A deicing assembly based on combined vibration excitation and heating

Abstract

The present invention belongs to the field of aircraft anti-icing systems, and particularly relates to a deicing assembly based on excitation vibration and heating. The assembly comprises: an excitation vibrator and a heater; the excitation vibrator is arranged on the inner surface of the skin and located at the edge of the ice protection area; the heater is arranged on the inner surface of the skin and located at the edge of the skin or the support part of the structural member.

Description

Technical Field

[0001] The invention belongs to the field of aircraft anti-icing systems, and in particular relates to a deicing component based on excitation vibration and heating combination. Background Art

[0002] Some surfaces of aircraft components, especially the leading edges of the air intakes of the engine nacelles, are easily exposed to ice, which can form ice accumulation. This ice may interfere with the normal operation of the aircraft and therefore needs to be removed. There are currently various systems for removing ice, such as heating the leading edge to prevent or remove ice accumulation, which can be achieved by electric heating devices or hot air circulation in the engine. Another method is to install de-icing boots on the surface to be de-iced. This boot includes an inflatable membrane to break up the ice. Another method is to protect a shielding layer on the surface and apply shocks to separate ice through high-current electromagnetic vibrators.

[0003] However, these traditional solutions are not entirely satisfactory as they may require high power, result in temperatures that are unsuitable for certain materials, or require extensive maintenance and may affect the aircraft’s aerodynamic performance. Summary of the invention

[0004] Purpose of the invention: To solve the problems mentioned in the background art, the present invention proposes a de-icing assembly based on combined excitation vibration and heating. De-icing is made more effective by homogenizing the deformation of the skin and amplifying the effect of the vibrator on the ice layer. The de-icing surface is achieved by reducing the consumption of electrical energy, protecting parts of the aircraft from the formation of ice layers.

[0005] The technical solution of the present invention:

[0006] A de-icing assembly based on excitation vibration and heating combination, comprising: an excitation vibrator and a heater;

[0007] The excitation vibrator is arranged on the inner surface of the skin, at the edge of the ice protection area;

[0008] The heater is arranged on the inner surface of the skin and is located at the edge of the skin or at the supporting position of the structural member.

[0009] Further, an excitation vibrator is used to apply physical shock, vibration or electromagnetic pulse to the skin.

[0010] Furthermore, the arrangement of the excitation vibrators is as follows: the spacing between two adjacent vibrators in the span direction should be controlled at 170-240 mm, and the design in the chord direction should be based on the specific wing leading edge shape. Other tools are needed to calculate the protection area of ​​the wing leading edge. The most important basis for measuring the protection area is the liquid water content collection coefficient. The position should be arranged in the liquid water content collection coefficient range of 0.2-0.3. According to the calculation results of multiple wing shapes, the coils should be arranged on the upper and lower surfaces at 100-118 mm chord-wise upward and 86-100 mm chord-wise downward at the stagnation point.

[0011] Furthermore, the excitation vibrator has the following working modes: The working mode of the excitation vibrator is determined by the properties of the skin material and the icing conditions. By analyzing the weight of the skin material and the distribution of the second moment (related to the geometric shape), the various parameters of the excitation vibrator are designed with the goal of achieving a certain value for the maximum variable of the skin. The icing conditions affect the working interval of the vibrator. A certain working interval needs to be guaranteed between two adjacent vibrators to ensure that the ice layer on the skin surface has a certain thickness. If the ice layer is too thin, the de-icing effect cannot be achieved. Its working cycle should be less than 868 seconds, but should exceed 180s.

[0012] Furthermore, the heater working mode is related to the vibrator working mode. As a supplement to the vibrator, the heater start time and end time must be before the vibrator is turned on. Its power and heating time must be strictly controlled. The general heating power is controlled at 1.2W / cm 2 ,The heating time does not exceed 10s. The control goal is to reduce the bonding force between the ice layer and the skin surface while preventing the skin and the ice layer from completely melting to avoid the formation of a water film structure.

[0013] Furthermore, a sandwich is arranged in the skin where the excitation vibrator is arranged; the sandwich includes thin and rigid outer layers on both sides and a light and thick inner core in the middle.

