Device for reducing hydrodynamic drag - Patents.com

Abstract

The invention relates to a device (40) for reducing the hydrodynamic drag of a vessel (10), comprising a hull (20), a fuel cell (30) and means (42) for conveying a first amount of air discharged by the fuel cell (30) to at least one injection means (50) constituted by the hull (20), the injection means (50) being configured to inject the first amount of air opposite the surface (22) of the hull (20) intended to be submerged.

Description

[Technical field]

[0001] The technical field of the invention relates to the field of warships. More precisely, it relates to devices for reducing the hydrodynamic drag of ships. The technical field of the invention therefore relates to the field of increasing the energy efficiency of ships. The technical field of the invention also relates to the field of ships using fuel cells to provide the electrical energy for driving the motors of the vehicle. [Background technology]

[0002] Drag force is the force that opposes the motion of an object immersed in a fluid. This force is exerted on an object moving through a fluid by the friction of the fluid on the object.

[0003] Thus, reducing hydrodynamic drag can improve the performance of the vessel by limiting the energy consumed by the vessel. Thus, devices for reducing hydrodynamic drag can improve the efficiency of the vehicle.

[0004] From the prior art it is known that it is possible to reduce the frictional forces due to the water acting on the hull of a vessel by using a static layer of air or an air flow in contact with the hull.

[0005] There are prior art vessels which include in their hull inter alia interfitting cavities which allow the creation of an air cushion covering a part of the surface of the hull which would otherwise be in contact with the water. Such a device is known in particular from US 2003 / 159637. Such a device allows an effective reduction of the hydrodynamic drag of the vessel. However, this type of device is ineffective when the swell is too strong, since the waves "destroy" the air cushion formed under the vessel. Furthermore, it is necessary to use a compressor capable of providing the pressure required for the formation and maintenance of the air cushion under the vessel. The operation of the compressor consumes energy, but the energy efficiency of such a device is insufficient. Moreover, the presence of the compressor increases the mass of the vessel, contributing to a decrease in its energy efficiency.

[0006] It is also known to use an injector located under the hull to inject air in direct contact with the hull. Such a device is known from Korean Patent Publication No. 2020-0011300, which discloses a device for reducing hydrodynamic drag including an injector located under the hull of a vessel. The injector injects a certain amount of air that is in direct contact with the hull and the water. This is the amount of air that lubricates the hull and reduces drag. Such devices, although effective, have the drawback that energy must be used to operate the compressor used to inject the air. Such use of energy significantly reduces the efficiency of such systems. Furthermore, the presence of the compressor increases the mass of the vessel, contributing to a decrease in its energy efficiency.

[0007] Also known from the prior art are ships that use fuel cells to electrically drive a motor. Ships that use hydrogen to drive a fuel cell and provide electrical energy to the motor are particularly known. Typically, the fuel cell provides a certain amount of electrical energy by utilizing a chemical reaction between dihydrogen, supplied from a tank, and dioxygen present in the atmosphere. During this process, the fuel cell expels a certain amount of warm and humid air into the atmosphere. Also, during the production of electrical energy, the fuel cell expels a certain amount of water. Such ships are of interest to provide motorization that limits greenhouse gas emissions.

[0008] SUMMARY OF THE PRESENT EMBODIMENTS The present invention therefore aims to provide a device for reducing hydrodynamic drag that can overcome the drawbacks of existing devices. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] US Patent Publication No. 2003 / 159637 [Patent Document 2] Korean Patent Publication No. 2020-0011300 Summary of the Invention

[0010] To this end, the present invention relates to a device for reducing the hydrodynamic drag of a ship, the device comprising: a vessel body including at least one first jetting means for jetting fluid; A fuel cell; means for conveying the first amount of air discharged by the fuel cell to at least the first injection means; Equipped with The first injection means is configured to inject a first quantity of air along a surface of the hull that is intended to be submerged.

[0011] Advantageously, the device for reducing hydrodynamic drag according to the invention allows to benefit from the limitation of greenhouse gas emissions by proposing the use of fuel cells. Likewise, as a result of the use of injection means, the device injects a volume of air under the hull which reduces the hydrodynamic drag of the vessel.

[0012] Finally, the device according to the invention allows air leaking from the fuel cells to be recycled and injected under the hull. This arrangement is particularly advantageous since it allows avoiding the use of a compressor dedicated to injecting air under the hull. The device according to the invention therefore allows a significant improvement in the energy efficiency of existing drag reduction systems, since it saves the energy used by the compressor. Also, the mass of the vessel can be reduced due to the fact that there is no dedicated compressor. Reducing the mass of the vessel also allows the energy consumption of the vessel to be reduced, which in turn allows the energy efficiency of the vessel to be improved.

