Fluid displacement or propulsion device having a progressively tapered HUB volume with periods formed into a surface, system and methods for moving a fluid or causing propulsion

Abstract

Disclosed herein is an propulsion system for causing fluid movement along an axis in line with the axis of rotation of an impeller disposed within an open-ended tube. The impeller is fashioned so as to substantially reduce areas of fluid acceleration and deceleration around a hub region of the impeller during fluid movement. The impeller has a generally circularly shaped hub having a forwardly-facing progressively tapered volume which has plurality of periods formed therein corresponding to the number of increasingly arced blades. Each of the increasingly arced blades flare outwards to a distal end region of the impeller and have an increasing radius to the arc towards a peripheral edge region of the hub. The flare to the increasingly arced blades defines a larger circumference than that of the hub, thereby imparting a generally frusto-conical shape to impeller. A method for causing fluid movement along an axis in line with the axis of rotation of an impeller or the impeller of the propulsion system disclosed herein is also disclosed.

Description

FLUID DISPLACEMENT OR PROPULSION DEVICE HAVING A PROGRESSIVELY TAPERED HUB VOLUME WITH PERIODS FORMED INTO A SURFACE, SYSTEM AND METHODS FOR MOVING A FLUID OR CAUSING PROPULSIONRELATED APPLICATION

[0001] The instant application claims the benefit of priority to U.S. Provisional Patent Application serial number: US 63 / 538,147, filed September 13, 2023, and entitled “FLUID DISPLACEMENT OR PROPULSION DEVICE HAVING A PROGRESSIVELY TAPERED HUB VOLUME WITH PERIODS FORMED INTO A SURFACE, SYSTEM AND METHODS FOR MOVING A FLUID OR CAUSING PROPULSION”, the disclosure of which is herein fully incorporated by reference.TECHNICAL FIELD

[0002] The present disclosure relates to a fluid displacement or propulsion device and / or system. In particular, the present disclosure relates to a fluid displacement or propulsion device system for displacing a fluid or propulsion.BACKGROUND

[0003] Fluid displacement, for example by way of a pump or in a vessel wherein fluid movement is desired, or in certain vehicle propulsion systems, propellers or impellers are known in the art and used. An impeller is generally defined as a device which drawing a fluid towards itself, whereas a propeller is generally defined as a device which moves a fluid away from itself, when caused to rotate owing to the helical pitch of the blades. Thus, from a simplistic point of view, impellers and propellers differ semantically in the relative direction in which they cause fluid movement when rotated.

[0004] In the case of a pump or, with respect to a vessel wherein it is desired to impart motion to a fluid contained therein, the impeller is generally rotated, yet maintained in a static location. In such systems, the impeller or propeller, by virtue of rotation, thus imparts motion to the fluid such that the fluid is caused to flow, or is displaced relative to the impeller or propeller. In cases where an impeller or propeller is used to move a vehicle, such as boat, rotation of the impeller or propeller, being coupled to the vehicle, when rotated remains in a static location relative to vehicle, and creates thrust by action of a screwing motion in the fluid thus causing the vehicle to move.

[0005] Water jet thrusters are known in the art. Known water jet thrusters, such as those commonly used on jetboats and small watercraft typically comprise a water inlet located to be submersed in water where water is drawn into the inlet by an impeller. Water which has been drawn into the inlet by the impeller is then moved into a smaller volume cavity having an open end or nozzle where the water is expelled at higher rate of speed due to an increase in pressure, resulting in thrust. The thrust is created due to the water being forced through the smaller volume cavity by the impeller, which owing to the non-compressibility of a fluid increases the pressure and causes the water to increase in speed before it exits the nozzle. In other systems, such as that known in the art for watercraft bow thrusters or certain types of azimuth thrusters, generally a propeller or impeller is located in an open-ended tub-like structure, which may or may not be tapered towards the waterexiting end. In such systems the propeller or impeller is generally a conventional helical screw-type propeller where the water is drawn through the tube-like structure from one end and exits through the other end, thus creating thrust exiting in direction from the end in which the water exits.

[0006] Also known in the art, and generally problematic with regard to impellers and propellers is cavitation. The phenomenon of cavitation is where the static pressure of a liquid reduces to below the liquid’s vapour pressure. This leads to the formation of small vapor-filled cavities or bubbles in the liquids, which subsequently implode under increased pressure on themselves causing shockwaves to travel through the liquid which may damage various parts of a pump, or as the case may be, a propulsion system. Furthermore, the formed bubbles create localized density changes in a given volume occupied by the liquid, which may be detected by certain sonar systems, and the like. The bubbles, when they implode en masse, create soundwaves which travel through the liquid due to the violent nature of the implosion of the bubbles. Such soundwaves are known to disturb local environments and wildlife. Furthermore, cavitation results in a diminishment of thrust as the impeller or propeller suffers from having to move the resultant lower density gas, along with the higher density liquid. Where cavitation does not occur, the propeller or impeller is only moving the higher density liquid.

[0007] Owing to the impeller or propeller having to move a gas along with the propulsion liquid when cavitation occurs, move power input is often needed to move the same volume of liquid. Therefore, more horsepower is needed to increase the speed of the impeller or propeller so as to result in the desired volume of fluid to be moved to create the desired thrust.

[0008] Conical impellers, such as those disclosed in U.S. Patent serial number 5,314,310, entitled “SPIDER MOUNTED CENTRIFUGAL MIXING IMPELLER”, issued May 24, 1994(Bachellier, Carl R.), U.S. Patent serial number 5,938,332, entitled “MIXING DEVICE”, issued August 17, 1999 (Bachellier, Carl R.) and International Patent Application serial number PCT / CA2012 / 050873, entitled “IMPROVED IMPELLER APPARATUS AND DISPERSION METHOD FIELD OF THE INVENTION”, filed December 5, 2012 (Bachellier, Carl R.) disclose various impellers for mixing fluids which comprise a top hub having a flat interior surface; that is, the inside bottom surface of the hub is parallel to the axis of rotation. For example, the bottom surface of the hub, when the impeller body on a central longitudinal axis is oriented in a vertical plane, is oriented horizontally. During use, when such impellers rotate, an upward spiral helical intake vortex to the fluid is created. This vortex collides with the flat surface, causing the vortex to compress and collapse on itself thereby creating an area of fluid deceleration and a turbulent region. In the upper part of these impellers, typically the top third, the fluid is discharged from the impeller at approximately a 90-degree angle to the axis of rotation, which disrupts the otherwise upward flow of fluid from the lower two thirds of the impeller. This can result in inadequate discharge of fluid to the exterior of the impeller of the fluid in approximately the upper third of the interior of the impeller, which then provides resistance to the fluid entering the bottom of the impeller (i.e. a backwash or stall effect), thereby impeding it from moving up to the hub. Thus, the fluid does not flow around and from the impeller in a smooth, substantially non-turbulent manner. In addition, particulates or other second phase materials, such as cells in a suspension culture, collide with the flat interior surface and may adhere to that surface in addition to colliding with one another in a detrimental fashion. This effect is exacerbated by the sharp interior angle where the upper edge of the blade attaches to the bottom surface of the hub.

