Airfoil type wave water surface environment lift augmentation and stability augmentation control method based on circular rector control technology

Abstract

The invention relates to the technical field of aircraft control, in particular to an airfoil profile wave water surface environment lift augmentation and stability augmentation control method based on a circular rector control technology, which comprises the following steps: modifying the shape of the rear edge of an NACA0012 airfoil profile, and arranging jet holes in the rear edge to form a circular rector control airfoil profile; performing a fluid simulation experiment on the circular rector control airfoil based on the wave parameters to obtain an influence relationship of the wave parameters on a lift coefficient of the circular rector control airfoil and wave response delay; performing a fluid simulation experiment on the circular rector control airfoil based on the trailing edge jet flow parameter to obtain an influence relationship of the trailing edge jet flow parameter on a lift coefficient of the circular rector control airfoil and jet flow response delay; constructing a lift augmentation and stability augmentation open-loop control law of the circular rector control airfoil type wave water surface environment; an open-loop control law is adopted to control jet flow of the trailing edge, and lift-augmentation and stability-augmentation control over the wave water surface environment of the circular rector control airfoil is completed; the lifting force and the stability of the wing on the wave water surface can be improved.

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 wave surface environment based on circulation control technology. Background Art

[0002] Jet control technology is a technology that changes the flow characteristics through the jet holes arranged on the wing, thereby achieving control of the flow including delaying / accelerating transition, suppressing / strengthening turbulence, preventing / promoting separation, and so on, thereby achieving the effect of actively regulating the lift and drag of the aircraft. Circulation control technology is one of the control methods of jet control technology. It is to blow the jet tangentially onto the deflected flap or the curved surface of the object, guide the airflow through a large deflection angle to maintain the attached flow by the balance of centripetal force and pressure difference, and produce the wall effect, thereby regulating the circulation of the wing and changing the lift.

[0003] The water surface is the place where seaplanes take off and land. The water surface in the natural environment generally has waves, so the impact of waves must be considered during water takeoff, landing and flight. Waves will produce a greater impact load on the belly of the gliding aircraft, and in severe cases will damage the fuselage structure, which is an important factor restricting the take-off and landing speed of seaplanes. In addition, when the wing is close to the water surface, the waves will also affect the aerodynamic force of the wing through the ground effect, causing the lift and drag of the wing to oscillate, resulting in turbulence when flying near the water surface. For seaplanes, they must fly close to the water surface during the take-off and landing process and the water-drawing process, and the impact of waves on their flight quality must be considered. Summary of the invention

[0004] In view of the above problems, the present invention provides a method for increasing lift and stability in a wing-shaped wave 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 stability of an airfoil wave 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 at the trailing edge to form a circulation control airfoil;

[0007] Step S2, determining the 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 the influence relationship of the wave parameters on the lift coefficient of the circulation controlled airfoil and the wave response delay;

[0008] Step S3, determining the trailing edge jet parameters of the circulation control airfoil during flight, and performing a fluid simulation experiment on the circulation control airfoil based on the trailing edge jet parameters to obtain the influence relationship of the trailing edge jet parameters on the lift coefficient of the circulation control airfoil and the 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 of the wave parameters on the lift coefficient of the circulation controlled airfoil and the influence relationship of the trailing edge jet parameters on the lift coefficient of the circulation controlled airfoil;

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

[0011] Preferably, the step S1 specifically comprises: for the NACA0012 airfoil, removing the original pointed trailing edge and replacing it with a semicircular trailing edge, and respectively arranging 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 slot to the radius of the semicircular trailing edge is 1:20.

[0013] Preferably, the step S2 specifically includes:

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

[0015] Step S2-2: Perform simulation experiments using computational fluid dynamics numerical calculation methods to calculate the airfoil lift coefficient change ΔC 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 by 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 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 stability 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 in magnitude to the wave response and opposite in direction.

[0023] Preferably, the expression of the open-loop control law for increasing lift and stability in the water surface environment of the control 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 jet momentum coefficient, T is the wave period, 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 With 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 trailing edge shape of the NACA0012 airfoil and arranges jet holes, uses computational fluid dynamics numerical calculation methods, captures the gas-liquid two-phase boundary and introduces waves, and calculates the change in the lift coefficient and response delay of the airfoil under different wave parameters. This 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 wave surface response characteristics with the aerodynamic control mechanism of the circulation control airfoil to design an open-loop control law for increasing lift and stability in a wave surface environment. By adjusting the jet momentum coefficient, an aerodynamic force change equal to the wave response and opposite in direction is generated, thereby achieving precise lift control of the airfoil. This method can effectively offset the influence of waves on the lift of the aircraft and ensure the stable flight of the aircraft in a wave environment. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0030] Figure 1 A flow chart of the method for increasing lift and stability in an airfoil wave 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 A schematic diagram of the lift coefficient-variation relationship curve of the circulation-controlled airfoil provided by the present invention.

