The present disclosure relates to anti-icing systems and, more particularly, to electrically powered anti-icing systems for aircraft nacelle noselips and other aerodynamic surfaces.
Forward facing aerodynamic surfaces on aircraft may be subject to the formation of ice when exposed to icing conditions, such as, for example, a combination of low temperature and high humidity. Such surfaces include the leading edges on wings and stabilizers and the noselips on nacelle inlets. The formation of ice on such aerodynamic surfaces may have an adverse effect upon the performance of the aircraft. For example, the formation of ice on a noselip can modify the aerodynamic properties of the nacelle inlet and disturb the flow of air toward the fan. In addition, the formation of ice on the noselip may bring about ingestion of ice into the engine, potentially damaging the engine. As such, various ice protection systems have been developed to prevent or reduce the formation of ice upon select aerodynamic surfaces. In this regard, ice protection systems may heat a leading edge or other aerodynamic surface to a temperature above that suitable for ice formation in order to prevent or reduce ice formation. In addition, conventional ice protection systems typically use higher power than is necessary for ice prevention due to power density requirements imposed by manufacturers of engines and airframes, resulting in heavy, expensive and energy inefficient systems.
An anti-icing system for an aerodynamic surface is disclosed. In various embodiments, the anti-icing system includes a plurality of conductive heating elements distributed about and in contact with the aerodynamic surface and a signal source configured to activate and deactivate an alternating current supplied to each one of the plurality of conductive heating elements in an ordered pattern.
In various embodiments, each one of the plurality of conductive heating elements is activated for a specific time period. In various embodiments, the specified time period is within a range from about 20 KHz to about 30 KHz. In various embodiments, the alternating current has a frequency within a frequency range from about 300 Hz to about 500 Hz. In various embodiments, the alternating current provides a power density within a range from about 10 KW/m2 to about 50 KW/m2. In various embodiments, the anti-icing system further includes a controller configured to select one or more of the specified time period, the frequency and the power density or voltage. In various embodiments, each one of the plurality of heating elements comprises a resistive material connected to an interior surface of an aircraft noselip. In various embodiments, the signal source is configured to provide one or more of a variable current, a pulsating current and an alternating current. In various embodiments, the aerodynamic surface is an aircraft noselip and the ordered pattern is a circular pattern. In various embodiments, the ordered pattern is a diagonal pattern.
A method of anti-icing an aircraft nacelle inlet having a plurality of conductive heating elements distributed about a noselip is disclosed. In various embodiments, the method includes activating and deactivating an alternating current supplied to each one of the plurality of conductive heating elements in an ordered pattern. In various embodiments, the method includes activating each one of the plurality of conductive heating elements for a specific time period. In various embodiments, the specified time period is within a range from about 20 KHz to about 30 KHz. In various embodiments, the alternating current has a frequency within a frequency range from about 300 Hz to about 500 Hz. In various embodiments, the alternating current provides a power density within a range from about 10 KW/m2 to about 50 KW/m2. In various embodiments, the ordered pattern is a circular pattern. In various embodiments, the ordered pattern is a diagonal pattern.
An anti-icing system for an aircraft nacelle is disclosed. In various embodiments, the anti-icing system includes a noselip and a conductive heating element distributed circumferentially about and in contact with the noselip, the conductive heating element having a first end connected to a ground and a second end connected to a signal source configured to provide an alternating current. In various embodiments, the alternating current has a frequency within a frequency range from about 300 Hz to about 500 Hz. In various embodiments, the alternating current provides a power density within a range from about 10 KW/m2 to about 50 KW/m2.
The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the following detailed description and claims in connection with the following drawings. While the drawings illustrate various embodiments employing the principles described herein, the drawings do not limit the scope of the claims.
The following detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that changes may be made without departing from the scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. It should also be understood that unless specifically stated otherwise, references to “a,” “an” or “the” may include one or more than one and that reference to an item in the singular may also include the item in the plural. Further, all ranges may include upper and lower values and all ranges and ratio limits disclosed herein may be combined.
