Method for controlling anti-icing device in aircraft as function of ice accretion rate and corresponding system

Abstract

A method for controlling an anti-icing device for protecting at least one outer surface of an aircraft, the device being provided with at least one anti-icing means (5, 6) and means (4) for measuring the rate of ice build-up, the method comprising the following steps: determining, as a function of the rate of ice build-up determined by the measuring means (4), the speed of ice build-up of the at least one anti-icing means (5, 6); 6) in order to prevent ice build-up on the at least one outer surface to be protected or in order to reduce the thickness of ice build-up on the at least one outer surface to be protected.

Description

Technical Field

[0001] The technical field of the invention is a device for controlling an anti-icing device, and more particularly such a control device coupled to a device for detecting icing conditions. Background Art

[0002] Aircraft may be subject to icing when operating in certain atmospheric conditions, particularly temperatures near or below freezing, and in a humid atmosphere. This humid atmosphere condition is particularly true when the aircraft passes through certain types of cloud layer.

[0003] Ice formation may block moving surfaces of an aircraft, such as leading edges, flaps, and tail components, and degrade the performance of, or even damage components of, the aircraft's engines.

[0004] Ice formation can also lead to a loss of lift and an increase in drag, which can be critical for aircraft.

[0005] In order to avoid this consequence, anti-icing devices have been developed. These anti-icing devices are, in particular, thermal elements arranged on the surfaces to be protected. These anti-icing devices can be used preventively, i.e. in "anti-icing" mode, by keeping the temperature of these surfaces above the melting point of water. These anti-icing devices can be used effectively in "de-icing" mode, by intermittently heating the surface in question to allow accumulated ice to break off. The thermal elements can be electrical elements that utilize the Joule effect, but more commonly they are hot air circulation thermal elements that utilize hot air from the motor. This type of thermal element using hot air circulation is only used in "anti-icing" mode. This is effective for anti-icing, but it cannot be controlled precisely and in a targeted manner and is accompanied by significant heat losses, thus increasing fuel consumption.

[0006] As for systems using electrical components, these electrical components can be used in both "anti-icing" mode and "de-icing" mode on the same aircraft.

[0007] Anti-icing devices may also include mechanical devices, for example in the form of inflatable cylinders, which are placed on the surface to be protected and are periodically inflated to mechanically break up accumulated ice.

[0008] Furthermore, various ice detectors have been developed over the years. While most provide a binary detection result (either the presence or absence of icing conditions), the most advanced detectors are able to provide information on the intensity of the encountered icing conditions by measuring the ice accretion rate (IAR). Document US8704181B2 in the name of the applicant discloses such a detector.

[0009] Ice prevention and anti-icing devices are activated by the aircraft pilot as soon as the detectors indicate icing conditions. Consequently, these activations do not truly take into account the rate of ice accumulation and indiscriminately apply the energy required for maximum protection.

[0010] This operation is not optimal, in particular with regard to energy savings and the life of the de-icing device. The activation of the thermal element is particularly energy-intensive.

[0011] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, countries have already adopted, are currently adopting, or will soon adopt various measures to limit carbon emissions. In particular, ambitious standards apply to both new and already-in-service aircraft, requiring the implementation of technical solutions to comply with existing regulations. For many years, civil aviation has been committed to contributing to the fight against climate change.

[0012] Various technical research efforts have significantly improved the environmental performance of aircraft. The applicant has considered influencing factors at all design and development stages to obtain aviation components and products that consume less energy and are more environmentally friendly. The integration and use of these aviation components and products in civil aviation have a moderate environmental impact to improve the energy efficiency of aircraft.

[0013] The Applicant has therefore been committed to reducing the environmental footprint of its activities by minimizing its negative impact on the climate through the use of benign development and manufacturing methods and processes that minimize greenhouse gas emissions.

[0014] These ongoing research and development efforts include the development of new generation aircraft engines, aircraft lightweighting (particularly through the materials used and lighter onboard equipment), the use of electrical technology to ensure propulsion, and aviation biofuels as an important complement to technological progress.

[0015] To this end, the present invention is the result of technical research aimed at significantly improving aircraft performance by saving energy, thus contributing to reducing the impact of aircraft on the environment.

