CN111896215A - A model support device for releasing two rigid body degrees of freedom of a wind tunnel test model - Google Patents

Abstract

The invention discloses a model support device for releasing two rigid body degrees of freedom of a wind tunnel test model, comprising upper and lower airfoils, two guide rail mounting seats, upper and lower hydraulic dampers, guide rails, a pitch limit structure and a motion realization mechanism , grating ruler, the upper end of the lower airfoil is connected with the lower end of the guide rail through the guide rail mounting seat, the lower end of the upper airfoil is connected with the upper end of the guide rail through the guide rail mounting seat, and the upper and lower ends of the guide rail are respectively installed with upper and lower hydraulic dampers, movement The realization mechanism is slidably connected with the guide rail through the guide rail, the test model is connected with the motion realization mechanism, and a pitch limit structure is installed on the motion realization mechanism to limit the pitch angle of the test model. The support device has the advantages of strong practicability, ingenious structure, and easy disassembly and assembly, avoids the coupling problem of the movement frequency of the gust generator, the vibration frequency of the model and the natural frequency of the support device, and reduces the blockage of the model support device in the gust test. Weak strength, improper model protection measures, etc.

Description

A model support device for releasing two rigid body degrees of freedom of a wind tunnel test model

technical field

The invention relates to a model support device for releasing two rigid body degrees of freedom of a wind tunnel test model.

Background technique

Gusts, also known as gusts or atmospheric turbulence, are deterministic wind disturbances with greater intensity in the atmosphere. When the aircraft encounters a gust of wind, the airframe will generate additional unsteady aerodynamic forces and moments, which will adversely affect the flight performance of the aircraft. Modern civil aircraft, such as large passenger aircraft, emphasize economy, comfort, safety, and reliability, and require high aerodynamic efficiency and low structural weight. Usually, large aspect ratio wings are used, which are widely used in structural materials. Composite materials, the aircraft wing has greater flexibility, so the aircraft is more sensitive to gust response, and gust loads, especially vertical discrete gust loads, often become the most serious flight loads, which are critical to the comfort, safety, and economy of large passenger aircraft. performance and reliability have a serious impact. When the aircraft encounters the unsteady aerodynamic load brought by the low-intensity gust of wind, it will cause the aircraft to turbulence, bring tension to the passengers, reduce the comfort of the civil aircraft, and even cause personal injury to the passengers; when the aircraft encounters high-intensity unsteady winds Under aerodynamic loads, the local overload of the aircraft can reach more than 2.5g, which will damage the aircraft structure or cause fatigue cracks, affect the service life of the aircraft, and have a great impact on the safety and reliability of the aircraft. For example, in 2016, The Il-18 passenger plane suffered strong gusts when it landed in Yakutia. Because the plane was not equipped with a gust mitigation system, the violent turbulence and hard landing impact caused serious injuries to 16 people and serious damage to the body structure. Civil aircraft are extremely sensitive to fatigue damage caused by gust load, and gust load spectrum is an important scientific basis for the reliability design of aircraft structure life. Due to the gust load problem, in order to ensure the strength of the aircraft, it is necessary to strengthen the aircraft structure, resulting in an increase in the weight of the aircraft, which in turn affects the economy of the aircraft.

Domestic and foreign civil aircraft airworthiness regulations have made clear regulations on gust load. Both the Chinese airworthiness standard for transport aircraft (CCAR-25-R4) and the US Aviation Regulations (FAR-25) provide corresponding regulations for the design criteria for gust loads. Accurately predicting gust loads is an important task that must be done in the aircraft design stage. The development of my country's large-scale civil aircraft has put forward an urgent need for the development of advanced large-scale high and low-speed wind tunnel gust test technology. In addition to the forecast requirements for gust loads required for aircraft strength design, gust load mitigation techniques need to be validated.

In the gust test, the model support device is one of the key technologies affecting the test results. In the full-model gust test, it is required to simulate the free flight state of the real aircraft as much as possible, thereby providing more degrees of freedom for the model. For example, some gust forms may be caused by the coupling of rigid body motion modes and structural elastic modes, and the dynamic characteristics of such gust forms are affected by the restraining loads of the support system, resulting in serious deviations in the gust test results. Therefore, in the gust test, it is necessary to fully consider the rigid body degrees of freedom in the heave and pitch directions of the model, and it is necessary to design a model support device that can realize the heave and pitch two rigid body degrees of freedom of the model.

