Abstract
The present invention relates to an ice detection/protection and flow control system based on printing of dielectric barrier discharge sliding plasma actuators. This invention has advantages such as: reduced weight, low maintenance cost, no environmental impact, fully electric operation and combination of functionalities (ice detection, deicing, anti-icing and flow control).
The system comprises the following components: exposed AC electrode (1), dielectric layer (2), embedded electrode (3), sliding/nanosecond electrode (4), ground plane (5), AC power supply (6), DC power supply (7), nanosecond range pulse generator (8), monitoring capacitor (9), high voltage probe (10), control module (11), temperature sensor (12), control signal input module (13) and monitoring system (14). The system senses ice formation and generates extensive surface heating to prevent ice accumulation.
Claims
1. Ice detection/protection system with ice detection, anti-frost and defrost operating modes and flow control comprising at least one dielectric barrier discharge plasma actuator, DC power supply, AC power supply, a high voltage probe, a nanosecond range pulse generator, and a control module, applicable on any surface; wherein the dielectric barrier discharge plasma actuator is connected in series with a monitoring capacitor, acts as an ice-forming sensor, and comprises a dielectric layer and three electrodes.
2. System according to claim 1, wherein the power supplies controlled by the control module switches between the ice detection, anti-frost and defrost operating modes.
3. System according to claim 1, wherein the nanosecond range pulse generator generates a pulsed voltage with a duration between 10 ns to 100 ns.
4. System according to claim 1, wherein two electrodes are exposed and positioned on the surface of the dielectric layer.
5. System according to claim 1, wherein one of the electrodes is covered by the dielectric layer.
6. System according to claim 1, wherein the three electrodes are: an exposed AC electrode is energized by AC voltage; the an exposed sliding/nanosecond electrode energized by DC voltage with a tendency for nanosecond pulses; an embedded electrode which is separated from the electrodes exposed by the dielectric material, is not exposed to air and is connected to the monitoring capacitor which is connected to a ground plane.
7. (canceled)
8. System according to claim 1, wherein in the anti-frost and defrost modes the AC voltage from the AC power supply has an amplitude between 5 and 80 kVpp and frequencies between 1 and 60 Hz.
9. System according to claim 1, wherein the monitoring capacitor is connected to the ground plane and monitors variations of the electric field of the plasma actuator.
10. System according to claim 1, further comprising at least one temperature sensor.
11. System according to claim 1, further comprising a control signal input module.
12. System according to claim 11, wherein in case of ice formation, the control module activates the AC power supply and the DC power supply, which adjusts the input signals from the exposed electrodes.
13. System according to claim 1, wherein an operating voltage is measured from the high voltage probe.
14. System according to claim 1, further comprising a monitoring system.
15. System according to claim 1, wherein the plasma actuator is manufactured by circuit printing technology with embedded temperature sensors.
16. (canceled)
Description
DESCRIPTION OF THE DRAWINGS
[0042] FIG. 1: Block diagram of the protection system against ice accumulation, in which (1) represents the exposed AC electrode, (2) represents the dielectric layer, (3) represents the embedded electrode, (4) represents the sliding/nanosecond electrode, (5) represents the ground plane, (6) represents the AC power supply, (7) represents the DC power supply, (8) represents the nanosecond range pulse generator, (9) represents the monitoring capacitor, (10) represents the high voltage probe, (12) represents the temperature sensor, (13) represents the control signal input module and (14) represents the monitoring system.
[0043] FIG. 2: Variation of the electric field due to different contaminations a) without contamination b) ice surface d) water
[0044] In which (1) represents the exposed AC electrode, (2) represents the dielectric layer, (3) represents the embedded electrode, (4) represents the sliding/nanosecond electrode, (15) represents the ice layer, (16) represents the water layer, (17) represents the electric field.
[0045] FIG. 3: I) Images obtained by Infrared techniques II) Spatial variation of temperature along the x axis III) Spatial variation of temperature along the y axis. For a) 0.3 mm Kapton b) 0.6 mm Kapton c) 1.12 mm Polycarbonate+Kapton. In which (1) represents the exposed AC electrode.