[0016] Therefore, there is a need for a system for controlling an anti-icing device that is capable of activating the system based on the rate of ice accumulation. Summary of the Invention

[0017] The object of the present invention is a method for controlling an anti-icing device for protecting at least one external surface of an aircraft, the device being provided with at least one anti-icing device and a device for measuring an ice accretion rate, the method comprising the steps of determining at least one activation parameter of the at least one anti-icing device as a function of the ice accretion rate determined by the measuring device in order to prevent ice accretion on the at least one external surface to be protected or to reduce the thickness of ice accumulated on the at least one external surface to be protected.

[0018] Since the at least one anti-icing device includes at least one anti-icing device having a heating element, the control method may include the following steps:

[0019] - determining a power density based on the ice accretion rate, the attitude of the aircraft, the air velocity and total ambient temperature received from a flight computer, and a predetermined temperature setpoint, and

[0020] - controlling the actuator of the at least one anti-icing device with a heating element such that power is transmitted to the anti-icing device with a heating element as a function of the determined power density in order to prevent ice formation on the anti-icing device with a heating element.

[0021] Since the at least one anti-icing device includes at least one anti-icing device having a heating element and / or at least one anti-icing device having a mechanical element, the control method may include the following steps:

[0022] - determining the duration between two activations as a function of the ice accretion rate, a correlation factor between the ice accretion rate determined by measuring the ice accretion rate and the ice accretion rate at the external surface to be protected, and a maximum permissible ice thickness,

[0023] - each time the determined duration between two activations has elapsed, the actuator of the anti-icing device is controlled in order to reduce the thickness of ice formed on the at least one external surface to be protected.

[0024] The correlation factor may depend on the attitude of the aircraft, air velocity, static ambient temperature, rotational speed of the propulsion device and the true speed of the aircraft.

[0025] When the anti-icing device is provided on the leading edge of a wing or a tail unit of an aircraft, the air flow rate may be equal to the true speed of the aircraft, or when the anti-icing device is provided on an engine air intake, an engine blade or a rotor blade, the air flow rate may depend on the true speed of the aircraft and the rotational speed of the propulsion unit.

[0026] The present invention also relates to a system for controlling an anti-icing system for protecting at least one external surface of an aircraft, the system being provided with at least one anti-icing device and means for measuring the ice accretion rate. The control system comprises a control device having an output connected to a flight computer, the flight computer being connected to a set of measuring devices, the set of measuring devices notably including means for measuring the ice accretion rate, the flight computer having an output connected to at least one of the anti-icing devices, the control device being capable of executing the control method described above.

[0027] The anti-icing device may be selected from an anti-icing device having a heating element and an anti-icing device having a mechanical element. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Other objects, features and advantages of the present invention will become apparent from a reading of the following description, which is given by way of non-limiting example only and with reference to the accompanying drawings, in which:

[0029] -picture[ Figure 1 ] shows the main elements of the system for controlling an anti-icing device according to the present invention,

[0030] -picture[ Figure 2 ] shows the duration between two activations of the anti-icing device,

[0031] -picture[ Figure 3 ] shows the variation of ice thickness as a function of time and the duration between two activations of the anti-icing device, and

[0032] -picture[ Figure 4 ] shows the difference between the air flow at the device for measuring the ice accretion rate and the flow at the area to be protected. DETAILED DESCRIPTION

[0033] The system according to the invention for controlling a de-icing device 1 comprises a control device 2 , the inputs of which are connected to a flight computer 3 and to a device 4 for measuring the ice accretion rate, and the outputs of which are connected to at least one anti-icing device 5 , 6 .

[0034] The anti-icing device 5 , 6 includes at least one of an anti-icing device 5 having a heating element and an anti-icing device 6 having a mechanical element.

[0035] picture[ Figure 1 ] shows such a system for controlling a de-icing device.

[0036] In one operating mode, the control device 2 controls the anti-icing device 5 with the heating element in an “anti-icing” mode. In other words, the aim is to prevent the formation of ice.

[0037] In this "anti-icing" control mode, the sufficient power density dP to be applied is determined, taking into account the information on the ice accretion rate, in order to optimize, i.e., adjust the reduction in, the electrical power to be used (consumed) in order to generate sufficient heating to prevent the formation of ice on the outer surfaces of the aircraft to be protected. This temperature to be reached, as well as the power to be supplied, will depend on the type of anti-icing required, i.e., dripping (in which the impacting droplets remain liquid) or evaporation (in which the droplets evaporate upon impact).

