CN108398228A - A kind of air-flotation type strain balance - Google Patents

Abstract

The invention discloses an air-floating strain balance. The balance is a combined balance, which includes a mandrel, an axial force component, a five-component component, and a protective cover. The mandrel includes a conical connection section and an equal straight section. The mandrel is installed with the axial force assembly, the axial force assembly is installed with the five-component assembly, the fixed end of the axial force assembly is fixed with the mandrel, the movable end is fixed with the fixed end of the five-component assembly, and the movable end of the five-component assembly is connected with the The model under test is fixed. The shaft, axial force component and five component component are coaxial. Compressed gas is charged from the fixed end of the mandrel, and the air bearing is formed between the movable end of the axial force component and the mandrel through the air hole at the front end of the mandrel, and the air bearing between the axial force component and the mandrel can be made Frictional resistance is negligible, which improves the measurement sensitivity and accuracy of axial force.

Description

An air-floating strain balance

technical field

The invention relates to an air-floating strain balance, which belongs to the field of aerodynamic force measurement in aerospace dynamometer tests, and is particularly suitable for wind tunnel tests of sub-, transonic- and supersonic-speed high-precision resistance measurements.

Background technique

Wind tunnel test is a key research method in the shape design of flying aircraft. In order to obtain high-precision aerodynamic data in the process of wind tunnel test, it is necessary to have a high-precision aerodynamic force measurement balance. For general aircraft measurement balances, the axial force (X component) is a small amount compared to the force in other directions, and it is the most difficult quantity to measure in aerodynamic measurement. It is even more difficult to measure the change in the shape of the aircraft corresponding to the change in the axial force. The six components of the traditional strain balance are on one measuring element, the full-scale strain of the axial force is small during measurement, and the interference and deformation of the other aerodynamic components on the axial force are greater than the principal strain of the axial force component, and the balance of the other components on the axis is stable when the balance is calibrated. The interference coefficient of the axial force is also large, which makes it difficult to improve the measurement accuracy of the axial force of the balance.

Contents of the invention

The technical problem solved by the present invention is to overcome the deficiencies of the prior art and provide an air-floating strain balance that can directly transmit the loads of lateral force, normal force, pitch moment, roll moment, and yaw moment to the core. On the shaft, without affecting the load of the axial force, the signal-to-noise ratio and sensitivity of the axial force measurement are improved, and the high-precision measurement of the axial force is realized.

The technical solution of the present invention is: an air-floating strain balance, which includes a mandrel and an axial force assembly for measuring axial force, one end of the mandrel is sleeved inside the axial force assembly, and the middle part is connected with the shaft The end of the axial force component is fixedly connected, and the other end extends out of the axial force and is fixedly connected with the test bracket. A hollow through hole is provided inside the mandrel, and the end of the hollow through hole located inside the axial force component is blocked. The other end is open, and the side wall of the mandrel is provided with a plurality of air holes connected with the hollow through hole, and the compressed gas is filled along the hollow through hole of the mandrel, and the axial force component and the mandrel are filled with compressed gas to form a suspension, and the axial Force components are used to measure axial force.

The mandrel includes a conical connecting section and an equal straight section, the equal straight section is fixedly connected to the axial force assembly near the conical section, the conical connecting section and the test bracket are connected through the conical surface and tightened with a wedge.

The axial force assembly measures the axial force through an axial force measuring element, the axial force measuring element is installed on a vertical beam structure on the side wall of the axial force assembly, and the plane where the axial force measuring element is located is vertical on the axis of the axial force component.

The above-mentioned air-floating strain balance also includes a five-component assembly for measuring lateral force, normal force, pitching moment, rolling moment, and yaw moment. Inside the test model; one end of the five-component component is fixedly connected to the measured model, and the other end is fixedly connected to the other end opposite to the end of the fixed connection between the axial force component and the mandrel, and the compressed gas passes along the hollow of the mandrel. After the hole is filled, the axial force component and the five-component component are also filled with compressed gas to form a suspension. The five-component component is not aligned with the axial force when measuring side force, normal force, pitch moment, roll moment, and yaw moment. load has an effect.

The mandrel, axial force assembly and five-component assembly are placed coaxially.

The five-component component and the measured model are fixed by pins; the five-component component and the axial force component are fixed by pins; the axial force component and the mandrel are fixed by pins.

The five-component component measures side force, normal force, pitch moment, roll moment, yaw moment, and The navigation moment, side force measurement element, normal force measurement element, pitch moment measurement element, roll moment measurement element and yaw moment measurement element are installed on multiple rectangular beams, and the installation surface is parallel to the axis of the five-component assembly.