[0009] International Patent Application serial number PCT / US2015 / 025820, entitled “CONICAL IMPELLER AND APPLICATIONS THEREOF”, filed April 14, 2015 (Bachellier, Carl R.) discloses a generally conically-shaped impeller for mixing fluids. The application, having the same inventor as the instant application, discloses a low shear impeller which has a hub with a conical surface extending into the interior of the impeller and a plurality spiral, or in other words, increasingly arced blades towards the outer peripheral are of the impeller. At the intersection of the conical surface and the spiral blades, during rotation in a fluid, this arrangement causes the fluid to form an upwardly swirling vortex in which entrained particles or gases are brought into the interior of the impeller and subsequently ejected from the impeller at a trailing edge of the spiral blades and along the trailing edge of the spiral blades. However, during testing and Computational Fluid Dynamics (CFD) modeling, it was discovered that at the conical surface of the hub, the fluid flow isrestrictive, that being having zones of fluid acceleration and deceleration where the fluid becomes trapped in a recirculating flow pattern. It was discovered that the conical surface acts as a deceleration mechanism and in conjunction with the spiral blades creates a turbulent discharge.

[0010] Therefore, in certain applications the impeller of International Patent Application serial number PCT / US2015 / 025820 has drawbacks for certain applications of suspension cell culturing techniques, and other uses. For example, the abovementioned impeller, during testing showed a significant deceleration of fluid at the apex of the interior conical surface by a factor of 190 times and a reacceleration of the fluid upon discharge. The impeller of International Patent Application serial number PCT / US2015 / 02580 also displayed a recirculatory eddy formation around the drive shaft assembly attachment point which may trap cells undergoing culturing into a zone which prevents even distribution to the rest of the colony growing in the bioreactor. Accordingly, although functional in many other applications, the fluid dynamic characteristics of the impeller disclosed in International Patent Application serial number PCT / US2015 / 02580 does not satisfactorily meet several of the needs for suspension cell propagation in bioreactors due to the inherent ultra-low stress requirements of certain cell types, in particular, stem cells, as well as fluid movement.

[0011] International Patent Application serial number PCT / CA2017 / 050845, entitled “LOW SHEAR, LOW VELOCITY DIFFERENTIAL, IMPELLER HAVING A PROGRESSIVELY TAPERED HUB VOLUME WITH PERIODS FORMED INTO A BOTTOM SURFACE”, filed July 11, 2017 (Bachellier, Carl R.) discloses an impeller for mixing a fluid wherein the impeller is fashioned so as to substantially reduce areas of fluid acceleration and deceleration around a hub region of the impeller during fluid mixing. The impeller has a generally circularly shaped hub having a progressively tapered volume which has plurality of periods formed therein corresponding to the number of increasingly arced blades. The progressively tapered volume extends from the hub interior of the increasingly arced blades and is along a central axis in line with the rotational axis. Each of the increasingly arced blades flare outwards to a distal end region of the impeller and have an increasing radius to the arc towards a peripheral edge region of the hub. The flare to the increasingly arced blades defines a larger circumference than that of the hub, thereby imparting a generally frusto-conical shape to the impeller. The impeller of International Patent Application serial number PCT / CA2017 / 050845 is designed such that when it is caused to rotate by way of a motor applying rotational forces to the rotatable drive attachment region located on a surface of the generally circularly shaped hub opposite the progressively tapered volume, for example, on the top of the generally circularly shaped hub, fluid is moved. During rotation of the impeller, a leadingedge region of the blades is moved though the fluid and the fluid is drawn toward the progressively tapered volume, ejected or discharged, in part, from the impeller at the trailing edge region of the blades and at discharge channels located near the peripheral region of the hub, thus causing movement of the fluid.

[0012] This background information is provided to reveal information believed by the applicant to be of possible relevance. No admission is necessarily intended, nor should it be construed, that any of the preceding information constitutes prior art.SUMMARY

[0013] The following presents a simplified summary of the general inventive concepts described herein to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to restrict key or critical elements of the invention or to delineate the scope of the invention beyond that which is explicitly or implicitly described by the following description and claims.

[0014] In light of the above background discussion it would be desirable to develop an impeller or propeller for causing fluid displacement or a propulsion device and / or system with substantially free from zones of turbulent flow velocity differentials, cavitation, and zones of fluid flow restriction in fluid mediums which may provide additional thrust as it is caused to rotate faster.

[0015] It has been surprisingly discovered that by providing an impeller having a hub with a shaft extending from a forwardly-facing progressively tapered volume interior to a proximal end region of the impeller where an outer edge of the blades are coupled to the hub and the blades being further coupled to the forwardly-facing progressively tapered volume in a decreasing arc is disposed, or in other words following a spiral helical pattern, inward to a predetermined point aids to produce a pre-whirl to a fluid in a path along an axis in line with the forwardly-facing progressively tapered volume produces thrust in which the impeller or propeller is substantially free from cavitation. Additionally, it has also been surprising discovered that by placing such an impeller in an open-ended tube-like structure may further improve performance of the impeller.

