Cylindrical hair sensor for improving critical Reynolds number based on fluid-solid coupling

Abstract

The invention discloses a cylindrical hair sensor for improving a critical Reynolds number based on fluid-solid coupling. The cylindrical hair sensor comprises a sensor body and a sensor support located at the bottom of the sensor body. Wherein the sensor main body is composed of a hemisphere and a cylinder, the hemisphere is located at the top of the cylinder, and the sensor support is installed at the bottom of the cylinder; the radius of the hemisphere is consistent with that of the cylinder; the sensor support is composed of an enveloping body which is gradually transited from a bottom S1048 wing section to a top circle, the top circle is connected with the bottom of the cylinder of the sensor main body, and the diameters of the top circle and the bottom of the cylinder are consistent; the sensor support is a rigid body, and the bottom is a fixed support. According to the sensor disclosed by the invention, an unsteady vortex is not easy to form at the tail part, and the cylindrical hair sensor is prevented from vibrating leftwards and rightwards due to the unsteady vortex, so that the sensor has higher stability; compared with a common cylindrical hair sensor with the same size, the critical Reynolds number of the cylindrical hair sensor is increased, and the measuring speed range of the sensor is increased.

Description

Technical Field

[0001] The invention relates to the field of aeroelasticity, and in particular to an improved cylindrical hair sensor for increasing a critical Reynolds number based on fluid-solid coupling. Background Art

[0002] With the development of UAV technology in recent years, people have been increasingly researching micro aerial vehicles (MAVs). Compared with traditional UAVs, MAVs are smaller, lighter, more flexible, and easier to deploy in clusters. Based on these advantages, MAVs can better perform tasks such as collaborative monitoring and indoor surveys. However, due to its lightweight design, MAVs are more susceptible to external interference such as gusts, and its payload is also small, so it is impossible to equip traditional airflow sensors such as anemometers to achieve flight control. In flight, accurate perception of atmospheric data plays a vital role in the navigation, guidance, and control of aircraft. Therefore, designing a small, compact, low-power, and highly sensitive sensor has important engineering and practical significance for the development of MAVs.

[0003] In nature, many organisms solve the problem of flight control at this scale by using hair-like mechanical sensors to measure the flow of fluid around them; inspired by these organisms, researchers have developed artificial hair sensors.

[0004] At present, most artificial hair sensors developed at home and abroad are cylindrical in shape. However, according to the theory of flow around cylinders, even at low Reynolds numbers, the fluid flowing through the cylinder is prone to generate unsteady vortices at the tail of the cylinder, such as Karman vortex street. And due to the existence of fluid viscosity, a boundary layer will be formed on the wall. The complex flow in the boundary layer will also affect the cylindrical hair sensor, which will cause the hair sensor to vibrate left and right due to unsteady vortices even at low flow rates, thus affecting stability and measurement accuracy.

[0005] In summary, the existing cylindrical hair sensor has the problems of low stability and low measurement accuracy due to the unsteady eddy current at the tail. Summary of the invention

[0006] The purpose of the present invention is to provide an improved cylindrical hair sensor based on fluid-solid coupling to increase the critical Reynolds number, so as to solve the problem of low working stability of the sensor due to unsteady eddy current in the prior art.

[0007] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0008] A cylindrical hair sensor for increasing the critical Reynolds number based on fluid-solid coupling, comprising a sensor body and a sensor support located at the bottom of the sensor body; wherein the sensor body is composed of a hemisphere and a cylinder, the hemisphere is located at the top of the cylinder, and the sensor support is installed at the bottom of the cylinder; the radius of the hemisphere is consistent with the radius of the cylinder;

[0009] The sensor support is composed of an S1048 airfoil at the bottom that gradually transitions to a circular envelope at the top, the circular top is connected to the cylindrical bottom of the sensor body and the two have the same diameter; the sensor support is a rigid body and the bottom is a fixed support.

[0010] Furthermore, the chord length of the S1048 airfoil is 0.55-1.1 mm, the maximum thickness of the S1048 airfoil is located at a position where the S1048 airfoil is 27% of the chord length from the leading edge, and the maximum thickness is 25.4% of the chord length.

[0011] Furthermore, the material parameters of the sensor body are as follows: the Young's modulus is in the range of 100-400 MPa, and the Poisson's ratio is 0.2-0.3.

[0012] Furthermore, the height of the cylinder is 4-6 mm, the radius is 1.25%-5% of the length of the cylinder, and the overall height of the sensor support is 0.3-0.5 mm.

[0013] Furthermore, the Young's modulus of the material of the sensor body in the cylindrical hair sensor is determined as follows:

[0014] A. Use CATIA software to build the geometric model of the cylindrical hair sensor and the fluid calculation domain;

[0015] B. Use Pointwsie software to divide the geometric model of the cylindrical hair sensor and the fluid calculation domain into flow field grids. The flow field grid is an unstructured grid, and the grid file is saved;

[0016] C. Import the grid file into Ansys Fluent software, set the inlet flow velocity and direction along the positive x-axis, where the positive x-axis is the radial direction of the cylindrical hair sensor, the positive y-axis is the span direction of the cylindrical hair sensor, and the z-axis is the axial direction of the cylindrical hair sensor. Set the turbulence model, flow conditions, boundary conditions, pressure-velocity coupling format, and time-space discretization.

