Design method for hypersonic silent nozzle suction channel and suction device

Abstract

The present application belongs to the technical field of hypersonic wind tunnel equipment construction, and discloses a design method for a hypersonic silent nozzle suction flow channel and a suction device. The design method is based on boundary layer thickness equivalent extrapolation for suction flow channel design. Numerical simulation is used with the nozzle outlet and the contraction section boundary layer thickness as the design input parameters. One-dimensional pipe flow theory is adopted, the lip vertex is the stagnation point, and there is no flow separation before the suction throat. The virtual interface between the inner and outer flows is reconstructed to ensure that the stagnation point position of the suction lip front edge is relatively fixed in a wide range of operation under the single-point design condition. The wall boundary layer is effectively sucked, and the upstream turbulent boundary layer disturbance of the nozzle is eliminated. The suction device is arranged upstream of the nozzle throat, and an annular suction pipe is arranged. The suction ring cavity is connected to the collection branch pipe, and the end of each collection branch pipe is inserted into the collection ring pipe. The incoming flow disturbance is suppressed, the flow is stabilized, the wide range operation requirement is met, and the engineering practical value is achieved.

Description

Technical Field

[0001] This invention belongs to the technical field of hypersonic wind tunnel equipment construction, specifically relating to a design method and suction device for a hypersonic silent nozzle suction channel. Background Technology

[0002] Silent wind tunnels are fundamental tools for boundary layer transition research and are crucial for aircraft drag reduction and heat protection design. Silent nozzles are essential components for achieving a silent flow field in silent wind tunnels. The key technology in silent nozzle design is its boundary layer laminar fluidization design technology, with the core technology being the nozzle's expansion section profile and contraction section suction system.

[0003] Installing a boundary layer suction device in the contraction section upstream of the nozzle throat to remove the turbulent boundary layer that has developed in the upstream tunnel wall of the contraction section, allowing the boundary layer on the nozzle wall to start developing again, is one of the important methods to maintain the laminar flow state of the nozzle boundary layer.

[0004] Because the boundary layer on the wall of the nozzle expansion section is highly sensitive to disturbances in the contraction section suction system, the quality of the suction system design can negatively impact its performance. Therefore, the suction channel of the boundary layer suction device requires careful design. Factors such as suction flow rate, lip geometry, lip bluntness, and lip position all affect the flow field noise characteristics of the test section.

[0005] Currently, there is an urgent need to develop a design method and suction device for the suction channel of hypersonic silent nozzles. Summary of the Invention

[0006] One technical problem to be solved by the present invention is to provide a design method for a suction channel of a hypersonic silent nozzle, and another technical problem to be solved by the present invention is to provide a suction device for a hypersonic silent nozzle, so as to overcome the defects of the prior art.