[0016] The internal surface structure of the hub, the forwardly-facing progressively tapered volume having the blades following along a corresponding period formed therein, acts to create as a pre-whirl device which substantially matches the pre-whirl generated by the circumferentially attached inwardly decreasingly arced blades. Swirling channels, the periods in some embodiments, intermittent the inwardly decreasingly arced blades allows the vortex created by the blades andmotion of the hub to meet and be divided inwardly toward the forwardly-facing progressively tapered volume and outwardly with minimal velocity change to the various regions of the fluid about the hub. The swirling internal channels of the forwardly-facing progressively tapered volume of the hub extend into discharge channels on the upper anterior side of the hub which provide a substantially smooth velocity transition of the fluid in various zones and reduce or substantially eliminate known zones of recirculation and turbulence associated with the above-discussed prior art, and, thus, may reduce zones of fluid flow restriction. Additionally, the fluid displacement or propulsion device described herein, unlike those of the abovementioned previously disclosed impellers, is substantially devoid of horizontal surfaces perpendicularly extending from the top of the hub.

[0017] In one aspect, there is provided a propulsion system comprising an open-ended tube and an impeller disposed therein where the open-ended tube has an inlet end and an outlet end. The impeller is oriented along its rotational axis within the open-ended tube in line a central axis of the open-ended tube. The open-ended tube is configured to allow and direct movement of a fluid from the inlet end to the outlet end of the open-ended tube when the impeller is caused to rotate. The impeller comprises a generally circularly shaped hub including a forwardly-facing progressively tapered volume having coupled thereto a first end region of one or more arced blades arranged along a periodic pattern formed into the forwardly-facing progressively tapered volume wherein the number of periods corresponds to the number of blades. Each of the one or more arced blades has an arc with an increasing radius to the arc towards a peripheral edge region of the hub. The proximal end region of the one or more increasing radius arced blades extends from the peripheral edge region of the hub along the forwardly-facing progressively tapered volume to a predetermined point inward of the peripheral edge region. The one or more arced blades is further flared as extending from the forwardly-facing progressively tapered volume such that a distal end region of each of the one or more increasing radius arced blades, in combination, defines a larger circumference than that of the hub, thereby imparting a generally frusto-conical shape to the impeller. The impeller has a shaft extending from a terminal centre region of the forwardly-facing progressively tapered volume for operably coupling to a rotatable drive.

[0018] In another aspect, there is provided a propulsion system which comprises an open- ended tube and an impeller disposed therein. The open-ended tube has an inlet end and an outlet end. The impeller is oriented along its rotational axis within the open-ended tube in line a central axis of the open-ended tube. The open-ended tube is configured to allow and direct movement of afluid from the inlet end to the outlet end of the open-ended tube when the impeller is caused to rotate. The impeller comprises a generally circularly shaped hub including a forwardly-facing progressively tapered volume having coupled thereto toward a peripheral end region thereof one or more flaring arced blades arranged along a periodic pattern formed into the forwardly-facing progressively tapered volume to project generally forwards from the peripheral edge region and to define a periodically flaring impeller radius along their length which allows for tangential fluid flow between adjacent blade ends. The impeller further comprising a shaft extending from a terminal centre region of the forwardly-facing progressively tapered volume for operably coupling to a rotatable drive.

[0019] In another aspect, there is provided an impeller comprising a generally circularly shaped hub including a forwardly-facing progressively tapered volume having coupled thereto a first end region of one or more arced blades arranged along a periodic pattern formed into the forwardly-facing progressively tapered volume wherein the number of periods corresponds to the number of blades. Each of the one or more arced blades having an arc with an increasing radius to the arc towards a peripheral edge region of the hub. The proximal end region of the one or more increasing radius arced blades extends from the peripheral edge region of the hub along the forwardly-facing progressively tapered volume to a predetermined point inward of the peripheral edge region. The one or more arced blades further being flared as extending from the forwardly- facing progressively tapered volume such that a distal end region of each of the one or more increasing radius arced blades, in combination, defines a larger circumference than that of the hub, thereby imparting a generally frusto-conical shape to the impeller. The impeller has a shaft extending from a terminal centre region of the forwardly-facing progressively tapered volume for operably coupling to a rotatable drive.

[0020] In another aspect, there is provided an impeller which comprises a generally circularly shaped hub including a forwardly-facing progressively tapered volume having coupled thereto toward a peripheral end region thereof one or more flaring arced blades arranged along a periodic pattern formed into the forwardly-facing progressively tapered volume to project generally forwards from the peripheral edge region and to define a periodically flaring impeller radius along their length which allows for tangential fluid flow between adjacent blade ends. The impeller also includes a shaft which extends from a terminal centre region of the forwardly-facing progressively tapered volume for operably coupling to a rotatable drive.

[0021] In yet another aspect, there is provided a method for causing fluid movement fluid which comprises introducing into a fluid the propulsion system as disclosed herein and causing at least the impeller to rotate.

[0022] In some embodiments, the impeller comprises at least two increasing radius arced blades.

[0023] In some embodiments, the periods formed into the forwardly-facing progressively tapered volume comprises a plurality of spiral helices which corresponds with the number of increasing radius arced blades.

[0024] In some embodiments, the one or more increasing radius arced blades extending from the peripheral edge region of the hub along the forwardly-facing progressively tapered volume extend from ridges of the spiral helices.

[0025] In some embodiments, the impeller has channels formed intermittent the ridges following the spiral helices so as to form a path continuous with a sequence of distinct conical spiral segments between the one or more increasing radius arced blades. In some embodiments, the channels have a substantially semicircular profile.

[0026] In some embodiments, the hub has a curved peripheral surface forming a discharge channel located at a peripheral terminus of the spiral helices adjacent each of the one or more arced blade proximal end region extending from the channels.

[0027] In some embodiments, the spiral helices of the forwardly-facing progressively tapered volume is a logarithmic spiral.

[0028] In some embodiments, the one or more increasing radius arced blades are integrally formed with the hub.

[0029] In some embodiments, the impeller further comprises a ring coupled near the distal end regions of the one or more increasing radius arced blades for connecting the one or more radius arced blades. In some embodiments, the ring is integrally formed with the one or more increasing radius arced blades.

[0030] In some embodiments, the forwardly-facing progressively tapered volume has a compound logarithmic taper.

[0031] In some embodiments, the open-ended tube and the impeller are operably coupled so as to be rotatable in unison.

