CN102958794A - Method and structure for reducing ship water friction - Google Patents

Abstract

The present invention relates to a method and structure for reducing the running resistance of a flat-bottomed floating ship by means of a gas layer at the bottom. This is mainly used in inland and ocean transportation. The purpose of the invention is to achieve as uniform a distribution of the gas or air layer at the bottom of the ship as possible, minimize gas loss, and calm the water flow below the gas layer by reducing resistance. The solution proposed here is that at least a first water level measuring device L1, L2 or L4 is provided in the front area of the chamber 5, and at least a second water level measuring device L3 is provided in the rear area. The measurement signals obtained by automatic comparison are controlled, and according to the comparison result obtained a) the liquid level in the trim box (12) is controlled to achieve the purpose of controlling the inclination angle of the transverse axis of the ship, and/or the hydrofoil (15) or components fixed to the ship are automatically adjusted to achieve the purpose of controlling the inclination angle of the transverse axis of the ship.

Description

Method and structure for reducing ship water friction

technical field

The present invention relates to a method of reducing the running resistance of a flat-bottomed floating vessel during inland and sea travel by means of a gas layer at the bottom, and to suitable structures required for carrying out this method.

Background technique

So far, in practice, the driving resistance can only be reduced through the shape of the ship. This method of introducing air, especially gas, between the bottom and the water is already known.

A method is described in DE 10 2004 024 343 A1, blowing gas into the bow just immersed in the lower part of the water surface, and introducing the lower part of the hull through the water flow. But this method needs a large amount of air, and according to known blowing practice experience, a power of about 40 kilowatts is required. This mainly consists of the energy required to squeeze the air from the traveling water and propellers under the hull.

Also known is a device for keeping the air at the bottom of the hull (DE 199 33 942 A1). If no other measures are taken, there will be a significant loss of air here and should always be filled.

As described in US 5 054 412 A and GB 1 300 132 A, according to DE 693 09 655 T2, the construction of small chambers has some problems with maintaining air. The purpose of the present invention is to design a method for reducing the running resistance of floating ships, by which the uniform gas or air layer distribution at the bottom of the ship can be achieved as much as possible, the gas loss can be minimized, and the water flow in the lower part of the gas layer can be reduced by reducing the resistance. become calm.

Contents of the invention

In addition, an appropriate structure should be designed to implement the method.

The object of the invention is achieved by the features stated in claim 1 . Further advantages of this method are specified in claims 2 to 10 . The subject matter of claim 11 is an arrangement for carrying out the method. The advantages of this construction are stated in claims 12 to 18 .

Along the longitudinal sides and in the center of the longitudinal direction of the ship, downwardly extending walls or projections are installed in the lower part of the hull, through which at least two chambers can be formed through which gas is introduced and formed between the bottom of the ship and the water in the lower part layer. As a preferred variant, the chamber of the gas layer can also be provided in a rotary shape.

At least a first water level measuring device is arranged in the front area of the chamber, and at least a second water level measuring device is arranged in the rear area of the chamber.

Automatic comparison of the resulting measurement signals.

The liquid level in the trim tank is controlled according to the obtained comparison results, so as to achieve the purpose of controlling the inclination angle of the transverse axis of the ship. In addition or according to another method, the measurement results can also be compared, and the hydrofoils fixed on the ship can be automatically adjusted to achieve the purpose of controlling the inclination angle of the transverse axis of the ship. Likewise, it is also possible to adjust only part of the hydrofoil. These two methods can be used alone or in combination. The advantage of adjusting the hydrofoils is that fundamental waves can be damped by adjusting the angle of inclination of the transverse axis of the hull on the ocean, a process that would be too slow if only trim box adjustments were used. This also applies if the vibrations near the transverse axis are excessive during inland driving.

Generally speaking, the inclination angle or space position of the ship related to the water surface of the chamber mentioned in the patent application is located in the lower part of the gas layer below the ship.