SUMMARY OF THE INVENTION

In order to solve the above problems, the purpose of the present invention is to provide a model support device that releases two rigid body degrees of freedom of a wind tunnel test model. The invention effectively solves the disadvantage that the full-mode support device of the wind tunnel gust test cannot realize the release of the two rigid body degrees of freedom of the heave and pitch of the model; avoids the coupling problem of the movement frequency of the gust generator, the vibration frequency of the model and the natural frequency of the support device; reduces the In the gust test, the model support device has a large blocking degree, weak strength, and improper model protection measures.

The present invention is mainly achieved through the following technical solutions: a model support device for releasing two rigid body degrees of freedom of a wind tunnel test model, comprising an upper airfoil, two guide rail mounting seats, an upper hydraulic damper, a guide rail, and a pitch limit structure , Motion realization mechanism, grating ruler, lower hydraulic damper and lower airfoil, the lower end of the lower airfoil is connected with the lower wall of the wind tunnel, and the upper end of the lower airfoil is connected with the lower end of the guide rail through the guide rail mounting seat, so The upper end of the upper airfoil is connected with the upper hole wall of the wind tunnel, the lower end of the upper airfoil is connected with the upper end of the guide rail through the guide rail mounting seat, and the upper and lower ends of the guide rail are respectively installed with an upper hydraulic damper and a lower hydraulic damper. The realization mechanism is slidably connected to the guide rail through the guide rail, the test model is connected to the motion realization mechanism, and a pitch limit structure is installed on the motion realization mechanism to limit the pitch angle of the test model, and a grating ruler is installed on the guide rail.

The present invention also has the following technical features:

1. The motion realization mechanism includes a model connector, two turntable bearings, an adapter frame, two impact blocks and a rolling bearing group. The inner side wall of the model connector rotates with the outer side wall of the adapter frame through the two turntable bearings. Connection, the inner side wall of the adapter frame is installed with a ring of rolling bearing group, which is connected with the guide rail through the rolling bearing group. There are also two impact blocks installed on the inner side wall of the adapter frame, the positions of which correspond to the upper hydraulic damper and the lower hydraulic damper .

2. There is a pitch angle limit hole on the model connector.

Advantages and beneficial effects of the present invention: the supporting device has the advantages of strong practicability, ingenious structure, easy disassembly and assembly, etc. The motion realization mechanism of the model supporting method of the two rigid body degrees of freedom of the test model is located on the guide rail, avoiding the gust generator The coupling problem of the motion frequency, the vibration frequency of the model and the natural frequency of the support device reduces the problems of large blockage, weak strength and improper model protection measures of the model support device in the gust test.

Description of drawings:

FIG. 1 is a schematic diagram of the overall structure of the model supporting device of the present invention.

Fig. 2 is a sectional view of the mechanism for realizing the movement of the device.

Figure 3 is a side view of the rolling bearing set.

Among them, 1, upper airfoil, 2, guide rail mounting seat, 3, upper hydraulic damper, 4, guide rail, 5, test model, 6, pitch limit structure, 7, motion realization mechanism, 8, grating ruler, 9, Lower hydraulic damper, 10, Lower airfoil, 21, Model connector, 22, Slewing bearing, 23, Adapter frame, 24, Impact stop, 25, Rolling bearing set, 31, Disc spring, 32, Pulley seat, 33 , Angular contact bearings.

Detailed ways:

The present invention will be further described below according to the accompanying drawings of the description:

Example 1

As shown in Figure 1-3, a model support device that releases the two rigid body degrees of freedom of the wind tunnel test model, including an upper airfoil 1, 2 guide rail mounts 2, an upper hydraulic damper 3, a guide rail 4, and a pitch limit Structure 6, motion realization mechanism 7, grating ruler 8, lower hydraulic damper 9, lower airfoil 10, the lower end of the lower airfoil 10 is connected with the lower wall of the wind tunnel, and the upper end of the lower airfoil 10 is installed through the guide rail The seat 2 is connected with the lower end of the guide rail 4, the upper end of the upper airfoil 1 is connected with the upper hole wall of the wind tunnel, the lower end of the upper airfoil 1 is connected with the upper end of the guide rail 4 through the guide rail mounting seat 2, and the upper end of the guide rail 4 and the upper end of the guide rail 4 are connected. The upper hydraulic damper 3 and the lower hydraulic damper 9 are respectively installed at the lower end, the motion realization mechanism 7 is slidably connected with the guide rail 4 through the guide rail 4, the test model 5 is connected with the motion realization mechanism 7, and a pitch limit is installed on the motion realization mechanism 7. In structure 6, the pitch angle of the test model 5 is limited, and a grating ruler 8 is installed on the guide rail 4. The motion realization mechanism 7 includes a model connector 21 , two turntable bearings 22 , an adapter frame 23 , two impact blocks 24 and a rolling bearing group 25 . The outer side wall of the connecting frame 23 is rotatably connected, and the inner side wall of the connecting frame 23 is installed with a ring of rolling bearing group 25, which is connected with the guide rail 4 through the rolling bearing group 25, and two impact blocks 24 are also installed on the inner side wall of the connecting frame 23. The positions correspond to the upper hydraulic damper 3 and the lower hydraulic damper 9 . The model connector 21 is provided with a pitch angle limit hole, which can realize a pitch angle change of -30° to 30°.

