difficult to identify.
How to obtain reliable stress data of the small-sized protrusion without contacting the flow, changing the boundary condition of the flowing surface and being affected by the error of the transmission process in the measurement system is a problem which needs to be solved by the technical personnel in the field.
Disclosure of Invention
The technical problem of the invention is solved: the device and the method for measuring the stress of the small bumps on the surface after eddy current is caused overcome, and the stress process of the small bumps is obtained in a non-contact local stress measurement mode.
In order to solve the technical problem, the invention discloses a device for measuring the stress after eddy current is caused by small protrusions on the surface, which comprises: the device comprises a first flat plate, a second flat plate, a horizontal balance, a vertical balance, a bracket, a convex structure and a watertight cylinder with an opening at the top;
the bracket is fixed in the watertight cylinder through the horizontal balance;
the convex structure is arranged on the bracket;
the first flat plate and the second flat plate are symmetrically arranged at two ends of the top opening of the watertight cylinder; the first flat plate, the bracket and the second flat plate are positioned on the same plane, and two ends of the bracket are respectively close to but not in contact with the first flat plate and the second flat plate;
the watertight cylinder is filled with liquid, and the horizontal balance is located below the liquid level of the liquid.
In the measuring device of the force after the small-sized bulges on the surface cause the eddy, the horizontal balance comprises: a first horizontal balance, a second horizontal balance, a third horizontal balance, and a fourth horizontal balance;
the four side surfaces of the bracket are respectively connected with the four inner wall side surfaces of the watertight cylinder through a first horizontal balance, a second horizontal balance, a third horizontal balance and a fourth horizontal balance;
the bottom of the bracket is connected with the bottom of the watertight cylinder through a vertical balance.
In the measuring device for measuring the force after the small-sized bulges on the surface cause the eddy current, the first horizontal balance, the second horizontal balance, the third horizontal balance and the fourth horizontal balance are positioned on the same horizontal plane; the first horizontal balance and the third horizontal balance are parallel to the flowing direction of the liquid, and the second horizontal balance and the fourth horizontal balance are vertical to the flowing direction of the liquid.
In the measuring device for measuring the force after the small-sized bulges on the surface cause the eddy current, the distance between the two ends of the bracket and the first flat plate and the second flat plate is less than 0.1 m.
In the measuring device for measuring the force after eddy current caused by the small protrusions on the surface, the first flat plate and the second flat plate are used for simulating the surface of an aircraft.
In the measuring device for measuring force after eddy current is caused by the small protrusions on the surface, the protrusion structure is a composite structure of protrusions and depressions and is used for simulating damage of the surface of an aircraft.
In the measuring device for the force after the small surface bulge causes the eddy current, the upper surface area of the first flat plate is a boundary layer generating area, and the length of the boundary layer generating area is 100-500 times of the thickness of the bulge structure.
In the above measuring device in which the small projections on the surface induce the eddy current after-load force, the maximum displacement in the vertical direction of the vertical balance is not more than 10% of the projection structure.
In the measuring device for measuring the force after the eddy current is caused by the small-sized protrusions on the surface, the outer edge material of the bracket is made of rubber, so that the bracket is prevented from colliding and damaging with the first plate or the second plate when the horizontal balance moves.
The invention also discloses a method for measuring stress after eddy current is caused by the small protrusions on the surface, which comprises the following steps:
placing the measuring device in a wind tunnel for blowing;
the convex structure is pushed to move by the acting force of flowing air flow so as to drive the horizontal and vertical balances to displace;
measuring by a horizontal balance and a vertical balance to obtain displacement signals;
determining acting forces of six components, which are applied to the raised structure after the raised structure causes the eddy current, according to the displacement signal;
wherein, measuring device includes: the device comprises a first flat plate, a second flat plate, a horizontal balance, a vertical balance, a bracket, a convex structure and a watertight cylinder with an opening at the top;
the bracket is fixed in the watertight cylinder through the horizontal balance; the convex structure is arranged on the bracket; the first flat plate and the second flat plate are symmetrically arranged at two ends of the top opening of the watertight cylinder; the first flat plate, the bracket and the second flat plate are positioned on the same plane, and two ends of the bracket are respectively close to but not in contact with the first flat plate and the second flat plate; the watertight cylinder is filled with liquid, and the horizontal balance is located below the liquid level of the liquid.
The invention has the following advantages:
(1) the invention discloses a scheme for measuring stress after eddy current is caused by small protrusions on the surface, which can peel off the independent stress of the protrusions and can obtain the acting force after eddy current is caused by the protrusions by using a small-range high-precision balance.
(2) The invention discloses a measuring scheme for stress after eddy caused by small-sized bulges on the surface.
(3) The invention discloses a measuring scheme for stress after eddy current is caused by small protrusions on the surface.
(4) The invention discloses a scheme for measuring stress after eddy current is caused by small protrusions on the surface, and the stress with 6 degrees of freedom can be measured simultaneously by a horizontal balance and a vertical balance.