[0038] To achieve this, the control means 2 determine the power P to be supplied by the anti-icing device 5 having a heating element, as a function of data received from the flight computer 3 and the means 4 for measuring the ice accretion rate.

[0039] The power P is the product of the area S of the zone to be protected and the power density dP, which is given by applying the following equation:

[0040] [Mathematical formula 1]

[0041]

[0042] in:

[0043] -Q conv : heat exchanged by convection between the protected surface and the air flow in contact with the surface and the device 4 for measuring the ice accretion rate;

[0044] -Q evp : Heat generated due to evaporation of water droplets in contact with the protected surface;

[0045] -Q direction : The amount of heat required to change the temperature of the water in contact with the protected surface;

[0046] -Q kaero : heat generated due to aerodynamic heating of the flow over the protected surface;

[0047] -Q kdrop : Heat generated due to the kinetic energy of the droplets in contact with the protected surface.

[0048] The document Meier & Scholz, "A Handbook method for the estimation of power requirements for electrical de-icing systems," DLRK Hamburg, August 31, 2010 - September 2, 2010, describes methods for evaluating the energy balance term of equation [Equation 1]. In a first method, the power density dP is determined based on the following parameters:

[0049] [Mathematical formula 2]

[0050] dP=f(LWC ∞ ,β loc ,Alt,ATT,V e ,Temp,T surf_target )

[0051] in:

[0052] -dP: power density, in W / cm 2 ;

[0053] -LWC ∞ : Liquid water content or water concentration of clouds encountered by the aircraft (g / m 3 );

[0054] -β loc : the capture coefficient of the area to be protected, which is related to the geometry of the area, the size of the droplets present in the encountered cloud, and the speed and attitude of the aircraft, and is a dimensionless number between 0 and 1;

[0055] -ATT: vehicle attitude, angle of attack or flight phase, which directly affects the capture zone;

[0056] -Ve: air velocity;

[0057] -Temp: total ambient temperature (TAT) or static temperature (SAT);

[0058] -T surf_target : The surface temperature threshold to achieve anti-icing effect (which depends on whether it will drip or evaporate).

[0059] It should be noted that the air flow rate Ve can be defined as a function of the position of the anti-icing device.

[0060] For the wing leading edge and tail unit, the air flow velocity Ve is equal to the True Air Speed ​​(TAS).

[0061] For an engine air inlet, an engine blade or a helicopter rotor blade, the air velocity Ve is equal to the combination of the true air speed TAS of the aircraft and the propeller's rotational speed ER (acronym standing for “Engine Round per minute”).

[0062] In order to solve the energy balance equation, the cloud water concentration LWC must be known. ∞ and capture coefficient β loc In addition to the surface temperature threshold T surftargetIn addition to the other parameters given by the avionics system, the surface temperature threshold is a constant value selected when designing the anti-icing device 5 with a heating element.

[0063] The ice accretion rate information IAR can be obtained analytically by the following equation IDS :

[0064] The detector IAR is analytically given by the following equation:

[0065] [Mathematical formula 3]

[0066]

[0067] in:

[0068] TAS = true air velocity (m / s);

[0069] LWC = liquid water content or water concentration near the detector (g / m 3 );

[0070] β IDS = capture coefficient on the reference surface of the ice probe;

[0071] η IDS = Freezing Fraction (FF), a dimensionless coefficient between 0 and 1, representing the fraction of water that will freeze on the surface of the detector;

[0072] ρ i = density of ice (g / m 3 ), usually ρ i =917000g / m 3 .

[0073] The capture coefficient β on the reference surface of the ice probe IDS is a function of the surface geometry, the diameter of the droplets present in the icing cloud and their trajectories (i.e. the velocity and the drag exerted on the droplets). The capture coefficient is a dimensionless coefficient between 0 and 1 that represents the probability of ice accumulation on a droplet impacting the surface.

[0074] The coefficient β IDS The freezing fraction η can be evaluated by numerical simulations of water capture on a reference surface of an ice probe. IDSThe ice accretion simulation depends on the solution of the Messinger balance equation (B. L. Messinger (1953), "Equilibrium Temperature of an Unheated Icing Surface as a Function of Air Speed", Journal of Aeronautical Science, 20(1), 29-42, doi: 10.2514 / 8.2520).