[0033] Figure 4 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 purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with 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, and therefore, the protection scope 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 wing-shaped wave surface environment based on circulation control technology is disclosed, and the specific implementation steps are as follows:

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

[0037] In some embodiments, the shape of the trailing edge of the NACA0012 airfoil is modified. The specific modification method is: the original sharp trailing edge is removed at 94.3% of the chord length of the original airfoil and replaced with a semicircular trailing edge with a radius r of 0.714% times the chord length, thereby constructing a 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 shown in FIG. Figure 2 shown.

[0038] Step S2, determining the wave parameters of the water surface when the circulation controlled airfoil is flying on the water surface; performing a fluid simulation experiment on the circulation controlled airfoil based on the 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;

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

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

[0041] In some embodiments, a simulation experiment is performed by using a computational fluid dynamics numerical calculation method, 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 lift coefficient change 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 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, to construct an open-loop control law for increasing lift and stability 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 the wave response in magnitude and opposite in direction.

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

[0046]

[0047] Among them, C μ (t) is the jet momentum coefficient at time t, It is the reference value of the jet momentum coefficient, which has the effect of increasing lift, ΔCμ is the range of the jet momentum coefficient, which plays a role in stabilizing control, 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 With 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 , being able to adjust the response time of the jet to synchronize it with the impact of the waves.

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

[0050] By using the method provided by the present invention, the lift and stability enhancement effect of the airfoil wave water surface environment 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 obtained by simulation 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 takeoff and landing in the wavy water surface 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 all illustrated actions or steps to be performed to obtain the desired results. Under certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be interpreted as limiting the scope of the present disclosure. Certain features described in the context of a separate embodiment can also be implemented in a single implementation in combination. On the contrary, 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 protection scope of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

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

Claims

1. A method for increasing lift and stability of airfoil wave surface environment 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 at the trailing edge to form a circulation control airfoil; Step S2, determining the 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 the influence relationship of the wave parameters on the lift coefficient of the circulation controlled airfoil and the wave response delay; Step S3, determining the trailing edge jet parameters of the circulation control airfoil during flight, and performing a fluid simulation experiment on the circulation control airfoil based on the trailing edge jet parameters to obtain the influence relationship of the trailing edge jet parameters on the lift coefficient of the circulation control airfoil and the jet response delay; 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 of the wave parameters on the lift coefficient of the circulation controlled airfoil and the influence relationship of the trailing edge jet parameters on the lift coefficient of the circulation controlled airfoil; Step S5: adopting the open-loop control law to control the jet at the trailing edge, so as to complete the lift and stability enhancement control of the circulation-controlled airfoil in a wavy water surface environment.

2. The airfoil wave water surface environment lift and stability control method based on circulation control technology according to claim 1 is characterized in that: 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 grooves are respectively arranged at the upper and lower positions of the semicircular trailing edge.

3. The airfoil wave water surface environment lift and stability control method based on circulation control technology according to claim 2 is characterized in that: The step S2 specifically includes: Step S2-1, using the fluid volume fraction method to capture the gas-liquid two-phase boundary, using the open channel flow wave generation method to introduce waves, and determining the wave parameters; Step S2-2: Perform simulation experiments using computational fluid dynamics numerical calculation methods to calculate the airfoil lift coefficient change ΔC caused by first-order linear regular waves with different wave parameters. l and response delay ΔT wave .

4. The method for increasing lift and stabilization of airfoil wave surface environment based on circulation control technology according to claim 3 is characterized in that: 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: Perform simulation experiments by 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 .

5. The method for increasing lift and stabilization of airfoil wave surface environment based on circulation control technology according to claim 4 is characterized in that: The open-loop control law for increasing lift and stability in a wave-surface environment of a controlled airfoil is used to regulate the trailing edge jet parameters, thereby generating aerodynamic force changes that are equal in magnitude to the wave response and opposite in direction.

6. The method for increasing lift and stabilization of airfoil wave surface environment based on circulation control technology according to claim 5 is characterized in that: The expression of the open-loop control law for increasing lift and stability in the wave surface environment of the control airfoil is: Among them, C μ (t) is the jet momentum coefficient at time t, is the reference value of the jet momentum coefficient, ΔC μ is the range of jet momentum coefficient, T is the wave period, 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 With ΔT jet correspond to the delays of wave response and jet response, respectively.

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