[0013] According to one embodiment, the first injection means comprises a sealing element that limits or prevents the upward flow of a certain amount of water into the vehicle, which prevents water from rising in the vehicle and / or the fuel cell.

[0014] According to one embodiment, the first amount of air is injected by the injection means in the form of bubbles, preferably with a diameter of less than 5 mm. Bubbles are an effective way to reduce hydrodynamic drag. A diameter of 5 mm corresponds to the thickness of the boundary layer close to the hull and represents a dimension where drag reduction is very effective.

[0015] According to one embodiment, the first amount of air is injected by the injection means in the form of bubbles, preferably having a diameter between 0.4 mm and 1.3 mm, these diameter values ​​allowing an effective reduction of the hydrodynamic drag.

[0016] According to one embodiment, the vessel comprises a hydrofoil intended to be immersed, the hydrofoil comprising at least one second jetting means configured to jet at least a portion of the first amount of air, which allows to reduce the hydrodynamic drag on the vessel comprising the hydrofoil.

[0017] According to one embodiment, the second injection means of the wing are arranged to inject a portion of the first amount of air along a vertical plane of the wing, which makes it possible to not reduce the lift of the wing when the injection is effective by injecting air in the vertical plane.

[0018] According to one embodiment, the hull comprises an additional part forming a setback upstream of the first jet means with respect to the direction of movement of the vessel. This arrangement allows forming a recess downstream of the additional part. This recess allows for drawing air through the jet means for injecting the air and reducing drag. This arrangement allows for creating a localized turbulence. The turbulence enhances the efficiency of the injected air to reduce hydrodynamic drag.

[0019] According to one embodiment, the apparatus comprises a device for directing and controlling airflow within the vehicle, whereby the injected airflow can be controlled to optimize hydrodynamic drag reduction.

[0020] According to one embodiment, the vehicle comprises at least one airflow sensor, which allows the airflow in the vehicle to be known and thus to be adjusted by taking into account the measurements. When the device according to the invention comprises a command control device, the flow information allows the device to provide the command control device with flow information, which allows for more effective control of the airflow.

[0021] According to one embodiment, the device comprises means for recovering a second volume of air from the apparent wind of the vehicle, the means for recovering the second volume of air being capable of conveying the second volume of air to the conveyance means, such that the airflow conveyed to the injection means can be supplemented by the apparent wind.

[0022] Also, according to one aspect, the present invention relates to a method for reducing hydrodynamic drag on a vessel, comprising the steps of: conveying, by a conveying means, a first amount of air discharged by the fuel cell to an injection means constituted by the hull; and Injecting a first quantity of air by an injection means along a surface of the hull intended to be immersed.

[0023] Advantageously, the method according to the invention makes it possible to benefit from the limitation of greenhouse gas emissions by proposing the use of fuel cells. Likewise, the use of the injection means results in a volume of air being injected under the hull, reducing the hydrodynamic drag of the vessel.

[0024] Finally, the method according to the invention allows air leaking from the fuel cells to be recycled and injected under the hull. This arrangement is particularly advantageous since it allows avoiding the use of a compressor dedicated to injecting air under the hull. The method according to the invention therefore allows a significant increase in the energy efficiency of existing drag reduction systems, since the energy used by the compressor is saved. Also, the mass of the vessel can be reduced due to the fact that there is no dedicated compressor. Reducing the mass of the vessel also allows the energy consumption of the vessel to be reduced, which increases the energy efficiency of the vessel. [Brief description of the drawings]

[0025] Other features and advantages of the present invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings. [Figure 1] 1 is a schematic longitudinal sectional view of a ship equipped with a device for reducing drag according to a first embodiment of the present invention. [Diagram 2] 11 is a schematic longitudinal sectional view of a ship equipped with a device for reducing drag according to a second embodiment of the present invention. FIG. [Diagram 3]FIG. 11 is a schematic partial cross-sectional view of a hull of a ship equipped with a device for reducing drag in accordance with a third embodiment of the present invention. [Figure 4] FIG. 11 is a cross-sectional view of a hull of a ship according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] FIG. 1 shows a first embodiment of the invention. It is a schematic cross-sectional view of a vessel 10 equipped with a device for reducing hydrodynamic drag according to the invention. Vessel 10 is intended in this application to mean any type of floating vehicle. The invention therefore relates to seagoing vessels such as, for example, boats and barges. Any type of floating device is also within the scope of the invention. Floating and / or submersible devices are also within the scope of the invention. In the remainder of this embodiment, the terms vessel 10 and boat 10 are used interchangeably.

