Patent Description:
Aircrafts implement de-icing systems to remove ice accumulation on a critical surface of the aircraft such as for example, a wing, horizontal stabilizer, engine, pylons, and/or a blade to name a few surfaces. An example of an aircraft de-icing system includes an electrothermal ice protection system (IPS), which utilizes one or more high-watt density parting strips disposed at one or more ice stagnation areas of the critical surface.

The parting strips can be heated in response to receiving electrical current, thereby facilitating anti-icing (e.g., prevent the formation of ice) and/or removal of accumulated ice, ideally from an area of maximum dynamic pressure location on the leading edge of the critical surface. By removing the ice at the targeted location, aerodynamic forces realized by the critical surface during aircraft flight assists to remove or "shed" remaining portions of accumulated ice from locations of the critical surface farther aft, thereby allowing for a reduction of ice-removing electrothermal power (de-icing) and enhancing shedding performance in those other zones of ice protection. <CIT> describes an electrothermal deicing system. <CIT> describes a method of calibrating a heater system. <CIT> describes an aircraft wing with electrothermal deicing.

An electrothermal ice protection system (IPS) installed on an aircraft is defined in claim <NUM> and includes a sensor, a parting strip assembly, and a controller. The sensor monitors a direction of a local incident airflow that is imparted on the sensor. The parting strip assembly is coupled to the critical surface and includes a plurality of heating sections. The controller is in signal communication with the sensor and the parting strip assembly. The controller determines a direction of surface airflow incident on a critical surface of the aircraft based on the local incident airflow and selectively concentrates power to at least one targeted heating section among the plurality of heating sections with respect to non-targeted heating sections among the plurality of heating sections based on the direction of the airflow.

According to an example not falling within the scope of the appended claims, a parting strip assembly is configured to be installed at one or more critical surfaces of an aircraft. The parting strip assembly comprises a middle parting strip section, a lower parting strip section, and an upper parting strip section. The middle parting strip is configured to contact a middle portion of the critical surface, the lower parting strip section is configured to contact a lower portion of the critical surface, and the upper parting strip section is configured to an upper portion of the critical surface. The middle parting strip section, the lower parting strip section, and the upper parting strip section are activated in response to receiving a concentration of power, wherein the at least one middle parting strip section, the at least one lower parting strip section, and the at least one upper parting strip section are configured to be activated independently from one another.

According to claim <NUM>, a method of de-icing a critical surface of an aircraft is provided. The method comprises determining a plurality of heating zones on a critical surface of the aircraft and coupling a parting strip to the critical surface such that a plurality of heating section of the parting strip correspond to the plurality of heating zones. The method further comprises monitoring, via a sensor, a direction of a local airflow imparted on the sensor and determining, via a controller, a direction of surface airflow incident on the critical surface based on the direction of the local airflow imparted on the sensor. The method further comprises selectively activating, via the controller, the plurality of heating sections independently from one another by concentrating electrical power to at least one targeted heating section among the plurality of heating sections with respect to non-targeted heating sections among the plurality of heating sections based on the direction of the airflow.

Certain embodiments of the present disclosure will now be described in greater detail by way of example only and with reference to the accompanying drawing in which:.

Aircraft designers constantly seek design solutions to reduce electrical power needs on an aircraft. This goal becomes more important as aircraft designs increase the number of systems based on electricity. Ice protection is particularly important to the aircraft electrical design because the maximum power draw is high and is specifically needed in icing conditions which are encountered only during a fraction of the operating hours. A conventional electrical or electrical mechanical IPS utilizes a single strip at a fixed location, sometimes referred to as a "parting strip zone". The parting strip or multiple heaters are all energized together simultaneously so as to uniformly heat the parting strip zone, regardless as to the actual location of accumulated ice. Consequently, conventional IPS designs do not optimize power consumption.

Various non-limiting illustrative examples not falling within the scope of the appended claims, improve upon a conventional IPS by providing a parting strip assembly that includes multiple parting strips that define respective parting strip zones. One or more targeted parting strip zones can be heated independently from one another based on the angle of airflow with respect to the critical surface. Accordingly, a targeted parting strip zone can be selected to be heated and can dynamically change based on changes to the location of maximum dynamic pressure as it varies with aircraft angle of attack (AOA), the airspeed, the configuration of high-lift devices, and/or other parameters. Therefore, rather than heating the entire area of a critical surface disposed with parting strips as currently performed by a conventional electrothermal IPS, one or more non-limiting embodiments allows for selectively heating targeted parting strips without heating other parting strips, thereby providing an optimized electrothermal IPS capable of operating with improved power efficiency.