[0046] FIG. 4: Dielectric barrier discharge for two different applied voltages. In which (3) represents the embedded electrode, (18) represents the plasma discharge region, (1) represents the exposed AC electrode and (19) represents the length of the plasma.
[0047] FIG. 5: Different components of the DBD sensor/actuator deicing system. In which (1) represents the exposed AC electrode, (2) represents the dielectric layer, (4) represents the sliding/nanosecond electrode, (3) represents the embedded electrode, (20) represents a wing profile, (21) represents the sensor/actuator applied to the front surface of the wing, (18) represents the plasma discharge region, (22) represents the water droplets, (23) represents the ice layer in the area behind the effective area of the plasma, (24) represents the flow lines, (25) represents the ice layer in the front area of the wing.
[0048] FIG. 6: Multiple DBD plasma actuators for flow control on curved surfaces. In which (26) represents the curved surface, (1) represents the exposed electrode AC, (3) represents the embedded electrode and (18) represents the plasma discharge region.
[0049] FIG. 7: Network of DBD sensor/actuator systems manufactured from circuit printing technology. In which (27) schematically represents the wing of an aircraft, (28) represents the network of sensors/DBD actuators manufactured as a sheet, (1) represents the exposed AC electrode, (2) represents the dielectric layer, (3) represents the embedded electrode, (4) represents the sliding/nanosecond electrode.
MATCHING NUMBERS
[0050] (1): represents the exposed AC electrode. [0051] (2): represents the dielectric layer. [0052] (3): represents the embedded electrode. [0053] (4): represents the sliding/nanosecond electrode. [0054] (5): represents the ground plane. [0055] (6): represents the AC power supply. [0056] (7): represents the DC power supply. [0057] (8): represents the nanosecond range pulse generator. [0058] (9): represents the monitoring capacitor. [0059] (10): represents the high voltage probe. [0060] (11): represents the control module. [0061] (12): represents the temperature sensor. [0062] (13): represents the control signal input module. [0063] (14): represents the monitoring system. [0064] (15): represents the ice layer. [0065] (16): represents the water layer. [0066] (17): represents the electric field. [0067] (18): represents the plasma discharge region. [0068] (19): represents the length of the plasma. [0069] (20): represents a wing profile. [0070] (21): represents the sensor/actuator applied to the front surface of the wing. [0071] (22): represents water droplets. [0072] (23): represents the ice layer in the area behind the effective area of the plasma. [0073] (24): represents the flow lines. [0074] (25): represents the ice layer in the front area of the wing. [0075] (26): represents a curved surface. [0076] (27): represents the wing of an aircraft. [0077] (28): represents the network of sensors/DBD actuators manufactured as a sheet.
DETAILED DESCRIPTION
[0078] This invention comprises a dielectric barrier discharge plasma actuator composed of three electrodes. FIG. 1 shows the physical outline of this novel invention where the high voltage electrodes can be distinguished from the dielectric barrier material (usually a high temperature resistant polymer, glass, Kapton or Teflon). Referring particularly to FIG. 1, a simple sensor/actuator of this invention comprises: a dielectric layer (2), two electrodes positioned on the surface of the dielectric layer, wherein the exposed AC electrode (1) is energized with AC voltage and the sliding/nanosecond electrode (4), which is also exposed, is energized by a continuous voltage with a tendency for nanosecond pulses and an embedded electrode (3) which is not exposed to air and is connected to the ground plane (5). In another embodiment, the exposed voltage-energized electrode is also energized with nanosecond voltage pulses in the range of 10 ns to 100 ns.