[0007] The present invention provides a design method for a hypersonic silent nozzle suction channel, the design method comprising the following steps: S10. Obtain the profile of the hypersonic nozzle without a suction system, and obtain the flow field parameters inside the hypersonic nozzle through numerical simulation. The flow field parameters include the axial Mach number distribution, the wall boundary layer thickness, and the nozzle flow rate. S20. Select the suction channel inlet on the axis of the contraction section of the hypersonic nozzle, within the range of 0.25 to 0.32 Mach number. The coordinates of the contraction section wall corresponding to the suction channel inlet are the coordinates of the apex of the suction lip, C. lip ( , ), With the radius r of the suction lip sep equal; S30. Based on the numerical simulation results, obtain the boundary layer thickness value corresponding to the inlet of the suction channel, and superimpose the boundary layer thickness value onto the lip apex. The value is used to obtain the coordinates C of the outer wall of the suction channel inlet. up ( , ), With the outer radius r of the suction lip entry equal; S40. Based on the nozzle flow rate, select the suction flow rate ratio within the range of 25% to 50%, and assume that the Mach number at the throat of the suction channel is 1, calculate the area of ​​the suction throat annular gap at the throat of the suction channel. S50. Assume the outer radius of the suction trachea is r. slu and make r slu >r sep Within the length-to-diameter ratio of the contraction section (1.5–2.5), the coordinates S of the outer wall of the suction channel throat are obtained. up ( , ),and > Then, using the suction flow rate and the throat Mach number 1, the coordinates S of the inner wall of the suction flow channel throat are calculated. tll ( , ); S60. Coordinates of the hypersonic nozzle inlet and the outer wall of the suction channel inlet C up ( , ), Coordinates S of the outer wall of the suction flow channel throat up ( , Using the length-to-diameter ratio of the contraction section as a constraint, and employing a pre-selected empirical curve formula, the new contraction section profile from the nozzle inlet to the suction throat is calculated, and the original contraction section profile from the nozzle inlet to the suction lip is removed; the original contraction section profile from the suction channel inlet to the nozzle throat is retained and remains as the contraction section profile from the nozzle inlet to the nozzle throat in the main nozzle path; furthermore, the new contraction section profile from the nozzle inlet to the suction throat ensures that the stagnation point of the streamline on the lip is aligned with the coordinates C of the apex of the suction lip. lip ( , )coincide; S70. Based on the profile of the outer wall from the suction channel inlet to the suction throat, calculate the profile of the inner wall from the suction channel inlet to the suction throat using one-dimensional pipe flow theory. The coordinates of the inner wall of the suction throat are S. tll ( , A suction bypass is established by means of the outer wall profile from the suction channel inlet to the suction throat and the inner wall profile from the suction channel inlet to the suction throat. S80. Coordinates C of the outer wall of the suction channel inlet. up ( , Draw a tangent line through the vertex C of the lip margin. lip ( , Draw a line parallel to the tangent, take the parallel line as the axis of symmetry, and draw an ellipse with the axis of symmetry as the major semi-axis. The ellipse is tangent to the inner wall surface of the suction throat and the original nozzle contraction section surface. S90. Adjust the major and minor semi-axes of the ellipse so that the upstream vertex of the major semi-axe is as close as possible to the vertex C of the suction lip. lip ( , The lip surface of the suction duct is obtained by cutting off the tangent point of the inner wall of the suction duct and the original constriction section from the apex of the lip, respectively. S100. Coordinates of the outer wall of the suction flow channel throat S up ( , ), Inner wall coordinates S tll ( , Starting from the nozzle axis, a straight section parallel to the nozzle axis is constructed downstream. The length-to-diameter ratio of the straight section is 5 to 10, and the length of the straight section is the length of the suction throat. S110. At the end of the straight section, the suction channel is gradually widened from the direction parallel to the axis to the direction perpendicular to the axis, forming a suction ring cavity. The cross-sectional area of ​​the suction ring cavity is larger than the area of ​​the suction throat ring slit. Numerical simulation software was used to simulate the main nozzle path and the suction bypass path as a whole. Based on the simulation results, the profile of the contraction section from the nozzle inlet to the suction throat was optimized to ensure that there is no flow separation near the suction lip, and that the streamline stagnation point coincides with the lip apex. The suction channel lip profile is elliptical, with the major axis of the ellipse aligned with the flow direction, and the suction channel lip profile smoothly transitions to the downstream wall.

[0008] S120. Several collecting branch pipes are evenly distributed circumferentially at the end of the suction ring cavity. The end of each collecting branch pipe is inserted into the collecting ring pipe. The sum of the cross-sectional areas of each collecting branch pipe and the cross-sectional area of ​​the collecting ring pipe are both greater than the area of ​​the suction throat annular slit.

[0009] Furthermore, the suction flow rate ratio ranges from 25% to 50% at a nozzle Mach number of 6 and from 30% to 50% at a nozzle Mach number of 8.

[0010] Furthermore, the empirical curve formula is a bicubic curve formula.