In order to achieve this goal, at least to achieve the purpose of reducing running resistance and gas loss, the water level of all lower parts of the ship should be set evenly and in a certain proportion on the upper part of the minimum of the overall structure. According to claim 3, the water level can be adjusted individually by controlling the gas supply to each chamber. In order to achieve the above-mentioned uniform setting of the water level, it is necessary to control the angle of inclination around the longitudinal axis (hereinafter referred to as inclination). According to claim 4: the inclination is calculated by means of two level gauges <L1, L2) in a chamber with approximately parallel longitudinal coordinates, and then a) according to the level of the trim tank and/or b) by automatic control The device is automatically controlled (by the pump). Hydrofoils mounted on ships control the inclination angle. Hydrofoils are preferentially used in marine vessels. Because the inclination is controlled less accurately by the angle of inclination than by the forward inclination, the sides can be adjusted by comparing the measurements of the control trim box and/or the foils, and the sides can be adjusted by comparing the measurements of the control trim box and/or the inclination of the foils, This method does not rely directly on level gauges, but indirectly through automatic vertical lines.

It should always be possible to automatically control the ship's forward heel directly from the liquid level measurement. Due to the often different influences (direction of travel on the river and downhill course, ocean waves and greater precision requirements), vertical lines are not suitable here.

If the function of the inclination controller is not working properly, a substantially uniform distribution of gas under the bottom solves this problem according to the features stated in claims 5, 6, 7. This is the case with restless oceans. However, the reaction force of the water to the bottom or the orifice plate cannot be suppressed here, and the friction-reducing gas layer can be formed again in a very short time. Additional installations on ships may also be provided with perforated plates. Claim 7 proposes to use a structure that maximizes the saving of air or gas loss, provided that the ship has a relatively large draft.

Claims 8, 9, 10 relate to the limitation around the sides of the ship's gas layer, that is to say, along the direction of travel, the forward and rearward projections in the chamber transverse to the direction of travel are limited, kept as small as possible. Low gas loss and relatively thick gas layer.

The structure proposed in claim 8 is provided with a deflector edge 3 which calms the water surface in the chamber and keeps it as horizontal as possible.

The measure of claim 9 should limit the loss of gas if the water surface in the lower part of the vessel is not stable.

The gas or water conductivity measuring device described in claim 10 can realize lower operating cost and better stability of the water level measuring device in the chamber during operation.

Since the electrodes involve a rapid exchange of gas and water, and the insulation between the electrodes may also remain wet all the time, it must be programmed from which current/voltage ratio and when the switching pulses should be released.

Electrodes should be arranged so that, as far as possible, they are protected from mechanical damage.

Description of drawings

The invention is further illustrated in the following structural examples. The associated graphics are:

The longitudinal sectional view of this ship of Fig. 1 invention (here is example with flat-bottomed cargo ship),

Fig. 2 Cross-section of line A-A in Fig. 1,

Partial cross-section A-A of the side wall of a flat-bottomed cargo ship of other structures in Fig. 3,

Figure 4 A reduced bottom view of the flat-bottomed cargo ship in Figure 1,

Figure 5 Bottom view of the second structure (ocean vessel),

Figure 6 is a longitudinal section along the center of Figure 5,

The cross section of line B-B in Fig. 7 and Fig. 6,

Figure 8 is the cross-section of line C-C in Figure 7, and

FIG. 9 is a partial longitudinal section of the rear chamber 5 .

Detailed ways

Figures 1 to 4 (structural examples) show a flat-bottomed cargo ship, which is preferably used in inland shipping. The force of pushing the boat should be indicated by the arrow marked F in Figure 1.

In the example below, the programming of the tilt and water level controller is shown in its entirety through the switch points of an inland flat-bottomed cargo ship (see Figures 1 to 4).

The side wall 7 protrudes 90 mm downwards from the bottom 1 of the flat-bottomed freighter. The rated water level 4 is measured from the lowest part of the side wall 7 and is 40 mm. The deflector edge 3 in the bow area is 30 mm, the transverse flange 8 in the stern area protrudes 20 mm upwards from the lowest part of the side wall 7 . The width of the chamber 5 of an example type of vessel is about 8.1 meters, and the overall length of the vessel is 55 to 65 meters.

The water level gauges L1 to L4 can work together with conductivity gauges, sonic devices or floats and are mounted on the downwardly extending side wall 7 . They can respectively continuously provide electronic signals for central processing. For example, due to the unsettled water surface 4 at the bottom of the ship, an average value of the last 10 seconds will be automatically formed according to the corresponding signal, avoiding unnecessary switching processes.