[0079] One of the electrodes is covered by a dielectric material and the remaining electrodes are exposed to free flow. Also observed in FIG. 1 is the use of a DC power supply (7), an AC power supply (6) and a nanosecond range pulse generator (8). The electrodes are connected to a high voltage generator. Preferably, the distance between the exposed electrode and the embedded electrode can be optimized in order to increase the performance of the plasma actuator. The power supply is configured to generate alternating current with frequency magnitudes in the order of kilohertz and voltage amplitudes in the order of kilovolt. Particularly the power supply can cause a modulated voltage. When the high voltage AC signal, which is applied to the exposed AC electrode (1), has sufficient voltage amplitudes (5-80 kVpp) and frequencies (1-60 kHz) a dynamic electric field change is produced and the intense electric field ionizes partially the adjacent air producing non-thermal plasma on the dielectric surface. Ionized air propagates from the front side of the exposed AC electrode (1) to the embedded electrode (3) creating a plasma track. The dielectric layer does not readily lead the current, so it prevents the formation of electric arc between the electrodes, which allows the electric field to suck the air down and form the plasma. The difference in potential applied leads to the change of charged ions in the plasma and some of these ions collide with the adjacent air molecules, which bounce in the same direction creating the so-called ionic wind. In this way, the plasma actuator accelerates the surrounding fluid. In this mode, the main flow control mechanism passes by movement induction to the adjacent flow. When the sliding/nanosecond electrode 4 is energized at the same time with a DC voltage with a tendency for nanosecond range pulses, a large plasma sheet is formed on the upper surface of the dielectric layer which covers the entire surface between the exposed AC electrode (1) and the sliding/nanosecond electrode (4), which in turn is also exposed. Collisions between neutral particles and accelerated ions give rise to a body force in the surrounding fluid leading to the formation of the so-called ionic wind. Body force can be used to induce a desired flow control of a fluid system. For the DBDs the amount of plasma and fluid movement induces an initial vortex propagating downstream from the exposed AC electrode (1) to the sliding/nanosecond electrode (4). The existence of the dielectric barrier introduces a region of high electric field force breakdown and therefore leads to high intensities in the plasma region. The discharge of plasma generated by the DBD triggers the ionization of the particles contained in the gas that is in the surrounding environment. Gas and surface heating due to plasma formation is caused by the work done by electric field ions, by the extinction of electronically energized species and by the impact of the elastic electrons with the ambient gas. The heat generated by the ionization is transmitted directly to the surface and is then positioned by the ionic wind thus preventing the formation of ice on that surface. In fact, a large part of the heat that is transferred to the dielectric layer derives from the convexity of the hot air flowing on its surface. The plasma actuator used in this invention is a DBD type actuator, which generates the so-called non-thermal plasma. The temperature of the ionized particles in this type of plasma is typically within the range of 40 C. to 100 C., and as such the presence of plasma has no destructive effects on the materials to which they are applied. The shape of the DBD electrodes may optionally be changed to circular or serpentine forms in order to obtain different force fields and associated flows. This system also comprises a control module (11) that can automatically control the power supplies according to a predetermined criterion, allowing the automatic switching between ice, anti-icing and deicing detection modes of operation, based on the fact that the heating of the surface caused by the formation of plasma will increase with the increase of the applied voltage and the voltage applied in the ice detection mode is much lower than the voltage applied in the anti-icing and deicing modes. The system also includes at least one temperature sensor (12) whose output signal is used to analyse the formation of ice on the surface. The sensor allows determining the presence of freezing conditions. If there is a possibility of freezing conditions, the system operates in ice detection mode in order to indicate the presence of ice. Other control signals, for example relative to weather conditions, may optionally be supplied to the system from the control signal input module (13). The control module can easily switch between modes, and in the absence of favourable conditions for ice formation, the system can then be used as a flow control device. However, in case of detection of ice formation on the surface, the control module activates the power supply by appropriately adjusting the input signals of the exposed electrodes and the system starts running in deicing mode. The operating voltage is measured from a high voltage probe (10) and the current consumed by the DBD plasma actuator is obtained by measuring the voltage to the terminals of the monitoring capacitor (9) which is connected to the ground plane (5). The voltage and current measured during operation of the system can be obtained by the user from the monitoring system (14). The DBD is used as an ice detector sensor in a manner similar to a capacitive sensor. Since the permissivities of air, water and ice are different, the accumulation of charge on the surface of the dielectric material will also be different. From the measurement of the effect of each material on the electric field or the load on the surface the different materials can be identified. FIG. 2 shows the electrical field disturbances near the sensor-actuator surface due to external contaminations such as water and ice layer. The exposed AC electrode (1) in this mode operates with a certain voltage and the embedded electrode (3) and the sliding/nanosecond electrode (4) act as charge receptors. The electric field (17), close to the surface, makes it possible to distinguish the presence of an ice layer (15) or a water layer (16) partially covering the surface. Using this principle, the DBD functions as an ice detector sensor. The energized voltage that is required for ice detection purposes is low and can be defined according to the capacity used for measuring surface charges. The ice sensor accordingly notifies the system on the existence of ice so that it can melt precisely and carefully the ice where it is needed and only when it is needed.