[0011] The present invention relates to a suction device for a hypersonic silent nozzle, used in a hypersonic silent wind tunnel. The hypersonic silent wind tunnel includes a contraction section, a nozzle throat, and an expansion section connected sequentially from front to back. An annular suction pipe is provided upstream of the nozzle throat. The inner flow channel of the annular suction pipe includes a suction lip, a suction throat, and a suction ring cavity arranged sequentially from front to back. The suction ring cavity is connected to several collecting branch pipes, and the end of each collecting branch pipe is inserted into the collecting ring pipe. The central part of the incoming flow of the hypersonic silent wind tunnel is the main nozzle path, which flows sequentially from the contraction section through the nozzle throat and the expansion section. The annular edge part is the suction bypass, which flows sequentially from the annular suction pipe through several collecting branch pipes and the collecting ring pipe. The diameter of the inlet of the contraction section is D i The length of the contracted section is L1, and the aspect ratio is L1 / D. i The radius of the nozzle throat is r * ; Suctioning the outer radius r of the lips entry The inner radius r of the suction lips sep ; suction larynx outer radius r slu r slu >r sep The radius r of the suction trachea sll r sll <r sep The height of the suction larynx suture is ΔD. s =r slu -r sll The length of the straight section is L2, and the aspect ratio of the straight section is L2 / ΔD. s The suction ring cavity width is L3, and the diameter of the collecting branch pipe is D. bp The diameter of the collecting ring pipe D rp 1.8≤L1 / D i ≤2.3; 5≤L2 / ΔD s ≤10; and simultaneously satisfy the following relationship: .

[0012] The design method for the suction channel of a hypersonic silent nozzle of the present invention is based on the equivalent extrapolation of boundary layer thickness for suction channel design. Using numerical simulation, the boundary layer thickness at the nozzle inlet and converging section, as well as the nozzle flow rate, are used as design input parameters. One-dimensional pipe flow theory is adopted, following the principle that the lip apex is the stagnation point and there is no flow separation in front of the suction throat, to reconstruct the virtual interface between the internal and external flows. This ensures that the stagnation point position at the leading edge of the suction lip is relatively fixed under single-point design conditions during wide-range operation, realizing effective suction of the wall boundary layer and eliminating turbulent boundary layer disturbances upstream of the nozzle.

[0013] The suction device for hypersonic silent nozzles of the present invention suppresses upstream flow disturbances, meets a wide range of operating requirements, achieves flow stability, and has practical engineering value. Attached Figure Description

[0014] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0015] Figure 1 This is a schematic diagram of the suction device for a hypersonic silent nozzle according to the present invention. Figure 2 This is a schematic diagram of the structure of the suction channel for a hypersonic silent nozzle according to the present invention.