[0017] D. Use Ansys Mechanical software to perform finite element solid meshing on the geometric model of the cylindrical hair sensor. The number and spacing of the grid distribution points of the solid mesh should be consistent with the flow field mesh; set the Young's modulus and Poisson's ratio of the material of the sensor body, set the number of load steps, nonlinear control method, constraint conditions, fluid-solid coupling surface, monitoring variables, and establish a static structural analysis model;

[0018] E. In Ansys Workbench, use the System Coupling module to perform bidirectional fluid-solid coupling calculations, set the number of iterations and convergence conditions, and establish data transfer between the flow field domain and the solid domain. The aerodynamic load on the surface of the cylindrical hair sensor calculated in the flow field domain is transferred to the solid domain as the main load. The deformation of the cylindrical hair sensor calculated in the solid domain is transferred back to the fluid domain as the main data. Repeat the transfer calculation several times until the calculation converges.

[0019] F. Check the flow field results calculated in step E. If the tail of the cylindrical hair sensor is a stable vortex, increase the inlet flow velocity in step C and repeat step E until an unsteady vortex is generated at the tail of the cylindrical hair sensor. Record the maximum flow velocity at which the tail of the cylindrical hair sensor is a stable vortex and calculate the critical Reynolds number. If the tail of the cylindrical hair sensor is an unsteady vortex, reduce the inlet flow velocity in step C and repeat step E until the tail of the cylindrical hair sensor is a steady vortex. Record the flow velocity at this time and calculate the critical Reynolds number.

[0020] G. Changing the Young's modulus in step D, repeating steps E and F until the critical Reynolds number corresponding to each Young's modulus in the preset Young's modulus selection range is calculated;

[0021] H. Use CATIA software to build the geometric model of the common hair sensor and the fluid calculation domain;

[0022] I. Use Pointwsie software to divide the geometric model of the common hair sensor and the fluid calculation domain into flow field grids. The distribution and number of grid nodes must be consistent with those in step B;

[0023] J. The remaining steps of calculating the critical Reynolds number of the common hair sensor are exactly the same as step CG, and the critical Reynolds numbers of the cylindrical hair sensor and the common hair sensor are compared;

[0024] K. Determine the optimal Young's modulus selection range of the cylindrical hair sensor based on the deformation of the cylindrical hair sensor and the ordinary hair sensor at the critical Reynolds number.

[0025] Furthermore, the relevant settings in step C are:

[0026] Turbulence model: laminar flow model is adopted; incoming flow condition: the incoming flow is steady flow, and the incoming flow density is 1.225kg / m 3 The kinematic viscosity of the incoming flow is 1.82×10 -5kg / (m·s); boundary conditions: the inlet is set as velocity inlet, the outlet is set as pressure outlet, the far field is set as symmetric boundary, and the wall is a no-slip wall; pressure-velocity coupling format: Coupled format is adopted; time-space discretization format: pressure is spatially discretized using the second-order format, and momentum is discretized using the second-order upwind format;

[0027] Dynamic mesh method: The dynamic mesh uses Smooting Methods and Remeshing, Smoothing is set to Diffusion, Remeshing is set to Unified Remeshing, and the cylindrical hair sensor is set as the fluid-solid coupling surface; monitoring variables: including mass residual, momentum residual in the xyz direction, surface pressure of the cylindrical hair sensor, and y-direction velocity of the tail of the cylindrical hair sensor; convergence condition: the residual value of all monitoring variables is reduced to 10 -4 Below and the monitored physical quantity tends to a stable value.

[0028] Furthermore, the relevant settings in step D are:

[0029] Number of load steps: the initial load step is 30, the minimum load step is 30, and the maximum load step is 100; nonlinear control method: the Newton-Raphson method is set to asymmetric, the displacement convergence is released, and the line search is turned on; constraints: the sensor support and the bottom plane of the cylindrical hair sensor are set as fixed support conditions; fluid-solid coupling surface: the sensor body is set as the fluid-solid coupling surface; monitoring variables: monitor the deformation of the top of the cylindrical hair sensor.

[0030] Furthermore, the relevant settings in step E are:

[0031] Iteration steps: minimum iteration step is 1, maximum iteration step is 7; Convergence condition: data transmission residual values ​​of fluid domain and solid domain are reduced to 10 -3 The following also satisfies the convergence conditions of flow field calculation.

[0032] Furthermore, the criterion for determining whether the tail of the cylindrical hair sensor is a steady vortex or an unsteady vortex in step F is: whether the monitored y-direction velocity curve of the tail of the cylindrical hair sensor converges to a certain stable value or shows oscillation. If the y-direction velocity curve converges to a certain stable value, it is a steady vortex; if the y-direction velocity curve shows oscillation, it is an unsteady vortex.