The mounting surface of the pitching moment, normal force and rolling moment measuring element is located on a plane passing through the axis of the five-component assembly and perpendicular to the cross-section of the five-component assembly, and the pitching moment measuring element, the normal force measuring element and the rolling moment are measured The elements are all one pair, and each pair of pitching moment measuring elements, normal force measuring elements and rolling moment measuring elements are arranged symmetrically with respect to the five-component axis; On the plane perpendicular to the force and rolling moment measuring elements, there is a pair of yaw moment measuring elements and normal force measuring elements, and each pair of yaw moment measuring elements and normal force measuring elements is arranged symmetrically with respect to the five-component axis .

The interior of the mandrel is parallel to the axis and avoids air holes and through holes. There are multiple outlet holes for axial force measurement elements, lateral force measurement elements, normal force measurement elements, pitching moment measurement elements, roll The moment measuring element and the yaw moment measuring element go out.

The above-mentioned air-floating strain balance also includes a protective cover, which is fixed to the fixed end of the five-component component and covers all measuring components, and its outer surface is parallel to the outer surface of the five-component component.

Compared with the prior art, the present invention has the following advantages:

(1), the present invention adopts the principle that air flotation is formed inside the balance device by compressed gas, and the strain balance is designed into a combined casing structure, and the axial force measuring element is connected with other forces (side force, normal force, pitch force, Rolling force, yaw force) are arranged on two different casings, compressed gas is charged from the fixed end of the mandrel, and the air hole for pressure relief is small, ensuring that the axial force component between the fixed end and the mandrel, the five-component component The suspension between the axial force component and the axial force component is caused by being filled with compressed gas. This structure can make the five-component component of the axial force component not bear the load of force in other directions except its measurement during the wind tunnel test, and can make the other four The load on the component is directly transmitted to the mandrel without affecting the load of the axial force, which improves the signal-to-noise ratio and sensitivity of axial force measurement and realizes high-precision measurement of axial force.

Description of drawings

Fig. 1 is a kind of air-floating type strain balance assembly schematic diagram of the embodiment of the present invention;

Fig. 2 is an assembly sectional view of an air-floating strain balance according to an embodiment of the present invention;

Fig. 3 (a) is the structural representation of the mandrel of the embodiment of the present invention;

Fig. 3 (b) is the structural sectional view of the mandrel of the embodiment of the present invention;

Fig. 4 is a schematic structural diagram of an axial force assembly according to an embodiment of the present invention;

5 is a schematic structural diagram of a five-component component according to an embodiment of the present invention;

Fig. 6 is a schematic structural view of the protective sleeve of the present invention;

In the figure: 1. Mandrel; 2. Axial force component; 3. Five-component component; 4. Protective sleeve; 5. Axial force measuring element; 6. Pitching moment measuring element; 7. Normal force measuring element; 8 , Rolling moment measuring element; 9, Yawing moment measuring element; 10, Lateral force measuring element.

Detailed ways

The present invention will be further introduced below in conjunction with the accompanying drawings.

As shown in Figures 1 and 2, an air-floating strain balance provided by the present invention is a combined balance, including a protective cover 4 and a mandrel 1 for measuring lateral force, normal force, pitching moment, and rolling moment. , The five-component component 3 of the yaw moment, the axial force component 2 for measuring the axial force, the five-component component 3 is set inside the measured model, the axial force component 2 is set inside the five-component component 3, and the mandrel 1 One end is sleeved inside the axial force assembly 2, and the other end protrudes outside the axial force assembly 2. One end of the five-component component 3 is fixedly connected to the model to be tested, and the other end is fixedly connected to one end of the axial force component 2 sleeved inside it. The other end of the axial force component 2 is fixedly connected to the middle of the mandrel 1. The mandrel 1 The end protruding from the outside of the axial force component is fixedly connected with the test bracket, and the mandrel 1, the axial force component 2 and the five-component component 3 are placed coaxially.

As shown in Fig. 3(a) and Fig. 3(b), the mandrel 1 includes a conical connection section and a straight section, the conical connection section and the test fixed end are fit through a conical surface, and are tightened with a wedge, and are straight The fixed end of the segment is connected with the axial force component 2 through a pin; a hollow through hole is provided inside the mandrel 1, and the end of the hollow through hole located inside the axial force component is blocked with a top wire, and the other end is open, and the core There are multiple air holes on the side wall of the shaft 1, which are connected with the hollow through hole. The compressed gas enters from the tail of the conical connecting section, and the gas is sent into the whole device through the air holes at the front end of the straight section. The axial force component and the mandrel 1 Both between the axial force component and the five-component component 3 are suspended due to being filled with compressed gas. The above-mentioned air bearing structure can make the frictional resistance between the axial force component and the mandrel negligible, and the five-component component 3 is not correct for the axial force when measuring the side force, normal force, pitch moment, roll moment, and yaw moment. Compared with the general strain balance, the load on the other four components can be directly transmitted to the mandrel without affecting the load of the axial force, which improves the signal-to-noise ratio and Sensitivity to achieve high-precision measurement of axial force.

