Shock / boundary layer interaction flow control method based on embedded moving wall

Abstract

This invention provides a shock wave / boundary layer interference control method based on an embedded moving wall, comprising a flexible conveyor belt embedded in the moving wall and multi-stage rollers driving and supporting the flexible conveyor belt. The flexible conveyor belt is embedded in the wall, with its two ends tangent to the fixed wall, and the wall's movement direction is consistent with the mainstream direction. The multi-stage rollers provide power while preventing the flexible conveyor belt from undergoing large deformation in the normal direction of its profile due to pressure difference. This technology reduces separation by embedding a section of flexible conveyor belt at a suitable position below the shock wave / boundary layer-induced separation packet, using the conveyor belt to drag the upper separation zone backflow. Applied to inlet flow field control, this invention can effectively reduce the size of the separation packet, improve the inlet flow field structure, enhance the inlet's resistance to back pressure, and reduce the total pressure loss and self-starting Mach number of the inlet, while ensuring the inlet's flow capture characteristics, thus improving the inlet's performance to a certain extent.

Description

Technical Field

[0001] The invention relates to the field of hypersonic vehicle design technology, specifically to the field of hypersonic inlet flow control. Background Technology

[0002] Hypersonic inlets primarily achieve pressurization through a series of shock waves. Furthermore, hypersonic inlets draw in a fully developed precursor boundary layer, leading to a prevalent shock wave / boundary layer interference phenomenon that significantly impacts inlet performance. Shock wave / boundary layer interference within inlets can be categorized into several types, including normal shock wave / boundary layer interference, oblique shock wave / boundary layer interference, and three-dimensional shock wave / boundary layer interference. Excessive shock wave intensity can induce boundary layer separation, reducing the inlet's aerodynamic performance. Improper handling of these issues can cause the inlet to deviate from its design operating conditions or even fail to operate.

[0003] Shock wave / boundary layer interference induced by the hypersonic inlet lip mask is a significant factor contributing to inlet performance degradation. Current mainstream control methods include boundary layer venting, microvortex generator control, and wall bulge control. Boundary layer venting is a relatively stable control method that effectively removes low-energy flow from the wall, but it causes flow loss and increases overflow drag. Microvortex generator control devices use flow-oriented vortices generated at the tail to draw high-energy flow from the upper boundary layer into the lower boundary layer, improving its resistance to adverse pressure gradients. However, vortex generators increase drag, and their performance is unsatisfactory at high Mach numbers, also facing serious burn-in issues.

[0004] Therefore, a new technical solution is needed to solve the above-mentioned technical problems. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a shock wave / boundary layer disturbance flow control method based on an embedded moving wall. The aim is to improve the inlet flow field, enhance the inlet's resistance to back pressure and total pressure recovery coefficient, reduce the inlet's self-starting Mach number, and improve the overall performance of the inlet.

[0006] To achieve the above objectives, the present invention provides a shock wave / boundary layer disturbance flow control method based on an embedded moving wall, which can adopt the following technical solution:

[0007] A shock wave / boundary layer interference flow control method based on an embedded moving wall is characterized by arranging a moving wall in the shock wave / boundary layer interference zone of the inlet. The moving wall includes multi-stage rollers and a flexible conveyor belt rolling on the multi-stage rollers. The moving wall is embedded below the separation pack induced by the shock wave / boundary layer interference of the lip mask. The front and rear sides of the moving wall are tangent to the fixed wall where the shock wave / boundary layer interference zone of the inlet is located. The driving wheel of the multi-stage rollers is driven by a motor embedded below the moving wall, which drives the flexible conveyor belt to rotate along the main flow direction.

[0008] Furthermore, the moving wall roughness is related to the local boundary layer thickness. The moving wall roughness is defined as the gravel height of a uniform gravel-like surface, specifically 18% of the local boundary layer thickness.

[0009] The velocity of the moving wall surface is positively correlated with the effect of inhibiting separation; specifically, the velocity of the moving wall surface is 120 m / s.