[0016] In the diagram, 1. contraction section; 2. nozzle throat; 3. expansion section; 4. annular suction tube; 5. collecting branch tube; 6. collecting ring tube; 7. suction lip; 8. suction throat; 9. suction ring cavity. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] like Figure 1 As shown, the present invention provides a design method for a hypersonic silent nozzle suction channel, the design method comprising the following steps: S10. Obtain the profile of the hypersonic nozzle without a suction system, and obtain the flow field parameters inside the hypersonic nozzle through numerical simulation. The flow field parameters include the axial Mach number distribution, the wall boundary layer thickness, and the nozzle flow rate. S20. Select the suction channel inlet on the axis of the contraction section 1 of the hypersonic nozzle, within the range of 0.25 to 0.32 Mach number. The coordinates of the contraction section wall corresponding to the suction channel inlet are the coordinates of the apex of the suction lip 7. lip ( , ), With the suction lip radius r sep equal; S30. Based on the numerical simulation results, obtain the boundary layer thickness value corresponding to the inlet of the suction channel, and superimpose the boundary layer thickness value onto the lip apex. The value is used to obtain the coordinates C of the outer wall of the suction channel inlet. up ( , ), With the outer radius r of the suction lip 7 entry equal; S40. Based on the nozzle flow rate, select the suction flow rate ratio within the range of 25% to 50%, and assume that the Mach number at the throat of the suction channel is 1, calculate the area of ​​the suction throat annular gap at the throat of the suction channel. S50. Assume the outer radius of the suction trachea is r. slu and make r slu >r sep Within the length-to-diameter ratio of the contraction section (1.5–2.5), the coordinates S of the outer wall of the suction channel throat are obtained. up ( , ),and > Then, using the suction flow rate and the throat Mach number 1, the coordinates S of the inner wall of the suction flow channel throat are calculated. tll ( , ); S60. Coordinates of the hypersonic nozzle inlet and the outer wall of the suction channel inlet C up ( , ), Coordinates S of the outer wall of the suction flow channel throat up ( , Using the length-to-diameter ratio of the contraction section as a constraint, and employing a pre-selected empirical curve formula, the new contraction section profile from the nozzle inlet to the suction throat 8 is calculated, and the original contraction section profile from the nozzle inlet to the suction lip 7 is removed; the original contraction section profile from the suction channel inlet to the nozzle throat 2 is retained, and remains the contraction section profile from the nozzle inlet to the nozzle throat 2 in the main nozzle path; furthermore, the new contraction section profile from the nozzle inlet to the suction throat 8 ensures that the stagnation point of the streamline on the lip is aligned with the coordinate C of the lip apex of the suction lip 7. lip ( , )coincide; S70. Based on the outer wall profile from the suction channel inlet to the suction throat 8, and using one-dimensional pipe flow theory, calculate the inner wall profile from the suction channel inlet to the suction throat 8. The coordinates of the inner wall of the suction throat are S. tll ( , A suction bypass is established through the outer wall profile of the suction channel inlet to the suction throat 8 and the inner wall profile of the suction channel inlet to the suction throat 8. S80. Coordinates C of the outer wall of the suction channel inlet. up ( , Draw a tangent line through the 7th vertex of the lip edge (C). lip ( , Draw a line parallel to the tangent, take the parallel line as the axis of symmetry, and draw an ellipse with the axis of symmetry as the major semi-axis. The ellipse is tangent to the inner wall surface of the suction throat 8 and the original nozzle contraction section surface. S90. Adjust the major and minor semi-axes of the ellipse so that the upstream vertex of the major semi-axe is as close as possible to the 7th vertex of the suction lip. (Coordinate C) lip ( , ), respectively cut off the inner wall surface of the suction larynx 8 and the surface portion from the incision point to the apex of the lip on the original constriction section surface, to obtain an elliptical suction flow channel lip surface; S100. Coordinates of the outer wall of the suction flow channel throat S up ( , ), Inner wall coordinates S tll ( , Starting from the nozzle axis, a straight section parallel to the nozzle axis is constructed downstream. The length-to-diameter ratio of the straight section is 5 to 10, and the length of the straight section is the length of the suction throat 8. S110. At the end of the straight section, the suction channel is gradually expanded from the direction parallel to the axis to the direction perpendicular to the axis, forming a suction ring cavity 9. The cross-sectional area of ​​the suction ring cavity 9 is larger than the area of ​​the suction throat ring slit. Numerical simulation software was used to simulate the main nozzle path and the suction bypass path as a whole. Based on the simulation results, the profile of the contraction section from the nozzle inlet to the suction throat 8 was optimized to ensure that there is no flow separation near the suction lip 7, and that the streamline stagnation point coincides with the lip apex. The suction channel lip profile is elliptical, with the major axis of the ellipse aligned with the flow direction, and the suction channel lip profile smoothly transitions to the downstream wall.

[0019] S120. Several collecting branch pipes 5 are evenly distributed circumferentially at the end of the suction ring cavity 9. The end of each collecting branch pipe 5 is inserted into the collecting ring pipe 6. The sum of the cross-sectional areas of each collecting branch pipe 5 and the cross-sectional area of ​​the collecting ring pipe 6 are both greater than the area of ​​the suction throat annular slit.

[0020] Furthermore, the suction flow rate ratio ranges from 25% to 50% at a nozzle Mach number of 6 and from 30% to 50% at a nozzle Mach number of 8.

