GB2466957A

GB2466957A - Fluid drive system comprising impeller vanes mounted within a longitudinal structure

Info

Publication number: GB2466957A
Application number: GB0900601A
Authority: GB
Inventors: Robert Ghanea-Hercock
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-01-14
Filing date: 2009-01-14
Publication date: 2010-07-21
Also published as: GB0900601D0

Abstract

A physical system, for both the transmission of energy into a fluid medium, and the extraction of energy from a fluid medium. The system comprises a number of arrangements for an internally structured impeller mechanism, which acts to induce, or utilise, a compressed fluid flow through the device. The device may either function as a vessel propulsion mechanism, a general purpose pump, or as a power generation unit. The principal feature being the internal mounting of impeller vanes 340 within a longitudinal structure formed from an outer pipe structure 380 and an inner sleeve 360, such that a reaction force may be imparted to, or extracted from, the flow 370 of any fluid medium through the invention. Rotational movement may be imparted to the longitudinal structure by means of one or more gears 310 and 350. In particular the system, imparts a vortex effect to the fluid flow through the device.

Description

Fluid Drive System

Field of the invention

The invention relates in one instantiation, to the field of vessel propulsion systems, i.e. a drive mechanism for both surface and sub-surface vessels and submarines. Current techniques rely on propeller form blades, mounted in a multi-blade arrangement around a central shaft. Such a propeller design may be externally mounted to a vessel, or it may be internally mounted within the body of a pump design, itself internally set within the vessel; with water fed from inlets to the pump, and output flow fed to a thrust vector nozzle.

The invention relates to the transmission of energy into a fluid flow for the purpose of forming a transport drive mechanism, or the pumping of fluid. In addition it relates to the extraction of energy from a fluid flow, for the purpose of electrical or mechanical energy generation.

Prior art

At present there are two principal mechanisms for the transmission of engine power into a fluid medium. One is the use of a multi-bEaded propeller, mounted on a drive shaft, which may have a gearbox transmission unit between the propeller drive shaft and the engine. The second method is the use of a water jet propulsion mechanism that uses a ducted impeller within a tube, which then ejects a pumped stream of water as a propulsion method. Both methods exert a propulsive force on a vessel by pushing a mass of water rearward from the vessel.

Each current method has distinct advantages and disadvantages, as listed below: Propellers Higher relative efficiency and torque at low speeds, (e.g. < 20 Knots).

Lower production and maintenance costs, compared to waterjet methods.

A key disadvantage is the noise and environmental damage caused by large propeller units.

A second disadvantage is the need for cathodic anti-corrosion protection on the propeller unit.

Waterjets These offer higher relative efficiency at speeds over 20 Knots; (depending on the exact design).

Greater manoeuvrability, (than propeller systems), due to a vectored thrust manoeuvring capability.

They also enable a vessel to traverse very shallow water, as no shafts or propellers protrude below the vessel.

One disadvantage is that the inlet nozzles of the waterjet can become clogged with solid or foreign matter sucked in by the pump action of the drive unit.

A second disadvantage is the highly variable torque response of the waterjet across the speed range of a vessel. This factor limits the size of vessel that can normally utilise waterjet methods, (e.g. typically less than 1 OOm in length.) Third is the relatively higher production, and maintenance costs of a waterjet pump system.

References a. Invention of First ship propeller 1827. Erhard Marschner: "Josef Ressel. Erfinder der Schiffsschraube -Seine Vorfahren und Nachkommen" [Josef Ressel. The inventor of the ship propeller -its ancestors and descendants], 1979, ISBN 3-7686-6016-8.

b. Reference for ducted propellers. Oosterveld, M.W.C. (1970): Wake Adapted Ducted Propellers, Nederlands Schip Model Basin, Wageningen c. Reference for Axial type Compressors. Hill, Philip and Carl Peterson. Mechanics and Thermodynamics of Propulsion,' 2nd edn, Prentice HaIl, 1991. ISBN 0201146592.