To illustrate functionality (switch specification):

- Control the forward tilt of the flat-bottomed cargo ship:

If the water level L1>(L3+5 mm), the pumps P1 and P2 will be activated.

If the water level L1<(L3-5 mm), the pump P3 will be activated.

If the water level L1=L3, the current supply to the side pump of the forward tilt controller will be switched off,

Pumps P1 and P2 are parallel to the forward and roll controllers respectively and supply current, as in the example pump P2, although switched off can continue to supply current until the barge roll controller completes its task.

- Flat-bottomed cargo ship roll controller:

If the water level L1>(L2+5 mm), the pump P1 will be activated.

If the water level L1<(L2-5 mm), the pump P2 will be activated.

If the water level L1=L2, the current supply to the side pump of the roll controller will be switched off.

- Chamber 5 water level controller:

If the water level L2>(L2 rated value+5 mm), the blower 9 and the corresponding valve 10 will be turned on.

If the water level L4>(L4 rated value+5 mm), the blower 9 and corresponding valve 10 will be turned on.

If the water level L2 or L4 is equal to or less than their rated value, the corresponding valve 10 will be closed, and if the water levels L2 and L4 are equal to or less than their rated value, the blower 9 will be turned off.

Functions of the control unit:

Via two parallel non-return valves 11 and a valve 10 DN 40 controlled by a magnet, a blower (centrifugal blower) 9 pushes about 40 l/s of gas into the corresponding chamber 5 . The immersion depth of the flat-bottomed cargo ship is 1.5 meters, and when the efficiency is 70%, the electric power of the blower 9 is about 1 kilowatt. Inflation of the half-filled chamber 5 lasts approximately 280 seconds.

Likewise, the blower 9 is also the tilt control device in the bow of the flat-bottomed cargo ship. On each side there is a trim box 12 with a volume of 4 cubic meters, a ventilation duct 13 and a pump P1 or P2 (centrifugal blower). The pumps P1 and P2 supply approximately 4 to 5 l/s, require approximately 200 watts of electric power each, and can also deliver backwards.

The pump P3 is likewise a centrifugal blower, but has a flatter characteristic curve and a delivery rate of 4 to 8 l/s at an electric power of about 250 Wh. All pumps have no sliding seals.

The entire piping system with a main nominal width of 50 mm should be maintenance free. Furthermore, apart from the manual shut-off valve 1 (DN 65 to 80) at the front of the pump P3, there is only one automatic air exchange valve E with a liquid check valve in the piping system. The function of valve E is to interrupt the water flow as soon as possible after shutting down the pump.

If, instead of the open, water-surrounded tilt control system described above, it is desired to provide a closed control system, two additional trim boxes of equal capacity must be installed in the stern of the barge. This required a total of four pumps and an additional approximately 55 meters of inclined piping, which presented greater difficulty in the subsequent installation on flat-bottomed cargo ships.

Problems with loading flat-bottomed cargo ships:

There is no gas layer 2 on the bottom of the flat-bottomed cargo ship during unloading and loading in the example. It also remains relatively stable in water, although due to larger impacts. The gas layer 2 can be released through a small valve not shown in the two figures, or the gas can be purposefully and slowly released through the check valve 11 . A precise vertical line is installed in flat-bottomed cargo ships, and the image of the vertical line can be transmitted to the loading manager through cameras and screens. At the end of loading, the angle of inclination of flat-bottomed cargo ships around the transverse axis should be less than 1:1000, and the angle of inclination around the longitudinal axis should be less than 1:250. This ratio can also be equalized by the capacity of the trim box 2 in the example 2x4000I.

In addition, it is possible to further reduce the inclination angle by observing the vertical line, via the manual remote control of the pumps P1, P2, P3, or by activating all the controls described in the above chapter "Switch control". For example, if the time period from the start-up procedure is set to 10 minutes, the process of automatic forward tilt control is more coordinated, it can periodically interrupt the gas supply of the two chambers 5, and reduce the average gas supply. The tilt controller should be able to reach the target range within 10 minutes.

Construction example 2 below concerns a fast flat container barge equipped with hydrofoils.

If the ship is pitching forward and there is too much gas being released from the gas layer 2, a hydrofoil 15 should be fitted aft of the driving propeller and rudder, similar to the seagoing ships described in Figures 5 and 6. The adjustment angle of the hydrofoil 15 is automatically adjusted, and according to the information obtained by the water level measuring device L, it can counteract the slow forward shaking.