[0014] Furthermore, the sandwich is a honeycomb core composed of medium on both sides and a honeycomb in the middle.

[0015] Furthermore, the two sides of the interlayer are dielectric and the middle is a laminated structure.

[0016] Beneficial Effects

[0017] The present invention provides a de-icing assembly based on combined excitation vibration and heating. De-icing is made more effective by homogenizing the deformation of the skin and amplifying the effect of the vibrator on the ice layer. The de-icing surface is achieved by reducing the consumption of electrical energy, protecting parts of the aircraft from the formation of ice layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1A schematic diagram of a de-icing assembly based on combined vibration excitation and heating;

[0019] Figure 2 Schematic diagram of the working mode of a de-icing component based on combined vibration excitation and heating. DETAILED DESCRIPTION

[0020] A specific embodiment of the de-icing element 1 is, for example, Figure 1 and Figure 2 As shown, it is an element that can be installed on various devices or systems. At least a part of the de-icing element 1 is exposed to the formation or deposition of ice. Here, "ice" refers to ice layers or ice blocks that may appear in the form of multiple superimposed layers.

[0021] The de-icing element 1 is peculiar in that it comprises a skin configured to eliminate these ice layers, as described below.

[0022] The invention is particularly suitable for smooth surfaces that require de-icing. A smooth surface is a surface that has no protruding shapes or elements. However, these elements may include any surface that is suitable for mechanical excitation.

[0023] The de-icing element 1 comprises a skin 2 having a characteristic thickness E which is generally constant. The skin 2 has a surface 3 to be de-iced. "Generally constant" means that the thickness varies by less than 10%, 5% or 1%. The surface 3 to be de-iced corresponds to a surface of the de-icing element 1 on which ice can accumulate as at least one layer 4 of ice. The surface 3 can in particular correspond to a face directly exposed to the outside of the aircraft, such as a leading edge.

[0024] Furthermore, the de-icing element 1 comprises at least one excitation vibrator 9 fixed to the skin 2. The excitation vibrator 9 can be fixed to a rear surface 16 opposite to the surface 4 to be de-iced. The rear surface 16 preferably corresponds to a heavily iced surface.

[0025] The excitation vibrator 9 may be an electromechanical type vibrator. It is configured to excite the skin 2 in at least one predetermined vibration mode. The action of "exciting" the skin 2 preferably includes applying a continuous mechanical load to it to make it vibrate. However, it may also apply an impact to the skin 2 or subject it to an impulse force. Thus, the excitation vibrator 9 may be configured to excite the skin 2 by vibration, impact or impulse force.

[0026] In addition, a vibration mode of the skin 2 corresponds to a characteristic deformation form of the skin 2 under a specific excitation. Figure 22 . They consist of antinodes 7 (represented as dark areas) and nodes 8 (represented as light areas). Antinodes 7 correspond to deformed areas of skin 2, nodes 8 correspond to areas without deformation. The deformation caused by the vibration mode or modes of skin 2 is capable of breaking up the ice layer 4. In particular, it is capable of generating cracks in the ice layer 4, thereby de-icing the surface 3 of the de-icing element 1.

[0027] The excitation vibrator 9 can be a standard electromechanical vibrator that uses various technologies to drive the skin 2 to vibrate. The excitation vibrator 9 is preferably a piezoelectric vibrator, such as a composite vibrator, a multilayer ceramic vibrator, or a prestressed transducer. If the skin material is a metal material, an electromagnetic pulse coil can be used.

[0028] In a non-limiting manner, the characteristic thickness E of the skin 2 is between 0.5 mm and 5 mm. Furthermore, as a non-limiting example, the skin 2 can be made of a metallic material, such as aluminum, or of a composite material. Thus, a flexible skin 2 is obtained, capable of inducing sufficient deformations to remove ice from the surface 3 to be de-iced, by means of low load forces and low power consumption, by exciting the vibrators 9.

[0029] In addition, the skin 2 has a thickness variation 11 that is localized according to a predetermined vibration mode. The thickness variation 11 is localized in a specific manner to optimize the deformation of the predetermined vibration mode, as described below. The effect of this specific localization of the thickness variation 11 is to maximize the efficiency of the deformation of the skin 2 to break or create cracks in the ice layer 4. All vibration modes can be measured in terms of the deicing effect by the maximum deformation of the skin. At a wind speed of 70m / s, the maximum deformation of the skin needs to reach 0.2mm to achieve the deicing effect.