[0021] Furthermore, the empirical curve formula is a bicubic curve formula.

[0022] The present invention relates to a suction device for a hypersonic silent nozzle, used in a hypersonic silent wind tunnel. The hypersonic silent wind tunnel includes a contraction section 1, a nozzle throat 2, and an expansion section 3 connected sequentially from front to back. An annular suction pipe 4 is provided upstream of the nozzle throat 2. The inner flow channel of the annular suction pipe 4 includes a suction lip 7, a suction throat 8, and a suction annular cavity 9 arranged sequentially from front to back. The suction annular cavity 9 is connected to several collecting branch pipes 5, and the end of each collecting branch pipe 5 is inserted into a collecting annular pipe 6. The central part of the incoming flow of the hypersonic silent wind tunnel is the main nozzle path, which flows from the contraction section 1 through the nozzle throat 2 and the expansion section 3 in sequence. The annular edge part is the suction bypass, which flows from the annular suction pipe 4 through several collecting branch pipes 5 and the collecting annular pipe 6 in sequence. like Figure 2 As shown, the inlet diameter of contraction section 1 is D. i The length of the contraction segment 1 is L1, and the aspect ratio is L1 / D. i The radius of nozzle throat 2 is r * ; Suctioning the outer radius of the lip 7 r entry The inner radius of the suction lip is 7 r. sep ; Suctioning the larynx with an outer radius of 8 r slu r slu >r sep The radius of the larynx within 8 mm is r. sll r sll <r sep The height of the suction larynx suture is ΔD. s =r slu -r sll The length of the straight section is L2, and the aspect ratio of the straight section is L2 / ΔD. s The suction ring cavity has a width of L3 and a diameter of D for the collecting branch pipe 5. bp The diameter of the collecting ring pipe is 6D. rp 1.8≤L1 / D i ≤2.3; 5≤L2 / ΔD s ≤10; and simultaneously satisfy the following relationship: .

[0023] Example: This example is based on one-dimensional pipe flow theory, following the principles of "lip apex as stagnation point" and "no flow separation before the suction throat" to design the suction flow channel. For a Mach 6 nozzle, six suction flow channels were designed and analyzed at 5% intervals within the suction flow ratio range of 25% to 50%. For a Mach 8 nozzle, five suction flow channels were designed and analyzed at 5% intervals within the suction flow ratio range of 30% to 50%.

[0024] At each suction flow rate ratio, keeping the main flow profile of the nozzle downstream of the suction lip unchanged, and fixing the coordinates C of the apex of the suction lip 7. lip ( , ), that is, the inner radius r of the suction lip 7. sep And follow these steps for a detailed design: a. Through numerical simulation, a series of flow field parameters are obtained, including the upstream boundary layer thickness of the nozzle, the Mach number distribution along the nozzle axis, the wall boundary layer thickness, and the nozzle flow rate. b. Based on the numerical simulation results, select the inlet location of the suction channel and obtain the coordinates C of the apex of the inlet lip of the suction channel. lip ( , ), With the suction lip radius r sep equal; c. Based on the numerical simulation results, obtain the boundary layer thickness value corresponding to the inlet position of the suction channel, and superimpose the boundary layer thickness value onto the lip apex. The value is used to obtain the coordinates C of the outer wall of the suction channel inlet. up ( , ), With the outer radius r of the suction lip 7 entry equal; d. Given the outer radius r of the suction trachea. slu r slu >r sep ; e. Assuming the airflow at the 8 points of the suction tract is at the speed of sound, according to Calculate the inner radius r of the suction trachea. sll r sll <r sep ; f. Given the coordinates S of the outer wall of the suction channel throat. up ( , ), based on the inlet diameter of contraction section 1 being D i and the coordinates of the outer wall of the suction inlet C up ( , The new contraction section profile is calculated using the bicubic curve formula; g. Given the Mach number distribution of the airflow from the suction lip 7 to the suction throat 8, calculate the coordinates C of the outer wall of the suction channel inlet according to the principle of mass conservation. up ( , (coordinate S of the outer wall of the suction flow channel throat) up ( , The inner wall profile of the ) is used to establish a suction bypass channel; It is important to note that the profile of the contraction section from the new nozzle inlet to the suction throat 8 must ensure that the stagnation point of the streamline on the lip edge is aligned with the coordinate C of the apex of the suction lip 7.lip ( , The suction throat 8 in this embodiment is a cylindrical segment with a length of 10 mm. The lip of the suction channel overlaps with the lip of the suction channel.