The hydrofoils 15 extend horizontally for 1.5 meters, are installed at the end and the middle, have an average thickness of 30 mm and a width of 250 mm, and generate propulsion and energy up to 6 kN at a flow speed of 8 m/s.

If, due to the propeller, the water surface 4 in the chamber 5 becomes unsettled, too much air is released from the lower part of the rear transverse flange 8, the direction of the water particles 23 around the airfoil 20 makes the horizontal direction The water flow becomes calm (see Figure 9). The airfoil 20 is 20 mm thick and 150 mm wide and extends across the entire width of the rear area of the chamber 5 . In order to avoid collision with the hard water bottom, the airfoil 20 on the bottom 1 can swing. If necessary, press down against a fixed stop by spring force.

Benefit Assessment/Cost and Application Variables (Inland Vessel Travel)

In the example of the above-mentioned flat-bottomed cargo ship (structural example 1), the material consumption of the additional device of the flat-bottomed cargo ship can be approximately 3 tons when the light weight of the flat-bottomed cargo ship is about 170 tons. At an average draft of 1.3 m, the proportion of the water circulation surface that no longer circulates through the gas layer system after installation is approximately 69%.

If the gross weight of the container ship exceeds 1000 tons, the estimated material consumption of 6 tons of auxiliary equipment appears relatively small.

Compared to current ship types without gas layer 2 , the additional costs for a hull with approximately half the engine power are relatively small in a newbuild of the same size and travel speed.

Therefore, the construction cost of such a ship is almost impossible to be greater than that of a conventional transport ship of the same type.

In addition to greatly reducing the water friction on the bottom 1, the air or gas layer 2 also reduces the bow/stern pressure difference, reducing the wave formation and wave resistance. Because water always flows in the path of least resistance, if the velocity of the water flow increases in the lower part of the hull, the velocity of the water flow in the side walls of the hull decreases. A propeller can also increase the speed of the water jet more or less.

Here, such means of transport should only be refitted or newly built in systems that travel for a longer period of time on long road sections. Normal cargo motor ships or fast trailer transport ships (eg on the Danube, width 22.8 m, ship draft up to 1.5 m, length 114 m, speed 20 km/h, 1800 kW) and fast shallow passenger ships are also suitable here. The aforementioned Danube ships can save up to 50% of energy.

The following relates to another structural example 3, and the advantages of the marine vessel structure are illustrated according to FIGS. 5, 6, 7 and 8. This add-on should be installed in marine vessels that have been in operation for a long time. Sea transport is more demanding than inland ship transport due to ocean waves, but the savings in energy and drive power are also greater due to the greater travel speed. For example, the Baltic Ferry, model 321Mukran, year of construction 1990, dimensions: length 190m, width 26m, vessel draft 6.8m, engine power 10600 kW, speed 31.5 km/h (from early + technology 10/1986 ). Attachment part: the side wall 7 protrudes downwards from the bottom 1 of the vessel by 1 meter. Chamber 5 is 120 meters long and can separate about 42% of the water in the uncirculated area.

The forward pitch angle is controlled by a trim box 12 of an open pump system in the stern. The roll angle is controlled by two pipelines connected to the trim box 12 and two pumps. The capacity of the trim box 12 should at least be set so as to balance the normal error when the ship is loaded. Normal water level 4 is rated at 0.5 meters, less in calm seas and more in unsettled seas. Air is supplied through an orifice 16 described below, and water level measurement is likewise performed. The protrusion 8 forms an acute angle with the front deflector edge 3 and the rear part of the water flow which conforms to the shape of the hull. It protrudes downwards about 0.4 meters from the upper part of the lowest part of the side wall 7 . Although the structure is different, the meaning of the tilt control is similar to the "switch control" of the flat-bottomed cargo ship in the above section.