[0030] Furthermore, the predetermined vibration modes correspond to the vibration modes of the skin selected in the preliminary study. In practice, the vibration modes of the skin 2 depend on its geometry, the materials used and its limit conditions, in particular how its ends are fixed. According to these criteria, the skin 2 has specific vibration modes, which should be identified to determine which modes are useful. The vibration modes of the skin 2 can be identified by numerical simulations (for example using the finite element method). However, they can also be identified empirically.

[0031] The predetermined vibration mode is selected from the vibration modes identified in the preliminary investigation. The vibration mode is preferably selected whose deformation covers the largest area of ​​the skin 3. A plurality of vibration modes is selected in particular in order to be able to cover the entire or nearly the entire area of ​​the surface 3 to be de-iced.

[0032] The thickness variations 11 are localized on the skin 2 according to a predetermined pattern. The so-called “homogenizing vibrations” means improving the distribution of deformations over the entire surface of the skin 2 .

[0033] In reality, for a skin with a generally constant thickness, the elastic deformation energy generated by the deformation is not uniform. In particular, when such a skin is excited, its elastic deformation energy is maximum at the antinodes and zero at the nodes. This produces a highly variable elastic energy release rate, which is detrimental to the adhesion fracture of ice.

[0034] The thickness variation 11 makes it possible to obtain in particular resonant bending modes, homogenizing the deformations and thus the distribution of the elastic deformation energy in the ice, facilitating the delamination process.

[0035] This homogenization of deformation has many consequences.

[0036] Firstly, homogenizing the deformation of the skin 2 makes it possible to homogenize the energy transmitted by the skin 2 to the ice layer 4. In fact, homogenizing the deformation makes it possible to homogenize the curvature, which is a high stress area and therefore a high energy concentration area. Therefore, homogenizing the curvature makes it possible to homogenize the elastic deformation energy at the antinodes 7 in the ice layer. Therefore, by homogenizing the curvature during the deformation of the skin 2, the thickness variation 11 makes it possible to homogenize the energy transmitted by the skin 2 to the ice layer 4. This energy is key to removing ice from the surface 3 that needs to be de-iced. It is particularly suitable for enlarging the delamination area of ​​the ice layer 4.

[0037] Secondly, homogenizing the deformation curvature of the skin 2 makes it possible to increase and homogenize the release of energy to the surface 3 that needs to be deiced. In fact, the energy release characterizes the ability of energy transfer, in particular the ability of crack propagation. Therefore, the thickness variation 11 makes it possible to enhance the energy transfer from the skin 2 to the ice layer 4, in particular to optimize the propagation of cracks in the ice layer 4. This in particular enables cracks to propagate more effectively on the surface 3 that needs to be deiced that carries multiple superimposed ice layers 4.

[0038] Third, making the deformation of the skin 2 uniform makes it possible to expand the curvature area of ​​the skin 2. Expanding the curvature area can improve the distribution of energy on the surface 3 that needs to be de-iced, thereby increasing the area of ​​the skin 2 that is effectively anti-icing.

[0039] Furthermore, the vibration modes of the skin 2 depend on the distribution of the weight and the second moment (related to the geometry). The vibration modes can be influenced by varying these parameters in order to obtain a specific excited vibration mode.

[0040] In fact, the energy density transmitted to the ice by the skin 2 depends on its elastic deformation energy density due to the mechanical stresses during the deformation of the skin 2. Therefore, by choosing a specific thickness at a specific location, it is possible to obtain more or less elastic energy during the deformation of the skin.

[0041] Another way to change these parameters may consist in optimizing the topology of the skin 2, for example by creating material-free zones in the skin. Such optimizations can be easily obtained by 3D printing. Another way may consist in manufacturing the skin 2 using different materials, for example combining metal materials and composite materials, or using so-called "sandwich" materials. Sandwich materials include two thin and rigid outer layers with a light and thick inner core in between, such as a honeycomb core or a laminate.