[0032] Other aims, objects, advantages, and features of the invention will become more apparent upon reading of the following non-restrictive description of specific embodiments thereof, given by way of example only with reference to the accompanying drawings.BRIEF DESCRIPTION OF THE FIGURES

[0033] In order that the invention may be better understood, exemplary embodiments will now be described by way of example only, with references to the accompanying drawings, wherein:

[0034] Figure l is a schematic representation of fluid flow through an exemplary embodiment of the propulsion system of instant disclosure;

[0035] Figure 2 is a cut-away perspective view along line A’ of Figure 6 of an embodiment of the propulsion system of the instant disclosure;

[0036] Figure 3 is a side view of an exemplary embodiment of the propulsion system of the instant disclosure coupled to a motor mounted to a boat;

[0037] Figure 4A is a side view of an exemplary embodiment of the propulsion system of the instant disclosure coupled to a motor;

[0038] Figure 4B is a side view of another exemplary embodiment of the propulsion system of the instant disclosure coupled to a motor;

[0039] Figure 5 is a cut-away perspective view along line A’ of Figure 6 of an embodiment of the impeller of the instant disclosure;

[0040] Figure 6 is a forward-facing plan view of the exemplary embodiment of the propulsion system of Figure 1;

[0041] Figure 7 is a rear-facing plan view of the exemplary embodiment of the propulsion system of Figure 1;

[0042] Figure 8 is a forward-facing plan view of the exemplary embodiment of the propulsion system of Figure 1 with the ring;

[0043] Figure 9 is a side view of an exemplary impeller of the instant disclosure;

[0044] Figure 10a is a side view of an exemplary embodiment of the impeller, the shaft, the generally circularly shaped hub, and the forwardly-facing progressively tapered volume with the blades removed of the impeller of Figure 1;

[0045] Figure 10b is a side view of an exemplary embodiment of the impeller, the shaft, the generally circularly shaped hub, and the forwardly-facing progressively tapered volume with theblades removed in accordance with the instant disclosure wherein the forwardly-facing progressively tapered volume has logarithmic taper;

[0046] Figure 10c is a side perspective view of an exemplary embodiment of the impeller showing the shaft, the generally circularly shaped hub, and the forwardly-facing progressively tapered volume with the blades removed;

[0047] Figure 11 is a graphical representation of a spiral having the general profile of a blade of the impeller of an embodiment of the instant application laid there-over; and

[0048] Figure 12 is a graph showing the volume displacement versus the impeller speed comparing an impeller of the instant disclosure to a marine impeller; and

[0049] Figure 13 is a graph showing the Reynolds number versus the Power number comparing an impeller of the instant disclosure to a marine impeller.

[0050] Elements in the several figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be emphasized relative to other elements for facilitating understanding of the various presently disclosed embodiments. Also, common, but well-understood elements that are useful or necessary in commercially feasible embodiments are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present disclosure.DETAILED DESCRIPTION

[0051] As used herein the term “impeller” is used and understand to mean a structure, which, when rotated in a fluid, causes directional movement to the fluid.

[0052] With reference to the disclosure herein and the appended figures, a propulsion system 10 and impeller 11b in accordance with various embodiments of the invention is described below.

[0053] With reference to Figure 1, there is schematically shown an embodiment of the propulsion system 10 as disclosed herein which, may, in some embodiments comprise two parts. The propulsion system 10, in general, includes an open-ended tube I la, and impeller 11b. The impeller 11b includes, or has operably coupled to, a rotatable drive attachment region 12a coupled to shaft 12b, which when caused to rotate draws a liquid into a first end 13a of the open-end tube I la and expels the liquid through the second end 13b of the open-end tube 1 la as shown in Figure 1 where “^4” denotes the flow the liquid shown by the arrows 15 in a first direction. In the foregoing disclosure reference is made to the various elements of the impeller 1 lb in terms of the direction ofshaft 12b of “7?” as noted in the figures so as to effect liquid flow 15 with reference to Figure 1. However, one of skill in the art will appreciate if the shaft 12b is caused to rotate in the direction of rotation opposite “ ?”, the flow of the liquid 15 will be reversed to enter from the second end 13b and be expelled through the first end 13a of the open-ended tube I la (not shown). Furthermore, in some embodiments the impeller 11b may be used without the open-ended tube I la, as may be desired from certain applications, where fluid is drawn toward center of the impeller 11b and expelled between the blades 18 and near a hub 14.

[0054] Figure 3 shows a boat 29, having an outboard motor 19 with an exemplary embodiment of the propulsion system 10 as disclosed herein coupled thereto. The coupling of the propulsion system 10 and rotation of the shaft 12b is described in more detail below with reference to Figures 4A and 4B having regard to presently contemplated embodiments. Additionally, is should be noted that although an outboard motor is shown in Figure 3, other suitable boat motors such as inboard motors, outboard motors, and others known in the art may be adapted to use the impellers 1 lb and / or propulsion system(s) 10 as disclosed herein.

[0055] Figures 4A and 4B show two embodiments of the propulsion system 10. In Figure 4A, the propulsion system 10 is shown in a first embodiment where in the shaft 12b is coupled to rotatable drive member 17 by means of the rotatable drive attachment region 12a of a schematically represented boat motor 19 and the open-ended tube I la is coupled to the cavitation plate 21 of the boat motor 19 by means of an open-ended tube coupling member 23. In this embodiment the open- ended tube coupling member 23 couples the open-ended tube I la to a cavitation plate 21 using bolts schematically represented as bolts 25. However, one of skill in the art will appreciate that other coupling means may be suitable, and appropriate, and thus substituted for a given application. Furthermore, one of skill in the art will also appreciate that the open-ended tube I la may be operably coupled to the motor by other means, and at other points, such as the motor leg, other than that shown for example in Figure 3 depending on the application and means used to effect rotation to the shaft 12b. For example Figure 4A is provided for exemplary and explanatory purpose to represent an embodiment of propulsion system 10 where the open-ended tube 11b is statically maintained relative to the motor 19 and where the impeller 1 lb is disposed within the cavity of the open-ended tube I la and allowed to rotate relative thereto. In certain embodiments, the impeller 1 lb may be used without the open-ended tube I la.

[0056] Similar to the embodiment of Figure 4A, Figure 4B shows an embodiment where the impeller 11b is maintained in the cavity of the open-ended tube I la. However, in the embodimentof Figure 4, the open-ended tube I la is coupled to the shaft 12b, by for example, legs 12c such that as the shaft 12b is rotated, the open-ended tube I la and the impeller 11b rotate in unison. In some embodiments, the open-ended tube I la may be attached, or caused to rotate with the impeller 11b, by other means or attachment points, as may be determined to be suitable by those of skill in the art.