In addition, a plurality of outlet holes are arranged inside the mandrel 1 parallel to the axis and avoiding air holes and through holes, which are used for axial force measurement elements, lateral force measurement elements, normal force measurement elements, and pitching moment measurement elements , Rolling moment measuring element and yaw moment measuring element are out of line.

The axial force component 2 measures axial force through an axial force measuring element. Fig. 4 is a schematic structural view of an axial force assembly. As shown in Fig. 4, the axial force assembly 2 is a hollow cylinder, and the axial force measuring element 5 is mounted on a vertical wall on the side wall of the axial force assembly. In the beam structure, the plane where the axial force measuring element is located is perpendicular to the axis of the axial force assembly 2, and the axial force is measured through the force transmission of the parallelogram structure.

The five-component component 3 and the model under test are fixed by pins; the five-component component 3 and the axial force component 2 are fixed by pins; the axial force component 2 and the mandrel 1 are fixed by pins.

The five-component assembly 3 measures side force, normal force, pitch moment, roll moment, The yaw moment, side force measurement element, normal force measurement element, pitch moment measurement element, roll moment measurement element and yaw moment measurement element are installed on multiple rectangular beams, and the installation surface is parallel to the five-component assembly 3 axes.

The mounting surface of the pitching moment, normal force and rolling moment measuring element is located on a plane passing through the axis of the five-component assembly and perpendicular to the cross-section of the five-component assembly, and the pitching moment measuring element, the normal force measuring element and the rolling moment are measured The elements are all in one pair, and each pair of pitching moment measuring elements, normal force measuring elements and rolling moment measuring elements are arranged symmetrically with respect to the five-component axis; On the plane perpendicular to the force and rolling moment measuring elements, there is a pair of yaw moment measuring elements and normal force measuring elements, and each pair of yaw moment measuring elements and normal force measuring elements is arranged symmetrically with respect to the five-component axis .

Fig. 5 is a schematic structural diagram of a five-component component. As shown in Figure 5, the five-component component 3 is a hollow cylinder, and the lateral force measuring element, the normal force measuring element, the pitching moment measuring element, the rolling moment measuring element and the yaw moment measuring element are parallel to the five-component axis The directions of are distributed on the side walls of the five-component component 3 . The five-component component 3 is provided with a monolithic rectangular beam above and below, the extension line of the wide side of the monolithic rectangular beam section is perpendicular to the axis of the five-component component, the wide side is perpendicular to the axis of the five-component component, and the plane where the wide side of the monolithic rectangular beam is placed The pitching moment measuring element 6 and the normal force measuring element 7 are used to measure the pitching moment and the normal force, and the rolling moment measuring element 8 is placed on the plane where the narrow side is located to measure the rolling moment. There are three-piece rectangular beams on the left and right, and the yaw moment 9 and side force measuring element 10 are placed on the middle beam along the outside of the five-component component for measuring yaw moment and side force.

The protective cover 4 is fixed to the fixed end of the five-component component 3 and covers all side force elements, and its outer surface is parallel to the outer surface of the five-component component 3 . Fig. 6 is a schematic structural view of the protective cover, which is fastened with the five-component assembly 3 by screws to protect the measuring element.

Working principle: The air-floating high-precision axial force-strain balance mandrel 1, axial force component 2, five-component component 3, and protective sleeve 4 are coaxially installed, and the fixed end of the mandrel 1 is fixed on the test bracket. The movable end of the component component is fixedly connected with the measured model, so that the aerodynamic force borne by the measured model is transmitted to the five-component component 3, and the five-component component 3 then transmits the aerodynamic force to the axial force component 2, and the axial force component 2 passes through the core The shaft 1 is fixed to transmit the pneumatic force to the bracket; by filling the fixed end of the mandrel 1 with compressed gas, the space between the mandrel 1, the axial force component 2, the five-component component 3 and the model under test can be filled with compressed gas The suspension is formed without mutual influence. Under this assembly structure, the whole set of balances can accurately measure the six components of the aerodynamic load acting on the model, especially the axial force can have high measurement accuracy.

The measuring element of the axial force assembly 2 is the axial force measuring element 5. On the side wall of the axial force assembly 2, the structure adopts a vertical beam type, and the axial force is measured through the force transmission of the parallelogram structure; the measuring element of the five-component assembly 3 Including pitching moment 6, normal force 7, rolling moment 8, yaw moment 9 and lateral force 10 measuring elements, all located on the side wall of the five-component component 3, where pitching moment 6, normal force 7 and rolling moment 8 The measuring elements are two sets of single-piece rectangular beams arranged symmetrically up and down; the yaw moment 9 and the side force 10 are two sets of three-piece rectangular beams arranged symmetrically left and right. Measure the force and moment in six directions on the model under test by measuring the strain of six different measuring elements.