[0033] Furthermore, the criterion for determining the optimal Young's modulus selection range of the cylindrical hair sensor in step K is:

[0034] The deformation of the cylindrical hair sensor is between 10% and 40% of the height of the cylindrical hair sensor, and the critical Reynolds number is increased by more than 10% compared with the ordinary cylindrical hair sensor under the same simulation conditions.

[0035] Compared with the prior art, the present invention has the following technical features:

[0036] 1. High stability: When the incoming flow passes through the cylindrical hair sensor, it is not easy to form an unsteady eddy current at the tail of the sensor, which avoids the left and right vibration of the cylindrical hair sensor caused by the unsteady eddy current, so it has stronger stability.

[0037] 2. Large measurement speed range: The present invention improves the critical Reynolds number of the cylindrical hair sensor, so that compared with ordinary cylindrical hair sensors of the same size, the tail of the sensor is still a stable vortex even at a larger incoming flow speed, thereby improving the speed range measured by the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of the structure of a cylindrical hair sensor provided by the present invention;

[0039] Figure 2 Three views of the cylindrical hair sensor provided by the present invention at a certain geometric parameter;

[0040] Figure 3 A flow chart of the CFD / CSD fluid-solid coupling method for calculating the critical Reynolds number of a cylindrical hair sensor under a certain Young's modulus provided by the present invention;

[0041] Figure 4 It is a schematic diagram of the structure of a common cylindrical hair sensor;

[0042] Figure 5 This is the velocity cloud diagram of the cylindrical hair sensor at the section Z = 3mm when the Young's modulus is 400Mpa and the incoming flow velocity is 25m / s;

[0043] Figure 6 The y-direction velocity curves of the three monitoring points Z=1mm, Z=2mm, and Z=3mm at the tail of the cylindrical hair sensor when the Young's modulus is 400Mpa and the incoming flow velocity is 25m / s;

[0044] Figure 7 This is the velocity cloud diagram of the cylindrical hair sensor at the section Z = 3mm when the Young's modulus is 400Mpa and the incoming flow velocity is 26m / s;

[0045] Figure 8 The y-direction velocity curves of the three monitoring points Z=1mm, Z=2mm, and Z=3mm at the tail of the cylindrical hair sensor when the Young's modulus is 400Mpa and the incoming flow velocity is 26m / s;

[0046] Fig. 9 The comparison diagram of the critical Reynolds number of two cylindrical hair sensors with the change of Young's modulus under a certain geometric parameter;

[0047] Fig.10 is the deformation amount of the cylindrical hair sensor of the present invention at the critical Reynolds number. DETAILED DESCRIPTION

[0048] In view of the problems existing in the existing cylindrical hair sensors, the present invention provides a cylindrical hair sensor based on fluid-solid coupling to increase the critical Reynolds number. The flow field characteristics are improved by adding a support composed of an envelope body which is a S1048 airfoil variation and gradually transitions to a circular shape at the bottom, thereby delaying the occurrence of an unsteady wake vortex. At the same time, the support has greater structural stiffness than the cylinder, and can reduce the influence of flow field disturbances in the boundary layer.

[0049] Referring to the accompanying drawings, the present invention provides a cylindrical hair sensor for improving the critical Reynolds number based on fluid-solid coupling, comprising a sensor body 1 and a sensor support 2 located at the bottom of the sensor body 1; wherein the sensor body 1 is composed of a hemisphere 101 and a cylinder 102, the hemisphere 101 is located at the top of the cylinder 102, and the sensor support 2 is installed at the bottom of the cylinder 102; in one embodiment of the present invention, the height of the cylinder 102 is 4-6 mm, and the radius is 1.25%-5% of the length of the cylinder 102, and the radius of the hemisphere 101 is consistent with the radius of the cylinder 102.

[0050] The material parameters of the sensor body 1 are as follows: the Young's modulus is in the range of 100-400Mpa, and the Poisson's ratio is 0.2-0.3.

[0051] The sensor support 2 is composed of an envelope body in which the bottom S1048 airfoil 201 gradually transitions to the top circle 202, wherein the S1048 airfoil 201 data is provided by the airfoil library of the software Profili, the chord length of the S1048 airfoil 201 is 0.55-1.1mm, the maximum thickness of the S1048 airfoil 201 is located at a chord length of 27% from the leading edge of the S1048 airfoil, and the maximum thickness is 25.4% of the chord length; the radius of the top circle 202 is consistent with the radius of the cylinder 102, and the overall height of the sensor support 2 is 0.3-0.5mm; the top circle 202 is connected to the bottom of the cylinder 102 of the sensor body 1; the sensor support 2 is a rigid body, and the bottom is a fixed support.