[0057] With regard to the motor 19, it is contemplated by the inventor that the motor 19 need not be a boat motor per se. But rather, in some embodiments, may be motor for mixing, or otherwise causing fluid flow in a vessel. Furthermore, although not shown, it is also contemplated by the inventor the open-ended tube I la may be pipe or a region of a pump system where the pipe thus remains static relative to the rotation of the impeller 1 lb, which when rotated causes fluid to move through the pipe or pumping system.

[0058] Turing now to Figure 5, there is shown an embodiment of the impeller 11b of the instant disclosure. In Figure 5, for the purposes of ease of explanation, the impeller 1 lb has been sliced along line A’ of Figure 6. Figure 5 shows the impeller 11b with the shaft 12b coupled to a forwardly-facing progressively tapered volume 16a as shown, for example, in Figures 2 to 6, 8, and 10a to 10c where the shaft 12b can then be coupled to rotatable drive member 17 at the rotatable drive attachment region 12a.

[0059] The impeller 11b has a generally circular shaped hub 14, as shown in Figures 5, 7, 9, and 10a to 10c. With the impeller 11b coupled to a rotatable drive member 17 via the shaft 12b at that rotatable drive attachment region 12a, for example the drive shaft 17 of a motor 19, the impeller 1 lb is rotated as the drive shaft 17 is turned. When immersed in a fluid, the rotation of the impeller 1 lb results in the fluid being moved, or moved though the open-ended tube I la, as shown in Figure 1, for example to produce thrust.

[0060] The impeller 1 lb, with reference to the figures, has a forwardly-facing progressively tapered volume 16a with the shaft 12b coupled to the forwardly-facing progressively tapered volume centre 42, also termed herein a terminal centre point 42 of the forwardly-facing progressively tapered volume, as shown for example in Figures 6, 8, 10a, and 10b. For ease of explanation the terminal centre point 42 of the forwardly-facing progressively tapered volume is noted by the black dot in in Figures 6 and 8. Opposite the forwardly-facing progressively tapered volume 16a, the generally circular shaped hub 14 has a rear-facing 16b side thereof. There is at last one, and in most embodiments, a plurality of increasingly arced blades 18 arranged along a periodic pattern formed into the forwardly-facing progressively tapered volume 16a. The number of periods corresponds to the number of increasingly arced blades 18, for example, as shown in Figures 6 and8, five increasingly arced blades 18. In some embodiments, not shown in the figures, the impeller 11b may be provided with only one blade 18, which, in such a case may follow a single helical period formed into the forwardly-facing progressively tapered volume 16a such that the single blade 18 extends helically substantially around the hub 14 thus providing the required balance as the impeller 11b is rotated during use. In other embodiments, the single bladed may be offset by counterbalance weight (not shown).

[0061] The increasingly arced blades 18 are coupled to the generally circularly shaped hub 14 at a proximal region 26a, noted in Figures 5 and 9. The proximal region 26a of the blades extend from a peripheral edge region 20 of the hub 14 along the forwardly-facing progressively tapered volume 16a to a predetermined point inward 24 of the peripheral edge region 20.

[0062] Turning now to Figure 9, for example, it is shown that the increasingly arced blades 18 are flared as they extend from the forwardly-facing progressively tapered volume 16a to a distal end region 26b of the blades 18. In doing so the circumference of the impeller 11b, as defined by the distal end regions 26b of the blades 18 is larger than the circumference of the hub 14 thereby imparting a generally frusto-conical, or flaring, shape to the impeller 11b. As more clearly seen in the front-facing plan view of Figure 8 and rear facing plan view of Figure 7, there is shown that the distal end regions 26b of the blades define a larger circumference to the impeller 1 lb in this distal area than near the hub 14. Thus, in other words, it can be said that the blades 18 are flared outwardly as they go from the peripheral end region 26a, coupled to the hub 14, to the distal end region 26b.

[0063] Arrow “ ?” of the figures shows the direction of rotation of the impeller 1 lb in use to move a fluid along the flow direction 15 of the arrows in Figure 1. During rotation of the impeller 1 lb, a leading edge region 38 of the blades 18 is moved though the fluid and the fluid is ejected or discharged, in part, from the impeller 1 lb at the trailing edge region 40 of the blades 18. In the case of the propulsion system 10 disclosed herein, the fluid moves along the interior wall of the open- ended tube I la towards the second end 13b in a manner as shown in Figure 1, for example. Rotating the impeller 11b in the direction opposite “ ”, will cause the fluid to move along the interior wall of the open-ended tube I la toward the first end 13a, thus reversing the direction of fluid movement opposite to that shown at 15 in Figure 1. Accordingly, by reversing the direction of rotation of the impeller 1 lb to opposite that shown at “ ”, the direction of fluid movement will be from second end 13b to towards the first end 13a, where it will be ejected from the open-ended tube I la.

[0064] With reference to the front-facing plan view of the impeller 1 lb as shown in Figures 6 and 8, the periods of the forwardly-facing progressively tapered volume 16a may take the form of, in some embodiments, a plurality of spiral helices 34 formed into the forwardly-facing progressively tapered volume 16a. For example, each spiral helix 34 is formed by a single period. The number of spiral helices 34 corresponds to the number of periods of the hub and thus also the number of increasing radius arced blades 18. The periods or spiral helices 34 emanate from near the outer surface of the shaft 12b sequentially as though from the centre point 42 of the forwardly- facing progressively tapered volume 16a, a point referred to herein as the forwardly-facing progressively tapered volume centre 42. Furthermore, the periods or spiral helices 34, extending from the forwardly-facing progressively tapered volume centre 42, have a ridge component, the spiral ridges 28a and channel component, the spiral channels or spiraling grooves, 28b, thus forming a corresponding period. It should be noted that in some embodiments, (not shown) that the periods may be a raised formation, as opposed to, for example, the channel. Figure 10c, in particular, shows an orthogonal view of the forwardly-facing progressively tapered volume 16a and the shaft 12b where the spiral helices 34 and corresponding spiral ridges 28a and the spiral channels 28b can be easily seen. In some embodiments, the spiral channels 28b have a semi-circular profiles, as can be seen in the embodiments shown in figures.