[0010] The position of the moving wall is strongly coupled with its velocity and roughness, and the moving wall is always located below the separation pack. Under fixed wall movement velocity and roughness, there is an optimal moving wall position. At this point, the suppression effect of the moving wall on the separation pack reaches its optimal value under the corresponding parameters. Specifically, the moving wall position is below the recirculation zone of the separation pack.

[0011] The length of the moving wall does not exceed the length of the separation package, and the tail of the moving wall is located before the reattachment point.

[0012] The present invention also provides an air intake based on an embedded moving wall, including a lip cover and an air intake wall located below the lip cover. The air intake wall has a section of moving wall, the front and rear of which are fixed walls of the air intake wall. The moving wall includes multiple rollers and a flexible conveyor belt that rolls on the multiple rollers. The top surface of the flexible conveyor belt is on the same plane as the fixed wall, and a gap is left between the front and rear ends of the flexible conveyor belt and the fixed wall for the flexible conveyor belt to roll.

[0013] Furthermore, the multi-stage roller includes a drive wheel and multiple driven wheels, and a motor embedded below the moving wall is provided to drive the drive wheel.

[0014] The moving wall is positioned in the intake shock / boundary layer interference zone.

[0015] Beneficial Effects: Compared to existing technologies, this invention provides a shock wave / boundary layer interference flow control method based on an embedded moving wall and an air intake. By arranging a moving wall at a suitable location in the shock wave / boundary layer interference zone of the air intake, local sliding motion is formed, increasing the near-wall airflow and enhancing its resistance to back pressure, thereby reducing the size of the separation pack. This invention can improve the air intake flow field, enhance the air intake's resistance to back pressure and total pressure recovery coefficient, reduce the air intake's self-starting Mach number, and improve the overall performance of the air intake. Attached Figure Description

[0016] Figure 1 This is a structural diagram of the shock wave / boundary layer interference control method based on embedded moving walls in the present invention applied to the air intake.

[0017] Figure 2 This is a schematic diagram of the internal structure of the air intake duct wall.

[0018] Figure 3 This is a top view of the air intake duct wall.

[0019] Figure 4 It is a two-dimensional Mach number cloud map of the original separation region and the separation region after using the present invention. Detailed Implementation

[0020] Please see Figures 1 to 3 The diagram illustrates an implementation of the shock wave / boundary layer interference control method based on an embedded moving wall, as described in this invention, in an air intake duct. The air intake duct includes a lip cover 200 and an air intake duct wall 100 located below the lip cover. A moving wall 101 is provided on the air intake duct wall 100, with its front and rear ends being fixed wall surfaces 5. The moving wall 101 includes multiple rollers and a flexible conveyor belt 3 rolling on the rollers. The top surface of the flexible conveyor belt 3 is on the same plane as the fixed wall surface 5. The multiple rollers include a driving roller 1, multiple driven rollers 2, and a motor 4 driving the driving roller.

[0021] The roughness of the moving wall is the first key aspect of this invention. Roughness is simplified to the height of rough particles on a uniform, gravelly surface. When the height of these rough particles on the moving wall is greater than the viscous sublayer of the airflow above it, the effect of the moving wall roughness becomes increasingly significant. Specifically, the greater the roughness of the moving wall, the greater the frictional resistance experienced by the gas above, resulting in greater kinetic energy loss, and the volume of the recirculation zone decreases with increasing roughness. Specifically, the roughness height is 18% of the local boundary layer thickness.

[0022] The velocity of the moving wall is the second key aspect of this invention. The moving wall transfers kinetic energy to the upper mainstream area, offsetting backflow to some extent; the higher the velocity, the more pronounced the separation suppression effect. For example... Figure 4As shown, the speed of the flexible conveyor belt in the specific moving wall is 120 m / s.

[0023] The location of the moving wall is the third key aspect of this invention. The moving wall should be located below the separation packet induced by the lip shock wave, with its starting point coinciding with the starting point of the separation packet. The location of the moving wall depends on many factors, and is strongly coupled with the location and size of the separation packet, as well as the roughness and velocity of the moving wall. Therefore, it needs to be calculated using fluid simulation software such as Fluent or CFX. By setting boundary conditions with fixed velocity and roughness for the moving wall below the defined separation packet, the optimal location of the moving wall is calculated iteratively.

