A method for increasing lift and stability in airfoil-shaped surface environment based on circulation control technology

Abstract

The present invention relates to the field of aircraft control technology, and in particular to a method for controlling lift and stabilization of an airfoil in a wavy water surface environment based on a circulation control technology. The method comprises the following steps: modifying the trailing edge shape of a NACA0012 airfoil and arranging jet holes at the trailing edge to form a circulation-controlled airfoil; conducting a fluid simulation experiment on the circulation-controlled airfoil based on wave parameters to obtain the influence relationship of the wave parameters on the lift coefficient of the circulation-controlled airfoil and the wave response delay; conducting a fluid simulation experiment on the circulation-controlled airfoil based on trailing edge jet parameters to obtain the influence relationship of the trailing edge jet parameters on the lift coefficient of the circulation-controlled airfoil and the jet response delay; constructing an open-loop control law for increasing lift and stabilization of the circulation-controlled airfoil in a wavy water surface environment; and adopting the open-loop control law to control the jet at the trailing edge to complete the lift and stabilization control of the circulation-controlled airfoil in a wavy water surface environment. The present invention can improve the lift and stability of an aircraft wing on a wavy water surface.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft control, and in particular to a method for increasing lift and stability in an airfoil-shaped wave surface environment based on circulation control technology. Background Art

[0002] Jet control technology uses jet holes placed on the wing to modify flow characteristics, thereby controlling the flow by delaying / accelerating transitions, suppressing / enhancing turbulence, and preventing / promoting separation, thereby actively regulating the aircraft's lift and drag. Circulation control technology is one of the control methods of jet control technology. It involves blowing a jet tangentially onto a deflected flap or curved surface, guiding the airflow through a large deflection angle. The balance between centripetal force and pressure differential maintains the attached flow, creating a wall effect, thereby regulating the wing's circulation and changing lift.

[0003] The water surface is where seaplanes take off and land. Naturally, water surfaces are generally wavy, so the effects of waves must be considered during water takeoff, landing, and flight. Waves exert a greater impact load on the belly of a gliding aircraft, and in severe cases, can damage the fuselage structure, significantly limiting the takeoff and landing speeds of seaplanes. Furthermore, when the wings are close to the water surface, waves affect the aerodynamic forces of the wings through ground effect, causing oscillations in the lift and drag of the wings, resulting in turbulence during flight near the water. Seaplanes must fly close to the water surface during takeoff, landing, and wading, so the impact of waves on their flight performance must be considered. Summary of the Invention

[0004] In view of the above problems, the present invention provides a method for controlling lift and stability of airfoil in a wave-like water surface environment based on circulation control technology, which solves the technical problem in the prior art that aircraft are greatly affected by surface waves when taking off and landing on water.

[0005] The present invention provides a method for increasing lift and stabilization of an airfoil in a wave-like water surface environment based on circulation control technology, comprising the following steps:

[0006] Step S1, modifying the trailing edge shape of the NACA0012 airfoil and arranging jet holes on the trailing edge to form a circulation control airfoil;

[0007] Step S2: determining wave parameters of the water surface when the circulation-controlled airfoil is flying over water; performing a fluid simulation experiment on the circulation-controlled airfoil based on the wave parameters to obtain an influence relationship between the wave parameters and the lift coefficient of the circulation-controlled airfoil and a wave response delay;

[0008] Step S3, determining the trailing edge jet parameters of the circulation controlled airfoil during flight, performing a fluid simulation experiment on the circulation controlled airfoil based on the trailing edge jet parameters, and obtaining an influence relationship of the trailing edge jet parameters on the lift coefficient of the circulation controlled airfoil and a jet response delay;

[0009] Step S4, constructing an open-loop control law for increasing lift and stability of the circulation-controlled airfoil in a wave water surface environment based on the influence relationship between the wave parameters and the influence relationship between the trailing edge jet parameters and the lift coefficient of the circulation-controlled airfoil;

[0010] Step S5: Using the open-loop control law to control the jet at the trailing edge, thereby completing the lift and stability enhancement control of the circulation-controlled airfoil in a wavy water environment.

[0011] Preferably, the step S1 specifically includes: for the NACA0012 airfoil, removing the original pointed trailing edge and replacing it with a semicircular trailing edge, and respectively providing jet grooves at the upper and lower positions of the semicircular trailing edge.

