US20120027526A1

US20120027526A1 - Method and structure for reducing turbulence around and erosion of underwater structures

Info

Publication number: US20120027526A1
Application number: US13/194,697
Authority: US
Inventors: Marty A. Ferman
Original assignee: St Louis University
Priority date: 2010-07-29
Filing date: 2011-07-29
Publication date: 2012-02-02

Abstract

An underwater structure for supporting an above-water structure having an underwater portion immersed for some period of time underneath a water line of a body of water is provided. The underwater structure includes, but is not limited to, a turbulence reducing member connected with the underwater portion.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

The Present Application claims the benefit of priority from U.S. Provisional Patent Application No. 61/368,883 entitled “METHOD AND STRUCTURE FOR REDUCING TURBULENCE AROUND AND EROSION OF UNDERWATER STRUCTURES” and filed on 29 Jul. 2010, the contents of which are hereby incorporated by reference in their entirety to the extent permitted by law.

FIELD OF THE INVENTION

The present invention relates to methods and structures for reducing turbulence around and erosion of underwater structures. More specifically, it relates to methods and structures for reducing turbulence around and erosion of underwater structures and reducing scouring of ground supporting and surrounding the underwater structure.

BACKGROUND

Traditionally, many underwater structures use a cylindrical, square or rectangular design, which are generally not considered aerodynamic. As used herein, an underwater structure is a structure of which at least a portion is immersed for some period of time in a body of water, such as a stream, a river, a lake, or an ocean. At least a portion of the underwater structure is therefore for some period of time under a water line of a body of water. Underwater structures include support structures and abutments. Support structures are meant to include any type of structure that is used to hold up a building, a bridge section, or a walkout for fishing or sight-seeing, and include bridge piers and pillars. An abutment is generally the point where two structures or objects meet, such as an end support of a bridge.
Since underwater structures are generally not aerodynamically shaped, the flow of water, and other liquids which flow around an underwater structure, may become a violent flow, such as a vortical flow, a turbulent flow, and a cavitational flow occurring around the underwater structures. There are several types of vortical flows in fluids, some are well defined regular, essentially laminar, rotational flows, some are random, essentially turbulent, rotational flows, and some are a mixture of regular and random flows. Vortical flows can be characterized as being either shed vortices or bound vortices.
Shed Vortices are the vortices most commonly encountered on support structures such as piers and pylons and are not as damaging as bound vortices. Shed vortices are essentially those described by Kármán's vortex laws, in which a well regulated series of vortices are shed from a support structure in the water, for example. One can observe them at any support structure in the water, especially rivers where muddy water allows them to be seen easily. Generally the vortices switch from side to side in the water, but not always, as some simply are always shed from the same side, especially in rivers where the mud content seems to force them to always be on one side. Shed vortices also appear in air, for example on tall chimneys, electric towers, and on electric wires stretched between poles or towers. Sometimes the regular shedding causes a resonance in the towers, chimneys, wires, etc, which can lead to structural damage from large amplitude vibrations.
Bound vortices are the most likely vortical flows to cause damage. Bound vortices are especially damaging to support structures and abutments, since they tend to form at a junction between a body of water and a mud line of the body of water, such as a river bed. The constant vortical action of bound vortices causes soil at the mud line to be sucked away and eventually develops into a continuous pattern of soil removal, typically behind the support structure that results in a sizeable hole forming This action at the support structure's bottom is called scouring. The removal of soil at the junction weakens the support structure's support, hence weakening the above-water structure being supported. Bound vortices are initially formed at some critical speed of flow, and are initially well defined and almost laminar at least in the vicinity of the support structure. The bound vortices that trail away eventually breakdown into more turbulent flows. As the flow speed is increased above that where the bound vortex is initially formed, even vortices at the support structure starts to show some signs of breakdown or random behavior. Likewise the vortices that trail behind the support structure are increasingly more turbulent which increases the scouring action.
Cavitational flows are similar to stall conditions of air flowing over a wing in air, except that they occur in water. Here a nominal laminar flow separates from the surface of an object in water, such as a wing, a propeller, or even a dam surface. This separation is severe, as cavitational flows behave very violently, and generally are random. Dams suffer frequent damage as chunks of concrete may be ripped, out necessitating major repairs. One major wear factor of boat propellers is damage due to cavitational flows, or cavitation.
Turbulent flows may add additional stress on the sides of the underwater structure, which may lead to erosion, wear, and a weakening of the underwater structure, and eventually, may lead to a catastrophic failure of the underwater structure. The turbulent flow causes turbulent loading of the support structure which is directly transmitted to the above-water structure being supported.
Moreover, at the mud line of the body of water in which the underwater structure is anchored, the soil around the underwater structure may become scoured and eroded due to turbulence which may form around the underwater structure at the mud line. As a result, the scouring and erosion at the mud line of an underwater structure may lead to the eventual weakening of the underwater structure at the mud line since soil which is typically used to stabilize the underwater structure is displaced. Often times, to combat this scouring, large concrete blocks or rocks are dropped near the base of the underwater structure around the underwater structure, at the mud line. However, many times these large concrete blocks or rocks just result in an increase of the turbulence around the underwater structure and causes further scouring of the soil around the base of the underwater structure.
The scouring and erosion of soil, such as mud, sand, or rocks, at the base of the underwater structure may weaken the underwater structure, potentially leading to erosion of or even catastrophic failure of the underwater structure. In addition to turbulence, cavitation effects in the fluid flow may form around the underwater structure which may also cause erosion of or even catastrophic failure of the underwater structure, and contribute to scouring and erosion of soil around the underwater structure.
As a result of stress, wear, and ground erosion around underwater structures due to violent flows, such as turbulence, vortical flows, and cavitation effects formed around the underwater structures, maintenance costs associated with underwater structures is often increased. Additionally, safety inspections of underwater structures may also need to be increased. As a result, it would be desirable to develop and deploy designs for underwater structures that will reduce stress, wear, and ground erosion around underwater structures due to violent flows.