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Under certain operating or environmental conditions, ice formation may occur on the inlet 110. In various embodiments, an electric heater may be provided at various locations within or adjacent to the inlet 110 in order to reduce the incidence of ice formation (anti-icing). For example, in various embodiments, the electric heater may be positioned between composite layers that make up the inlet 110 or on the inner surfaces comprised by the inlet 110. While the following disclosure is directed toward various embodiments concerning anti-icing of an aircraft nacelle inlet, the disclosure contemplates the various embodiments as being applicable to anti-icing other portions of the aircraft, such as the leading edges of the wings and the stabilizer, as well as other unrelated technologies, such as the blades and various other components of wind turbines.
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As will be described in additional detail below, the first noselip heating system 300a operates by periodically directing an alternating current to each of the plurality of N=8 heating elements. In various embodiments, for example, the first heating element 302 includes a first power lead 308 and a second power lead 310 connected to a first alternating current signal source 312. Similarly, the second heating element 304 includes a third power lead 314 and a fourth power lead 316 connected to a second alternating current signal source 318. In various embodiments, the first alternating current signal source 312 and the second alternating current signal source 318 may be configured to provide variable currents, pulsating currents or alternating currents in the form of sine waves, square waves or triangular waves. Both the first heating element 302 and the second heating element 304 are conductors or resistive heating elements and are separated by an insulator 320. In various embodiments, the insulator 320 is a strip of non-conductive material. In various embodiments, the insulator 320 is a gap between adjacent heating elements. In various embodiments, each of the heating elements is activated (or powered), individually and singularly, for a time period T1, and then deactivated (or depowered), such that only a single heating element is powered at any time. For example, the first heating element 302 is activated by the first alternating current signal source 312 for a first duration of time (0<t≤T1). During the first duration of time, each of the other heating elements is inactive—i.e., there is no power provided to the other heating elements during the first duration of time (0<t≤T1). During a second duration of time (T<t≤2T1), the second heating element 304 is activated, while each of the other heating elements, including the first heating element 302, is inactive. The process continues until each one of the plurality of heating elements is, individually and singularly, activated and deactivated (or powered and depowered). Following the activation and deactivation of each of the N heating elements (e.g., at t=8T1), the process repeats, in an ordered pattern, as above described, or in some other predetermined pattern, such that each of the N heating elements is activated and deactivated during any duration of time equal to the number of heating elements, N, times the time period, T1.
In various embodiments, the ordered pattern is circular, such that each of the heating elements is activated and deactivated in a clockwise or counterclockwise direction. For the N=8 configuration illustrated in
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The above disclosure provides systems and methods of maintaining an aerodynamic surface free of ice using a low peak power throughout the system's use. As described, and in accordance with various embodiments, the systems work by activating and deactivating heating elements positioned adjacent to a noselip periodically at high frequencies to reduce the incidence of ice formation, as opposed to removing the ice following formation. By periodically powering the heating elements at a high frequency one is able to heat small sections of the noselip at such a high rate that before power returns to that section of the noselip, the section has not lost the thermal energy previously supplied. Therefore, by adding more thermal energy to the noselip section, one may further increase the temperature of the section until a steady state is reached. The systems are also self-regulating as the temperature increase of each section of a noselip with each powering period will be smaller and smaller as the temperature increases toward steady state. The above described systems will also allow anti-icing ice protection to be performed with a low peak power, allowing for the implementation of an electric ice protection system without having to add heavy or costly generators to currently existing system architectures.
Finally, it should be understood that any of the above described concepts can be used alone or in combination with any or all of the other above described concepts. Although various embodiments have been disclosed and described, one of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. Accordingly, the description is not intended to be exhaustive or to limit the principles described or illustrated herein to any precise form. Many modifications and variations are possible in light of the above teaching.
Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials.
Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment”, “an embodiment”, “various embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.
Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.