With reference now to <FIG>, an aircraft <NUM> equipped with an optimized electrothermal ice protection system (IPS) <NUM> is illustrated according to a non-limiting embodiment. The aircraft <NUM> includes a critical surface <NUM> that can be heated by the electrothermal IPS <NUM>. Although the critical surface <NUM> is described going forward as a wing, for example, it should be appreciated that the critical surface may also include, but is not limited to, an airfoil, a blade or any curved leading edge surface.

The electrothermal IPS <NUM> includes one or more sensors <NUM>, a parting strip assembly <NUM>, and a controller <NUM>. The electrothermal IPS <NUM> is configured to remove ice from a leading edge <NUM> of wing <NUM>. In accordance with the claims, the electrothermal IPS <NUM> provides heat to leading edge <NUM> so as to melt ice accreted thereto. Although leading edge <NUM> of wing <NUM> is depicted as being ice free, due to the ice removal capability of the electrothermal IPS <NUM>, ice accumulation <NUM> is shown at stagnation areas located aft of the electrothermal IPS <NUM>.

In illustrative examples not falling within the scope of the claims, sensors <NUM> can perform various types of sensing functions and measurements including, but not limited to, temperature measurement, atmospheric pressure measurement, airflow speed measurement, and airflow direction measurement. In one or more of said illustrative examples, the sensors <NUM> include a probe that extends out from the aircraft <NUM> (e.g., the side of the fuselage), thereby exposing the surface region to the atmosphere adjacent to the aircraft <NUM>. Various technologies can be used to detect ice accumulation on the exposed sensors <NUM>. For example, a resonant probe can be used to detect ice accumulation upon these surface regions. The resonant probe can have a resonant frequency change that is indicative of ice accumulation upon the surface region of sensor <NUM> which correlates to ice accumulation on the critical surfaces of the aircraft <NUM>. In some illustrative examples, two adjacent conductors can be located on the surface regions of parting strip assembly <NUM> such that the conductors are exposed to the atmosphere adjacent to wing <NUM>. When water or ice accretes on the surface region and spans two adjacent conductors, the conductivity therebetween can be indicative of such conditions. A temperature sensor located in proximity to the surface sensor can be used to differentiate between detection of water and ice.

In one or more non-limiting embodiments, the sensors <NUM> are configured to monitor a direction of incident airflow correlated to the direction of airflow incident on a critical surface <NUM> of the aircraft <NUM>. The incidence travel can be described as the variation of the incidence along the critical surface <NUM> (e.g., wing) during flight of the aircraft <NUM>. In some instances, during flight of the aircraft <NUM>, airflow angles close to the surfaces of an aircraft <NUM> are affected by boundary layer effects and may not be the same as the true airflow angle of the aircraft <NUM> relative to free stream conditions.

Some sensors <NUM> may be capable of sensing what is known as a local AOA or local airflow angle (i.e., the airflow angle at the localized area of the sensor) but may not be capable of provide an accurate measurement of the local airflow angle at other critical locations on the aircraft <NUM>. Therefore, an accurate determination of the local airflow angle at other critical locations on the aircraft may involve determining a correlation between the local sensed airflow angle and the local critical surface airflow angle. Accordingly, the sensors <NUM> can operate together with the controller to provide a local and specific information of the incidence. For instance, the airflow angle at the localized area of a sensor <NUM> can be delivered to the controller <NUM>, which then determines a correlation (e.g., through arithmetic calculations and/or using a predetermined look-up table stored in memory) between the local airflow angle and the direction of airflow incident on a critical surface <NUM> of the aircraft <NUM>.

The electrothermal IPS <NUM>, parting strip assembly <NUM>, and sensors <NUM> are in signal communication with a controller <NUM>. The controller <NUM> can control various operations of the electrothermal IPS <NUM>. In one or more non-limiting embodiments, the controller <NUM> controls operation of the parting strip assembly <NUM> based on one or more signals provided by the sensors <NUM>. For example, the controller can control a power supply (not depicted) to output electrical current to the parting strip assembly <NUM> based on a signal indicating ice accumulation detected by one or more of the sensors <NUM>. In turn, the current induces the parting strip assembly <NUM> to emit heat, thereby melting the ice. One or more non-limiting embodiments, the sensors <NUM> can determine a direction of airflow with respect to wing <NUM>. Based on the direction of the airflow, the controller <NUM> can activate a section of the parting strip assembly <NUM> to heat a targeted zone of the wing <NUM>, while deactivating other sections of the parting strip assembly <NUM>. In this manner, the power efficiency of the electrothermal IPS <NUM> can be improved as described in greater detail below.

<FIG> and <FIG> collectively illustrate a parting strip assembly <NUM> capable of heating a critical surface such as wing <NUM>. The wing <NUM> has a main body <NUM> extending between a trailing edge <NUM> and a leading edge <NUM>. In one or more non-limiting embodiments, the main body <NUM> has a recess <NUM> can be formed gradually by tapering, or can alternatively be formed by a step in the reduction of thickness.