[0052] The critical Reynolds number in the present invention is defined as: under the structural parameters and material parameters determined by the cylindrical hair sensor, the cylindrical hair sensor is located in the flow field and is stable at a certain deformation amount, and the tail still maintains a stable vortex without generating a maximum incoming flow velocity corresponding to an unsteady vortex. The Reynolds number calculated at this velocity is the critical Reynolds number; the critical Reynolds number is calculated by CFD / CSD fluid-solid coupling.

[0053] In one embodiment of the present invention, a method for calculating the optimal selection range and critical Reynolds number of a cylindrical hair sensor within a preset Young's modulus selection range using CFD / CSD fluid-solid coupling is as follows; in this embodiment, the preset Young's modulus selection range is 100-400Mpa; and the Poisson's ratio is 0.3.

[0054] A. Use CATIA software to build the geometric model of the cylindrical hair sensor and the fluid calculation domain;

[0055] B. Use Pointwsie software to divide the geometric model of the cylindrical hair sensor and the fluid calculation domain into flow field grids. The flow field grid is an unstructured grid, and the grid file is saved;

[0056] C. Import the grid file into Ansys Fluent software, set the inlet flow velocity and direction along the positive x-axis, where the positive x-axis is the radial direction of the sensor, the positive y-axis is the span direction of the sensor, and the z-axis is the axial direction of the sensor. Set the turbulence model, flow conditions, boundary conditions, pressure-velocity coupling format, and time-space discretization.

[0057] Among them: Turbulence model: laminar flow model is adopted; incoming flow condition: the incoming flow is steady flow, and the incoming flow density is 1.225kg / m 3 The kinematic viscosity of the incoming flow is 1.82×10 -5 kg / (m·s); boundary conditions: the inlet is set as velocity inlet, the outlet is set as pressure outlet, the far field is set as symmetric boundary, and the wall is a no-slip wall; pressure-velocity coupling format: Coupled format is adopted; time-space discretization format: pressure is spatially discretized using the second-order format, and momentum is discretized using the second-order upwind format;

[0058] Dynamic mesh method: The dynamic mesh uses Smooting Methods and Remeshing, Smoothing is set to Diffusion, Remeshing is set to Unified Remeshing, and the cylindrical hair sensor is set as the fluid-solid coupling surface; monitoring variables: including mass residual, momentum residual in the three directions of xyz, surface pressure of the cylindrical hair sensor, and improved y-direction velocity of the tail of the cylindrical hair sensor; convergence condition: the residual value of all monitoring variables is reduced to 10 -4 Below and the monitored physical quantity tends to a stable value.

[0059] D. Use Ansys Mechanical software to perform finite element solid meshing on the geometric model of the cylindrical hair sensor. The number and spacing of the solid mesh distribution points should be consistent with the flow field mesh. Set the Young's modulus and Poisson's ratio of the material, set the number of load steps, nonlinear control method, constraint conditions, fluid-solid coupling surface, monitoring variables, and establish a static structural analysis model.

[0060] The static structural analysis model in step D needs to set the number of load steps, nonlinear control method, constraints, fluid-solid coupling surface, and monitoring variables; among them: number of load steps: the initial load step is 30, the minimum load step is 30, and the maximum load step is 100; nonlinear control method: the Newton-Raphson method is set to asymmetric, displacement convergence is released, and line search is turned on; constraints: the cylindrical hair sensor support and the bottom plane are set as fixed support conditions; fluid-solid coupling surface: the cylindrical hair sensor body is set as the fluid-solid coupling surface; monitoring variables: monitor the deformation of the top of the cylindrical hair sensor.

[0061] E. In Ansys Workbench, use the System Coupling module to perform bidirectional fluid-solid coupling calculations, set the number of iterations and convergence conditions, and establish data transfer between the flow field domain and the solid domain. The aerodynamic load on the surface of the cylindrical hair sensor calculated in the flow field domain is transferred to the solid domain as the main load. The deformation of the cylindrical hair sensor calculated in the solid domain is transferred back to the fluid domain as the main data. Repeat the transfer calculation several times until the calculation converges.

[0062] In step E, the two-way fluid-solid coupling calculation needs to set the number of iterations and convergence conditions, where: the minimum number of iterations is 1 and the maximum number of iterations is 7; the convergence condition is that the data transmission residual values ​​of the fluid domain and the solid domain are reduced to 10 -3 The following also satisfies the convergence conditions of flow field calculation.

[0063] F. Check the flow field results calculated in step E. If the tail of the cylindrical hair sensor is a steady vortex, increase the inlet flow velocity in step C and repeat step E until an unsteady vortex is generated at the tail of the cylindrical hair sensor. Record the maximum flow velocity when the tail of the cylindrical hair sensor is a steady vortex and calculate the critical Reynolds number. If the tail of the cylindrical hair sensor is an unsteady vortex, reduce the inlet flow velocity in step C and repeat step E until the tail of the cylindrical hair sensor is a steady vortex. Record the flow velocity at this time and calculate the critical Reynolds number.