[0025] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. For those skilled in the art, all features disclosed in the present invention, or all steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way without departing from the principles of the present invention. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A design method for the suction flow channel of a hypersonic silent nozzle, characterized in that, The design method includes the following steps: S10. Obtain the profile of the hypersonic nozzle without a suction system, and obtain the flow field parameters inside the hypersonic nozzle through numerical simulation. The flow field parameters include the axial Mach number distribution, the wall boundary layer thickness, and the nozzle flow rate. S20. On the axis of the contraction section (1) of the hypersonic nozzle, within the range of 0.25 to 0.32 Mach number, select the suction channel inlet. The coordinates of the contraction section wall corresponding to the suction channel inlet are the coordinates of the apex of the suction lip (7). lip ( , ), Radius r of the suction lip (7) sep equal; S30. Based on the numerical simulation results, obtain the boundary layer thickness value corresponding to the inlet of the suction channel, and superimpose the boundary layer thickness value onto the lip apex. The value is used to obtain the coordinates C of the outer wall of the suction channel inlet. up ( , ), The outer radius r of the suction lip (7) entry equal; S40. Based on the nozzle flow rate, select the suction flow rate ratio within the range of 25% to 50%, and assume that the Mach number at the throat of the suction channel is 1, calculate the area of ​​the suction throat annular gap at the throat of the suction channel. S50. Assume the outer radius of the suction trachea (8) is r. slu and make r slu >r sep Within the length-to-diameter ratio of the contraction section (1.5–2.5), the coordinates S of the outer wall of the suction channel throat are obtained. up ( , ),and > Then, using the suction flow rate and the throat Mach number 1, the coordinates S of the inner wall of the suction flow channel throat are calculated. tll ( , ); S60. Coordinates of the hypersonic nozzle inlet and the outer wall of the suction channel inlet C up ( , ), Coordinates S of the outer wall of the suction flow channel throat up ( , Using the length-to-diameter ratio of the contraction section as a constraint, and employing a pre-selected empirical curve formula, the new contraction section profile from the nozzle inlet to the suction throat (8) is calculated, and the original contraction section profile from the nozzle inlet to the suction lip (7) is removed; the original contraction section profile from the suction channel inlet to the nozzle throat (2) is retained, and remains as the contraction section profile from the nozzle inlet to the nozzle throat (2) of the main nozzle path; furthermore, the new contraction section profile from the nozzle inlet to the suction throat (8) ensures that the stagnation point of the streamline on the lip is aligned with the apex coordinate C of the suction lip (7). lip ( , )coincide; S70. Based on the outer wall profile from the inlet of the suction channel to the suction throat (8), the inner wall profile from the inlet of the suction channel to the suction throat (8) is calculated using one-dimensional pipe flow theory. The coordinates of the inner wall of the suction throat are S. tll ( , A suction bypass is established through the outer wall profile of the suction channel inlet to the suction throat (8) and the inner wall profile of the suction channel inlet to the suction throat (8); S80. Coordinates C of the outer wall of the suction channel inlet. up ( , Draw a tangent line through the lip opening (7) where the coordinates of the lip vertex are C. lip ( , Draw a line parallel to the tangent, take the parallel line as the axis of symmetry, and draw an ellipse with the axis of symmetry as the major semi-axis. The ellipse is tangent to the inner wall surface of the suction throat (8) and the original nozzle contraction section surface that is retained. S90. Adjust the major and minor axes of the ellipse so that the upstream vertex of the major axis is as close as possible to the suction lip (7) lip vertex coordinates C lip ( , ), respectively cut off the inner wall surface of the suction larynx (8) and the surface portion from the incision point to the apex of the lip on the original constriction section surface, to obtain an elliptical suction flow channel lip surface; S100. Coordinates of the outer wall of the suction flow channel throat. up ( , ), inner wall coordinates S tll ( , Starting from the nozzle axis, a straight section parallel to the nozzle axis is made downstream. The length-to-diameter ratio of the straight section is 5 to 10, and the length of the straight section is the length of the suction throat (8). S110. At the end of the straight section, the suction channel is gradually expanded from the direction parallel to the axis to the direction perpendicular to the axis to form a suction ring cavity (9). The cross-sectional area of ​​the suction ring cavity (9) is greater than the area of ​​the suction throat ring slit. Numerical simulation software was used to simulate the main nozzle path and the suction bypass path in one go. Based on the simulation results, the profile of the contraction section from the nozzle inlet to the suction throat (8) was optimized to ensure that there is no separation flow near the suction lip (7) and that the streamline stagnation point coincides with the lip edge vertex. The suction channel lip profile is elliptical, and the major axis of the ellipse is consistent with the flow direction. The suction channel lip profile and the downstream wall are smoothly transitioned. S120. Several collecting branch pipes (5) are evenly distributed along the circumference at the end of the suction ring cavity (9). The end of each collecting branch pipe (5) is inserted into the collecting ring pipe (6). The sum of the cross-sectional areas of each collecting branch pipe (5) and the cross-sectional area of ​​the collecting ring pipe (6) are both greater than the area of ​​the suction throat ring seam.