[0027] All the features of the device for reducing hydrodynamic drag according to the invention are also applicable to the method for reducing hydrodynamic drag according to the invention.

[0028] The vessel 10 comprises a hull 20. The hull 20 is the outer casing of the vessel 10 and contacts the water in which the vessel 10 floats and / or is immersed.

[0029] The vessel of FIG. 1 comprises a fuel cell 30. The fuel cell 30 uses hydrogen to generate electrical energy. This electrical energy is used to power the vessel. The energy generated by the fuel cell may be used to power an electric motor 30. The electric motor 30 serves to propel the vessel 10. Alternatively or in addition, the fuel cell 30 supplies electrical energy to on-board systems such as lighting, heating or other systems. The invention also relates to fuel cells that do not use hydrogen. Thus, it is possible to have fuel cells that operate on reformed methanol or direct methanol. It is also possible to provide fuel cells that operate on direct borohydride, formic acid, phosphoric acid, molten carbonates or protic ceramics. All types of fuel cell chemistries can be envisaged.

[0030] Fuel cell 30 is considered to mean a fuel cell system assembly. Thus, we refer to the fuel cell core, which is any electrochemical device that generates electricity by converting chemical energy into electrical energy by virtue of a redox chemical reaction in which production is achieved by virtue of the oxidation of a reduced fuel coupled to the reduction on the other electrode of an oxidant, such as oxygen in the air, and the auxiliary systems of both the fuel cell, notably the cell management electronics and a compressor that supplies air to the fuel cell core to provide oxygen.

[0031] The fuel cell 30 produces electrical energy using a chemical reaction between dihydrogen and dioxygen taken from the surrounding air. Operation of the fuel cell 30 produces emissions of air that are normally vented to the surrounding environment for hydrogen-powered vessels. In the case of fuel cells not supplied with hydrogen, such as those described above, the fuel cell also emits air during operation. Thus, the features described herein apply to fuel cells other than hydrogen fuel cells.

[0032] Within the scope of the present invention, the device 40 for reducing hydrodynamic drag comprises an air conveying means 42. The air conveying means 42 is arranged at the outlet of the fuel cell 30. This conveying means 42 collects gases escaping from the fuel cell 30 during normal operation of the fuel cell. The conveying means 42 is directly connected to the exhaust of the fuel cell 30.

[0033] The conveying means 42 are connected to jetting means 50, which are integrated into the hull 20. The jetting means 50 are configured to inject the air conveyed by the conveying means 42. To do this, the jetting means 50 inject a quantity of air 52 near the hull 20 opposite the surface of the hull 20 that is intended to be immersed when the boat 10 is sailing. The jetting means 50 is therefore located below the waterline of the vessel 10. More precisely, the jetting means 50 injects the air 52 near the surface 22 of the hull 20 that is intended to be immersed.

[0034] The operation of system 40 for reducing hydrodynamic drag will now be described.

[0035] The fuel cell 30 generates electrical energy for the vessel 10 during operation of the vessel 10. When the fuel cell 30 generates electrical energy, it releases a first amount of air. This first amount of air is the exhaust of the fuel cell 30. The first amount of air is collected by a transport means 42. The transport means 42 transport the first amount of air to an injection means 50, which is located below the hull 20 of the vessel 10. The injection means 50 injects the first amount of air 52 opposite the surface 22 of the hull 20 intended to be immersed. The surface 22 of the hull 20 intended to be immersed is recalled to mean the surface 22 of the hull 20 that is located below the waterline of the vessel 10.

[0036] Thus, the apparatus for reducing hydrodynamic drag comprises a fuel cell 30 , a vehicle 42 , a vessel 20 , and an injection means 50 .

[0037] Thus, the device for reducing hydrodynamic drag according to the present invention allows for the reuse of air discharged from a fuel cell when the fuel cell produces electrical energy, where air discharged from a fuel cell is taken to mean air produced during the chemical reactions occurring within the fuel cell.