[0064] The criterion for determining whether the tail of the cylindrical hair sensor is a steady vortex or an unsteady vortex in step F is: whether the monitored y-direction velocity curve of the tail of the cylindrical hair sensor converges to a certain stable value or shows oscillation. If the y-direction velocity curve converges to a certain stable value, it is a steady vortex; if the y-direction velocity curve shows oscillation, it is an unsteady vortex.

[0065] G. Change the Young's modulus in step D and repeat steps E and F until the critical Reynolds numbers corresponding to all Young's moduli are calculated.

[0066] H. Use CATIA software to build the geometric model of the common cylindrical hair sensor and the fluid calculation domain. The common cylindrical hair sensor model is as follows: Figure 4 As shown, the height of the cylinder 4 is consistent with the sum of the heights of the cylinder 102 and the sensor support 2 , the radius of the cylinder 4 is consistent with the radius of the cylinder 102 , and the radius of the hemisphere 3 is consistent with the radius of the cylinder 4 .

[0067] I. Use Pointwsie software to divide the flow field grid of the geometric model of the ordinary cylindrical hair sensor and the fluid calculation domain. The distribution and number of grid nodes must be consistent with those in step B to reduce calculation errors. The flow field grid is an unstructured grid and the grid file is saved.

[0068] J. The remaining steps of calculating the critical Reynolds number of an ordinary cylindrical hair sensor are completely consistent with steps CG, and the critical Reynolds numbers of the cylindrical hair sensor and the ordinary hair sensor are compared.

[0069] K. By comparing the deformation of the cylindrical hair sensor at the critical Reynolds number calculated in step E with the critical Reynolds numbers of the two cylindrical hair sensors calculated in steps G and J, the optimal selection range of the Young's modulus of the cylindrical hair sensor can be obtained.

[0070] The criterion for determining the optimal Young's modulus selection range of the cylindrical hair sensor in step K is that, in order to ensure that the sensor is as free from noise interference as possible and that the sensor does not become unstable due to excessive deformation, the deformation amount of the sensor is between 10% and 40% of the sensor height, and the critical Reynolds number should be increased by more than 10% compared with that of an ordinary cylindrical hair sensor; that is, firstly, based on the simulation results, the Young's modulus corresponding to the data satisfying the range of 10% to 40% of the sensor height among all deformation amounts is screened out, and then from these data, the Young's modulus that is more than 10% higher than the critical Reynolds number of an ordinary hair sensor under the same simulation conditions is screened out, and the range formed by these Young's moduli is the optimal selection range.

[0071] In practical applications, the new cylindrical hair sensor provided by the present invention is evenly fixed on the wing surface of an aircraft to form a sensor array. The pressure sensor at the bottom of the sensor sends the force and deformation of the sensor to the aircraft's onboard analysis computer, and the neural network can quickly analyze the outflow velocity, incoming flow angle of attack, incoming flow sideslip angle and other parameters.

[0072] Example:

[0073] Reference Figure 3 As shown, the critical Reynolds numbers of the improved cylindrical hair sensor and the ordinary cylindrical hair sensor provided by the present invention are calculated respectively, and the specific calculation steps are as follows:

[0074] A. Use CATIA software to build the geometric model of the improved cylindrical hair sensor and the fluid calculation domain. The geometric parameters of the improved cylindrical hair sensor model are as follows: Figure 1 , 2 As shown: the radius of the hemisphere 101 is 0.05mm, the radius of the cylinder 102 is 0.05mm, the height is 4mm, the chord length of the bottom airfoil S1048 is 0.55mm, the maximum thickness of the airfoil S1048 is 0.14mm, located at 27% of the chord length of the airfoil S1048 from the leading edge, the radius of the circle 202 is 0.05mm, the height of the improved cylindrical hair sensor support 2 is 0.3mm, and the total height of the improved cylindrical hair sensor is 4.35mm. The geometric parameters of the fluid calculation domain are: the calculation fluid domain is a cuboid, the distance between the inlet and the leading edge of the improved cylindrical hair sensor is 2mm, the distance between the inlet and the trailing edge of the improved cylindrical hair sensor is 10mm, the distance between the side and the improved cylindrical hair sensor is 1mm, and the top height is 6mm;

[0075] B. Use Pointwsie software to divide the flow field grid of the geometric model and fluid calculation domain of the improved cylindrical hair sensor. Due to the characteristics of the flow around the cylinder, it is necessary to locally encrypt the flow field grid near the improved cylindrical hair sensor, especially the tail. The flow field grid is an unstructured grid with a total grid size of 170w. Save the grid file;

[0076] C. Import the mesh file into Ansys Fluent software. Since the Reynolds number is small, the laminar flow model is selected for calculation. Since the flow velocity is low, the air is considered incompressible and the incoming flow density is set to 1.225kg / m 3 The kinematic viscosity coefficient of the incoming flow is 1.82×10 -5 kg / (m·s). The inlet is set as the velocity inlet, and the inlet velocity is set as U ∞ , the direction is along the positive x-axis. Because the incoming flow is viscous, there will be a boundary layer near the ground. The velocity magnitude U(z) distribution along the vertical direction of the ground satisfies:

[0077]

[0078] Where y is the height from the ground, x is the distance from the inlet, Re x is the local Reynolds number with x as the characteristic length, and its calculation formula is:

[0079]

[0080] Where ρ ∞ is the incoming flow density, μ ∞ is the kinematic viscosity coefficient of the incoming flow.