(5) The invention discloses a scheme for measuring the stress after eddy current is caused by small protrusions on the surface, and boundary layers with different thicknesses can be generated by adjusting the length of a boundary layer generation area.
Drawings
FIG. 1 is a schematic structural diagram of a measuring device with a small surface bulge causing eddy current stress in an embodiment of the invention;
FIG. 2 is a schematic structural diagram of a first plate according to an embodiment of the present invention;
FIG. 3 is a top view of a device for measuring the force after eddy current is induced by small protrusions on a surface according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Example 1
In order to test the flow change caused by small bulges on the surface of a measuring object, the magnitude of the stress of the bulges is small relative to the overall stress of the test piece, so that the measurement is difficult. The bumps need to be isolated locally for individual force measurement. Meanwhile, to avoid the influence of the external environment on the flow, the flow needs to be sealed. But to avoid the sealing system disturbing the measurement accuracy of the balance. The invention provides a device for measuring the stress of a small-sized bulge on the surface after eddy current is caused, wherein the small-sized bulge on the surface can be isolated by a bracket to independently measure the local stress, and meanwhile, the external flow is isolated from the surface flow by adopting the water seal under the surface.
In this embodiment, as shown in fig. 1, the device for measuring eddy current induced back stress includes: a first plate 1, a second plate 2, a horizontal balance, a vertical balance 6, a bracket 3, a raised structure 4 and an open-top watertight box 5. The specific installation/connection relationships are as follows: the bracket 3 is fixed in the watertight cylinder 5 through a horizontal balance 6; the convex structure 4 is arranged on the bracket 3; the first flat plate 1 and the second flat plate 2 are symmetrically arranged at two ends of the top opening of the watertight cylinder 5; the watertight cylinder 5 is filled with liquid, and the horizontal balance is positioned below the liquid level of the liquid.
Preferably, the first plate 1 and the second plate 2 are used to simulate the surface of an aircraft. The raised structures 4 are intended to simulate damage to the surface of an aircraft, and therefore the raised structures 4 may be a complex shape of protrusions and depressions.
Preferably, as shown in fig. 2, which is a schematic structural diagram of the first flat plate 1, the first flat plate 1 is specifically used for simulating a front edge portion surface, that is, an upper surface area of the first flat plate 1 may be used as a boundary layer generation area, and a length of the boundary layer generation area is 100 to 500 times of a thickness of the protruding structure 4.
Preferably, the first plate 1, the bracket 3 and the second plate 2 are all located on the same plane, and two ends of the bracket 3 are respectively close to but not in contact with the first plate 1 and the second plate 2, that is: the distance between the two ends of the bracket 3 and the first plate 1 and the second plate 2 is less than 0.1 m.
Preferably, the outer edge material of bracket 3 adopts the rubber material, prevents that horizontal balance when moving, bracket 3 and first flat board 1 or second flat board 2 from producing collision damage.
Example 2
In a preferred embodiment of the present invention, as shown in fig. 3, the horizontal balance may specifically include: a first horizontal balance 71, a second horizontal balance 72, a third horizontal balance 73 and a fourth horizontal balance 74.
Four sides of the bracket 3 are respectively connected with four inner wall sides of the watertight box 5 through a first horizontal balance 71, a second horizontal balance 72, a third horizontal balance 73 and a fourth horizontal balance 74; the bottom of the bracket 3 is connected to the bottom of the watertight drum 5 by a vertical balance 6.
Preferably, the first horizontal balance 71, the second horizontal balance 72, the third horizontal balance 73 and the fourth horizontal balance 74 are on the same horizontal plane; the first horizontal balance 71 and the third horizontal balance 73 are parallel to the flow direction of the liquid, and the second horizontal balance 72 and the fourth horizontal balance 74 are perpendicular to the flow direction of the liquid.
Preferably, in order to prevent the flow variation caused by the height variation of the convex structures 4, the maximum displacement in the vertical direction of the vertical balance 6 is not more than 10% of the convex structures 4.
Example 3
On the basis of the above embodiments, the present invention describes a measurement method implemented based on the measurement apparatus.
In this embodiment, the method for measuring the force after the surface small-sized protrusion induces the eddy current comprises the following steps:
and step S1, placing the measuring device in a wind tunnel for blowing.
In step S2, the protruding structure 4 is forced by the flowing air to move the bracket 3, and further, the horizontal and vertical scales 6 are driven to displace.
In step S3, the horizontal and vertical scales 6 measure the displacement signals.
Step S4, according to the displacement signal, six component acting forces received after the protruding structure 4 induces the vortex are determined, and a basis is provided for analyzing how the small damage induces the vortex to change the flow characteristics.
In summary, in this embodiment, the raised structures are isolated by the bracket, local stress is measured separately, and external flow is isolated from the flow on the surface by using subsurface water sealing. The following problems are avoided: the flow of the air flow is affected by the external environment and the sealing system disturbs the measurement accuracy of the balance.