[0075] The ice detector follows the guidelines given in ED103revB (EUROCAE ED103, “Minimum Operational Performance Standard for Inflight Icing Detection Systems”, Revision B, April 2022) and Appendix K of AC 20-73A, issued on April 16, 2006 (FAA “Advisory Circular 20-73A. Aircraft Ice Protection”), and the ice detector must be installed in an appropriate position on the aircraft to allow it to measure the IAR (IAR) representing the upstream unlimited flow. ∞ ),in

[0076] [Formula 4]

[0077] IAR ∞ =(TAS·LWC ∞ ) / ρ i

[0078] IAR ∞ Expressed in m / s.

[0079] On-duty IAR IDS tends to the value IAR ∞ When η IDS tends to 1, value β IDS Also tends to 1, and the value LWC tends to the value LWC ∞ .

[0080] As defined in ED103revB, ice probes must be able to provide IAR measurements with the following accuracy:

[0081] [Formula 5]

[0082] IAR IDS =IAR ∞ ±30% IAR∞

[0083] The information provided by the device 4 for measuring the ice accretion rate makes it possible to calculate the cloud water concentration value LWC for the energy balance ∞ :

[0084] [Formula 6]

[0085]

[0086] To be conservative, the capture coefficient β loc Can be considered equal to 1.

[0087] Therefore, the formula [Math 2] can use this LWC value to calculate the minimum power density applied to the surface to be protected.

[0088] As already stated, the power density dP is thus continuously determined from the IAR measurement value, which is transmitted as a control input for the actuator of the anti-icing device 5 with the heating element, and remains so as long as the IAR value is not zero.

[0089] In principle, the "anti-icing" control mode is still very energy-intensive.

[0090] Another control mode, the so-called "de-icing" control mode, allows reducing these losses while tolerating a certain thickness of ice accumulation. This thickness must be defined by the aircraft manufacturer. Therefore, provision is made for the control device 2 to control the anti-icing devices 5, 6 in de-icing mode.

[0091] The "de-icing" control mode enables ice to be deposited or accumulated to a thickness compatible with flight safety. Therefore, accumulated ice is periodically removed before it reaches its maximum permissible thickness.

[0092] In fact, the "de-ice" mode can:

[0093] - use of an anti-icing device 5 with a heating element, such as that used in the "anti-icing" control mode disclosed previously, but with cyclic, aggressive activation, and / or

[0094] - Use of an anti-icing device 6 with mechanical elements, also activated cyclically, in order to break up accumulated ice.

[0095] In particular, the anti-icing device 6 having a mechanical element is an actuator of the “inflatable cylinder” type.

[0096] In the present invention, it is proposed to optimize this cyclic activation by determining the time interval dT between two activations A, as shown in FIG. Figure 2 ] as shown.

[0097] picture[ Figure 2 ] shows the time interval dt between two activations A of the anti-icing devices 5, 6 in the "de-icing" mode. The time interval dt between two activations (also called duration dt) is defined by the following equation:

[0098] [Formula 7]

[0099]

[0100] -τ: ice thickness (in m);

[0101] -IAR loc : Ice accretion rate on the surface to be protected (in m / s).

[0102] It should be noted that the ice thickness τ must be between the minimum thickness required for effective de-icing and the maximum thickness allowed for safety and to ensure optimal performance of the anti-icing device.

[0103] Knowledge of the ice accretion rate allows activation of the anti-icing device with the heating element within a time window such that the thickness of the ice deposits is between a minimum threshold (the minimum thickness required for effective de-icing, in particular 2 mm) and a maximum threshold permitted for aircraft safety (the maximum permissible thickness, in particular 5 mm). The activation (e.g., de-icing) rate is therefore dependent on the ice accretion rate.

[0104] picture[ Figure 3 ] shows the change of ice thickness e with time, the minimum ice thickness e min , maximum ice thickness e max and the duration dt between two activations A of the anti-icing device. Each time the anti-icing device is activated, the ice thickness decreases to a negligible value. Figure 3 ] also shows the ice accumulation trend curve. Due to the gradual growth of ice, it can be understood that the cycle duration dt, that is, the time interval between two activations, is equal to the minimum ice thickness e min The minimum value dt for the second activation min When the ice thickness reaches its maximum value, e max The maximum value dt for the second activation is max Therefore, the duration dt between two activations of the anti-icing device must be within this minimum value dt min With the maximum value dt max This adjustment of the duration dt results from a strategy that makes it possible to optimize the energetic performance without compromising the safety and aerodynamic performance of the aircraft.