In normal waves, the roll angle is controlled by unilaterally automatically and quickly adjusting the positioning angle of the hydrofoil 15 that can be removed in the hull, and the forward tilt angle is controlled by the hydrofoil 15 in the stern. The average thickness of the side hydrofoils 5 is 200 millimeters, 6 meters long, and can generate a vertical force of about 300 kilonewtons. According to estimation, the driving power of about 43 kW is required when the adjustment angle is 0. 300 kN, allowing short-term boosts to approximately 400 kW. As mentioned above, the measured value of the water level 4 during the control process is calculated according to the time axis. The forward and roll angles can also be controlled independently. The target of the control error is zero, and the adjustment angle of the hydrofoil 15 can suppress the movement of the hull when it is leaning forward and backward.

In larger waves, the water in the chamber 5 impinges from below and rubs against the hull bottom 1 . In order to avoid this as much as possible, a perforated plate 16 is installed below the base 1 according to claim 5 . For example, in the flat ship bottom 1 (see FIGS. 5 to 8 ) or at least inside the chamber 5 is thermally bonded a small open-top capsule. This will form gas chambers respectively 2 meters long, 1 meter wide and 0.05 meters high, which extend transversely to the direction of travel with gas distribution lines 17 (see FIGS. 7 and 8 ). For increased stability, the capsule or perforated plate 16 is also provided with a protective element 18 which is likewise glued to the bottom 1 .

Due to the pressure difference between the gas distribution line 7 and the surrounding environment of approximately 10 kPa and the low tightness requirements, space-saving and cost-saving hydraulic or pneumatic valves 19 in the shape of a grid orifice can be realized. The thermal bonding compound can be removed again for servicing.

The water level 4 needed to control the pneumatic valve 19 should be measured on the basis of sound reflection or conductivity principles. According to claim 7 , the measured values are not calculated over a period of time, but are applied immediately and directly to the control of the pneumatic valve 19 . If two mesh throttle plates 19 of different sizes are used, each capsule can be controlled pneumatically (open-close only) if necessary, with 3 levels of air flow.

At a pressure differential of approximately 5 kPa, the gas is squeezed downwards from a distance of 20 mm through a 2 mm thick stainless steel metal plate 16 through a 2 mm diameter hole. For example, if the external air of 2.4 m/s needs to be supplied by the blower, the driving power of the blower should reach about 274 kW. In order to save power, in ships with a large draft, it is first possible to install an additional air collector respectively in a small box in a specific area of the bottom of the ship (first of all, the rear and side rear). If the water level 4 exceeds the maximum value, the valve of the air collector will open and air will be led back. That is, a portion of 2.4 nfVs of air flows into the circulation through a blower pressure difference of about 10 kPa. It is evenly distributed on the bottom of the ship. In principle, exhaust gas from the engine can also replace air. However, attention should be paid to the separation of dust and water. The most suitable range of applications for engine exhaust is found in military speedboats, where it is used as add-ons and new build components.

In addition to transport ferries on adjacent seas, this proposed solution is also suitable in fast container ships.

Claims (18)