The parting strip assembly <NUM> is configured to be disposed against an outer surface <NUM> of the leading edge <NUM> of the wing <NUM>. In one or more non-limiting embodiments, the parting strip assembly <NUM> can be sized and shaped so that it fits snugly within this recessed section <NUM> of the main body <NUM>. In one or more non-limiting embodiments, the outer surface of the parting strip assembly <NUM> is flush with the outer surface <NUM> of the wing <NUM> so that the surfaces are flush with each other and there is no step between their outer surfaces.

The parting strip assembly <NUM> covers at least part of the leading edge <NUM> of the wing <NUM>. In one or more non-limiting embodiments, the part of the wing <NUM> covered by the parting strip assembly <NUM> can include an expected ice stagnation area. In one or more non-limiting embodiments, the parting strip assembly <NUM> covers the upper surface, middle surface and lower surface of the wing <NUM> to define a heating zone <NUM> as shown in <FIG>. In some examples, the parting strip assembly <NUM> includes one or more parting strips, where each parting strip serves as a heating element. In one or more non-limiting embodiments, the parting strips are embedded in a resin or other matrix that provides anti-erosion protection and also serves as a thermal insulation layer. In at least one non-limiting embodiment, one or more of the parting strips include a strip of metallic foil that is resistive and generates heat when connected to an electric power supply by the Joule Effect. Other heating elements and matrices, however, can be employed without departing from the scope of the invention.

With continued reference to <FIG> and <FIG>, the parting strip assembly <NUM> includes a plurality of individual parting strip sections. In the example illustrated in <FIG> and <FIG>, the parting strip assembly <NUM> includes a lower parting strip section <NUM>, a middle parting strip section <NUM>, and an upper parting strip section <NUM>. It should be appreciated, however, that more or less parting strip sections can be employed without departing from the scope of the invention. The lower parting strip section <NUM> can define a lower heating zone, the middle parting strip section <NUM> can define a middle heating zone, and the upper parting strip section <NUM> can define an upper heating zone.

The lower parting strip section <NUM>, middle parting strip section <NUM>, and upper parting strip section <NUM> are in signal communication with the controller <NUM> and each can be independently activated and deactivated with respect to one another. In one or more non-limiting embodiments, a given parting strip section <NUM>, <NUM><NUM> can be activated by concentrating power to the given section given section <NUM>, <NUM><NUM>. For example, the controller <NUM> can activate the middle parting strip section <NUM> without activating the lower parting strip section <NUM> and the upper parting strip section <NUM>. In other scenarios, the controller <NUM> can activate a combination of the parting strip sections <NUM>, <NUM> and <NUM>. For example, the controller <NUM> can activate the lower parting strip section <NUM> and the middle parting strip section <NUM> without activating the upper parting strip section <NUM>. If necessary, the controller <NUM> can activate all of the lower parting strip section <NUM>, the middle parting strip section <NUM>, and the upper parting strip section <NUM> simultaneously.

In one or more non-limiting embodiments, the controller <NUM> can provide a higher power level to one parting strip section <NUM>, <NUM>, <NUM>, while providing a lower power level to one or more of the other parting strip sections <NUM>, <NUM>, <NUM>. In addition, the controller <NUM> can adjust the power levels (e.g., the power density) for a given parting strip section <NUM>, <NUM>, <NUM> based on the local AOA at the parting strip, while one or more targeted parting strip sections <NUM>, <NUM>, <NUM> to be controlled (e.g., thermally adjusted) for power optimization. The range of incident airflow angles over the flight envelope of the aircraft is used to locate and size the different parting strips.

Turning now to <FIG>, the parting strip assembly <NUM> is illustrated heating a middle heating zone <NUM> in response to detecting airflow <NUM> incident to the wing <NUM> at a first direction (e.g., in a forward direction) according to a non-limiting embodiment. As described herein, one or more sensors <NUM> can detect the direction of the airflow <NUM> with respect to the wing <NUM>. Accordingly, the controller <NUM> can receive the output signal from the sensor <NUM> to determine the direction of the airflow <NUM> at any given moment during the flight of the aircraft.

The forward direction of the airflow <NUM> incident on the middle of the middle area of the wing <NUM> is often the area of maximum dynamic pressure during typical flight conditions of an aircraft. Accordingly, the middle heating zone <NUM> is determined to be the optimum zone to be heated based on the current location of maximum dynamic pressure applied by the airflow <NUM>. As described herein, the controller <NUM> can selectively heat the middle heating zone <NUM> by activating the middle parting strip section <NUM> (e.g., by delivering electrical current to the middle parting strip section <NUM>) while deactivating the lower parting strip section <NUM> and the upper parting strip section <NUM> (e.g., by refraining from delivering current to the lower and upper parting strip sections <NUM> and <NUM>).