[0065] With respect to the forwardly-facing progressively tapered volume 16a, in some embodiments, it is provided as having a generally conical shape having the spiral ridges 26a and spiral channels 26b formed in its surface. In such an embodiment, the slope to the conical volume may have angle 0, as shown for example in Figure 10a. However, in other embodiments, the forwardly-facing progressively tapered volume 16a may have a profile such that a cross-sectional profile of forwardly-facing progressively tapered volume 16a is not seen as a straight line from the forwardly-facing progressively tapered volume centre 42 to the outer peripheral region near the hub 14. That being, in some embodiments, the forwardly-facing progressively tapered volume 16a may have a curved profile and furthermore, an exponentially increasing curve, or in other words a compound logarithmic taper to the forwardly-facing progressively tapered volume 16a, as shown for example, in Figure 10b.

[0066] In some embodiments, the spiral component, formed by the spiral ridges 28a is provided as a logarithmic spiral. The logarithmic spiral pattern as formed on the surface of the forwardly- facing progressively tapered volume 16a aids to create a pre-whirl effect along a path extending from the progressively tapered volume centre 42 which matches a pre-whirl generated by thecircumferentially attached increasingly arced blades. The spiral channels 28b, or in other words, the swirling channels intermittent the increasingly arced blades allows the vortex created by the blades and motion of the hub to meet and be divided inwardly to the progressively tapered volume centre 42 and outwardly with minimal velocity change to the various regions of the fluid about the hub 14. The swirling internal channels 28b of the forwardly-facing progressively tapered volume of the hub extended into discharge channels 32a on the upper anterior side of the hub which provide a substantially smooth velocity transition of the fluid in various zones and reduce or substantially eliminate known zones of recirculation as the fluid tangentially flows between adjacent blade ends. Accordingly, cavitation by the instantly disclosed impeller 11b, and in some embodiments, the propulsion system 10 may be reduced around the impeller 11b by fluid displacement rather than pressure differentials by creating a pre-whirl condition, allowing for a shockless entry of the peripherally mounted blades 18 rotated internal to a tube / tunnel I la, thus reducing power requirements, increasing range in the case of vehicle propulsion system, while having a low sound signature. In the case of vehicle propulsion, this may allow for higher speeds, resulting in higher fluid displacement and higher thrust speeds with less power input and / or requirements to achieve similar speeds compared with a convention impeller system.

[0067] Furthermore, with respect to a height and a depth of the spiral ridges 28a and the spiral channels 28b, these may be variable. For example, one of skill in the art may wish to increase the depth of the spiral channels 28b in certain applications and decrease it in others. Additionally, in some embodiments, the depth of the spiral channels 28b may be increased or decreased along a spiral path from the progressively tapered volume centre 42 to the discharge channel outer end region 32b (See Figure 7) of the discharge channels 32a near the peripheral region of the hub 14.

[0068] Turning now to Figure 11, with reference to the terminology of the increasing arced blade, a logarithmic spiral is graphically shown. The spiral ridges 28a are formed along, for example, with reference to Figure 11, line “Z>”. As one looks toward the peripheral region 44 of the spiral 46, as graphically shown in Figure 11, it can be noted that the spiral expands. Therefore, as the blades follow this profile, the arc or radius to the blades 18 increases towards the peripheral region 20 of the hub 14 (See Figure 7 with respect to the impeller 1 lb); hence arc to the blades can be defined as an increasing radius. For the purposes of reference, line “C” is provided so as to show schematic reference to the peripheral edge region 20 of the generally circularly shaped hub 14. Therefore, the logarithmic spiral path of the spiral ridges 28a is shown by line D over-laid and reference to the peripheral edge path of the generally circularly shaped hub 14 by line C.

[0069] During rotation of the impeller 1 lb in the open-ended tube 1 la in a fluid, the fluid 15 is drawn into the first end 13a of the open-ended tube I la into the impeller 11b towards the forwardly-facing progressively tapered volume centre 42. The spiral ridges 28a and the spiral channels 28b create a pre-whirl effect to the fluid. The fluid is drawn into the forwardly-facing progressively tapered volume centre 42, then travels along spiral channels 28b and then forwarded to the peripheral edge region 20 where is it ejected or discharged from the hub region via discharge channels 32a, and in cases where the open-ended tube 1 la is provided, along the interior wall of the open-ended tube 11b towards the second end 13b where it is expelled, thus creating thrust. At the peripheral edge regions, in some embodiments, the discharge channels 32a have a curved peripheral surface 32c, as shown in Figure 7.

[0070] Although it is contemplated by the inventor that the impeller 11b of the instant disclosure can be formed through joining several independent parts, for example attaching the blades 18 and the shaft 12b to the hub 14, in preferred embodiments, the blades 18 and / or the shaft 12b are integrally formed with the hub 14. In more preferred embodiments, the impeller 1 lb and the various components are formed of a monolithic structure. Furthermore, in some embodiments, a connecting ring 36 is provided for joining each blade or blade ends to the next near the distal end region 26b, as shown in Figures 7 and 9.

[0071] With regard to the clearance spacing 37, as shown for example in Figures 1, 6, to 8, between the distal end region 26b of the blades 18 and / or, in some embodiments, the connecting ring 36, and the interior wall of the open-ended tube I la such the impeller 1 lb is allowed to freely rotate within the open-ended tube I la, the spacing should be suitable to minimize turbulence, and / or fluid flow restriction such that the fluid discharging from the impeller 1 lb can be efficiently moved along the interior wall of the open-ended tube I la. Such spacing may be determined by one of skill in the art as may be required for given applications. Additionally, with regard to the open- ended tube I la, the length may be determined for a given application so as to provide a desired / required liquid movement efficiency as deemed appropriate for a given application, as shown schematically by the waved break lines of Figure 2 at “7”.EXAMPLESExample 1

[0072] Theoretical computer modelling was undertaken to compare the impeller disclosed herein with an impeller devoid of the forwardly-facing progressively tapered volume 16a forcreating a pre-whirl. In comparison the impeller 11b as disclosed herein showed approximately a 15% improvement in the volume of liquid moved per unit time with the same number of revolutions per minute in a test tank. Additionally, the impeller 11b as disclosed herein also showed approximately a 30% higher intake volume of liquid with the same number of revolutions per minute. Therefore, computer modelling predicts that the impeller 1 lb as disclosed herein would be able to produce almost twice the fluid speed in open water compared to an impeller devoid of the forwardly-facing progressively tapered volume 16a for creating pre-whirl, while being substantially quiet in the water and substantially devoid of cavitation. Furthermore, the computer modelling also predicts that by placing the impeller 1 lb as disclosed herein in an open-ended tube, an additional 30 to 40% improvement in thrust (i.e. fluid flow along arrows 15 of Figure 1, for example) may be observed in open water testing. Accordingly, it is believed by the inventor that fluid flow, and thus, thrust can be improved over conventional impeller systems with similar power input or, alternatively, less horsepower may be required to achieve similar thrust when the impeller and / or propulsion system as disclosed herein is utilizedExample 2