[0038] The recycling of the first amount of air delivered to the injection means 50 allows for the injection of said amount of air near the hull 20. This air injection allows for the "lubrication" of the hull 20, which reduces the hydrodynamic drag that the water exerts on the hull 20. The device 40 of the present invention therefore allows for a reduction in hydrodynamic drag, which can reduce the energy consumption of the vessel 10. Furthermore, since the air is taken directly from the fuel cell, the device 40 lacks an external means for pressurizing the air to perform the injection. The device 20 of the present invention therefore allows for a significant increase in the power available in the prior art devices, since no energy is consumed to inject the air, which is a by-product of the generation of electrical energy in the fuel cell 30. Furthermore, the device for reducing drag of the present invention allows for a reduction in the mass of the vessel 10, since a compressor is a heavy device. The reduction in mass also allows for an increase in the energy efficiency of the vessel 10. Alternatively, the device for reducing drag 40 may comprise an additional compressor, which supplements the air flow in the conveyance means 42. In this manner, if the flow rate and / or air pressure provided by the fuel cell 30 is insufficient, the additional compressor provides the necessary flow rate and / or pressure. Despite the presence of the additional compressor, the device for reducing drag 40 still allows for improved energy efficiency compared to conventional devices for reducing drag, since the required additional compressor is constructed with a lower power and mass than the compressors used in prior art devices.

[0039] The vessel 10 may also include hydrogen tanks 32. In the example shown in Figure 1, the vessel 10 includes three hydrogen tanks 32. These tanks 32 are configured with lower power and mass than the vessel 10. The hydrogen tanks 32 are an effective means of storing dihydrogen in gaseous and / or liquid form that the fuel cell 30 uses for its operation. For fuel cells that operate on other than hydrogen, the tanks 32 may be used to store gases other than dihydrogen.

[0040] Advantageously, the vessel 10 may be a catamaran. A catamaran is taken to mean a vessel comprising two hulls or floating bodies. This is in particular the case for the vessel 10 shown in the figures of the present application, where the portion of the hull 20 shown is one of the two floating bodies that comprise the vessel 20. However, the invention also relates to monohulls and multihulls. Thus, all the characteristics of the device 40 for reducing drag according to the invention presented in the present application apply independently to monohulls, catamarans, multihulls or any other type of vessel.

[0041] The vessel 10 may also include an exhaust stack 37 that allows for the escape of any gas overpressure that may build up in the fuel cell 30. The exhaust stack 37 is connected to the fuel cell and is used in the event of overpressure in the fuel cell 30. The exhaust stack 37 is also used in the event of overpressure in auxiliary systems of the fuel cell 30, such as, for example, a distribution system or tanks.

[0042] According to one embodiment, the fuel cell 30 electrically powers an electric motor 35. The electric motor 35 enables propulsion of the marine vessel 10.

[0043] According to one embodiment, the fuel cell 30 electrically powers one or more batteries that are charged by the fuel cell 30. According to this embodiment, it is the batteries that electrically power the electric motor 35.

[0044] According to one embodiment, the vessel 10 is a passenger carrying vessel. According to this aspect, passengers are transported within the cabin 12 of the vessel 10. Alternatively or additionally, the vessel 10 is a specialized vessel for another purpose, such as, for example, cargo transportation, fishing, recreational, military use, etc. This list of uses for the boat 10 is not exhaustive.

[0045] Conveying the first volume of air According to one embodiment, the conveying means for the air exhausted by the fuel cell 30 is a conduit. A conduit is taken to mean any type of means such as a pipe or a set of pipes connected together. Alternatively or additionally, the conveying means 42 is a tube, preferably a flexible tube. The conveying means 42 may also be a set of tubes connected together. For example, the conveying means may be provided to include a rigid tube and a flexible tube arranged in series.

[0046] According to one embodiment, the transport means 42 is provided on its passage with a heat exchanger 44 for recovering heat from a first quantity of air exhausted by the fuel cell 30, the air being at a high temperature. Advantageously, the heat recovered by the heat exchanger 30 is used for heating the cabin 12 of the vessel 10.

[0047] According to one embodiment, the device for reducing hydrodynamic drag comprises a command control for the air flow conveyed by the conveying means 42. According to this embodiment, the command control allows to control the flow through the conveying means 42. This arrangement allows to control the air flow leaving the fuel cell 30. This arrangement also allows to control the air flow injected by the injection means 50. In this way, the injected air flow can be controlled to optimize the lubrication of the hull 20 by the air. According to one embodiment, the conveying means 42 comprises an exhaust (not shown). This allows to release excess air flow. Thus, if the air flow leaving the fuel cell 30 is greater than desired for lubrication, a part of this air flow can be released into the surrounding air or water to accommodate the flow released by the injection means 50.

