Dual solid block contoured continuous semi-flexible wall nozzle and method of use

Abstract

This invention discloses a continuous semi-flexible wall nozzle with a dual-solid-block profile and its usage method, belonging to the field of wind tunnel equipment. The semi-flexible wall nozzle includes an outer frame, a throat block, and a downstream flexible plate. The throat block and the downstream flexible plate are connected to the outer frame via a drive rod. The downstream flexible plate is connected to the downstream end of the throat block. A downstream small flexible plate, a solid block panel, and an upstream small flexible plate are sequentially connected to the upstream end of the throat block. A panel adjustment frame is slidably mounted on the solid block panel. The downstream end of the panel adjustment frame is drivenly connected to the throat block via a connecting rod, and the upstream end of the panel adjustment frame is rotatably connected to the outer frame. The other end of the connecting rod is rotatably connected to the upstream end of the throat block. The upstream portion of the throat block is connected to the outer frame via a drive rod, and the downstream end of the throat block is also connected to the outer frame via a drive rod. This invention solves the contradiction between profile continuity and profile stiffness maintenance in existing semi-flexible wall nozzle technology, simplifies control, effectively shortens the Mach number variation time, and thus ensures wind tunnel testing efficiency.

Description

Technical Field

[0001] This invention relates to the field of wind tunnel equipment, specifically to a double-solid-block continuous semi-flexible wall nozzle and its usage method. Background Technology

[0002] In existing wind tunnel design technology, nozzles can be classified into solid block nozzles, semi-flexible wall nozzles, and fully flexible wall nozzles. Solid block nozzles have a simple structure, but their disadvantage is that they can only achieve one Mach number per solid block, and there are significant intervals between Mach numbers, which cannot meet the needs of continuous variable Mach number testing. Semi-flexible wall nozzles consist of rigidly moving solid blocks and elastically deformable flexible plates. The upstream contraction section of the profile is the solid block region (generally including the solid block faceplate and throat), thus forming a large curvature profile and shortening the overall nozzle length. However, the overlap between the solid block faceplate and the throat creates a mid-profile overlap seam, which affects the flow field. Fully flexible wall nozzles have the advantages of a wide Mach number adjustment range and good flow field quality, but their disadvantages include a longer flexible plate length, a larger number of drive points, and a complex control system.

[0003] Semi-flexible wall nozzles, due to their profile curves being controllable by a few actuators and their overall rigidity being good, can achieve continuous Mach number variations during wind tunnel operation and have been widely used in various types of wind tunnels. In existing semi-flexible wall nozzles, to overcome the aforementioned problem of central overlap seams, patents such as CN114894425A (published as "Large Transonic Wind Tunnel Semi-flexible Wall Nozzle") employ a single-fixed-block semi-flexible wall nozzle design, replacing the fixed-block panel with a flexible plate, retaining only the throat block as the sole fixed block. While this design ensures profile continuity, it reduces profile stiffness. The added flexible plate area requires a synchronously configured drive mechanism, increasing control difficulty and potentially prolonging the Mach number variation time, thus reducing wind tunnel testing efficiency. Summary of the Invention

[0004] Therefore, to resolve the contradiction between profile continuity and profile stiffness maintenance in existing semi-flexible wall nozzle technology, this invention provides a dual-fixed-block profile continuous semi-flexible wall nozzle and its usage method. This dual-fixed-block profile continuous semi-flexible wall nozzle can achieve profile continuity while maintaining profile stiffness. Utilizing the high rigidity of the dual-fixed-block structure (throat block and fixed-block panel) and the linkage transmission between the two fixed blocks, no drive rod is needed in front of the throat block, simplifying and facilitating profile control, effectively shortening the Mach number change time, and thus ensuring wind tunnel testing efficiency.

[0005] On one hand, the present invention provides a dual-fixed-block continuous semi-flexible wall nozzle, including an outer frame, a throat block, and a downstream flexible plate. The throat block and the downstream flexible plate are respectively connected to the outer frame via a drive rod. The downstream flexible plate is connected to the downstream end of the throat block. A downstream small flexible plate of a specified thickness, a fixed block panel, and an upstream small flexible plate are sequentially fixedly connected to the upstream end of the throat block. The connection is a smooth transition (i.e., the two surfaces at the connection do not overlap and are treated with a smooth transition). A panel adjustment bracket is slidably installed on the inner side (the side closest to the outer frame) of the fixed block panel. The downstream end of the panel adjustment bracket is connected to the throat block via a connecting rod, the upstream end of the panel adjustment bracket is rotatably connected to the outer frame, and the other end of the connecting rod is rotatably connected to the upstream end of the throat block. The upstream portion of the throat block is connected to the outer frame via a first drive rod, and the downstream end of the throat block is connected to the outer frame via a second drive rod. The upstream portion of the upstream flexible plate overlaps with the upstream plate, which is a fixing component extending upstream of the nozzle into the nozzle.