[0012] Preferably, the original sharp trailing edge is removed at 94.3% of the original airfoil chord length, the radius r of the semicircular trailing edge is 0.714% of the chord length, and the ratio of the height of the jet groove to the radius of the semicircular trailing edge is 1:20.

[0013] Preferably, the step S2 specifically includes:

[0014] Step S2-1: Capture the gas-liquid two-phase boundary using the fluid volume fraction method, introduce waves using the open channel flow wave generation method, and determine the wave parameters;

[0015] Step S2-2: Perform simulation experiments using computational fluid dynamics numerical calculation methods to calculate the lift coefficient change ΔC of the airfoil caused by first-order linear regular waves with different wave parameters. l and response delay ΔT wave .

[0016] Preferably, the step S3 specifically includes:

[0017] Step S3-1, introducing a trailing edge jet using a velocity inlet boundary condition, and determining the momentum coefficient of the jet as the trailing edge jet parameter;

[0018] Step S3-2: Perform simulation experiments using computational fluid dynamics numerical calculation methods to calculate the lift coefficient variation of the circulation-controlled airfoil under different momentum coefficients, and obtain the lift coefficient-momentum coefficient variation relationship and response delay ΔT of the circulation-controlled airfoil. jet .

[0019] Preferably, the momentum coefficient of the jet is expressed as:

[0020]

[0021] in, is the mass flow rate at the jet outlet; V jet is the jet velocity; ρ ∞ is the far-field incoming current density; V ∞ is the far-field incoming flow velocity; S represents the reference area. For a two-dimensional airfoil, it is the chord length c of the airfoil.

[0022] Preferably, the open-loop control law for increasing lift and stabilization in a wavy water surface environment of the airfoil is used to regulate the trailing edge jet parameters to generate aerodynamic force changes that are equal to and opposite in direction to the wave response.

[0023] Preferably, the expression of the open-loop control law for increasing lift and stability in the water surface environment of the airfoil wave is:

[0024]

[0025] Among them, C μ (t) is the jet momentum coefficient at time t, C μ0 is the reference value of the jet momentum coefficient, ΔC μ is the range of variation of the jet momentum coefficient, T is the period of the wave, t wave ΔT is the moment when the lowest point of the wave reaches the point just below the 50% chord length of the airfoil. wave and ΔT jet correspond to the delays of wave response and jet response, respectively.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] (1) The present invention modifies the shape of the trailing edge of the NACA0012 airfoil and arranges jet holes. It uses the numerical calculation method of computational fluid dynamics to capture the gas-liquid two-phase boundary and introduce waves. It calculates the change in the lift coefficient and the response delay of the airfoil under different wave parameters. It can effectively improve the lift and stability of the airfoil in a wavy water environment and ensure the flight quality of the aircraft in a wavy environment.

[0028] (2) The present invention combines the characteristics of wave surface response with the aerodynamic control mechanism of the circulation-controlled airfoil to design an open-loop control law for increasing lift and stability in a wave surface environment. By regulating the jet momentum coefficient, an aerodynamic force change equal in magnitude and opposite in direction to the wave response is generated, thereby achieving precise lift control of the airfoil. This method can effectively offset the effect of waves on the lift of an aircraft, ensuring stable flight of the aircraft in a wave environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings are only for purposes of illustrating particular embodiments and are not to be considered limiting of the invention.

[0030] Figure 1 This is a flow chart of the method for increasing lift and stability in a wing-shaped wave water surface environment based on circulation control technology provided by the present invention.

[0031] Figure 2 Schematic diagram of the circulation-controlled airfoil provided by the present invention.

[0032] Figure 3 This is a schematic diagram of the lift coefficient-variation relationship curve of the circulation-controlled airfoil provided by the present invention.