[0048] According to one embodiment, the command and control device also controls the operation of the fuel cell 30. For example, the command and control device may control the power generated by the fuel cell 30, as well as the supply of reagents, such as hydrogen. The command and control device may also be used to control other elements of the vessel 10 in addition to the apparatus 10 for reducing drag.

[0049] According to an embodiment, the device 10 for reducing hydrodynamic drag comprises at least one flow sensor 46. The flow sensor 46 measures the air flow. The flow sensor 46 may be arranged at the outlet of the fuel cell 30. For example, the flow sensor may be constituted by the air conveying means 42. For example, the flow sensor may be arranged at the outlet of the fuel cell 30 to measure the air flow in the conveying means 42. Also, the flow sensor 46 may be provided at the outlet of the conveying means 42 before the injection means 50. According to an embodiment, the device 10 comprises several flow sensors 46. For example, these sensors may be arranged at the inlet and outlet of the conveying means 42.

[0050] According to an embodiment, the device 10 for reducing hydrodynamic drag comprises at least one pressure sensor 48. The pressure sensor 48 measures the air pressure. The pressure sensor 48 may be arranged at the outlet of the fuel cell 30. For example, the pressure sensor 48 may be constituted by the air conveyance means 42. For example, the pressure sensor 48 may be arranged at the outlet of the fuel cell 30 to measure the air pressure in the conveyance means 42. It is also possible to provide a pressure sensor 48 at the outlet of the conveyance means 42 before the injection means 50. According to an embodiment, the device 10 comprises several pressure sensors 48. For example, these pressure sensors 48 may be arranged at the inlet and outlet of the conveyance means 42.

[0051] According to one aspect, the conveying means 42 comprises at least one pressure sensor 48 and at least one flow sensor 46. According to the embodiment shown in Fig. 1, the conveying means 42 comprises a flow sensor 46 and a pressure sensor 48 at the outlet of the fuel cell 30. According to this embodiment, the conveying means 42 also comprises a flow sensor 46 and a pressure sensor 48 at the outlet of the conveying means 42 upstream of the injection means 50.

[0052] According to one aspect of the invention, the device 40 for reducing hydrodynamic drag comprises an airflow command and control system. According to this aspect, the device 40 comprises at least one pressure sensor 48 and one flow sensor 46. According to this aspect, the device 40 also comprises at least one exhaust as described above. According to this aspect, the command and control device is able to open the exhaust as a function of the pressure and / or flow information transmitted by the sensors 46, 48. This arrangement allows, for example, to automatically open a circuit in case of overpressure.

[0053] According to one aspect, the apparatus 40 for reducing drag includes a calculator configured to command the opening of the exhaust as a function of pressure data from the pressure sensor 48. The calculator may also command the opening of the exhaust as a function of flow data from the flow sensor 46.

[0054] Capturing apparent wind According to an embodiment shown in figure 3, the device 40 for reducing drag comprises means 43 for recovering air from the apparent wind of the vessel 10. The apparent wind is taken to mean the wind experienced on the vessel 10 when it is moving. The apparent wind is a combination of the actual wind and the relative wind caused by the movement of the vessel 10.

[0055] The apparent wind recovery means 43 is arranged on the vessel 10 at a level above the water line of the vessel 10. The recovery means 43 therefore recovers apparent wind and not water.

[0056] The recovery means 43 deliver a second amount of air to the transport means 42. In this way, the second amount of air is added to the first amount of air coming from the fuel cell 30. Thus, the airflow delivered to the one or more injection means 50 may be increased. Similarly, if the fuel cell 30 does not provide enough air to ensure sufficient drag reduction, the second amount of air can be added in order to inject enough air.

[0057] According to one embodiment, the collection means 43 includes an opening 45 through which the apparent wind is collected. This opening 45 may be an intake for fresh air.

[0058] According to one embodiment, the collecting means 43 comprises a tube or pipe, which may be rigid or flexible, that connects the opening 45 or inlet of the collecting means 43 to the conveying means 42.

[0059] According to one embodiment, the recovery means 43 are connected to the transport means 42 at the level of the joint 47 .

[0060] According to one embodiment, the collection means 43 comprises a section reduction 49. According to this configuration, the tube or pipe of the collection means 43 comprises a regular section. The regular section is substantially constant along the tube or pipe. At the level of the section reduction 49, the section narrows. This configuration makes it possible to accelerate the flow of air into the collection means 43 by the Venturi effect.