SUMMARY OF THE INVENTION

The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims.
In one aspect, an underwater structure for supporting an above-water structure having an underwater portion immersed for some period of time underneath a water line of a body of water is provided. The underwater structure includes, but is not limited to a turbulence reducing member connected with the underwater portion.
In one aspect, a turbulence reducing member connected with an underwater water structure for supporting an above-water structure having an underwater portion immersed for some period of time underneath a water line of a body of water is provided. The turbulence reducing member includes, but is not limited to, a fixed air foil, a vertical fence, a horizontal fence, a curved fillet, a straight fillet, an articulating air foil, or a fluttering air foil. The turbulence reducing member is aerodynamically shaped to break up or reduce the turbulence of a flow of water flowing around the underwater portion. The flow of water is flowing in a first direction towards the underwater structure.
In one aspect a method for reducing turbulence around and erosion of an underwater structure for supporting an above-water structure having an underwater portion immersed for some period of time underneath a water line of a body of water is provided. The method includes, but is not limited to, connecting a turbulence reducing member with the underwater portion. The turbulence reducing member is aerodynamically shaped to break up or reduce the turbulence of a flow of water flowing around the underwater portion. The flow of water is flowing in a first direction towards the underwater structure. The method further includes, but is not limited to, aligning the turbulence reducing member with the first direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

FIG. 1 depicts a perspective view of an underwater structure, in accordance with one embodiment of the present invention.

FIG. 2A depicts a perspective view of a turbulence reducing member surrounding an underwater structure, in accordance with one embodiment of the present invention.

FIG. 2B depicts a top cross sectional view taken along line A-A of the turbulence reducing member surrounding the underwater structure of FIG. 2A, in accordance with one embodiment of the present invention.

FIG. 3A depicts a side view of a movable turbulence reducing member surrounding an underwater structure, in accordance with one embodiment of the present invention.

FIG. 3B depicts a top cross sectional view taken along line B-B of the movable turbulence reducing member surrounding the underwater structure of FIG. 3A, in accordance with one embodiment of the present invention.

FIG. 4A depicts a side perspective view of a vertical fence used as a turbulence reducing member connected with an underwater structure, in accordance with one embodiment of the present invention.

FIG. 4B depicts a side view of a horizontal fence used as a turbulence reducing member connected with an underwater structure, in accordance with one embodiment of the present invention.

FIG. 5A depicts a side perspective view of a vertical fence used as a turbulence reducing member connected with an underwater structure with fillets, in accordance with one embodiment of the present invention.

FIG. 5B depicts a side perspective view of a turbulence reducing member connected with an underwater structure with curved fillets, in accordance with one embodiment of the present invention.

FIG. 5C depicts a side perspective view of a turbulence reducing member connected with an underwater structure with straight fillets, in accordance with one embodiment of the present invention.

FIG. 6A depicts a side perspective view of a vertical fillet used as a turbulence reducing member connected with an underwater structure, in accordance with one embodiment of the present invention.