As shown in Figure 1, during the test, first connect the lower airfoil to the lower wall of the wind tunnel, install the guide rail on the lower airfoil, pass the motion realization mechanism 7 through the guide rail 4, and then connect the test model 5 through the model connector 21 is connected with the motion realization mechanism 7, and the upper airfoil 1 is connected with the guide rail 4, and finally the upper airfoil 1 is fixed with the upper wall of the wind tunnel. The airfoil design of the support device is carried out to reduce the blocking degree; the strength analysis is carried out to ensure that the strength of the device meets the test requirements, and the model protection problem is solved by installing hydraulic dampers at the upper and lower ends.

As shown in FIGS. 2 to 3 , the rolling bearing group 25 and the slewing bearing 22 respectively release the two rigid body degrees of freedom of the test model 5 up and down and pitch, and realize the free movement of the test model 5 in the up and down and pitch directions. The rolling bearing group 25 and the adapter frame 23 are connected by a bolt group to realize the ups and downs of the test model 5 along the guide rail 4; the inner ring of the turntable bearing 22 is connected with the model connector 21 by a bolt group, and the model connector 21 has a pitch angle limit Hole, the pitch angle can be changed from -30° to 30°. The outer side wall of the adapter frame 23 and the outer ring 22 of the slewing bearing are connected by a bolt group, and the relative rotation of the slewing bearing 22 and the linear motion of the rolling bearing group 25 along the guide rail 4 are combined to the test model 5, and the ups and downs of the test model 5 are realized. Free movement in the pitch direction; in the later test, the fluid-structure coupling analysis of the device was carried out, and the device was locally strengthened according to the analysis results to ensure that the movement frequency of the gust generator, the vibration frequency of the model and the natural frequency of the support device did not coincide, and no resonance occurred; The airfoil design of the support device is carried out to reduce the blocking degree; the strength analysis is carried out to ensure that the strength of the device meets the test requirements; the model protection problem is solved by means of a pitch angle limit mechanism and a hydraulic damper for ups and downs. The supporting device has the advantages of strong practicability, ingenious structure, convenient disassembly and assembly, and the like.

Claims (3)

1. The utility model provides a release model strutting arrangement of two rigid body degrees of freedom of wind tunnel test model, includes wing section (1), 2 guide rail mount pad (2), goes up hydraulic damper (3), guide rail (4), every single move limit structure (6), motion realization mechanism (7), grating chi (8) and lower hydraulic damper (9) and wing section (10) down, its characterized in that: lower extreme and the wind-tunnel of lower wing section (10) hole wall under be connected, the upper end of lower wing section (10) is connected with the lower extreme of guide rail (4) through guide rail mount pad (2), the upper end of going up wing section (1) be connected with the wind-tunnel hole wall on, the lower extreme of going up wing section (1) is connected with the upper end of guide rail (4) through guide rail mount pad (2), hydraulic damper (3) and lower hydraulic damper (9) are installed respectively to the upper end and the lower extreme of guide rail (4), motion realization mechanism (7) pass guide rail (4) and guide rail (4) sliding connection, test model (5) are connected with motion realization mechanism (7), install every single move limit structure (6) on motion realization mechanism (7), restrict the every single move angle of test model (5), install grating chi (8) on guide rail (4).

2. The model supporting device for releasing two rigid body degrees of freedom of a wind tunnel test model according to claim 1, is characterized in that: motion realization mechanism (7) including model connecting piece (21), two carousel bearing (22), switching frame (23), 2 impact dog (24) and rolling bearing group (25), the inside wall of model connecting piece (21) is rotated through the lateral wall of two carousel bearing (22) with switching frame (23) and is connected, round rolling bearing group (25) are installed to the inside wall of switching frame (23), and be connected with guide rail (4) through rolling bearing group (25), 2 impact dog (24) are still installed to switching frame (23) inside wall, its position is corresponding with last hydraulic damper (3) and lower hydraulic damper (9).

3. The model supporting device for releasing two rigid body degrees of freedom of a wind tunnel test model according to claim 2, is characterized in that: the model connecting piece (21) is provided with a pitching angle limiting hole.

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