[0073] Figure 12 is a graph plotting the impeller speed (rpm) versus the volume discharge (mL / s), or the volume of fluid moved per revolution. In this test, the impeller of the instant disclosure (Bach) was compared to a conventional marine impeller (Marine) of the same size. The “D / T” ratio number of both the Bach impeller and Marine impeller was D / T = 0.44, where D = diameter of the impeller and T = the diameter of the testing tank. As can be seen in the graph of Figure 12, the Bach impeller moved more fluid per revolution that the Marine Impeller with the same D / T number per revolution. Furthermore, it should be noted that the slope of the trend line “E” for Bach impeller is greater than that of the slope of the trend “E” for the Marine Impeller, thus indicating that the Bach impeller is more efficient than the conventional marine impeller.Example 3

[0074] Figure 13 is a graph showing the Reynolds number versus the Power number comparing the fluid turbulence per unit power of the impeller of the instant disclosure (Bach impeller) at line “G” to that of a convention impeller (Marine impeller) at line “77”. The impellers compared where the same as the ones used in Example 2, above.

[0075] The relationship between the Reynolds number and the Power number is generally proportional. That being, as the power is increased, in general, the Reynolds number is increased, indicating a more turbulent flow. Therefore, in terms of efficiency related to the instant disclosure, a lower Reynold number indicates less turbulence. Accordingly, less turbulence in the fluid flow created around an impeller equates to increased efficiency.

[0076] In testing, as shown for example in the graph of Figure 13, the impeller of the instant disclosure showed that about 50% less power (0.36 for Bach impeller versus 0.23 for the conventional marine impeller) is needed to move the same volume of fluid per unit time. Accordingly, testing has shown that the impeller of instant disclosure is more efficient than that of a marine impeller. It has been contemplated by the inventor that the efficiency increase is due to instantly disclosed impeller creating a less turbulent fluid flow, resulting in an increase in the of fluid moved per unit of power.

[0077] It is to be understood that the above description it is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those skilled in the art, upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0078] Although the present invention has been described with reference to specific exemplary embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the disclosed subject matter as defined by the appended claims.