FIG. 6B depicts a side perspective view of a vertical fillet and a horizontal fence used as turbulence reducing members connected with an underwater structure, in accordance with one embodiment of the present invention.

FIG. 7A depicts a side view of a fluttering movable turbulence reducing member surrounding an underwater structure, in accordance with one embodiment of the present invention.

FIG. 7B depicts a top cross sectional view taken along line C-C of the fluttering movable turbulence reducing member surrounding the underwater structure of FIG. 7A, in accordance with one embodiment of the present invention.

FIG. 7C depicts a schematic diagram of a power generating apparatus using a fluttering movable turbulence reducing member surrounding an underwater structure, in accordance with one embodiment of the present invention.

FIG. 8A depicts a perspective view of an underwater structure in which a vortex is generated, in accordance with one embodiment of the present invention.

FIG. 8B depicts a perspective view of a movable turbulence reducing member surrounding the underwater structure of FIG. 8A, in accordance with one embodiment of the present invention.

FIG. 8C depicts a perspective view of a movable turbulence reducing member surrounding the underwater structure of FIG. 8A and forming a muted vortex, in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION

Applicant has discovered that the use of aerodynamically shaped structures, called turbulence reducing members, connected with an underwater structure can reduce turbulent flow, reduce drag, and weaken some of the nominal shed vortices, around the underwater structure. The turbulence reducing members can be connected with the underwater structure at the time the underwater structure is formed, such as by pouring these new turbulence reducing members in concrete when the concrete for the underwater structure is initially poured. The turbulence reducing members may also be later added to an already existing underwater structure. Additionally, Applicant has discovered that movable turbulence reducing members connected with an underwater structure can also be used to reduce turbulent flow, reduce drag, and weaken some of the nominal shed vortices, around the underwater structure. Applicant has also discovered that movable turbulence reducing members may be used to generate energy.
Referring to FIG. 1, there is shown an underwater structure 100 connected with an above-water structure 110. Underwater structure 100 is a structure of which at least an underwater portion 108 of underwater structure 100 is immersed for some period of time underneath a water line 116 of a body of water 120, such as a stream, a river, a lake, or an ocean. Underwater structure 100 may be formed from a variety of rigid materials, such as concrete, wood, steel, and rock. Preferably, the underwater structure 100 is connected to an above-water structure 110, such as a bridge or walkway, for which the underwater structure 100 provides support. Preferably, another portion 109 of the underwater structure 100 is buried in soil 112 at the bottom of the body of water 120, beneath a mud line 114 of the body of water 120. Burying portion 109 beneath the mud line 114 and in the soil 112, provides additional support to the underwater structure 100.
The underwater structure 100 may have a cross sectional shape, when the cross section is taken along a direction generally parallel to the direction of flow 118, which is circular (as shown in FIG. 1), square, rectangular, or some combination of circular, square and rectangular, all of which are not very aerodynamic shapes. Flow 118 has a free stream velocity of fluid in the body of water 120 denoted as V. As a result, a turbulent flow 107, having a velocity V₁, is induced in and around portion 108 of the underwater structure 100 which is beneath the water line 116, above the mud line 114, and in the body of water 120.
Underwater structure 100 includes support structures 102 and abutments. Support structures 102 are any type of structure that is used to hold up and support any structure, such as a building, a roadway, a bridge section, or a walkout, and include bridge piers and pillars. An abutment is generally the point where two structures or objects meet, such as an end support of a bridge. In one embodiment, the underwater structure 100 is a support structure 102 with a circular cross sectional shape having a diameter (D). Preferably, the diameter (D) is from 0.15 to 7 meters, and more preferably, from 0.15 to 1.5 meters.
Referring to FIG. 2, in one embodiment a turbulence reducing member 130 is connected with underwater structure 100 in order to reduce the amount of turbulent flow 107 surrounding the portion 108 of underwater structure 100 beneath the water line 116. Preferably, the turbulence reducing member 130 is connected with or surrounds portion 108. Turbulence reducing member 130 may be formed from a variety of rigid materials, such as concrete, wood, steel, fiberglass, carbon fiber, and stone. The turbulence reducing member 130 is aerodynamically shaped to break up or reduce the turbulent flow 107 so that damage from the turbulent flow 107 to the soil 112 through scouring, or damage to the underwater structure 100, through erosion, wear, or rust, can be minimized or reduced. The turbulence reducing member 130 may any one of a variety of aerodynamic structures, such as an air foil 132, a vertical fence 134, a horizontal fence 135, a curved fillet 136, a straight fillet 137, or any combination of aerodynamic structures.