[0081] The inflow outlet is set as the pressure outlet, the static pressure is 0Pa, the ground and cylindrical sensor surfaces are set as no-slip walls, and the sides and top of the fluid calculation domain are set as symmetric boundary conditions. The pressure-velocity coupling format uses the Coupled format, the pressure uses the second-order format for spatial discretization, the momentum uses the second-order upwind format for discretization, the dynamic mesh uses SmootingMethods and Remeshing, Smoothing is set to Diffusion, Remeshing is set to Unified Remeshing, the improved cylindrical hair sensor is set as the fluid-solid coupling surface, the monitoring variables added include mass residuals, momentum residuals in the xyz directions, the surface pressure of the improved cylindrical hair sensor, the y-direction velocity of the tail of the improved cylindrical hair sensor, and the convergence condition is set to reduce the residual value of all monitoring variables to 10 -4 The following and the monitored physical quantity tends to a stable value;

[0082] D. Use Ansys Mechanical software to perform finite element solid meshing on the geometric model of the improved cylindrical hair sensor. The solid mesh should ensure that the number and distribution of nodes on the surface flow field of the geometric model are similar. The Young's modulus of the material is set to 400Mpa and the Poisson's ratio is set to 0.3. The structural motion equation is:

[0083] K·ξ=Q (3)

[0084] Where K represents the structural stiffness matrix, ξ represents the displacement of the object, and Q represents the aerodynamic matrix.

[0085] Set the initial load step to 30, the minimum load step to 30, and the maximum load step to 100. In the nonlinear control method, set the Newton-Raphson method to asymmetric, release the displacement convergence, and enable line search. Set the improved cylindrical hair sensor support and the bottom plane as fixed support conditions, and set the improved cylindrical hair sensor body to the fluid-solid coupling surface. Set the deformation of the top of the improved cylindrical hair sensor as the monitoring variable;

[0086] E. In Ansys Workbench, use the System Coupling module to perform bidirectional fluid-solid coupling calculations, set the minimum iteration number to 1, the maximum iteration number to 7, and the convergence condition that the data transmission residual values ​​of the fluid domain and the solid domain are reduced to 10 -3 The following and the convergence conditions in step C are met at the same time, the data transfer between the flow field domain and the solid domain is established, the aerodynamic load on the surface of the improved cylindrical hair sensor calculated by the flow field domain is transferred to the solid domain as the main load, and the deformation of the improved cylindrical hair sensor calculated by the solid domain is transferred back to the fluid domain as the main data, and the transfer calculation is repeated several times until the calculation converges;

[0087] F. Check the flow field results calculated in step E. If the tail of the improved cylindrical hair sensor is a stable vortex, refer to Figure 5 , 6 As shown, at this time, the y-direction velocity curve of the tail of the improved cylindrical hair sensor converges to a certain stable value, then increase the inlet flow velocity in step C, and keep the other settings unchanged, repeat step E until an unsteady vortex is generated at the tail of the improved cylindrical hair sensor, record the maximum flow velocity of the stable vortex at the tail of the improved cylindrical hair sensor, and calculate the critical Reynolds number. If the tail of the improved cylindrical hair sensor is an unsteady vortex, refer to Figure 7 , 8 As shown, at this time, the y-direction velocity curve of the tail of the improved cylindrical hair sensor is oscillating, then reduce the inlet flow velocity in step C, repeat step E until the tail of the improved cylindrical hair sensor is a steady vortex, record the flow velocity at this time, and calculate the critical Reynolds number according to equation (2);

[0088] G. Change the Young's modulus in step D to 350 MPa, 300 MPa, 250 MPa, 200 MPa, 150 MPa, and 100 MPa in sequence, keep the other conditions unchanged, and repeat steps E and F until the critical Reynolds numbers corresponding to all Young's moduli are calculated.

[0089] H. Use CATIA software to build the geometric model of the common cylindrical hair sensor and the fluid calculation domain. The model geometric parameters of the common cylindrical hair sensor are as follows: Figure 4 As shown: the radius of the hemisphere 3 is 0.05mm, the radius of the cylinder 4 is 0.05mm, the height is 4.3mm, and the total height of the ordinary cylindrical hair sensor is 4.35mm, which is consistent with the geometric parameters of the improved cylindrical hair sensor. The geometric parameters of the fluid calculation domain are: the calculation fluid domain is a cuboid, the inlet is 2mm away from the front edge of the ordinary cylindrical hair sensor, the outlet is 10mm away from the rear edge of the ordinary cylindrical hair sensor, the side is 1mm away from the ordinary cylindrical hair sensor, and the top height is 6mm;

[0090] I. Use Pointwsie software to divide the flow field grid of the geometric model of the common cylindrical hair sensor and the fluid calculation domain. The distribution and number of grid nodes should be consistent with those in step B to reduce calculation errors. The total number of grids is 150w, and the grid file is saved;

[0091] J. The remaining steps of calculating the critical Reynolds number of the ordinary cylindrical hair sensor are completely consistent with step CG. By comparing the critical Reynolds numbers of the improved cylindrical hair sensor and the ordinary hair sensor, the following is obtained: Fig. 9 Results shown.