[0105] The above equation [Equation 7] does not take into account the duration of the anti-icing device's activation. This duration must be much shorter than the inter-cycle duration dt (a few seconds at most) in order to limit the number of simultaneously activated actuators throughout the aircraft and maintain the energy savings provided by the "de-ice" mode. It should be noted that the duration of the anti-icing device's activation is independent of the IAR. Furthermore, this duration depends heavily on the anti-icing device's technology.

[0106] picture[ Figure 4 ] shows the difference between the position 8 of the device for measuring the ice accretion rate 4 and the position 9 of the surface to be protected. Also shown is the air flow common to the device for measuring the ice accretion rate 4 and the surface to be protected, which is referenced 10.

[0107] Since it is used to measure ice accretion rate IAR IDS The device 4 is installed in different areas of the surface to be protected, so that the ice accretion rate IAR received from the measuring device 4 IDS The measured value must be compared with the ice accretion rate IAR at the surface to be protected to be applied to equation [Math. 7] loc This allows determining the most suitable inter-cycle duration dt, i.e. the most suitable time interval dt between two activations A of the anti-icing devices 5, 6 (or the most suitable inter-cycle duration dt between two activations A of the anti-icing devices 5, 6). The following equation illustrates this correlation.

[0108] [Formula 8]

[0109] IAR loc =C·IAR IDS

[0110] The correlation coefficient C is given by the following equation:

[0111] [Formula 9]

[0112] C=f(V e ,ATT,SAT)

[0113] To determine the function f for evaluating the coefficient C, the following method steps can be performed:

[0114] 1. Identify at least one of the most critical flight conditions of the aircraft,

[0115] 2. For each of the most critical flight conditions, an aircraft equipped with a device to measure ice accretion rate4 is subjected to aerodynamic and water capture simulations. The water capture simulation is a two-stage simulation in the aerodynamic field, where the droplet distribution of the spray is representative of the icing cloud encountered by the aircraft.

[0116] 3. For each analyzed flight condition and each capture simulation, evaluate the ice accretion rate IAR measured by the device for measuring the ice accretion rate 4 IDS and the ice accretion rate IAR of the surface to be protected loc To estimate the ice accretion rate on the surface to be protected, the analytical formulas described in the above-mentioned Messinger publication (B.L. (1953), "Equilibrium Temperature of an Unheated Icing Surface as a Function of Air Speed", Journal of Aeronautical Sciences, 20 (1), 29-42, doi: 10.2514 / 8.2520) can be used or ice accretion simulations can be performed using special tools.

[0117] 4. Based on the results of these simulations, a linear regression method is used to determine a polynomial approximation for the coefficients C. The following equation illustrates this linear regression:

[0118] [Formula 10]

[0119]

[0120] The coefficients b0, b1, b2, b3, b4 obtained using the above method are only valid for the analyzed aircraft and the area to be protected.

[0121] When the correlation factor C is known, the ice accretion rate IAR received from the device 4 for measuring the ice accretion rate can be calculated. IDS The value of is determined by applying the following equation to determine the inter-cycle duration dt:

[0122] [Mathematical formula 11]

[0123]

[0124] As previously mentioned, the duration dt of this period between two activations of the anti-icing devices 5 , 6 is between the minimum time required for the accumulation of a minimum ice thickness and the maximum time corresponding to the maximum acceptable ice thickness for the protected area.

[0125] The minimum ice thickness corresponds to the minimum thickness required for the actuator to be within its effective range. In particular, when the anti-icing device is a mechanical treatment device, its effectiveness is usually only applicable when the minimum ice thickness is exceeded.

[0126] The maximum ice thickness corresponds to the maximum thickness that the anti-icing device can handle, beyond which the anti-icing device is no longer effective. However, for technical, safety or regulatory reasons, the maximum ice thickness usually corresponds to the maximum value that the aircraft can withstand.