[0033] Figure 4 This is a schematic diagram of the lift and stabilization control effect of the wave water surface environment provided by the present invention. DETAILED DESCRIPTION

[0034] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. In addition, the present invention can also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0035] In order to illustrate the effectiveness of the method proposed by the present invention, the above technical solution of the present invention is described in detail below through a specific embodiment. Figure 1 As shown, a method for increasing lift and stability in a water surface environment of an airfoil wave based on circulation control technology is disclosed. The specific implementation steps are as follows:

[0036] Step S1, modifying the trailing edge shape of the NACA0012 airfoil and arranging jet holes on the trailing edge to form a circulation control airfoil;

[0037] In some embodiments, the trailing edge shape of the NACA0012 airfoil is modified. The specific modification method is as follows: the original sharp trailing edge is removed at 94.3% of the original airfoil chord length and replaced with a semicircular trailing edge with a radius r of 0.714% times the chord length, thereby constructing the Coanda trailing edge used by the jet airfoil. At the same time, jet grooves are respectively provided on the upper and lower parts of the trailing edge, and the ratio of the height of the jet groove to the radius of the semicircular trailing edge is 1:20. The modified circulation control airfoil is as follows: Figure 2 shown.

[0038] Step S2: determining wave parameters of the water surface when the circulation-controlled airfoil is flying over the water surface; performing a fluid simulation experiment on the circulation-controlled airfoil based on the wave parameters to obtain an influence relationship between the wave parameters and the lift coefficient of the circulation-controlled airfoil and a wave response delay;

[0039] In some embodiments, simulation experiments are conducted using computational fluid dynamics numerical calculation methods, the gas-liquid two-phase boundary is captured using the fluid volume fraction method, and waves are introduced using the open channel flow wave generation method to calculate the change in the airfoil lift coefficient ΔC caused by the first-order linear regular wave with different wave parameters. l and response delay ΔT wave .

[0040] Step S3, determining the trailing edge jet parameters of the circulation controlled airfoil during flight, performing a fluid simulation experiment on the circulation controlled airfoil based on the trailing edge jet parameters, and obtaining an influence relationship of the trailing edge jet parameters on the lift coefficient of the circulation controlled airfoil and a jet response delay;

[0041] In some embodiments, a simulation experiment is conducted by using a computational fluid dynamics numerical calculation method, and a trailing edge jet is introduced using a velocity inlet boundary condition. The momentum coefficient of the jet is used as the trailing edge jet parameter, and the change in the lift coefficient of the circulation-controlled airfoil under different momentum coefficients is calculated to obtain the lift coefficient-momentum coefficient change relationship of the circulation-controlled airfoil and the response delay ΔT. jet ,like Figure 3 As shown. Among them, the momentum coefficient expression of the jet is:

[0042]

[0043] in, is the mass flow rate at the jet outlet; V jet is the jet velocity; ρ ∞ is the far-field incoming current density; V ∞ is the far-field incoming flow velocity; S represents the reference area. For a two-dimensional airfoil, it is the chord length c of the airfoil.

[0044] Step S4: Combining the influence relationship of the wave parameters on the lift coefficient of the circulation-controlled airfoil with the influence relationship of the trailing edge jet parameters on the lift coefficient of the circulation-controlled airfoil, constructing an open-loop control law for increasing lift and stabilization of the circulation-controlled airfoil in a wave water surface environment; the open-loop control law regulates the trailing edge jet parameters to generate aerodynamic changes that are equal to and opposite in direction to the wave response.

[0045] In this step, by regulating the jet momentum coefficient, an aerodynamic change of equal magnitude and opposite direction to the wave response is generated, thereby achieving lift and stabilization of the airfoil in the wave surface environment. The jet velocity control law for lift and stabilization in the wave surface environment of a first-order linear sinusoidal wave is:

[0046]

[0047] Among them, C μ (t) is the jet momentum coefficient at time t, It is the base value of the jet momentum coefficient, which has the effect of increasing the lift, ΔCμ is the range of variation of the jet momentum coefficient, which plays a stabilization control role, T is the period of the wave, t wave ΔT is the moment when the lowest point of the wave reaches the point just below the 50% chord length of the airfoil. wave and ΔT jet correspond to the delays of wave response and jet response, respectively.

[0048] In the above jet velocity control law, the cosine function is used to describe the periodic change of the jet momentum coefficient, matching the periodicity of the wave, by setting the time delay offset term ΔT wave , ΔT jet , able to adjust the response time of the jet to synchronize it with the impact of the waves.

[0049] Step S5: Using the open-loop control law to control the jet at the trailing edge, thereby completing the lift and stability enhancement control of the circulation-controlled airfoil in a wavy water environment.