[0006] Optionally, a rolling pressure roller is installed upstream of the outer frame, which presses against the upstream small flexible plate; the rotation axis of the pressure roller is the same as the rotation axis of the panel adjustment frame connected to the outer frame.

[0007] Optionally, the inner side of the fixed block panel is slidably connected to the panel adjustment frame via a slider assembly. The slider assembly includes a slide rail and a slider that matches the slide rail. The slide rail is fixedly installed on the panel adjustment frame, and the slider is fixedly installed on the fixed block panel.

[0008] Optionally, when the connecting rod and the first driving rod are in their initial positions, the extension line of the connecting rod is perpendicular to the downstream flexible plate, and they maintain an approximately perpendicular relationship during the movement.

[0009] Optionally, the downstream flexible plate is the segment with the greatest curvature in the airflow channel profile curve.

[0010] Optionally, the upstream end of the downstream flexible plate is fixedly connected to the downstream end of the throat block, the downstream end of the downstream flexible plate is fixedly connected to the outer frame, and the inner side of the flexible plate (the side closer to the outer frame) is connected to the outer frame through a third drive rod and a fourth drive rod.

[0011] On the other hand, the present invention provides a method for using the aforementioned dual-solid-block profile continuous semi-flexible wall nozzle, comprising the following: Based on the airflow channel profile curve, the third and fourth drive rods are driven to adjust the profile of the downstream flexible plate; The throat block is rotated by the first and second drive rods to adjust its shape. During the process of the first drive rod driving the throat block to rotate, the rotation of the throat block pushes or pulls the downstream small flexible plate, the fixed block panel and the upstream small flexible plate to move, wherein the upstream small flexible plate slides on the upstream plate under the support of the pressure roller; As the throat block rotates, it drives the connecting rod to swing. The swing of the connecting rod drives the panel adjustment frame to rotate. The rotation of the panel adjustment frame drives the fixed panel to rotate or slide. The coordinated operation of the upstream flexible plate, the solid block panel, the downstream flexible plate, the throat block, and the downstream flexible plate completes the change of the nozzle airflow channel profile curve.

[0012] The present invention has the following advantages: The dual-solid-block profile continuous semi-flexible wall nozzle of this invention can achieve profile continuity while maintaining profile stiffness. Utilizing the high rigidity of the dual-solid-block (throat block and solid-block panel) structure, the stiffness of the semi-flexible wall nozzle is maintained. By employing a linkage between the two solid blocks (throat block and solid-block panel), no drive rod is needed in front of the throat block, simplifying and facilitating profile control, effectively shortening the Mach number change time, and thus ensuring wind tunnel testing efficiency.

[0013] Compared to traditional semi-flexible wall nozzles, the dual-solid-block profile continuous semi-flexible wall nozzle adopts a downstream small flexible plate connecting the solid block panel and the throat block, avoiding the middle overlap seam caused by the overlap between the solid block panel and the throat block, which is more conducive to ensuring the flow field quality of the airflow.

[0014] Meanwhile, the dual-solid-block profile continuous semi-flexible wall nozzle has fewer control objects compared to the traditional semi-flexible wall nozzle, making profile control simpler and shortening the Mach number change time. Furthermore, the reduction in control objects is accompanied by a reduction in drive rods, which lowers the overall failure rate and cost. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the dual-solid-block continuous semi-flexible wall nozzle described in this invention; Figure 2 This is a schematic diagram of the structure of the dual-solid block profile continuous semi-flexible wall nozzle profile assembly described in this invention (the arrows in the diagram indicate the direction of airflow). Figure 3 This is an isometric schematic diagram of the connecting rod region of the double-solid block continuous semi-flexible wall nozzle described in this invention; Figure 4 This is a schematic diagram of the thickness design process for the downstream flexible plate; In the diagram: 1. Outer frame; 2. Upstream flexible plate; 3. Downstream flexible plate; 4. Downstream flexible plate; 5. Pressure roller; 6. Fixed block panel; 7. Slider assembly; 8. Panel adjustment frame; 9. Connecting rod; 10. Throat block; 11. First drive rod; 12. Second drive rod; 13. Third drive rod; 14. Fourth drive rod; 15. Upstream plate. Detailed Implementation