d. Kerrebrock, Jack L. Aircraft Engines and Gas Turbines,' 2nd edn, Cambridge, Massachusetts: The MIT Press, 1992. ISBN 0-262-1 1162-4.

e. Rangwalla, Abdulla. S. Turbo-Machinery Dynamics: Design and Operation,' New York: McGraw-Hill: 2005. ISBN 0-07-145369-5.

f. Water jet propulsion: see http://www.hamiltonjet.co.nz

Summary of the Invention

According to the present invention there is provided a mechanical system, which provides a continuous propulsion effect for any vessel, either on the surface or beneath a water line. In this embodiment the invention would be driven by an engine of some known form, (i.e. a combustion type or electrical motor), either directly, or via a gearbox arrangement. The engine would provide rotational motion to the invention, which would result in a flow of compressed fluid being expelled from the invention resulting in a net forward thrust. The principal feature, being the internal mounting of impeller vanes within a longitudinal structure; such that a reaction force may be imparted to, or extracted from, the flow of any fluid medium through the invention.

In another aspect, the invention may also provide a pump-action effect that may be utilised to pump any fluid, or achieve a pressure difference between two or more reservoirs of fluid. In this embodiment an external engine would again provide a rotational drive input to the invention, which would then operate to pump any fluid it was immersed within, from one side of the device to the other, resulting in a usable pressure difference. Such an effect would allow the device to function as a general purpose pump.

In another aspect, the invention may be used as a power generation device, by being placed within a fluid flow, such that the flow induces rotational motion of the invention. This rotational motion may then be converted, by known electrical power generation techniques into electricity.

An example application being to capture tidal energy, with the device immersed in a tidal flow system.

Other, preferred, aspects of the invention are set out in the claims.

Detailed Description of the implementation

Some embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of the system components in one or more embodiments of the invention; Figure 2 illustrates the cross-sectional arrangement of the invention, in one possible configuration; along with possible cross-sectional configurations of the invention.

Figure 3 illustrates the coupling of the invention to one possible engine or power drive mechanism.

Figure 4 illustrates one possible arrangement of the impeller fins within the invention.

A full description is as follows. The process of transferring energy to or from a fluid medium is a complex technical problem, due to the variations in fluid density and viscosity, across a range of environmental domains. For example, the temperature of the fluid and its chemical properties, have a marked impact on the efficiency and design of any mechanical process for such energy transfer. The earliest technologies developed to address this problem were the helical screw, developed around the 7th Century BC; (also known as the Archimedes' screw). This functioned as a pumping mechanism to raise water from one level to another. A later development was the paddle-wheel, originally designing as a mechanism for extracting rotational mechanical energy from a fluid flow, and later applied to ships as a propulsion mechanism.

The concept of a helical blade arrangement, i.e. a propeller or impeller, being used as a vessel drive mechanism was developed from approximately 1830-1845. Direct comparison of the efficiency of propeller drive systems versus the paddle wheel drive, was demonstrated by Isambard Brunel in 1845. Since then the dominant form of vessel propulsion has been the multi-blade propeller design. Since the 1970's the use of waterjet propulsion technologies, has been used in some small-scale vessels, for the advantages cited in the prior art section. In concept however, this is actually very similar to the traditional multi-blade propeller design; as most waterjets use a propeller set within a tube or duct, to act as the fluid pumping mechanism. In contrast the proposed invention uses a fundamentally different fluid transmission process, as detailed in the following sections.

Each of the known prior art methods has a range of advantages and disadvantages, as cited in the prior art section. The proposed invention provides a range of advantages as listed below: Advantages a. The invention would enable a significant reduction in the noise level produced by a vessels drive system, relative to any known prior art drive method.

b. The invention would provide significantly reduced energy consumption, when used as a vessel drive system, relative to any prior art drive method.

c. The invention would offer all of the advantages of current waterjet propulsion methods, i.e. no protruding drive shaft, or impeller system, and shallow water capability.

d. The invention would offer high torque power transmission capability across a wide speed range; (in contrast current waterjet methods have poor efficiency and torque at low speeds.) e. The invention would not suffer from clogging due to foreign matter being sucked into the drive system, as is the case with known waterjet methods.

f. The invention would offer reduced production costs, and maintenance costs relative to any known vessel drive system. Due to the simplicity of the inventions design and specific architecture.