[0080] FIG. 3 shows thermal images obtained by Infrared techniques and the spatial variation of the temperatures along x and y of conventional DBD plasma actuators but with different layers of dielectric material. In this Figure, (1) represents the exposed AC electrode. As the applied voltage increases, the heating of the surface provided by the plasma actuator is improved. This is used as the basis for the control system, which controls the supply voltage and from this control it can switch between the anti-icing and deicing modes. If a layer of thinner dielectric material is used the heating effect is also improved. Therefore, thinner dielectric layers can also be used in the manufacture of the present invention in order to improve its efficiency in surface heating.
[0081] FIG. 4 shows the plasma surface extension for typical plasma actuators with two electrodes with applied voltages of different amplitudes, where (3) represents the embedded electrode, (18) represents the plasma discharge region, (1) represents the exposed AC electrode and (19) represents the length of the plasma. When the applied voltage is increased, the plasma surface extends over a larger area. This again confirms that the control system can be used to change the applied voltage depending on the different purposes of deicing or anti-icing operation.
[0082] FIG. 5 demonstrates an ice protection system on the surface of a wing using multiple sensors and DBD actuators. The different layers of the system including the electrodes and the dielectric layer are shown, in which (1) represents the exposed AC electrode, (2) represents the dielectric layer, (3) represents the embedded electrode, (20) represents a wing profile and (21) represents the sensor/actuator applied to the front surface of the wing representing one of the most critical areas for ice formation. By using multiple sensors/actuators it is then possible to cover larger surfaces. When an ice layer is formed in the front area of the wing (25), the actuator system will be activated in deicing mode by rapidly removing the ice from the surface. In this case the exposed AC electrode (1) will be energized with high AC voltage and at the same time the sliding/nanosecond electrode will be fed with nanosecond pulse high voltage. In view of the formation of plasma on the surface, the surface temperature of the wing increases to a temperature higher than the melting temperature of the water. The formation of micro-shockwaves together with a rapid heating of the sliding/nanosecond electrode (4) will separate the ice layer from the surface. Thus, the ice present on the front edge of the wing is melted and poured out by the flow around the wing. A few drops of water (22) resulting from the deicing performed on the front edge of the wing will be drawn by the flow to the surface of the wing. If the rear part of the wing is not protected, then an ice layer forms in the area behind the effective area of the plasma (23). A portion of this reforming ice layer will be melted by the heat produced by the pulse electrode in the nanosecond range and the remaining portion will be melted by the second sensor/actuator which is installed on the surface.
[0083] FIG. 6 shows multiple DBD actuators for flow control on curved surfaces. In this FIG. 26) represents the curved surface, (1) represents the exposed AC electrode, (3) represents the embedded electrode and (18) represents the plasma discharge region. Since DBD sensors/actuators are composed of thin, flexible layers of electrodes and dielectric material, they can be used on a variety of surfaces including flat or curved surfaces. Therefore, they can be applied to practically all kinds of surfaces.
[0084] FIG. 7 schematises a top view of an aircraft wing equipped with a network of these DBD sensor/actuator systems, manufactured from circuit printing technology as flexible surfaces embedded in the wing surface and exposed to air, wherein (27) represents the wing of an aircraft, (28) represents the network of DBD sensors/actuators manufactured as a sheet, (1) represents the exposed AC electrode, (2) represents the dielectric layer, (3) represents the embedded electrode, and (4) represents the sliding/nanosecond electrode. The DBD sensor/actuator sets are staggered between each other and are connected in parallel forming a sensor/actuator network capable of covering the entire aerodynamic surface. This network of actuators comprises a number of flexible sheets each containing multiple DBD sensors/actuators intended to be applied to surfaces for control thereof and prepared to generate multiple plasma discharges in order to induce a flow of ionized hot particles in the direction of the surface. By using circuit printing technology, customizing the dimensions of the DBD sensors/actuators is something that is done with extreme ease. The production of continuous and flexible bands of DBD sensor/actuator networks from printing technology also ensures the reduction of installation and maintenance costs.