The turbulence reducing member 130 can be connected with the underwater structure 100 at the time the underwater structure 100 is formed, such as by pouring the turbulence reducing member 130 in concrete when the underwater structure 100 is poured initially. The turbulence reducing member 130 may also be later added to an already existing underwater structure 100 as a retrofit. If the turbulence reducing member 130 is added as a retrofit, it may be formed of steel wrapped in a non-corrosive skin such as fiberglass, carbon fiber, or rubber. In one embodiment, if added as a retrofit, turbulence reducing member 130 may be formed of primarily of carbon fiber or fiberglass alone, so as to reduce the weight of turbulence reducing member 130 and to prevent corrosion.
Referring to FIGS. 2A and 2B, in one embodiment, turbulence reducing member 130 is a fixed air foil 132 which surrounds portion 108 of underwater structure 100. Preferably, the fixed air foil 132 is aligned, along a line L₁-L₂, to be parallel to or within ±30 degrees, and more preferably within ±20 degrees, and most preferably within ±5 degrees of the direction of flow 118, as shown in FIG. 2B. Alignment of the air foil 132 is taken along a line L₁-L₂formed from a center point (L₁) of a head 133 of the air foil 132 to an end point (L₂) of a tail 138 of the air foil 132. Preferably, the direction of flow 118 is parallel to or within ±30 degrees, and preferably within ±20 degrees, of line L₁-L₂. The fixed air foil 132 would be connected with the underwater structure 100 so that an aerodynamic center (A.C.) is at or as close as possible to a center (C.) of the underwater structure 100, taken along a cross section A-A generally parallel to the direction of flow 118, as shown in FIG. 2B. By aligning the Aerodynamic Center (A.C.) at or near a center (C.) of the underwater structure 100, any moment effect from the air foil 132 onto the underwater structure 100 can be reduced. The moment effect may cause an undesirable twisting effect to occur onto the underwater structure 100.
Preferably, the air foil 132 has a depth (h) to chord (c) ratio, h/c, of at least 1/5. This makes for an air foil 132 with good lift and low drag in a subsonic flow. More preferably, the depth (h) to chord (c) ratio is at least 2/5, which would reduce the chord length and hence the volume of the air foil 132, thus reducing the amount of material used in forming the air foil 132, reducing costs as well. Alternative shapes for the air foil 132 may also be used, such as a more fully rounded shape, for example, as used on “Wheels Pants” of light aircraft to reduce turbulence from wheels of fixed landing gears.
Referring to FIGS. 3A and 3B, in one embodiment, the turbulence reducing member 130 is a movable turbulence reducing member 140 such as an articulating air foil 141 which surrounds portion 108 of underwater structure 100. Movable turbulence reducing member 140 is movably connected with underwater structure 100, and specifically portion 108 of underwater structure 100. By using a movable turbulence reducing member 140, the movable turbulence reducing member 140 can better align with a changing direction of flow 118, in order to better minimize or reduce turbulent flow 107 around underwater structure 100.
Referring to FIGS. 3A and 3B, in one embodiment, the movable turbulence reducing member 140 is an articulating air foil 141 which is movably connected with underwater structure 100 through bearings 142. The articulating air foil 141 is preferably connected with the underwater structure 100 so that an aerodynamic center (A.C.) is behind a center (C.) of the underwater structure 100, taken along a cross section B-B generally parallel to the direction of flow 118, as shown in FIG. 3B. By aligning the Aerodynamic Center (A.C.) behind a center (C.) of the underwater structure 100, any moment effect from the articulating air foil 141 onto the underwater structure 100 can be used to allow the articulating air foil 141 to weather vane when on-coming flows change their angle relative to the nominal flow (V) 118. The articulating airfoil 141 is self-aligning and designed to weather-vane, i.e., always turning into the oncoming direction of flow 118, as do Weather Cocks on farm buildings. Referring to FIG. 3B, preferably, the articulating air foil 141 is able to weather vane and move an angle ±θ of ±180° around underwater structure 100.