Invention Description

The invention is composed of several elements as illustrated in figures 1, 2, 3 and 4. As shown in figure 3, the invention is comprised of an outer pipe structure 380, within which runs lengthwise along the pipe an inner sleeve 360. The inner sleeve is comprised of a shell element and a set of internal impeller vanes that run the length of the sleeve 340. The impeller vanes may be either a fixed part of the sleeve structure, or mounted to the sleeve via keyed grooves; (a known impeller attachment method as used in prior turbine technology.) The inner sleeve is arranged within the outer pipe and is attached via a set of fixing bolts, such that as the outer pipe rotates the inner sleeve rotates at the same velocity.

The purpose of the outer and inner sleeve arrangement is to permit the easy removal of the impeller structure with the inner sleeve. Hence a new sleeve and impeller may be exchanged for the purpose of maintenance, or for the purpose of fitting an alternative impeller design.

Alternative impeller designs are described in the following section and in figure 2.

The outer pipe component has attached to its external surface a set of one, or more, gears 310, 350, or pulley drive transmission elements, (see figure 3). These elements enable the invention to be rotated at speed by a coupled engine system, 320. Any known engine system, could be utilised for this purpose, such as an internal combustion engine, gas turbine, or electric motor.

The outer pipe also has two, or more, external bearing units 330 fitted to permit high speed rotational motion, (see figure 3).

Operation The invention may function in one of several modes depending on the specific application. A set of non-exclusive potential applications will be described below, and how the invention A. Vessel Propulsion Mode In this mode the invention would operate in the following manner. The invention would be mounted internally to a vessel, (or externally if preferred), and driven by a suitable engine unit as described above. An inlet pipe would transfer the external fluid 370, (presumed to be water in the case of most vessels, but may be a gas or other fluid medium), from the external environment to the input side of the invention. The rotational motion of the device will result in the input flow of fluid being imparted a rotational velocity, such that it moves to the output side of the invention and exits into an outlet pipe. From the outlet pipe the fluid would be delivered to the external environment of the vessel, and used to impart momentum to the vessel itself.

The process of passing through the invention would impart the input fluid with an increased velocity, and resulting increase in kinetic energy. In particular, the invention may induce a vortex motion within the input fluid, such that the resulting output flow possesses a greater kinetic energy, relative to known prior art methods of vessel propulsion. The process of generating a vortex flow within the structure of the propulsion mechanism is believed to be a novel element of the invention. If required the invention could also be operated such that a laminar fluid flow was developed through the device. Depending on the impeller configuration.

In addition, the extended length of the inventions' impeller design, relative to the pitch length of known propeller mechanisms, also imparts a high degree of torque force to the fluid as it traverses the length of the invention. This process results in the high torque capability of the invention across a wide speed range, as cited in the preceding section, on the advantages of the invention.

The vortex generation process is a function of the specific impeller design as shown in figures 2a-d. In particular the central region of the invention, (see figure 2 end section diagram), is open, i.e. it does not contain a central drive shaft, or similar unit, as used in prior art drive methods. As the fluid enters the invention the longitudinal impellers 210, impart a rotational force to the fluid which results in a vortex flow of fluid along the central axis of the invention 220.

The design function of the resulting vortex flow has several elements. i.e.: i. The vortex flow reduces the amount of noise generated, within the surrounding fluid, by

the invention, compared to prior art methods.

ii. In particular it reduces the amount of cavitation, occurring in the output fluid stream, which is a major source of noise, and physical damage to known propulsion mechanisms.

iii. The vortex flow increases the power efficiency of the invention relative to known prior art propulsion methods.