[0042] The predetermined vibration mode preferably corresponds to the resonance mode of the skin 2. Resonance modes are vibration modes that are particularly suitable for deicing because they maximize the deformation of the skin 2, thereby optimizing the deicing effect of the surface 3 that needs to be deiced. It should be emphasized here that the shorter the vibration interval, the better the deicing effect. There needs to be a sufficient time interval between two adjacent deicing operations. The ice layer needs to have a certain thickness to achieve deicing. This thickness is not a fixed value. If it is on a flat structure, the thickness needs to reach at least 3 mm so that the vibrator can achieve better deicing. On a curved surface structure, the minimum ice thickness will increase.

[0043] In addition, due to the defects of the vibration mode itself, the vibration mode variable generated at the edge and the supporting part of the structural member is small. If the overall vibration amount is increased, the fatigue wear of the skin will be greatly increased, and the effect is not obvious. Therefore, the heater 5 is arranged as shown in the figure.

[0044] The heating strips 5 are generally heating devices using electrical resistance elements. They can be fixed on the skin 2 in a conventional manner, for example by bonding.

[0045] exist Figure 2 In the second variant embodiment shown, the deicing element 1 comprises heating strips 14 on the surface to be deiced 3 of the skin 2. These heating strips 14 are fixed at the nodes 8 of the predetermined vibration mode. In this embodiment, the heating strips are specially configured to generate heat in order to reduce adhesion or de-ice, in particular at the nodes where they are arranged.

[0046] The heating strip 14 assists the deicing of the skin 2 by reducing the adhesion of ice at the node 8. In fact, when the excitation vibrator 9 excites the skin 2 to deform, the node 8 is subjected to shear stress, but the shear stress at the node 8 needs to achieve the deicing effect, and the skin at the excitation point 12 will be subjected to excessive stress, which aggravates the reduction of the skin life. The heating strip 14 can achieve the deicing effect with a smaller shear stress, thereby promoting the start of the rupture of the ice layer 4 at the node 8. Therefore, the heating strip 14 makes the deicing effect of the skin 2 more significant.

Claims

1. A de-icing assembly based on combined excitation vibration and heating, characterized in that: The assembly includes: an excitation vibrator and a heater; The excitation vibrator is arranged on the inner surface of the skin, at the edge of the ice protection area; The heater is arranged on the inner surface of the skin and is located at the edge of the skin or at the supporting position of the structural member.

2. The de-icing assembly based on combined excitation vibration and heating according to claim 1, characterized in that: Excitation shakers are used to apply physical shock, vibration or electromagnetic pulse to the skin.

3. The de-icing assembly based on combined excitation vibration and heating according to claim 2, characterized in that: The excitation vibrators are arranged as follows: the distance between two adjacent excitation vibrators in the span direction is 170-240 mm, and the excitation vibrators are arranged on the upper and lower surfaces of the stationary point at 100-118 mm upward along the chord direction and 86-100 mm downward along the chord direction.

4. The de-icing assembly based on combined excitation vibration and heating according to claim 3, characterized in that: The excitation vibrator has the following working modes: The working mode of the excitation vibrator is determined by the properties of the skin material and the icing conditions. By analyzing the weight and the distribution of the second moment of the skin material, the parameters of the excitation vibrator are designed with the goal of achieving a certain value for the maximum variable of the skin; The working cycle is less than 868 seconds and greater than 180 seconds.

5. The de-icing assembly based on combined excitation vibration and heating according to claim 4, characterized in that: Heater working mode: The heater starts and ends before the vibrator starts; heating power 1.2W / cm 2 , heating time does not exceed 10s.

6. The de-icing assembly based on combined excitation vibration and heating according to claim 1, characterized in that: A sandwich is arranged in the skin where the excitation vibrator is arranged; the sandwich includes thin and rigid outer layers on both sides and a light and tight inner core in the middle.

7. The de-icing assembly based on combined excitation vibration and heating according to claim 6, characterized in that: The sandwich is a honeycomb core consisting of media on both sides and honeycomb in the middle.

8. The de-icing assembly based on combined excitation vibration and heating according to claim 1, characterized in that: There are dielectrics on both sides of the sandwich and a laminated structure in the middle.

Images