Claims

CLAIMSWhat is claimed is:1) A propulsion system comprising an open-ended tube and an impeller disposed therein, said open-ended tube having an inlet end and an outlet end; said impeller oriented along its rotational axis within said open-ended tube in line with a central axis of the open-ended tube; said open-ended tube configured to allow and direct movement of a fluid from the inlet end to the outlet end of said open-ended tube when said impeller is caused to rotate; said impeller comprising a generally circularly shaped hub including a forwardly-facing progressively tapered volume having coupled thereto a first end region of one or more arced blades arranged along a periodic pattern formed into said forwardly-facing progressively tapered volume wherein the number of periods corresponds to the number of blades; each of said one or more arced blades having an arc with and increasing radius to said arc towards a peripheral edge region of said hub; said proximal end region of said one or more increasing radius arced blades extending from said peripheral edge region of said hub along said forwardly-facing progressively tapered volume to a predetermined point inward of said forwardly-facing peripheral edge region; said one or more arced blades further being flared as extending from said forwardly-facing progressively tapered volume such that a distal end region of each of said one or more increasing radius arced blades, in combination, defines a larger circumference than that of said hub, thereby imparting a generally frusto-conical shape to the impeller; and said impeller having a shaft extending from a terminal centre region of the forwardly-facing progressively tapered volume for operably coupling to a rotatable drive.2) The propulsion system of claim 1, the impeller comprises at least two increasing radius arced blades.3) The propulsion system of either one of claim 1 or claim 2, wherein said periods formed into said forwardly-facing progressively tapered volume comprise a plurality of spiral helices which corresponds with the number of increasing radius arced blades.4) The propulsion system of claim 3, wherein said one or more increasing radius arced blades extending from said peripheral edge region of said hub along said forwardly-facing progressively tapered volume extend from ridges of said spiral helices.5) The propulsion system of claim 4, having channels formed intermittent said ridges following said spiral helices so as to form a path continuous with a sequence of distinct conical spiral segments between said one or more increasing radius arced blades.6) The propulsion system of claim 5, wherein said channels have a substantially semicircular profile.7) The propulsion system of either one of claim 5 or claim 6, said hub having a curved peripheral surface forming a discharge channel located at a peripheral terminus of said spiral helices adjacent each of the one or more arced blade proximal end region extending from said channels.8) The propulsion system of any one of claims 3 to 7, wherein said spiral helices of the forwardly-facing progressively tapered volume is a logarithmic spiral.9) The propulsion system of any one of claims 1 to 8, wherein said one or more increasing radius arced blades are integrally formed with said hub.10) The propulsion system of any one of claims 2 to 9, the impeller further comprising a ring coupled near the distal end regions of said one or more increasing radius arced blades for connecting said one or more radius arced blades.11) The propulsion system of claim 10, wherein said ring is integrally formed with said one or more increasing radius arced blades.12) The propulsion system of any one of claims 1 to 11, wherein said forwardly-facing progressively tapered volume has a compound logarithmic taper.13) The propulsion system of any one or claims 1 to 12, wherein the open-ended tube and the impeller are operably coupled so as to be rotatable in unison.14) A propulsion system comprising an open-ended tube and an impeller disposed therein, said open-ended tube having an inlet end and an outlet end; said impeller oriented along its rotational axis within said open-ended tube in line with a central axis of the open-ended tube; said open-ended tube configured to allow and direct movement of a fluid from the inlet end to the outlet end of said open-ended tube when said impeller is caused to rotate: said impeller comprising a generally circularly shaped hub including a forwardly-facing progressively tapered volume having coupled thereto toward a peripheral end region thereof one or more flaring arced blades arranged along a periodic pattern formed into said forwardly-facing progressively tapered volume to project generally forwards from said peripheral edge region and todefine a periodically flaring impeller radius along their length which allows for tangential fluid flow between adjacent blade ends; said impeller having a shaft extending from a terminal centre region of the forwardly-facing progressively tapered volume for operably coupling to a rotatable drive.15) The propulsion system of claim 14, the impeller comprising at least two flaring arced blades.16) The propulsion system of either one of claim 14 or claim 15, wherein said periods formed into said forwardly-facing progressively tapered volume comprises a plurality of spiraling grooves each flowing toward a corresponding one of said arced blades.17) The propulsion system of claim 16, wherein said spiraling grooves are defined by respective outer ridges and wherein each of said arced blades extends from a corresponding one of said outer ridges.18) The propulsion system of claim 17, wherein said spiraling grooves define helical channels that flow toward said adjacent blade ends.19) The propulsion system of claim 18, wherein said spiraling grooves have a substantially semicircular profile.20) The propulsion system of either one of claim 18 or claim 19, wherein said spiraling grooves discharge between said adjacent blade ends.21) The propulsion system of any one of claims 16 to 20, wherein said spiraling grooves are logarithmically spiraling grooves.22) The propulsion system of any one of claims 14 to 21, wherein said one or more flaring arced blades are integrally formed with said hub.23) The propulsion system of any one of claims 14 to 22, the impeller further comprising a ring coupled near the distal end region of said one or more flaring arced blades for connecting said one or more flaring arced blade ends.24) The propulsion system of claim 23, wherein said ring is integrally formed with said one or more flaring arced blades.25) The propulsion system of any one of claims 14 to 24, wherein said forwardly-facing progressively tapered volume has a compound logarithmic taper.26) The propulsion system of any one or claims 14 to 25, wherein the open-ended tube and the impeller are operably coupled so as to be rotatable in unison.27) A method for causing fluid movement fluid comprising: introducing into a fluid the propulsion system of any one of claims 1 to 26; andcausing at least the impeller to rotate.28) An impeller comprising a generally circularly shaped hub including a forwardly-facing progressively tapered volume having coupled thereto a first end region of one or more arced blades arranged along a periodic pattern formed into said forwardly-facing progressively tapered volume wherein the number of periods corresponds to the number of blades; each of said one or more arced blades having an arc with and increasing radius to said arc towards a peripheral edge region of said hub; said proximal end region of said one or more increasing radius arced blades extending from said peripheral edge region of said hub along said forwardly-facing progressively tapered volume to a predetermined point inward of said peripheral edge region; said one or more arced blades further being flared as extending from said forwardly-facing progressively tapered volume such that a distal end region of each of said one or more increasing radius arced blades, in combination, defines a larger circumference than that of said hub, thereby imparting a generally frusto-conical shape to the impeller; and said impeller having a shaft extending from a terminal centre region of the forwardly-facing progressively tapered volume for operably coupling to a rotatable drive.29) The impeller of claim 28, the impeller comprises at least two increasing radius arced blades.30) The impeller of either one of claim 28 or claim 29, wherein said periods formed into said forwardly-facing progressively tapered volume comprises a plurality of spiral helices which corresponds with the number of increasing radius arced blades.31) The impeller of claim 30, wherein said one or more increasing radius arced blades extending from said peripheral edge region of said hub along said forwardly-facing progressively tapered volume extend from ridges of said spiral helices.32) The impeller of claim 31, having channels formed intermittent said ridges following said spiral helices so as to form a path continuous with a sequence of distinct conical spiral segments between said one or more increasing radius arced blades.33) The impeller of claim 32, wherein said channels have a substantially semicircular profile.34) The impeller of either one of claim 32 or claim 33, said hub having a curved peripheral surface forming a discharge channel located at a peripheral terminus of said spiral helices adjacent each of the one or more arced blade proximal end region extending from said channels.35) The impeller of any one of claims 30 to 34, wherein said spiral helices of the forwardly- facing progressively tapered volume is a logarithmic spiral.36) The impeller of any one of claims 28 to 35, wherein said one or more increasing radius arced blades are integrally formed with said hub.37) The impeller of any one of claims 29 to 36, the impeller further comprising a ring coupled near the distal end regions of said one or more increasing radius arced blades for connecting said one or more radius arced blades.38) The impeller of claim 37, wherein said ring is integrally formed with said one or more increasing radius arced blades.39) The impeller of any one of claims 28 to 38, wherein said forwardly-facing progressively tapered volume has a compound logarithmic taper.40) An impeller comprising a generally circularly shaped hub including a forwardly-facing progressively tapered volume having coupled thereto toward a peripheral end region thereof one or more flaring arced blades arranged along a periodic pattern formed into said forwardly-facing progressively tapered volume to project generally forwards from said peripheral edge region and to define a periodically flaring impeller radius along their length which allows for tangential fluid flow between adjacent blade ends; and a shaft extending from a terminal centre region of the forwardly-facing progressively tapered volume for operably coupling to a rotatable drive.41) The impeller of claim 40, the impeller comprising at least two flaring arced blades.42) The impeller of either one of claim 40 or claim 41, wherein said periods formed into said forwardly-facing progressively tapered volume comprises a plurality of spiraling grooves each flowing toward a corresponding one of said arced blades.43) The impeller of claim 42, wherein said spiraling grooves are defined by respective outer ridges and wherein each of said arced blades extends from a corresponding one of said outer ridges.44) The impeller of claim 43, wherein said spiraling grooves define helical channels that flow toward said adjacent blade ends.45) The impeller of claim 44, wherein said spiraling grooves have a substantially semicircular profile.46) The impeller of either one of claim 44 or claim 45, wherein said spiraling grooves discharge between said adjacent blade ends.47) The impeller of any one of claims 42 to 46, wherein said spiraling grooves are logarithmically spiraling grooves.48) The impeller of any one of claims 40 to 47, wherein said one or more flaring arced blades are integrally formed with said hub.49) The impeller of any one of claims 40 to 48, the impeller further comprising a ring coupled near the distal end region of said one or more flaring arced blades for connecting said one or more flaring arced blade ends.50) The impeller of claim 49, wherein said ring is integrally formed with said one or more flaring arced blades.51) The impeller of any one of claims 40 to 49, wherein said forwardly-facing progressively tapered volume has a compound logarithmic taper.52) A method for causing fluid movement fluid comprising: introducing into a fluid the impeller of any one of claims 28 to 51; and causing at least the impeller to rotate.

Images