Parts not described in detail in the present invention belong to the common knowledge of those skilled in the art.

Claims (10)

1. a kind of air-flotation type strain balance, it is characterised in that：Axial force component including mandrel (1) and for measuring axial force (2), one end of mandrel (1) is sleeved on axial force component (2) inside, and middle part is fixedly connected with the end of axial force component (2), separately One end is stretched out outside axial force to be fixedly connected with test bracket, and the mandrel (1) is internally provided with hollow via-hole, and the hollow via-hole position It is blocked in the end of axial force component internal, another end opening, mandrel (1) side wall is equipped with multiple stomatas and hollow via-hole phase Even, compressed gas is filled with along mandrel (1) hollow via-hole, is formed between axial force component and mandrel (1) because being full of compressed gas It suspends, axial force component is for measuring axial force.

2. a kind of air-flotation type strain balance according to claim 1, it is characterised in that：The mandrel (1) includes that taper connects It connects section and waits straight sections, wait straight sections to be fixedly connected with axial force component (2) close to cone section position, taper connection section is logical with test bracket Cone match connection is crossed, chock is used in combination to tense.

3. a kind of air-flotation type strain balance according to claim 1, it is characterised in that：The axial force component (2) passes through Axial force measuration element measures axial force, and the axial force measuration element is mounted on the vertical beam type on the side wall of axial force component In structure, axis of the plane perpendicular to the axial force component (2) where axial force measuration element.

4. a kind of air-flotation type strain balance according to claim 1, it is characterised in that：Further include for measuring side force, normal direction Five component components (3) of power, pitching moment, rolling moment, yawing, axial force component (2) are sleeved in five component components (3) Portion, five component components (3) are sleeved on inside tested model；One end of five component components (3) is fixedly connected with tested model, the other end The other end opposite with the end that the axial force component (2) of set inside it is fixedly connected with mandrel (1) is fixedly connected, compressed gas Body is after mandrel (1) hollow via-hole is filled with, between axial force component (2) and five component components (3) also due to being full of compressed gas It is formed and is suspended, not to axial force when five component components (3) measure side force, normal force, pitching moment, rolling moment, yawing Load have an impact.

5. a kind of air-flotation type strain balance according to claim 4, it is characterised in that：The mandrel (1), axial force component (2) and five component component (3) coaxial placements.

6. a kind of air-flotation type strain balance according to claim 4, it is characterised in that：The five components component (3) and quilt Model is surveyed to fix by pin；The five components component (3) is fixed with axial force component (2) by pin；The axial force group Part (2) is fixed with mandrel (1) by pin.

7. a kind of air-flotation type strain balance according to claim 4, it is characterised in that：The five components component (3) passes through Side force measuring cell, normal force measuring cell, pitching moment measuring cell, rolling moment measuring cell and yawing measure member Part measures side force, normal force, pitching moment, rolling moment, yawing respectively, side force measuring cell, normal force measuring cell, Pitching moment measuring cell, rolling moment measuring cell and yawing measuring cell are mounted on multiple rectangular beams, mounting surface It is parallel to five component component (3) axis.

8. a kind of air-flotation type strain balance according to claim 7, it is characterised in that：The pitching moment, normal force and The mounting surface of rolling moment measuring cell is located across five component arrangement axis and the plane vertical with five component module transverse sections On, pitching moment measuring cell, normal force measuring cell and rolling moment measuring cell are 1 pair, and each pair of pitching moment measures Element, normal force measuring cell and rolling moment measuring cell are arranged both with respect to five component axisymmetricals；Yawing element, Side force measuring cell is arranged in the plane perpendicular with pitching moment, normal force and rolling moment measuring cell, yawing Measuring cell, normal force measuring cell are 1 pair, each pair of yawing measuring cell, normal force measuring cell, relative to five points Measure axisymmetrical arrangement.

9. a kind of air-flotation type strain balance according to claim 7, it is characterised in that：Mandrel (1) interior parallel in The axis and position for avoiding stomata and through-hole is furnished with multiple outlet holes, for axial force measuration element, side force measuring cell, normal direction Power measuring cell, pitching moment measuring cell, rolling moment measuring cell and yawing measuring cell outlet.

10. according to a kind of air-flotation type strain balance of claim 1~9 any one of them, it is characterised in that：It further include protective case (4), protective case (4) is fixed with five component component (3) fixing ends, covers all measuring cells, outer surface and five component components (3) outer surface is parallel.