[0016] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0017] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0018] As described in the background section, semi-flexible wall nozzles, due to their profile curves being controllable by a few actuators and their overall rigidity being good, can achieve continuous Mach number variations during wind tunnel operation and have been widely used in various types of wind tunnels. In existing semi-flexible wall nozzles, to overcome the aforementioned problem of central overlap seams, patents such as CN114894425A (patent title: Semi-flexible wall nozzle for large transonic wind tunnels) employ a single-fixed-block semi-flexible wall nozzle design, replacing the fixed-block panel with a flexible plate, retaining only the throat block as the sole fixed block. While this design ensures continuous profile contours, it reduces profile stiffness. The added flexible plate area requires a synchronously configured drive mechanism, increasing control complexity and potentially prolonging the Mach number variation time, thus reducing wind tunnel testing efficiency.

[0019] For the reasons mentioned above, this embodiment provides a continuous semi-flexible wall nozzle with a dual-solid-block profile, such as... Figures 1-3 As shown, it includes an outer frame 1, a throat block 10, and a downstream flexible plate 4. The downstream flexible plate 4 is connected downstream of the throat block 10 (downstream or upstream is referenced to the direction of airflow in the nozzle, and the airflow direction is as follows). Figure 2 As indicated by the middle arrow, the upstream end of the throat block 10 is sequentially fixedly connected to a downstream flexible plate 3 of a specified thickness, a fixed block panel 6, and an upstream flexible plate 2, with a smooth transition at the connection point (i.e., the two surfaces at the connection point do not overlap and are treated as a smooth transition); the downstream flexible plate is the section with the greatest curvature in the airflow channel profile curve.

[0020] A panel adjustment bracket 8 is slidably installed on the inner side of the fixed block panel 6 (the inner side refers to the side close to the outer frame). The downstream end of the panel adjustment bracket 8 is connected to the throat block 10 through a connecting rod 9. One end of the connecting rod is rotatably connected to the panel adjustment bracket 8 through a rotating shaft. The upstream end of the panel adjustment bracket 8 is rotatably connected to the outer frame. The other end of the connecting rod 9 is rotatably connected to the upstream end of the throat block through a rotating shaft. The upstream portion of the throat block 10 is connected to the outer frame 1 via the first drive rod 11, and the downstream end of the throat block 10 is connected to the outer frame 1 via the second drive rod 12. The upstream portion of the upstream flexible plate 2 overlaps with the upstream plate 15, which is a fixing member extending upstream of the nozzle into the nozzle. The overlap is located at the front end of the nozzle and will not affect the shape of the nozzle.

[0021] A rolling pressure roller 5 is installed upstream of the outer frame 1, and the pressure roller 5 presses against the upstream small flexible plate 2; the rotation axis of the pressure roller 5 is the same axis as the rotation axis of the panel adjustment frame 8 connected to the outer frame 1.

[0022] The upstream end of the downstream flexible plate 4 is fixedly connected to the downstream end of the throat block 10, and the downstream end of the downstream flexible plate 4 is fixedly connected to the outer frame. The inner side of the flexible plate (the side closer to the outer frame) is connected to the outer frame 1 through the third drive rod 13 and the fourth drive rod 14.

[0023] The aforementioned technical features maintain nozzle profile stiffness while ensuring profile continuity; the use of a throat block and a fixed plate to achieve two double-fixed-block profiles maintains profile stiffness; to enable linkage between the throat block and the fixed plate, they are connected by a connecting rod, and the power is transmitted through the swing of the connecting rod, adapting to changes in the position of the throat block and the fixed plate during linkage; furthermore, the connecting rod transmission eliminates the need for a drive rod upstream of the throat block, simplifying and facilitating profile control, effectively shortening Mach number variation time, and thus ensuring wind tunnel testing efficiency. To achieve continuous profiles between the throat block and the fixed block panel, a downstream flexible plate is used to connect them. This downstream flexible plate is fixed to achieve continuous profiles. At the same time, the downstream flexible plate is located in the section with the greatest curvature in the airflow channel profile curve, which can adapt to changes in curvature. The downstream flexible plate, together with the throat block and the fixed block panel connected by the connecting rod, can replace the traditional overlapping connection method in this section, thereby avoiding the discontinuity of the profile caused by the traditional overlapping and the problem that the overlapping seam will affect the flow field of the airflow.