Referring to <FIG>, the parting strip assembly <NUM> is illustrated heating the lower heating zone <NUM> in response to detecting airflow <NUM> incident to the wing <NUM> at a second direction (e.g., in an upward direction) according to a non-limiting embodiment. In one or more non-limiting embodiments, the direction of the airflow <NUM> actively changes from the forward direction shown in <FIG> to the upward direction <NUM> shown in <FIG> during the flight of the aircraft. This scenario is typical during a "hold condition" or during descent and/or landing events. Accordingly, the location of maximum dynamic pressure moves to a lower location on the wing <NUM>.

In response to the upward direction of the airflow <NUM>, the controller can dynamically determine that the optimum zone to be heated is the lower heating zone <NUM>. In this manner, the controller can dynamically stop heating the middle heating zone <NUM> by deactivating the middle parting strip section <NUM> (e.g., stopping current flow thereto), and initiate heating of the lower heating zone <NUM> by activating the lower parting strip section <NUM> (e.g., delivering current flow thereto), while deactivating the middle parting strip section <NUM> and the upper parting strip section <NUM> (e.g., by refraining from delivering current to the middle and upper parting strip sections <NUM> and <NUM>).

Turning to <FIG> and <FIG>, the parting strip assembly <NUM> is illustrated heating the upper heating zone <NUM> in response to detecting airflow <NUM> incident to the wing <NUM> at a third direction (e.g., in a downward direction) according to a non-limiting embodiment. In one or more non-limiting embodiments, the direction of the airflow <NUM> actively changes direction (e.g., from the forward direction shown in <FIG>) to the downward direction <NUM> shown in <FIG> and <FIG> during the flight of the aircraft. This scenario is typical during a descent. Accordingly, the location of maximum dynamic pressure moves to an upper location on the wing <NUM>.

In response to the downward direction of the airflow <NUM>, the controller <NUM> can dynamically determine that the optimum zone to be heated is the upper heating zone <NUM>. In this manner, the controller <NUM> can dynamically initiate heating of the upper heating zone <NUM> by activating the upper parting strip section <NUM> (e.g., delivering current flow thereto), while deactivating the lower parting strip section <NUM> and the middle parting strip section <NUM> (e.g., by refraining from delivering current to the lower and middle parting strip sections <NUM> and <NUM>).

With reference now to <FIG>, a method of de-icing a critical surface of an aircraft is illustrated according to a non-limiting embodiment. The method begins at operation <NUM>, and at operation <NUM> an electrothermal IPS installed on an aircraft is activated. At operation <NUM>, a direction of airflow incident on a critical surface of an aircraft is monitored. The critical surface can include, but is not limited to, a wing, airfoil, and/or a blade. At operation <NUM>, an optimal heating zone of the critical surface is determined based on the direction of the airflow. At operation <NUM>, one or more targeted sections of a parting strip assembly are determined based on the optimal heating zone. At operation <NUM>, the targeted section(s) of the parting strip assembly are activated while non-targeted sections of the parting strip assembly are de-activated or reduced in power. Accordingly, the optimal heating zone is heating using the activated sections of the parting strip assembly. At operation <NUM>, a determination is made as to whether the electrothermal IPS has been deactivated. When the electrothermal IPS has been deactivated, the parting strip assembly is deactivated at operation <NUM> (e.g., current is halted to the targeted sections of the parting strip assembly), and the method ends at operation <NUM>.

When, however, the electrothermal IPS is not deactivated, the method returns to operation <NUM> and continues monitoring the direction of the airflow incident on the critical surface. It is typical for the aircraft to change direction, thus dynamically changing the direction of the airflow incident on the critical surface as described herein. For example, the direction of the airflow may change from a forward direction to an upward direction as the aircraft transitions from a cruise flight phase to a climb flight phase. When a change in the direction of the airflow is determined at operation <NUM>, a new optimal heating zone can be determined at operation <NUM>, and one or more different targeted sections of the parting strip assembly can be dynamically activated based on the newly determined optimal heating zone. Accordingly, the new targeted sections of the parting strip can be activated to account for the change in the airflow direction, and the method continues to operation <NUM> as described above.

Claim 1:
An electrothermal ice protection system "IPS" installed on an aircraft, the electrothermal IPS comprising:
a sensor (<NUM>) configured to monitor a direction of a local incident airflow imparted on the sensor (<NUM>);
a parting strip assembly coupled to a critical surface of a leading edge of a wing of the aircraft, the parting strip assembly including a plurality of heating sections; and
a controller (<NUM>) in signal communication with the sensor (<NUM>) and the parting strip assembly, the controller (<NUM>) configured to determine a direction of surface airflow incident on a critical surface of the aircraft based on the local incident airflow, and to selectively concentrate power to at least one targeted heating section among the plurality of heating sections with respect to non-targeted heating sections among the plurality of heating sections based on the direction of the surface airflow.