[0061] According to one embodiment, the junction 47 between the conveying means 42 and the collecting means 43 is located at the level of the reduced portion 49 of the section of the collecting means 43. This configuration is shown in figure 3. This configuration makes it possible to accelerate the flow of the first amount of air coming from the conveying means 42 by the Venturi effect.

[0062] According to one embodiment, the junction 47 is located at the level of the reduction 41 of the section of the conveying means. This configuration accelerates the flow of the second amount of air from the recovery means 43 due to the Venturi effect.

[0063] According to one embodiment, the withdrawal means 43 comprises at least one pressure sensor (not shown), which measures the air pressure in the withdrawal means 43.

[0064] According to one embodiment, the collecting means 43 comprises at least one flow sensor (not shown). The flow sensor measures the air flow in the collecting means 43.

[0065] According to one embodiment, the flow sensor of the collection means 43 and / or the pressure sensor of the collection means 43 are connected to a command and control system which can control the opening and closing of the collection means 43 to control the air flow from the collection means 43 to the transport means 42.

[0066] All configurations described herein with respect to the apparent wind recovery means 43 are compatible with the features described in the other embodiments.

[0067] Air injection As mentioned above, the device 40 for reducing drag comprises at least one jet 50 of air.

[0068] The injection means 50 is taken to mean, for example, an injector 50. The injection means may also be an opening in the carrier means 42 at the level of the hull 20 of the vessel 10.

[0069] According to one configuration, the hull 20 comprises, in addition to the jet means 50 shown in FIG. 1, several jet means 50. For example, the hull 50 may comprise two jet means 50, one located slightly to port and another to starboard with respect to the longitudinal axis of the hull of the vessel 10. In this way, the submerged part of the hull 50 is lubricated by the air jetted over the entire width of the hull 50. Also, several jet means 50 may be provided on an axis going from bow to stern of the vessel 10. According to one embodiment, the several jet means 50 cover a large part of the surface 22 of the hull 20 intended to be submerged. When the drag reducing system 40 comprises several jet means 50, the conveying means 42 comprises several branches for supplying air to all the jet means 50.

[0070] There may also be a number of jet means 50 arranged along the surface 22 of the hull 20 that is intended to be submerged. For example, there may be a number of jet means 50 aligned along two lines forming a "V" under the hull 20. The tip of the "V" may be directed towards the bow of the vessel 10 or towards the stern of the vessel 10. There may also be several jet means 50 arranged along a line of the hull 20 perpendicular to the longitudinal axis of the vessel 10. There may also be several lines of jet means 50 along the hull 20. For example, there may be two parallel lines, each including a number of jet means 50. The two lines are perpendicular to the longitudinal axis of the vessel 10. The number of jet means 50 along each line may differ from line to line. For example, there may be ten jet means 50 per line. There may also be one line with ten jet means 50 and another line with five jet means 50.

[0071] The number and distribution of the jet means 50 is left to the discretion of one skilled in the art to maximize the efficiency of hydrodynamic drag reduction.

[0072] According to one embodiment, the surface 22 of the hull 20 intended to be submerged comprises a substantially flat bottom. According to this configuration, the flat bottom allows the injected airflow to be kept below the hull. In this way, the air does not rise to the water surface through the sides of the hull 20. As a result, the injected airflow covers a larger surface instead of escaping at the edges. In this way, a larger part of the surface 22 intended to be submerged is covered by the airflow. Lubrication of the hull 20 is therefore more efficient.

[0073] According to one embodiment, the injection means 50 comprises an anti-return means, which is a device that prevents the transport means 42 from taking up water from outside the vessel 10. This arrangement makes it possible to prevent water from taking up inside the vessel, and in particular towards the fuel cells 30.

[0074] According to one embodiment, the anti-return means is a non-return valve. Alternatively, the anti-return means is a valve, preferably a solenoid valve, commanded by the command control system.

[0075] According to one embodiment, the jet means 50 does not include an anti-return means. According to this alternative, external water may enter the vehicle 42. Without the air jet, the water rises in the vehicle 42 to the waterline of the vessel 10. When the device for reducing drag 40 is switched on, the jet of air pushes the water out of the vehicle 42.

[0076] According to one embodiment, the air injected by the injection means 50 is injected in the form of air bubbles. Air bubbles are a very effective means of air lubrication of the hull 20.

[0077] According to one embodiment, the injected gas bubbles have a diameter comprised between 0.1 mm and 100 mm. According to one embodiment, the injected gas bubbles have a diameter comprised between 0.2 mm and 20 mm.