[0092] like Fig. 9The results show that the present invention can significantly improve the critical Reynolds number of the cylindrical hair sensor, especially when the Young's modulus is 400 MPa, the critical Reynolds number of the improved cylindrical hair sensor is increased from 134 to 168, an increase of 34 compared with the ordinary cylindrical hair sensor. When the Young's modulus is 250 MPa and 200 MPa, the increase in the critical Reynolds number is the lowest, but it also increases by 20.

[0093] K. The deformation of the improved cylindrical hair sensor calculated in step E at the critical Reynolds number is as follows: Fig.10 As shown, combined Fig. 9 The results shown can obtain the optimal selection range of Young's modulus for the improved cylindrical hair sensor.

[0094] The criteria for determining the optimal Young's modulus selection range of the improved cylindrical hair sensor in step K are that, in order to ensure that the sensor is as free from noise interference as possible and does not become unstable due to excessive deformation, the deformation of the sensor is between 10% and 40% of the sensor height, and the critical Reynolds number should be improved by more than 10% compared with the ordinary cylindrical hair sensor. Fig. 9 and Fig.10 According to this criterion, it can be obtained that under the geometric parameters of this embodiment, the optimal Young's modulus range of the cylindrical hair sensor provided by the present invention is 200-400Mpa.

[0095] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A cylindrical hair sensor for increasing the critical Reynolds number based on fluid-solid coupling, characterized in that: The sensor comprises a sensor body (1) and a sensor support (2) located at the bottom of the sensor body (1); wherein the sensor body (1) is composed of a hemisphere (101) and a cylinder (102); the hemisphere (101) is located at the top of the cylinder (102); and the sensor support (2) is installed at the bottom of the cylinder (102); the radius of the hemisphere (101) is consistent with the radius of the cylinder (102); The sensor support (2) is composed of an envelope body that gradually transitions from a bottom S1048 airfoil (201) to a top circular shape (202), the top circular shape (202) being connected to the bottom of a cylinder (102) of the sensor body (1) and having the same diameter; the sensor support (2) is a rigid body, and the bottom is a fixed support.

2. The cylindrical hair sensor for increasing the critical Reynolds number based on fluid-solid coupling according to claim 1, characterized in that: The chord length of the S1048 airfoil (201) is 0.55-1.1 mm, the maximum thickness of the S1048 airfoil (201) is located at 27% of the chord length of the S1048 airfoil (201) from the leading edge, and the maximum thickness is 25.4% of the chord length.

3. The cylindrical hair sensor for increasing critical Reynolds number based on fluid-solid coupling according to claim 1, characterized in that: The material parameters of the sensor body (1) are as follows: the Young's modulus is in the range of 100-400 MPa, and the Poisson's ratio is 0.2-0.

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4. The cylindrical hair sensor for increasing critical Reynolds number based on fluid-solid coupling according to claim 1, characterized in that: The height of the cylinder (102) is 4-6 mm, the radius is 1.25%-5% of the length of the cylinder (102), and the overall height of the sensor support (2) is 0.3-0.5 mm.