1. A method for reducing the running resistance of a flat-bottomed floating vessel by means of a downward wall (7) or protrusion fixed to the bottom (1) along the direction of travel, and at least two chambers (5) open downwards. The chamber is limited forwards and backwards in the direction of travel by protrusions, wherein the gas layer (2) formed between the bottom of the ship (1) and the water below is introduced into the chamber (5), characterized in that the chamber Chamber (5) with at least a first water level gauge (L1, L2 or L4) in the front area and at least a second water level gauge (L3) in the rear area, automatically comparing the resulting measurement signals , according to the comparison results a) Control the liquid level in the trim box (12) to achieve the purpose of controlling the inclination angle of the transverse axis of the ship, and/or b) Automatically adjust the hydrofoil (15) or components fixed on the ship to achieve the purpose of controlling the inclination angle of the transverse axis of the ship. 2. The method according to claim 1, characterized in that, by uniformly distributing the gas layer (2) formed between the bottom of the ship (1) and the water in the lower part, the purpose of controlling the inclination angle of the transverse axis of the ship is achieved. 3. The method according to claim 1 or 2, characterized in that a water level measuring device (L1, L2, L3 or L4) is set in the chamber (5), and the measuring signal of the measuring device is used automatically to control each The water level in the chamber, the gas is introduced into the corresponding chamber (5) through the valve (10). 4. The method according to claims 1 to 3, characterized in that at least two water level gauges (L1, L2) are arranged in a chamber (5), by automatically comparing the two water level gauges (L1, L2 ) measurement signal to obtain the inclination angle of the longitudinal axis of the ship, and according to the result a) controlling the liquid level through at least two distribution boxes (12), automatically controlling the inclination angle of the longitudinal axis of the ship, and/or b) Automatic control of the angle of inclination of the longitudinal axis of the vessel at least by hydrofoils (15) or components fixed to the vessel. 5. The method according to claims 1 to 4, characterized in that at least one horizontal orifice plate (16) is installed at the bottom of the bottom (1), and the gas layer is introduced downwards along the direction of water through the formed gas layer . 6. The method according to claims 1 to 4, characterized in that the bottom (1) is provided with holes through which gas is introduced downwards in the direction of the water through the formed gas layer. 7. The method according to claim 5 or 6, characterized in that the space above the orifice plate (16) or the bottom (1) is divided into several independent parts, which can be supplied by at least one pneumatic valve (19) when needed Gas, wherein each part is provided with at least a water level measuring device, and the purpose of the automatic controller measurement signal of the pneumatic valve (19) is to keep the water flow at the bottom (1) and the bottom of the orifice plate (16) as much as possible. within distance. 8. The method according to claims 1 to 7, characterized in that the sides of the gas layer (2) are limited, wherein at least A deflector edge (3) is provided which calms the water flow. 9. Method and structure according to claims 1 to 8, characterized in that at least one airfoil (20) is installed in the chamber (5) transversely to the direction of travel, which reduces the lower part of the bottom (1) Movement of vertical water flow. 10. The method according to claims 1 to 10, characterized in that the water level (4) in the chamber (5) can be determined by measuring the conductivity of the medium between at least two electrodes. 11. A structure for carrying out the method in the preceding claims, characterized in that at least one wall (7) or protrusion extending downwards along the longitudinal side is provided at the bottom of the vessel, wherein the unrestricted space is at least divided into In two chambers (5), gas can be introduced into the gas layer (2) formed between the bottom (1) and the lower part of the water, at least the first water level measuring device is installed in the front area of the chamber (5) Measuring device (L1, L2 or L4) with at least a second measuring device (L3) for measuring the water level in the rear area, which is connected to the automatic comparison device of the measuring signal, and at least one control for changing the liquid level is installed and adjusting device, at least one hydrofoil (15) for controlling the inclination angle of the ship's transverse axis is installed in the distribution box (2) and/or the ship, wherein, through the control and regulating device, at least one control ship's transverse axis is inclined The angled hydrofoils (15) are connected to an automatic comparison device of the measurement signals. 12. The structure according to claim 11, characterized in that in each chamber (5) is installed a measuring device (L1, L2, L3 or L4) for measuring the water level, by means of which each chamber can be controlled individually The water level in the chamber (5), the gas can be introduced into the corresponding chamber (5) through the valve (10). 13. The structure according to claim 11 or 12, characterized in that at least two measuring devices (L1, L2) for measuring the water level are installed in the chamber (5), and they are connected with the measuring signal automatic comparison device for measuring the water level Together, a control and regulation device connecting at least two distribution boxes (12) is installed, and the inclination angle of the longitudinal axis of the ship can be automatically controlled through the liquid level. 14. The structure according to claims 11 to 13, characterized in that at least one horizontal orifice plate (16) is installed on the lower part of the ship bottom (1), through which gas can be introduced into the formed gas layer (2) middle. 15. Structure according to claims 11 to 13, characterized in that the bottom (1) of the vessel is provided with holes through which gas can be introduced into the formed gas layer (2). 16. The structure according to claim 14 or 15, characterized in that the orifice (16) or the space above the bottom (1) is divided into several separate parts, which can be supplied by at least one pneumatic valve (19) when required Air, wherein each part is equipped with at least one measuring device for measuring the water level, which is connected with the automatic control device of the pneumatic valve (19). 17. The structure according to claims 11 to 16, characterized in that the space of the vessel bottom (1) containing the gas layer (2) is limited by walls and/or raised sides, wherein in the direction of travel the chamber (5) At least one deflector edge is provided in the front portion of and transversely to the direction of water flow. 18. The structure according to claims 11 to 17, characterized in that at least one airfoil (20) is installed in the chamber (5) transverse to the direction of travel, which can reduce the vertical water flow under the bottom (1) of the mobile.

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