Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63H—MARINE PROPULSION OR STEERING
  • B63H11/00—Marine propulsion by water jets
  • B63H11/02—Marine propulsion by water jets the propulsive medium being ambient water
  • B63H11/04—Marine propulsion by water jets the propulsive medium being ambient water by means of pumps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63H—MARINE PROPULSION OR STEERING
  • B63H11/00—Marine propulsion by water jets
  • B63H2011/004—Marine propulsion by water jets using the eductor or injector pump principle, e.g. jets with by-pass fluid paths

Definitions

• the present invention relates to a propulsion unit for propelling watercrafts in general.
• watercrafts are typically provided with a directional propulsion system based on the use of rotating propellers and a rudder.
• This type of propulsion is undoubtedly disadvantageous, because the propeller has a relatively low efficiency, since the volume of the displaced water mass corresponds approximately to 40% of the generated disk area and depends on the movement of the watercraft.
• the efficiency of a good screw if the vessel proceeds at high speed, may be over 55%; nonetheless, the propeller is used universally because mechanizing a propeller with a rotary engine is relatively simple, whereas, despite many attempts, advantageous mechanization of an oar has never been achieved.
• the volume of the mass below the oar that has a circular blade is equal to all the blade area, multiplied by 2-3 times its diameter.
• propellers can have damaging effects for example in the case of watercrafts in shallow waters, or in canals, in which the rotation of the propeller causes problems to the bed and in any case creates waves which, for example in the case of narrow canals, tend to erode the banks of the canal.
• Italian Patent application MI2004A000060 proposes a propulsion unit for propelling watercrafts in general that has the peculiarity of comprising an impulsive propulsion element actuated by a motor assembly and capable of operating on a large mass of water, which thus, by exiting from a submerged and flooded diffuser, deals with the external mass like a 'disposable' oar, accelerating and reacting on the associated watercraft with an equal and opposite thrust.
• the diffuser is re-flooded laterally through the wall with each cycle, which wall is unidirectionally permeable from outside.
• the aim of the present invention is to provide a propulsion unit for propelling watercrafts in general that makes it possible to obtain an optimum propulsion which is particularly effective from the point of view of efficiency, where the formula of efficiency is 2VN/(VN+VE), where VN is the speed of the watercraft and VE is the speed of the external water mass measured at the outlet of the diffuser.
• an object of the present invention is to provide a propulsion unit in which propulsion occurs in a fluid and homogeneous manner.
• Another object of the present invention is to provide a propulsion unit for propelling watercraft that can be obtained easily starting from commonly commercially available elements and materials and is also competitive from a merely economic point of view both as regards the provision of the propulsion unit and as regards operating costs.
• a propulsion unit for propelling watercrafts comprising an impulsive propulsion element, which is actuated from outside and is connected to a submerged diffuser associated with a watercraft, characterized in that said impulsive propulsion element comprises a cylindrical tube provided with means for injecting a dose of fluid into said diffuser, said injection of fluid being provided in alternating steps upon the actuation of pumping means adapted to supply said fluid to said injection means.
• Figure 1 is a schematic view of the propulsion unit according to the present invention.
• Figure 2 is a view of the propulsion unit according to the invention in the inactive step
• Figure 3 is a chart which plots, on the axis of the abscissas, the flow as a function of time;
• Figure 4 is a chart related to the thrust cycle
• Figure 5 is a schematic view of the propulsion unit according to the invention, for mathematical purposes;
• Figure 6 is a view of a step of the operation of the propulsion unit according to the invention;
• Figure 7 is a view of a further step of the operation of the propulsion unit according to the invention.
• Figure 8 is a view of the inactive step of the propulsion unit according to the invention.
• the propulsion unit for propelling watercrafts comprises an impulsive propulsion element, generally designated by the reference numeral 1, which is constituted conveniently by a cylindrical tube 2 that leads into a diffuser 3 whose surface is constituted, for example, by a spirally arranged lamina, which in practice provides a one-way valve that prevents the passage of water from the inside of the diffuser body toward the outside through the lateral surface.
• an impulsive propulsion element generally designated by the reference numeral 1
• the reference numeral 1 is constituted conveniently by a cylindrical tube 2 that leads into a diffuser 3 whose surface is constituted, for example, by a spirally arranged lamina, which in practice provides a one-way valve that prevents the passage of water from the inside of the diffuser body toward the outside through the lateral surface.