[0050] By applying the method provided by the present invention, the lift and stabilization effect of the airfoil wave water surface environment obtained by simulation for a first-order linear sinusoidal wave with a wave height of 0.1 times the chord length and a wavelength of 1 times the chord length is as follows: Figure 3 As shown in the figure, it can be seen that the variation amplitude of the lift coefficient on the wavy water surface is reduced by 90%, while the lift coefficient is significantly increased, which greatly improves the safety of aircraft taking off and landing in the wavy water environment.

[0051] Although the specific embodiments of the present invention depict various actions or steps in a specific order, this should be understood as requiring such actions or steps to be performed in the specific order shown or in a sequential order, or requiring that all illustrated actions or steps should be performed to obtain the desired results. Under certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although a number of specific implementation details are included in the above discussion, these should not be interpreted as limiting the scope of this disclosure. Certain features described in the context of separate embodiments can also be implemented in combination in a single implementation. Conversely, the various features described in the context of a single implementation can also be implemented in multiple implementations individually or in any suitable sub-combination. The above is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered within the scope of protection of the present invention.

[0052] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for increasing lift and stability in a water surface environment of an airfoil wave based on circulation control technology, characterized in that: The following steps are involved: Step S1, modifying the trailing edge shape of the NACA0012 airfoil and arranging jet holes on the trailing edge to form a circulation control airfoil; The step S1 specifically includes: For the NACA0012 airfoil, the original pointed trailing edge is removed and replaced with a semicircular trailing edge, and jet slots are respectively provided at the upper and lower positions of the semicircular trailing edge; Step S2: determining wave parameters of the water surface when the circulation-controlled airfoil is flying over water; performing a fluid simulation experiment on the circulation-controlled airfoil based on the wave parameters to obtain an influence relationship between the wave parameters and the lift coefficient of the circulation-controlled airfoil and a wave response delay; The step S2 specifically includes: Step S2-1: Capture the gas-liquid two-phase boundary using the fluid volume fraction method, introduce waves using the open channel flow wave generation method, and determine the wave parameters; Step S2-2: Perform simulation experiments using computational fluid dynamics numerical calculation methods to calculate the change in lift coefficient of the airfoil caused by first-order linear regular waves with different wave parameters. and response delay ; Step S3, determining the trailing edge jet parameters of the circulation controlled airfoil during flight, performing a fluid simulation experiment on the circulation controlled airfoil based on the trailing edge jet parameters, and obtaining an influence relationship of the trailing edge jet parameters on the lift coefficient of the circulation controlled airfoil and a jet response delay; The step S3 specifically includes: Step S3-1, introducing a trailing edge jet using a velocity inlet boundary condition, and determining the momentum coefficient of the jet as the trailing edge jet parameter; Step S3-2: Conduct simulation experiments using computational fluid dynamics numerical calculation methods to calculate the lift coefficient variation of the circulation-controlled airfoil under different momentum coefficients, and obtain the lift coefficient-momentum coefficient variation relationship and response delay of the circulation-controlled airfoil. ; Step S4, constructing an open-loop control law for increasing lift and stability of the circulation-controlled airfoil in a wave water surface environment based on the influence relationship between the wave parameters and the influence relationship between the trailing edge jet parameters and the lift coefficient of the circulation-controlled airfoil; Step S5: Using the open-loop control law to control the jet at the trailing edge, thereby completing the lift and stability enhancement control of the circulation-controlled airfoil in a wavy water environment.

2. The airfoil wave surface environment lift and stability control method based on circulation control technology according to claim 1 is characterized in that: The open-loop control law for increasing lift and stabilization in a wave-water-surface environment of a controlled airfoil is used to regulate the trailing edge jet parameters, thereby generating aerodynamic changes that are equal in magnitude to the wave response and opposite in direction.

3. The airfoil wave surface environment lift and stability control method based on circulation control technology according to claim 2 is characterized in that: The expression of the open-loop control law for increasing lift and stability in the wavy water surface environment of the control airfoil is: in, for The jet momentum coefficient at time t, is the reference value of the jet momentum coefficient, is the range of variation of the jet momentum coefficient, is the period of the wave, It is the moment when the lowest point of the wave reaches the point just below the 50% chord length of the airfoil. and correspond to the delays of wave response and jet response, respectively.

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