[0024] In the above technical features, the upstream flexible plate is fixedly connected to the solid block panel. The upstream flexible plate can adapt to changes in the curvature of the surface at that location, and the surface profile is continuous. In order to adapt to the movement of the upstream flexible plate when adjusting the surface, the front part of the upstream flexible plate overlaps with the upstream plate of the nozzle. The position of this overlap will not affect the continuity of the entire surface profile because the overlap is outside the effective profile (the effective profile is the part of the surface profile that actually participates in controlling the airflow). The overlap can adapt to the displacement changes of the upstream flexible plate. At the same time, the use of a rotating pressure roller can ensure that the upstream flexible plate and the upstream plate are tightly fitted, achieving effective overlap and preventing the upstream flexible plate from separating from the upstream plate and affecting the surface profile of the upstream end of the solid block panel.

[0025] Among the above technical features, by adopting a sliding connection between the fixed block panel and the panel adjustment frame, it is possible to achieve relative movement between the panel adjustment frame and the fixed block panel when the connecting rod drives the panel adjustment frame, so as to adjust the overall surface contour.

[0026] In order to enable relative movement between the panel adjustment frame and the fixed panel, in one embodiment, the inner side (the side closer to the outer frame) of the fixed panel 6 is slidably connected to the panel adjustment frame 8 via a slider assembly 7. The slider assembly 7 includes a slide rail and a slider that matches the slide rail. The slide rail is fixedly installed on the panel adjustment frame, and the slider is fixedly installed on the fixed panel.

[0027] To improve the rigidity of the connection between the throat block and the panel adjustment frame, in one embodiment, when the connecting rod 9 and the first drive rod 11 are in the initial position (i.e., the design position) of the nozzle, the connecting rod and the first drive rod are parallel to each other and their extension lines are perpendicular to the downstream small flexible plate. The intersection of the extension lines and the frame is the installation position of the first drive rod. During the process of changing the Mach number of the nozzle, the extension line of the connecting rod and the downstream small flexible plate maintain an approximately perpendicular relationship (not requiring absolute perpendicularity), while an angle is generated between the connecting rod and the first drive rod.

[0028] In the field of wind tunnel equipment design, the input condition for nozzle design is the airflow channel profile curve given by aerodynamics. This curve changes with Mach number, and it has a curvature portion that changes with time and a curvature portion that remains constant with time. The dual-solid-block profile continuous semi-flexible wall nozzle described in this embodiment uses the time-invariant curvature portion as the solid block profile, and the curve between the two solid block profiles is the downstream flexible plate 3. Since the curve to which the downstream flexible plate belongs is the segment with the greatest curvature in the profile curve, previous dual-solid-block semi-flexible wall nozzles used an overlapping form to avoid plate breakage, resulting in an overlapping seam in the middle of the profile. To overcome the problem of the overlapping seam in the middle, this invention designs a downstream flexible plate connecting the solid block panel and the throat block. The length of the downstream flexible plate can be obtained by extending the curve it belongs to, while the thickness needs to be determined through simulation iteration. Excessive thickness leads to poor plate flexibility and the risk of plate breakage, while insufficient thickness leads to weak plate stiffness and the risk of plate instability. For this reason, in one embodiment, as... Figure 4 As shown, the thickness of the downstream flexible plate 3 is calculated as follows: S100. Establish a finite element model of the nozzle at the maximum Mach number, making the thickness of the downstream flexible plate a variable (maximum positive bending). S200. Establish a finite element model of the nozzle at the minimum Mach number, making the thickness of the downstream flexible plate a variable (maximum reverse bending). S300, Preset a thickness, which can be set to a large value; S400. Input the thickness into both models and calculate using finite element software; S500. Check the calculation results of the two models, extract the maximum stress value between them, and determine whether it is greater than the allowable stress of the material. S600. If the result is greater than the allowable stress, reduce the thickness and return to step S400. S700 If the result is less than or equal to the allowable stress, then the current thickness is the optimal downstream flexible plate thickness.

[0029] The aforementioned technical features can determine the appropriate thickness of the downstream flexible plate. A downstream flexible plate with an appropriate thickness avoids the risk of plate breakage. Based on this thickness, the downstream flexible plate, throat block, fixed plate panel, and the throat block and fixed plate panel are connected by a linkage drive, which can replace the traditional overlapping design at this point and solve the problem of discontinuous surface caused by overlapping, which affects the flow field of airflow.