APPLICATION EXAMPLES
[0085] The present invention has various industrial applications such as deicing and flow control in aircraft components including fixed wings, stabilizers, jet engine inlet, engine inlet, helicopter rotor blades, rotary blades, air turbine blades.
[0086] It can also be applied as a deicing system in critical tubular systems.
REFERENCES
[0087] [1] E. MERLO, A. Gurioli, E. MAGNOLI, G. MATTIUZZO, R. PERTILE, System for preventing icing on an aircraft surface operationally exposed to air, WO 2014122568 A1, 2014. [0088] [2] S. G. Saddoughi, B. J. Badding, P. Giguere, M. P. Boespflug, J. G. A. Bennett, A. Gupta, System for deicing a wind turbine blade, EP 2365219 A2, 2011. [0089] [3] S. G. Saddoughi, B. J. Badding, P. Giguere, M. P. Boespflug, G. A. Bennett, A. Gupta, System and method of deicing and prevention or delay of flow separation over wind turbine blades, 2011. [0090] [4] G. Herbaut, D. Bouillon, Splitter nose with plasma de-icing for axial turbomachine compressor, CA 2908979 A1, 2016. [0091] [5] G. CORREALE, I. Popov, Boundary layer control via nanosecond dielectric/resistive barrier discharge, WO 2015024601 A1, 2015. [0092] [6] R. B. Miles, S. O. Macheret, M. Shneider, A. Likhanskii, J. S. Silkey, Systems and methods for controlling flows with electrical pulses, 2010. [0093] [7] W. Guang-qiu, X. Bang-meng, Y. Guang-quan, Laminated plate aircraft skin with flow control and deicing prevention functions, CN 102991666 A, 2013. [0094] [8] C. Jinsheng, T. Yongqiang, M. Xuan-shi, Z. Qi, Icing removing device and method of dielectric barrier discharge plasma, CN 104890881 A, 2015. [0095] [9] E. Merlo, A. Gurioli, E. Magnoli, G. Mattiuzzo, R. Pertile, System for preventing icing on na aircraft surfasse operationally exposed to air, WO2014122568 A1, 2014. [0096] [10] R. Miles, S. Macheret, M. Shneider, A. Likhanskii, J. Silkey, Systems and methods for controlling flows with electrical pulses, US 20080023589 A1, 2008. [0097] [11] S. G. Saddoughi, B. J. Badding, P. Giguere, M. P. Boespflug, G. A. Bennett, JR, A. Gupta, System and method of deicing and prevention or delay of flow separation over wind turbine blades, US20110135467 A1, 2011. [0098] [12] L. M. Weinstein, Ice detector, U.S. Pat. No. 4,766,369 A, 1988. [0099] [13] J. J. Gerardi, G. A. Hickman, A. A. Khatkhate, D. A. Pruzan, Apparatus for measuring ice distribution profiles, U.S. Pat. No. 5,398,547 A, 1995. [0100] [14] Surface Dielectric Barrier Discharge Plasma Actuators, (n.d.). [0101] [15] G. W. Codner, D. A. Pruzan, R. L. Rauckhorst, A. D. Reich, D. B. Sweet, Impedance type ice detector, U.S. Pat. No. 5,955,887 A, 1999. [0102] [16] V. Correia, C. Caparros, C. Casellas, L. Francesch, J. G. Rocha, S. Lanceros-Mendez, Development of inkjet printed strain sensors, Smart Mater. Struct. 22 (2103) 105028. [0103] [17] S. Khan, L. Lorenzelli, R. S. Dahiya, Technologies for Printing Sensors and Electronics Over Large Flexible Substrates: A Review, IEEE Sens. J. 15 (2015) 3164-3185.