[0127] In one embodiment, the control device 2 periodically controls the anti-icing device 6 having a mechanical element in a "de-icing" control mode in order to break up ice present on the protected surface. This control device can be used alone or in combination with the control of the anti-icing device 5 having a heating element. The broken ice is then carried away by the air flow.

[0128] To achieve this, the control device 2 determines the inter-cycle duration dt between two activations by applying the aforementioned equation [Equation 7], similar to the duration between two activations for the anti-icing device 5 with a heating element. Therefore, the determined inter-cycle duration dt depends on the specific characteristics of the anti-icing device 6 with a mechanical element, in particular, the minimum and maximum ice thicknesses with which the anti-icing device 6 with a mechanical element can operate. The duration dt thus determined between two activations of the anti-icing device 6 with a mechanical element can therefore differ from the duration dt determined between two activations of the anti-icing device 5 with a heating element. In practice, the size of the crushed ice must be taken into account when determining the inter-cycle duration dt between two activations of the anti-icing device 5 with a heating element. In order to limit the size of the ice fragments removed by the operation of the anti-icing device 6 with a mechanical element, the inter-cycle duration dt should be limited according to the IAR so that the thickness of the crushed ice does not exceed the permitted limit.

Claims

1. A method for controlling an anti-icing device for protecting at least one outer surface of an aircraft, the device being provided with at least one anti-icing device (5, 6) and a device (4) for measuring the ice accretion rate, the method comprising the following steps: At least one activation parameter of the at least one anti-icing device (5, 6) is determined as a function of the ice accretion rate determined by the measuring device (4) in order to prevent ice accretion on the at least one external surface to be protected or to reduce the thickness of ice accumulated on the at least one external surface to be protected.

2. The method for controlling an anti-icing device in an aircraft according to claim 1, wherein the at least one anti-icing device comprises at least one anti-icing device (5) having a heating element, the control method comprising the following steps: - determining a power density dP as a function of the ice accretion rate, the attitude of the aircraft, the air velocity and the total ambient temperature received from a flight computer, and a predetermined temperature setpoint, and - controlling the actuator of the at least one anti-icing device with a heating element (5) so that power is transmitted to the anti-icing device with a heating element (5) as a function of a determined power density in order to prevent ice from forming on the anti-icing device with a heating element (5).

3. The method for controlling an anti-icing device in an aircraft according to claim 1 or 2, wherein the at least one anti-icing device comprises at least one anti-icing device (5) with a heating element and / or at least one anti-icing device (6) with a mechanical element, the control method comprising the following steps: - determining a duration dt between two activations as a function of said ice accretion rate, a correlation factor between said ice accretion rate measured by measuring (4) said ice accretion rate and the ice accretion rate at said external surface to be protected, and a maximum permissible ice thickness, - each time said determined duration dt between two activations has elapsed, the actuator of the anti-icing device is controlled in order to reduce the thickness of ice formed on said at least one external surface to be protected.

4. The method for controlling an anti-icing device in an aircraft according to any one of claims 1 to 3, wherein: The relevant factors depend on the attitude of the aircraft, air velocity, static ambient temperature, rotation speed of the propulsion device and the true speed of the aircraft.

5. The method for controlling an anti-icing device in an aircraft according to any one of claims 1 to 4, wherein: When the anti-icing device is provided on the leading edge of a wing or a tail unit of an aircraft, the air flow rate is equal to the true speed of the aircraft, or when the anti-icing device is provided on an engine air intake, an engine blade or a rotor blade, the air flow rate depends on the true speed of the aircraft and the rotational speed of the propulsion unit.

6. A system for controlling an anti-icing device for protecting at least one outer surface of an aircraft, said anti-icing device being provided with at least one anti-icing device (5, 6) and a device (4) for measuring the rate of ice accretion, said control system comprising a control device (2), the input of said control device (2) being connected to a flight computer (3), said flight computer (3) being connected to a set of measuring devices, said set of measuring devices in particular including the device (4) for measuring the rate of ice accretion, and an output of said flight computer (3) being connected to at least one of said anti-icing devices (5, 6), characterised in that The control device (2) is capable of executing the control method according to any one of claims 1 to 5.

7. The control system according to claim 6, wherein: The anti-icing device (5, 6) is selected from an anti-icing device (5) having a heating element and an anti-icing device (6) having a mechanical element.

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