[0078] According to one embodiment, the bubbles have a diameter of less than 5 mm. Thus, according to this configuration, the bubbles have a diameter of less than 5 mm, a distance that corresponds to the boundary layer thickness of the fluid flow adjacent the hull 20.

[0079] According to one embodiment, the injected bubbles have an average diameter comprised between 0.4 mm and 1.3 mm. Bubbles with diameters in this range have a high efficiency for reducing hydrodynamic drag.

[0080] According to one embodiment, the injected air bubbles form an air sheet under the hull of the vessel. According to one embodiment, the air bubbles are injected at a flow rate sufficient to merge after leaving the injection means. Such an arrangement allows to form an air sheet under the hull, which can significantly reduce friction on the hull. Thus, hydrodynamic drag is significantly reduced.

[0081] According to one embodiment, the air bubbles form a mixed layer under the hull, which is taken to mean a layer that includes parts in the form of sheets and parts in the form of air bubbles, which allows for a reduction in friction of the ship's hull while requiring less jet air than a sheet.

[0082] According to one embodiment, the injection means 50 comprises an adaptive nozzle. According to this embodiment, the nozzle has an adaptable shape in order to adapt the air injection. According to one embodiment, the diameter of the nozzle is adaptable. According to this embodiment, the diameter of the nozzle is adapted in order to control the size of the injected air bubble. According to one embodiment, the nozzle adaptation is controlled by a command control device. In this way, the command control device can control the air injection. Preferably, the command control device controls the diameter of the nozzle. Thus, the diameter of the air bubble is directly controlled by the command control device.

[0083] water wing According to one embodiment, the hull 20 comprises at least one hydrofoil 60. The hull may also comprise one, two, three, four or more additional hydrofoils 60. The hydrofoil 60 is part of the hull 20 and comprises a hydrodynamic profile that allows the vessel 10 to lift while the hydrofoil 60 is moving. This type of device is also often referred to as a hydrofoil or foil.

[0084] By raising the vessel 10 while it is moving, the surface and volume of the vessel that is underwater can be reduced, and thus this type of device can reduce the force that the surrounding water exerts on the vessel 10 as it moves.

[0085] Figure 2 shows the case of a hull 20 with two hydrofoils 60. Figure 2 also shows the waterline 70 of the vessel, which, under the influence of the hydrofoils 60, is lower on the hull 30 than the waterline of the vessel 10 at rest. Thus, when the boat 10 is moving at the level of the waterline 70 in Archimedes mode, the force of the water impeding its motion is lower at that waterline than it would be without the hydrofoils 60.

[0086] According to one embodiment, the water foil 60 comprises at least one jet means 50 of air conveyed by the conveying means 42. The jet means 50 of the water foil 60 makes it possible to lubricate the surface of the water foil 60. This configuration makes it possible to increase the efficiency of the device 40 for reducing drag by reducing the hydrodynamic drag experienced by the water foil 60. If the hull 20 comprises several water foils 60, each of them may comprise at least one jet means 50.

[0087] According to one embodiment, the jetting means 50 of the hydrofoil 60 are arranged only on the vertical parts of the hydrofoil. With this configuration, the air jetted near the hydrofoil 60 does not involve the vicinity of the horizontal parts of the hydrofoil. The horizontal parts of the hydrofoil are responsible for the lifting force of the hydrofoil 60. In other words, the horizontal parts of the hydrofoil 60 can lift the vessel 10 when the vessel 10 is moving. By not lubricating these parts with the jetted air, the lifting force involved by the hydrofoil 60 can be undiminished. In this way, the lifting effect of the hydrofoil 60 is not limited.

[0088] According to one embodiment, the command and control system makes it possible to stop the injection of air at the level of one or several of the injection means 50.

[0089] According to one embodiment, the command and control system can control the closure of valves on the vehicle 42. Thus, the command and control system can stop the injection of air in the desired injection means 50.

[0090] Hull layout In accordance with one aspect of the invention, the hull 20 includes a setback 24, which is illustrated in Figure 3. The setback 24 is a step in the hull 24 that includes a surface that is vertical when the vessel 10 is on the water. The vertical surface of the setback 24 faces free toward the aft of the vessel 10.

[0091] According to one embodiment, the jet means 50 is disposed on the vertical surface of the setback 24. In this way, the jet means 50 jets air into the water in a direction from the front to the rear of the boat 10. Advantageously, the setback 24 allows a depression of water behind the setback 24 when the boat 10 is moving. This depression allows the jet means 50 to suck air from the conveying means 42. Thus, this configuration facilitates the jetting of air. Furthermore, the setback 24 allows the water flow close to the setback 24 to be turbulent. The creation of turbulence near and behind the setback 24 allows the injected air bubbles to oscillate along the length of the hull 30. The oscillation of the injected air bubbles increases the lubrication efficiency and therefore the efficiency of the device 40 for reducing drag.