B. Pump Action Mode In this mode the invention would operate in the following manner. The invention would be mounted in a static framework, but with input and output fluid flows as described in the preceding section, A. (Vessel Propulsion Mode). A drive engine would provide external power to rotate the invention as in section (A), but in this mode the purpose would be to pump the input fluid from one location to another. Or, to raise the pressure of the input fluid for some purpose.

C. Energy Generation Mode In this mode the invention would operate in the following manner. The invention would be mounted such that a fluid flow occurs through the impeller mechanism, resulting in rotational motion of the impeller and attached inner sleeve component, see 230. This rotational motion would be transferred via the outer pipe component to a physically coupled power generator unit, of known type. (Which may be an AC, or DC electrical current generator, or turbine unit). The fluid flow would therefore result in electrical power generation. The vortex process described in section (A) above would also operate in this mode, such that the invention would produce power more efficiently than known prior art. An example application for this mode would be if the invention was situated within a tidal stream, or hydro-electric dam, such that a pressured stream of input fluid was available to provide the rotational force.

Impeller Design A further novel aspect of the invention is that the longitudinal cross-section of the impeller design can be configured in a highly flexible manner, to suit specific applications. (See figure 2. for a non-exhaustive set of example configurations.) For example the impeller cross-sectional form could be one of the following forms: i. Venturi -in this form the impeller would taper along its length as in figure 2a.

ii. Linear -in this form the impeller would taper along its length as in figure 2b.

iii. Concave -in this form the impeller would taper along its length as in figure 2c.

iv. Convex -in this form the impeller would taper along its length as in figure 2d.

The impeller may also have several configurations for its cross-sectional pitch, as shown in figure 4. For example: i. Straight 410: In this configuration the impeller blades run straight along the length of the unit with zero degree rotational pitch.

ii. Radial 400: In this configuration the impeller blades have a spiral pitch along their length.

In addition the blade thickness of the impeller blades may be varied to Suit differing application domains.

Alternative Applications The invention could be applied to a wide range of alternative applications, as would be evident to practitioners in the field of fluid-dynamics. For example, micro-fluidic applications, gas transport or pumping, jet engine refinements, or plasma flow control.

Claims

CLAIMS1. A fluid drive system in the first instance, comprising: (a) a mechanical means for the translation of energy into a fluid flow.(b) and alternatively a mechanical means for the extraction of energy from a fluid flow.
2. A system for the translation of energy into a propulsive force within a fluid medium.
3. A system according to claims (1), (2) such that it may act to translate mechanical force, so as to pump a fluid medium, via a pressure difference.
4. A system according to claim (2) that provides: a. High torque capability at low fluid velocities, (relative to prior art methods.) b. Reduced frictional drag within a fluid flow, (relative to prior art methods.) c. Increased power efficiency according to claims (1), (2), and (3), (relative to prior art methods.) d. Reduced probability of internal blockage compared to waterjet propulsion methods.e. Reduced noise generation within the fluid medium, due to the impeller design in figures 2a-d.
5. A system that translates a rotational drive force into a compressed fluid flow, for the purposes, according to claims (1) and (2), via a longitudinal impeller design.
6. A system, according to claims (1) and (2) that generates a net force on a fluid medium, via the creation of a vortex, or laminar, flow within the fluid.
7. A system that enables rapid reconfiguration of the impeller design via the means of a two-part sleeve configuration, as illustrated in figures (2, [200][210], ) and (3).
8. A system that according to claim (3) and claim (6) enables an efficient transmission of fluid from one region of pressure to another of different pressure.
9. A system that according to claim (7) allows for the operational replacement of the impeller system, with an alternative impeller structure for revised functional requirements.-10 -
10. A system according to claims (1), (2) and (5) that utilises a rotating tube with a set of internal impeller vanes, to generate a compressed fluid flow through the device.