For the method embodiment, since it corresponds to the apparatus embodiment, the description is relatively simple, and for the relevant points, refer to the description of the apparatus embodiment section.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.
Those skilled in the art will appreciate that the invention may be practiced without these specific details.
Claims (6)
1. A device for measuring the force exerted by a small protrusion on a surface after an eddy current is induced, comprising: the device comprises a first flat plate (1), a second flat plate (2), a horizontal balance, a vertical balance (6), a bracket (3), a convex structure (4) and a watertight cylinder (5) with an opening at the top;
the bracket (3) is fixed in the watertight cylinder (5) through a horizontal balance and a vertical balance (6);
the convex structure (4) is used for simulating damage of the surface of the aircraft; the convex structure (4) is arranged on the bracket (3);
-a first plate (1) and a second plate (2) for simulating the surface of an aircraft; the first flat plate (1) and the second flat plate (2) are symmetrically arranged at two ends of the top opening of the watertight cylinder (5); the first flat plate (1), the bracket (3) and the second flat plate (2) are positioned on the same plane, and two ends of the bracket (3) are respectively close to but not in contact with the first flat plate (1) and the second flat plate (2);
the watertight cylinder (5) is filled with liquid, and the horizontal balance is positioned below the liquid level of the liquid;
wherein:
a horizontal balance comprising: a first horizontal balance (71), a second horizontal balance (72), a third horizontal balance (73), and a fourth horizontal balance (74);
four sides of the bracket (3) are respectively connected with four inner wall sides of the watertight barrel (5) through a first horizontal balance (71), a second horizontal balance (72), a third horizontal balance (73) and a fourth horizontal balance (74);
the first horizontal balance (71), the second horizontal balance (72), the third horizontal balance (73) and the fourth horizontal balance (74) are positioned on the same horizontal plane, the first horizontal balance (71) and the third horizontal balance (73) are parallel to the flowing direction of the liquid, and the second horizontal balance (72) and the fourth horizontal balance (74) are perpendicular to the flowing direction of the liquid;
the bottom of the bracket (3) is connected with the bottom of the watertight cylinder (5) through a vertical balance (6).
2. Device for measuring the force exerted after an eddy current caused by small projections on the surface according to claim 1, characterized in that the distance between the two ends of the bracket (3) and the first plate (1) and the second plate (2) is less than 0.1 m.
3. The device for measuring eddy current induced back stress with small protrusions on the surface according to claim 1, wherein the protrusion structure (4) is a composite structure of protrusion and depression.
4. The device for measuring eddy current induced back stress of small surface protrusions according to claim 1, wherein the upper surface area of the first plate (1) is a boundary layer generating area, and the length is 100-500 times the thickness of the protrusion structure (4).
5. The device for measuring the force after the vortex caused by the small-sized protrusions on the surface is characterized in that the outer edge material of the bracket (3) is made of rubber, so that the bracket (3) is prevented from colliding and damaging with the first flat plate (1) or the second flat plate (2) when the horizontal balance moves.
6. A measuring method based on the measuring device for measuring the force after the surface small-sized bulge induces the eddy current of the claim 1 is characterized by comprising the following steps:
placing the measuring device in a wind tunnel for blowing;
the convex structure (4) is pushed by the acting force of flowing air flow to move the bracket (3) so as to drive the horizontal balance and the vertical balance (6) to displace;
measuring a horizontal balance and a vertical balance (6) to obtain a displacement signal;
from the displacement signal, six component forces to which the protruding structure (4) is subjected after inducing the eddy currents are determined.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911167033.4A CN111024356B (en) | 2019-11-25 | 2019-11-25 | Device and method for measuring stress after eddy current caused by small-sized bulges on surface |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911167033.4A CN111024356B (en) | 2019-11-25 | 2019-11-25 | Device and method for measuring stress after eddy current caused by small-sized bulges on surface |
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| CN111024356A CN111024356A (en) | 2020-04-17 |
| CN111024356B true CN111024356B (en) | 2021-12-07 |
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Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH109997A (en) * | 1996-06-20 | 1998-01-16 | Mitsubishi Heavy Ind Ltd | Balance for wind tunnel test |
| CN104089753A (en) * | 2014-07-08 | 2014-10-08 | 中国空气动力研究与发展中心低速空气动力研究所 | Tester used for measuring stress of flexible objects in low-speed wind tunnel and testing method thereof |
| CN104236849B (en) * | 2014-09-23 | 2016-08-17 | 中国运载火箭技术研究院 | A kind of underwater sailing body hydrodynamic measurement system |
| CN106153289A (en) * | 2015-04-08 | 2016-11-23 | 大连理工大学 | A kind of device for measuring force of model in wind tunnel |
| CN204852859U (en) * | 2015-08-13 | 2015-12-09 | 湖南科技大学 | Six weight measured force balance fixing device in wind -tunnel |
| CN206710057U (en) * | 2017-05-05 | 2017-12-05 | 山东大学 | A kind of six component measurement balances and model for wind tunnel experiment |
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