[0092] According to one embodiment, the hull 20 includes a notch 26. The notch 26 is a part of the hull 20 that is pushed inwards from the hull 26. Advantageously, the notch 26 includes a setback 24. The notch 26 is also formed by at least two other lateral setbacks. The notch 26 forms a cavity in the surface 22 of the hull 20 that holds the injected air in contact with the hull 20, which prevents the air from rising up the sides of the hull 20. In this way, the injected air follows the hull along its entire length. The rear of the hull 20 is therefore well lubricated by the injected air. The notch 26 therefore forms a channel for the injected air.

[0093] According to one configuration, the hull 20 comprises at least one slider arranged on its surface 22. A slider is taken to mean a form of a bead protruding from the hull 20. Preferably, the protrusion is of low height and therefore allows the water flow downstream of the slider to be turbulent. In other words, the slider has a bead or semi-bead shape arranged on the hull 20. One or more sliders may also be provided having a semi-cylindrical shape. Preferably, the slider has a streamlined shape. A streamlined shape is taken to mean a shape that offers less resistance to the flow of fluid around the shape. Preferably, this slider is located immediately upstream of one or more jet means 50. This slider may also be located immediately downstream of one or more jet means 50. Advantageously, the slider allows the water flow to be turbulent in the path of the slider. This configuration therefore makes the lubrication by the injected air more effective. Furthermore, the hull 20 may comprise several sliders located upstream and downstream of each jet means 50. The sliders may also be provided downstream of the injection means 50, but may also be located further away from them. These sliders can prevent the flow in contact with the hull from becoming laminar, in order to maintain a turbulent flow in contact with the hull through the passage of the injected air. [Explanation of symbols]

[0094] 10: Ship 12: Cabin 20: Hull 22: Surface of the vessel intended to be immersed 24: Hull setback 26:Notch in the hull 30: Fuel cell 32: Hydrogen tank 35: Motor 37: Exhaust stack 40: Device for reducing hydrodynamic drag 42: Means for transporting air exhausted by fuel cells 43: Recovery means for apparent wind 44:Heat exchanger 45: Opening of recovery means for apparent wind 46: Airflow sensor 47: Joint 48: Pressure sensor 49: Reduction of apparent wind recovery means section 50: Means for injecting a first amount of air 52: Air injected by injection means 60:Water wing 70: Floating line

Claims

1. 1. An apparatus for reducing hydrodynamic drag on a vessel, comprising: a vessel body including at least one first injection means configured to inject a fluid; A fuel cell; a transport means configured to transport a first amount of air discharged by the fuel cell to at least the first injection means; Equipped with the first injection means is configured to inject the first quantity of air along a surface of the hull intended to be immersed; Device.

2. the first jetting means includes a sealing element that restricts or prevents the upward flow of a quantity of water into the conveying means; 2. The apparatus of claim 1.

3. the first amount of air is injected by the first injection means in the form of bubbles, the bubbles having a diameter of less than 5 mm; 3. Apparatus according to claim 1 or 2.

4. the hull comprises a water wing intended to be immersed, the water wing including at least one second injection means configured to inject at least a portion of the first quantity of air, 4. Apparatus according to any one of claims 1 to 3.

5. the second injection means of the water wing is configured to inject a portion of the first quantity of air along a vertical surface of the water wing; 5. The apparatus of claim 4.

6. the hull includes an additional portion forming a setback upstream of the first jetting means relative to the direction of movement of the vessel; 6. Apparatus according to any one of claims 1 to 5.

7. a command control device for airflow in the vehicle; 7. Apparatus according to any one of claims 1 to 6.

8. the transport means includes at least one airflow sensor; 8. Apparatus according to any one of claims 1 to 7.

9. [0023] Further comprising: a recovery means configured to recover a second amount of air from the vessel apparent wind; the collecting means being capable of conveying the second quantity of air to the conveying means.

9. Apparatus according to any one of claims 1 to 8.

10. 1. A method for reducing hydrodynamic drag on a marine vessel, comprising: A transport means transports the first amount of air discharged by the fuel cell to an injection means constituted by the hull; injecting said first quantity of air by said injection means along a surface of said hull intended to be immersed; method.

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