[0030] In another embodiment, a method of using the aforementioned dual-solid-block profile continuous semi-flexible wall nozzle is provided, comprising the following: Based on the airflow channel profile curve, the third and fourth drive rods are driven to adjust the profile of the downstream flexible plate; The throat block is rotated by the first and second drive rods to adjust its shape. During the process of the first drive rod driving the throat block to rotate, the rotation of the throat block pushes or pulls the downstream small flexible plate, the fixed block panel and the upstream small flexible plate to move, wherein the upstream small flexible plate slides on the upstream plate under the support of the pressure roller; As the throat block rotates, it drives the connecting rod to swing. The swing of the connecting rod drives the panel adjustment frame to rotate. The rotation of the panel adjustment frame drives the fixed panel to rotate or slide. The coordinated operation of the upstream flexible plate, the solid block panel, the downstream flexible plate, the throat block, and the downstream flexible plate completes the change of the nozzle airflow channel profile curve.

[0031] The aforementioned technical features enable simple and convenient control of the wind tunnel profile, effectively shortening the Mach number variation time and thus ensuring the efficiency of wind tunnel testing.

[0032] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A continuous semi-flexible wall nozzle with a dual-solid-block profile, comprising an outer frame, a throat block, and a downstream flexible plate, wherein the throat block and the downstream flexible plate are respectively connected to the outer frame via a drive rod, and the downstream flexible plate is connected to the downstream end of the throat block, characterized in that: The upstream end of the throat block is sequentially fixedly connected to a downstream flexible plate of a specified thickness, a fixed block panel, and an upstream flexible plate. A panel adjustment frame is slidably installed on the inner side of the fixed block panel. The downstream end of the panel adjustment frame is connected to the throat block via a connecting rod. The upstream end of the panel adjustment frame is rotatably connected to the outer frame. The other end of the connecting rod is rotatably connected to the upstream end of the throat block. The upstream portion of the throat block is connected to the outer frame via a first drive rod, and the downstream end of the throat block is connected to the outer frame via a second drive rod. The upstream portion of the upstream flexible plate overlaps with the upstream plate, which is a fixing component extending upstream of the nozzle into the nozzle. The inner side of the fixed block panel is slidably connected to the panel adjustment frame via a slider assembly. The slider assembly includes a slide rail and a slider that matches the slide rail. The slide rail is fixedly installed on the panel adjustment frame, and the slider is fixedly installed on the fixed block panel. The downstream flexible plate is the segment with the greatest curvature in the airflow channel profile curve. The thickness of the downstream flexible plate is calculated as follows: S100. Establish a finite element model of the nozzle at the maximum Mach number, making the thickness of the downstream flexible plate a variable. S200. Establish a finite element model of the nozzle at the minimum Mach number, making the thickness of the downstream flexible plate a variable. S300, preset a thickness; S400. Input the thickness into both models and calculate using finite element software; S500. Check the calculation results of the two models, extract the maximum stress value between them, and determine whether it is greater than the allowable stress of the material. S600. If the result is greater than the allowable stress, reduce the thickness and return to step S400. S700. If the result is less than or equal to the allowable stress, then the current thickness is taken as the downstream flexible plate thickness.

2. The dual-solid-block profile continuous semi-flexible wall nozzle according to claim 1, characterized in that: A rolling pressure roller is installed upstream of the outer frame, which presses against the upstream small flexible plate.

3. The dual-solid-block profile continuous semi-flexible wall nozzle according to claim 2, characterized in that: The shaft of the pressure roller is the same as the shaft connecting the panel adjustment frame to the outer frame.

4. The dual-solid-block profile continuous semi-flexible wall nozzle according to claim 2, characterized in that: The upstream end of the downstream flexible plate is fixedly connected to the downstream end of the throat block, and the downstream end of the downstream flexible plate is fixedly connected to the outer frame. The inner side of the flexible plate is connected to the outer frame through a third drive rod and a fourth drive rod.

5. A method of using the dual-solid-block profile continuous semi-flexible wall nozzle as described in any one of claims 1-4, characterized in that, Including the following: Based on the airflow channel profile curve, the third and fourth drive rods are driven to adjust the profile of the downstream flexible plate; The throat block is rotated by the first and second drive rods to adjust its shape. During the process of the first drive rod driving the throat block to rotate, the rotation of the throat block pushes or pulls the downstream small flexible plate, the fixed block panel and the upstream small flexible plate to move, wherein the upstream small flexible plate slides on the upstream plate under the support of the pressure roller; As the throat block rotates, it drives the connecting rod to swing. The swing of the connecting rod drives the panel adjustment frame to rotate. The rotation of the panel adjustment frame drives the fixed panel to rotate or slide. The coordinated operation of the upstream flexible plate, the solid block panel, the downstream flexible plate, the throat block, and the downstream flexible plate changes the nozzle airflow channel profile curve.

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