• the cylindrical tube 2 is provided internally with at least one means for injecting water that arrives from pumping means actuated, for example, by a piston crank system.
• the pumping means are not shown in the figures and can be constituted, for example, by a high-pressure dosage pump.
• the dosage pump should be capable of providing, with a pressure of at least 15 atm, more than five liters of water at least three times per second. Each dose provided by the pump has enough kinetic energy to push, entrain and discharge all the ducted mass of water.
• the divergent part (diffuser) is perfectly permeable from the outside and therefore is re-flooded in the same time during which the ducted flow is discharged. In this way the propulsion unit returns to the initial conditions at the end of each action.
• the at least one nozzle is designated by the reference numeral 4.
• the cylindrical tube and the corresponding diffuser 3 are designed to be arranged in a submerged position, connected to the hull of the watercraft. With the configuration described above it happens that, by injection of the dose of water with sufficient energy by means of the at least one nozzle 4, into the outflow port of the diffuser 3, which is submerged and flooded, all the water contained in the cylindrical tube 2 and in the diffuser 3 is accelerated.
• the pumping means that send to the nozzle the water to be injected, actuated by a piston crank system, cause the water to be expelled cyclically at the nozzle, following only the positive half-axis of the speed, according to the trend shown in Figure 3.
• a single thrust cycle is thus represented by a step of expulsion of the water jet from the nozzle and a step in which the nozzle is inactive (but the cylindrical portion and the diffuser continue to "work" in order to facilitate thrust).
• step I this is a step of short duration, totally independent of the shape of the nozzle, in which the flow follows ideal flow lines and the motion regime contains neither viscous effects nor rotational effects.
• - step II vortical step: because of the effect of the gradients of pressure and viscous entrainment, one or more vortical recirculation structures are created proximate to the nozzle 4 and are deformed and elongated during the emission but remain substantially unchanged in their function of perturbation of the field of motion.
• step III active step: the entire capacity of the pump has been expelled, the flow retains its own inertia and the membranes (which form the spirally arranged lamina) on the diffuser open, facilitating the passage of the external water.
• the motion regime that is established in the "potential" step of the propulsion unit can be fully likened to a non-rotational non-viscous flow (hence the name "potential").
• the pressure gradient along the portion 2 and 3 is given by:
• the constant acceleration of the fluid ensures that an overpressure is maintained inside the diffuser, keeping the membrane closed.
• the nozzle 4 is closed.
• the water, accelerated in the cylindrical portion 2, proceeds by inertia, while the water that leaves the diffuser 3 draws an equal flow inside it, opening the membranes, as shown in Figure 8.
• the water discharged suddenly, contained, compacted and directed by the inlet duct behaves for an instant like a solid body, and exactly like an oar faces, pushes and entrains the adjacent external mass, pushing, by reaction in the opposite direction, the diffuser and the associated watercraft, with an equal and opposite force.
• the duration of the thrust is shorter than that obtained from an oar, but the thrust can be repeated with the most suitable frequency and intensity, so as to achieve a practically continuous thrust.
• the diffuser must always be available, i.e., always perfectly flooded.
• the perfect one-way permeability of the diffuser 3 obtained for example by means of an elastomeric tape a few centimeters wide, anchored on one side to a steel profile, free to oscillate and vibrate, makes it possible to provide in practice a one-way valve which is integral and active over the entire surface of the wall; moreover, there are no mechanical losses and any hydraulic losses are negligible because they are discharged in the opposite direction to the motion of the watercraft.
• the propulsion unit according to the invention fully achieves the intended aim and objects, since it is particularly suitable for use at low speeds, with substantially no environmental impacts.
• the materials used may be any according to requirements and to the state of the art.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• Ocean & Marine Engineering (AREA)
• Other Liquid Machine Or Engine Such As Wave Power Use (AREA)
• Laminated Bodies (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=43738965

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Country Status (3)

Family Cites Families (5)

• 2010
  • 2010-09-28 IT ITMI2010A001764A patent/IT1401976B1/it active
• 2011
  • 2011-09-21 WO PCT/EP2011/066436 patent/WO2012041751A1/en active Application Filing
  • 2011-09-21 EP EP11757902.9A patent/EP2621800A1/en not_active Withdrawn

Non-Patent Citations (1)

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