5. The cylindrical hair sensor for increasing critical Reynolds number based on fluid-structure coupling according to claim 1, characterized in that: The method for determining the Young's modulus of the material of the sensor body (1) in the cylindrical hair sensor is as follows: A. Use CATIA software to build the geometric model of the cylindrical hair sensor and the fluid calculation domain; B. Use Pointwsie software to divide the geometric model of the cylindrical hair sensor and the fluid calculation domain into flow field grids. The flow field grid is an unstructured grid, and the grid file is saved; C. Import the grid file into Ansys Fluent software, set the inlet flow velocity and direction along the positive x-axis, where the positive x-axis is the radial direction of the cylindrical hair sensor, the positive y-axis is the span direction of the cylindrical hair sensor, and the z-axis is the axial direction of the cylindrical hair sensor. Set the turbulence model, flow conditions, boundary conditions, pressure-velocity coupling format, and time-space discretization. D. Use Ansys Mechanical software to perform finite element solid meshing on the geometric model of the cylindrical hair sensor. The number of points and intervals of the solid mesh should be consistent with the flow field mesh. Set the Young's modulus and Poisson's ratio of the material of the sensor body (1), set the number of load steps, nonlinear control method, constraint conditions, fluid-solid coupling surface, monitoring variables, and establish a static structural analysis model. E. In Ansys Workbench, use the System Coupling module to perform bidirectional fluid-solid coupling calculations, set the number of iterations and convergence conditions, and establish data transfer between the flow field domain and the solid domain. The aerodynamic load on the surface of the cylindrical hair sensor calculated in the flow field domain is transferred to the solid domain as the main load. The deformation of the cylindrical hair sensor calculated in the solid domain is transferred back to the fluid domain as the main data. Repeat the transfer calculation several times until the calculation converges. F. Check the flow field results calculated in step E. If the tail of the cylindrical hair sensor is a stable vortex, increase the inlet flow velocity in step C and repeat step E until an unsteady vortex is generated at the tail of the cylindrical hair sensor. Record the maximum flow velocity at which the tail of the cylindrical hair sensor is a stable vortex and calculate the critical Reynolds number. If the tail of the cylindrical hair sensor is an unsteady vortex, reduce the inlet flow velocity in step C and repeat step E until the tail of the cylindrical hair sensor is a steady vortex. Record the flow velocity at this time and calculate the critical Reynolds number. G. Changing the Young's modulus in step D, repeating steps E and F until the critical Reynolds number corresponding to each Young's modulus in the preset Young's modulus selection range is calculated; H. Use CATIA software to build the geometric model of the common hair sensor and the fluid calculation domain; I. Use Pointwsie software to divide the geometric model of the common hair sensor and the fluid calculation domain into flow field grids. The distribution and number of grid nodes must be consistent with those in step B; J. The remaining steps of calculating the critical Reynolds number of the common hair sensor are exactly the same as step CG, and the critical Reynolds numbers of the cylindrical hair sensor and the common hair sensor are compared; K. Determine the optimal Young's modulus selection range of the cylindrical hair sensor based on the deformation of the cylindrical hair sensor and the ordinary hair sensor at the critical Reynolds number.

6. The cylindrical hair sensor for increasing the critical Reynolds number based on fluid-solid coupling according to claim 5, characterized in that: The relevant settings in step C are: Turbulence model: laminar flow model is adopted; incoming flow condition: the incoming flow is steady flow, and the incoming flow density is 1.225kg / m 3 The kinematic viscosity of the incoming flow is 1.82×10 -5 kg / (m·s); boundary conditions: the inlet is set as velocity inlet, the outlet is set as pressure outlet, the far field is set as symmetric boundary, and the wall is set as no-slip wall; Pressure-velocity coupling format: Coupled format is used; Space-time discretization format: pressure is spatially discretized using the second-order format, and momentum is discretized using the second-order upwind format; Dynamic mesh method: The dynamic mesh uses Smooting Methods and Remeshing, Smoothing is set to Diffusion, Remeshing is set to Unified Remeshing, and the cylindrical hair sensor is set as the fluid-solid coupling surface; monitoring variables: including mass residual, momentum residual in the xyz direction, surface pressure of the cylindrical hair sensor, and y-direction velocity of the tail of the cylindrical hair sensor; convergence condition: the residual value of all monitoring variables is reduced to 10 -4 Below and the monitored physical quantity tends to a stable value.

7. The cylindrical hair sensor for increasing critical Reynolds number based on fluid-solid coupling according to claim 5, characterized in that: The relevant settings in step D are: Number of load steps: initial load step is 30, minimum load step is 30, maximum load step is 100; nonlinear control method: Newton-Raphson method is set to asymmetric, displacement convergence is released, and line search is turned on; constraint conditions: the sensor support and bottom plane of the cylindrical hair sensor are set as fixed support conditions; fluid-solid coupling surface: the sensor body (1) is set as the fluid-solid coupling surface; monitoring variable: monitor the deformation of the top of the cylindrical hair sensor.

8. The cylindrical hair sensor for increasing critical Reynolds number based on fluid-solid coupling according to claim 5, characterized in that: The relevant settings in step E are: Iteration steps: minimum iteration step is 1, maximum iteration step is 7; Convergence condition: data transmission residual values ​​of fluid domain and solid domain are reduced to 10 -3 The following also satisfies the convergence conditions of flow field calculation.

9. The cylindrical hair sensor for increasing critical Reynolds number based on fluid-structure coupling according to claim 5, characterized in that: The criterion for determining whether the tail of the cylindrical hair sensor is a steady vortex or an unsteady vortex in step F is: whether the monitored y-direction velocity curve of the tail of the cylindrical hair sensor converges to a certain stable value or shows oscillation. If the y-direction velocity curve converges to a certain stable value, it is a steady vortex; if the y-direction velocity curve shows oscillation, it is an unsteady vortex.

10. The cylindrical hair sensor for increasing critical Reynolds number based on fluid-structure coupling according to claim 5, characterized in that: The criterion for determining the optimal Young's modulus selection range of the cylindrical hair sensor in step K is: The deformation of the cylindrical hair sensor is between 10% and 40% of the height of the cylindrical hair sensor, and the critical Reynolds number is increased by more than 10% compared with the ordinary cylindrical hair sensor under the same simulation conditions.

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