2. The design method for the suction flow channel of a hypersonic silent nozzle according to claim 1, characterized in that, The suction flow rate ratio is 25% to 50% at a nozzle Mach number of 6 and 30% to 50% at a nozzle Mach number of 8.

3. The design method for the suction flow channel of a hypersonic silent nozzle according to claim 1, characterized in that, The empirical curve formula is a bicubic curve formula.

4. A suction device for a hypersonic silent nozzle, designed using the design method for the suction flow channel of a hypersonic silent nozzle as described in any one of claims 1 to 3, characterized in that... The suction device is used in a hypersonic silent wind tunnel. The hypersonic silent wind tunnel includes a contraction section (1), a nozzle throat (2), and an expansion section (3) connected sequentially from front to back. An annular suction pipe (4) is set upstream of the nozzle throat (2). The inner flow channel of the annular suction pipe (4) includes a suction lip (7), a suction throat (8), and a suction ring cavity (9) arranged sequentially from front to back. The suction ring cavity (9) is connected to several collecting branch pipes (5). The end of each collecting branch pipe (5) is inserted into the collecting ring pipe (6). The central part of the incoming flow of the hypersonic silent wind tunnel is the main nozzle path. The main nozzle path flows from the contraction section (1) through the nozzle throat (2) and the expansion section (3) in sequence. The annular edge part is the suction bypass path. The suction bypass path flows from the annular suction pipe (4) through several collecting branch pipes (5) and the collecting ring pipe (6) in sequence. The inlet diameter of the contraction section (1) is D. i The length of the contracted segment (1) is L1, and the aspect ratio is L1 / D. i The radius of the nozzle throat (2) is r * ; Suction lip (7) outer radius r entry The inner radius r of the suction lip (7) sep ; Suction trachea (8) outer radius r slu r slu >r sep The inner radius r of the suction trachea (8) sll r sll <r sep The height of the suction larynx suture is ΔD. s =r slu -r sll The length of the straight section is L2, and the aspect ratio of the straight section is L2 / ΔD. s The suction ring cavity (9) has a width of L3, and the collecting branch pipe (5) has a diameter of D. bp The diameter D of the collecting ring pipe (6) rp ; 1.8≤L1 / D i ≤2.3; 5≤L2 / ΔD s ≤10; and simultaneously satisfy the following relationship: 。

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