[0024] The length of the moving wall is the fourth key aspect of this invention. The length of the moving wall should not exceed the length of the separation package, and the end point of the moving wall should be before the reattachment point.

[0025] Please see Figure 4 As shown: This figure is a two-dimensional Mach number cloud map of the original separation structure and the separation structure after adopting the present invention. The horizontal axis is X, the vertical axis is Y, and the unit is meters. It can be seen from the figure that compared with the original separation packet, the separation packet is significantly reduced and the separation point shifts backward after adopting the shock wave / boundary layer disturbance flow control technology based on embedded moving walls. This invention effectively suppresses boundary layer separation induced by shock wave / boundary layer disturbance, significantly improves the flow state within the inlet, and reduces the corresponding flow losses.

[0026] There are many methods and approaches to implement this technical solution, and the above description is only a preferred embodiment of this invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this invention, and these improvements and modifications should also be considered as all clearly protected components of this invention being implementable using existing technology.

Claims

1. A method for controlling shock wave / boundary layer disturbance flow based on an embedded moving wall, characterized in that, A moving wall is arranged in the shock wave / boundary layer interference zone of the inlet. The moving wall includes multi-stage rollers and a flexible conveyor belt rolling on the multi-stage rollers. The moving wall is embedded in the wall of the area where the separation pack induced by the shock wave / boundary layer interference of the lip mask is located. The front and rear ends of the moving wall are tangent to the fixed wall. The driving wheel in the multi-stage rollers is driven by a motor, which drives the flexible conveyor belt to move along the mainstream direction. The roughness of the moving wall is related to the local boundary layer thickness. The roughness of the moving wall is defined as the gravel height of a uniform gravel-like surface, specifically 18% of the local boundary layer thickness. The velocity of the moving wall surface is positively correlated with the effect of inhibiting separation; specifically, the velocity of the moving wall surface is 120 m / s. The position of the moving wall is strongly coupled with its velocity and roughness, and the moving wall is always located below the separation pack. Under fixed wall movement velocity and roughness, there is an optimal moving wall position. At this point, the suppression effect of the moving wall on the separation pack reaches its optimal value under the corresponding parameters. Specifically, the moving wall position is below the recirculation zone of the separation pack.

2. The shock wave / boundary layer disturbance flow control method based on embedded moving walls according to claim 1, characterized in that: The length of the moving wall does not exceed the length of the separation package, and the tail of the moving wall is located before the reattachment point.

3. An air intake based on an embedded moving wall, comprising a lip cover and an air intake wall located below the lip cover, characterized in that, The intake duct wall is provided with a movable wall section. The front and rear ends of the movable wall are tangent to the fixed wall of the intake duct and have a certain gap for the flexible conveyor belt to roll. The movable wall includes multiple rollers and a flexible conveyor belt that rolls on the multiple rollers. The roughness of the moving wall is related to the local boundary layer thickness. The roughness of the moving wall is defined as the gravel height of a uniform gravel-like surface, specifically 18% of the local boundary layer thickness. The velocity of the moving wall surface is positively correlated with the effect of inhibiting separation; specifically, the velocity of the moving wall surface is 120 m / s. The position of the moving wall is strongly coupled with its velocity and roughness, and the moving wall is always located below the separation pack. Under fixed wall movement velocity and roughness, there is an optimal moving wall position. At this point, the suppression effect of the moving wall on the separation pack reaches its optimal value under the corresponding parameters. Specifically, the moving wall position is below the recirculation zone of the separation pack.

4. The air intake duct based on an embedded moving wall according to claim 3, characterized in that: The multi-stage roller includes a drive wheel and multiple driven wheels, and also has a motor embedded below the moving wall to drive the drive wheel.

5. The air intake duct based on an embedded moving wall according to claim 4, characterized in that: The moving wall is positioned in the intake shock / boundary layer interference zone.

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