By using a turbulence reducing member 130, 140, the turbulent flow 107 around underwater structure 100 can be better controlled and often reduced. The shape of the turbulence reducing member 130, 140 will cause the flow 107 to move past the underwater structure 100 without generating as much turbulence as would the shape of the underwater structure 100 without the turbulence reducing member 130, 140. If turbulence around the underwater structure 100 is reduced, scouring or erosion of the mud, sand and small rocks at the mud line 114 and under the water line 116, may be reduced. Reducing turbulence around the underwater structure 100 also reduces the erosion of the underwater structure 100, and reduces the forces from water and other liquids in the body of water 120 on the underwater structure 100, and hence the above-water structure 110.
Turbulence reducing members 130, 140 may be connected with any underwater structure 100, including support structures 102 and abutments. For abutments, a similar approach as described herein would be considered to try to control the flow 107 past the abutment to reduce turbulence. In one embodiment, a vortex generator is used as a turbulence reducing member 130, 140 and connected with an abutment. The vortex generator is a device used to cause low level vortices to be generated that dissipate the overall turbulence in flow 107.
Referring to FIG. 4A, in one embodiment, turbulence reducing member 130 comprises a vertical fence 134 connected with a front side of underwater structure 100. The vertical fence 134 is a partial disc-shaped member whose length (L) is generally greater than longer than its thickness (t). Preferably, the vertical fence 134 has a curved leading edge 143 facing into the direction of flow 118, as shown in FIG. 4A. This curved leading edge 143 helps to break up the flow 107 and reduce turbulence. In one embodiment, a vertical fence 134′ may be positioned on a backside of underwater structure 100. Preferably, the vertical fence 134′ has a curved leading edge 143′ facing away from the direction of flow 118, as shown in FIG. 4A.
Referring to FIG. 4B, in one embodiment, turbulence reducing member 130 comprises a horizontal fence 135 connected with, and preferably around, a front side of underwater structure 100. The horizontal fence 135 is a partial or fully disc-shaped member whose length (L) is generally greater than longer than its thickness (t). Preferably, the horizontal fence 134 has a curved leading edge 144 facing into the direction of flow 118, as shown in FIG. 4A. This curved leading edge 144 helps to break up the flow 107 and reduce turbulence. In one embodiment, a horizontal fence 135′ may be positioned on, and preferably around, a backside of underwater structure 100. Preferably, the horizontal fence 135′ has a curved leading edge 144′ facing away from the direction of flow 118, as shown in FIG. 4B.
Referring to FIG. 5A, in one embodiment, turbulence reducing member 130 comprises a vertical fence 134 and curved fillets 136 connected with underwater structure 100. The curved fillets 136 have a curved leading edge 145 facing into the direction of flow 118. The curved fillets 136 are connected with both the vertical fence 134 and the underwater structure 100 in order to further reduce the amount of turbulence in the flow 107. Preferably, the curved fillets 136 are vertically oriented, as shown in FIG. 5A, having a first edge 186 connected with the underwater structure 100 and a second edge 187 connected with the vertical fence 134. In one embodiment, curved fillets 136′ may be positioned on the backside of underwater structure 100, facing away from the direction of flow 118, as shown in FIG. 5A.
Referring to FIG. 5B, in one embodiment, turbulence reducing member 130 comprises air foil 132 and curved fillets 136 connected with underwater structure 100. The curved fillets 136 have a curved leading edge 145 facing into the direction of flow 118. The curved fillets 136 are connected with both the air foil 132 and the underwater structure 100 in order to further reduce the amount of turbulence in the flow 107. Preferably, the curved fillets 136 are vertically oriented, as shown in FIG. 5B, having a first edge 186 connected with the underwater structure 100 and a second edge 187 connected with the air foil 132. In one embodiment, curved fillets 136′ may be positioned on the backside of underwater structure 100, facing away from the direction of flow 118, as shown in FIG. 5B.
Referring to FIG. 5C, in one embodiment, turbulence reducing member 130 comprises air foil 132 and straight fillets 137 connected with underwater structure 100. The straight fillets 137 have a straight leading edge 146 facing into the direction of flow 118. The straight fillets 137 are connected with both the air foil 132 and the underwater structure 100 in order to further reduce the amount of turbulence in the flow 107. Preferably, the straight fillets 137 are vertically oriented, as shown in FIG. 5C, having a first edge 188 connected with the underwater structure 100 and a second edge 189 connected with the air foil 132. In one embodiment, straight fillets 137′ may be positioned on the backside of underwater structure 100, facing away from the direction of flow 118, as shown in FIG. 5C.
Referring to FIG. 6A, in one embodiment, turbulence reducing member 130 comprises vertically oriented curved fillets 139 connected with underwater structure 100. The curved fillets 136 have a curved leading edge 147 facing into the direction of flow 118. The curved fillets 139 are connected with the underwater structure 100 in order to further reduce the amount of turbulence in the flow 107. Preferably, a portion of the curved fillets 139 touches or is embedded in the soil 112 below the mud line 114. The curved fillets 139 are vertically oriented, as shown in FIG. 6A, having a first edge 190 connected with the underwater structure 100 and a second edge 191 embedded below in or facing the mud line 114. In one embodiment, curved fillets 139′ may be positioned on the backside of underwater structure 100, facing away from the direction of flow 118, as shown in FIG. 6A.
Referring to FIG. 6B, in one embodiment, turbulence reducing member 130 comprises a vertically oriented curved fillet 139 and a vertical fence or a horizontal fence 135 connected with underwater structure 100. The curved fillet 139 has a curved leading edge 147 facing into the direction of flow 118. The curved fillet 139 is combined with horizontal fence 135, both connected with the underwater structure 100, in order to further reduce the amount of turbulence in the flow 107. Preferably, a portion of the curved fillet 139 touches or is embedded in the soil 112 below the mud line 114. The curved fillet 139 is vertically oriented, as shown in FIG. 6A, having a first edge 190 connected with the underwater structure 100 and a second edge 191 embedded below in or facing the mud line 114. In one embodiment, curved fillets 139′ may be positioned on the backside of underwater structure 100, facing away from the direction of flow 118, as shown in FIG. 6A. In one embodiment a second curved fillet 136 is connected with curved fillet 139 and fence 135, as shown in FIG. 6B to further reduce turbulence.
Referring to FIGS. 7A and 7B, in one embodiment, movable turbulence reducing member 140 is a fluttering air foil 150 which surrounds portion 108 of underwater structure 100. The fluttering air foil 150 includes a flap 154 which is connected to a main airfoil body 151 via a hinge 156. The addition of the flap 154 would allow for relocation of the fore-aft position of the fluttering air foil 150 to enhance a stronger flutter at lower speeds of flow (V) 118. Also, the flap 154 would act as a weathervane effect to control, or actually eliminate, divergence. Preferably, fluttering air foil 150 is movably connected with underwater structure 100, and specifically portion 108 of underwater structure 100. By using fluttering air foil 150, the movable turbulence reducing member 140 can better align with a changing direction of flow 118, in order to better minimize or reduce turbulent flow 107 around underwater structure 100.
Preferably, the fluttering air foil 150 is movably connected with underwater structure 100 through bearings 142. Preferably, the fluttering air foil 150 is connected with the underwater structure 100 so that an aerodynamic center (A.C.) is behind a center (C.) of the underwater structure 100, taken along a cross section C-C generally parallel to the direction of flow 118, as shown in FIG. 7B. By aligning the Aerodynamic Center (A.C.) behind a center (C.) of the underwater structure 100, any moment effect from the fluttering air foil 150 onto the underwater structure 100 can be used to allow the fluttering air foil 150 to weather vane and flutter when on-coming flows change their angle relative to the nominal flow (V) 118. The fluttering air foil 150 is designed to weather-vane, i.e., always turning into the oncoming direction of flow 118, quicker than the articulating air foil 132 without a flap 154.
Additionally, since the fluttering air foil 150 moves more than a typical articulating air foil 141, the fluttering air foil 150 can be used to generate power. Referring to FIG. 7C, a power generating apparatus 148 is provided which includes a fluttering air foil 150 connected with a generator 160 for generating electricity. The generator 160 is in turn connected with an energy receiving apparatus 162, such as lights. The lights could serve to illuminate the underwater structure 100 or an above-water structure 110. A feedback and control mechanism 164 is connected with the energy receiving apparatus 162, the generator 160, and the fluttering airfoil 150, so as to provide feedback and better direct the fluttering air foil 150. Electrical power generation can be made with oscillating airfoils in air or water. More control and mitigation of the turbulent flow is accomplished via controls 164. Flutter from the air foil 150 and flap 154 absorbs energy from the flow 107, thus weakening any shed vortices. Modulation of the absorbed energy from the flow 107 could be used to control any shed vortices.
Referring to FIGS. 8A, 8B, and 8C, in one embodiment, movable turbulence reducing member 140 is an energy wheel 170 which surrounds portion 108 of underwater structure 100. Energy wheel 170 may be a propeller 170 or turbine. Preferably, energy wheel 170 is movably connected with underwater structure 100 through bearings 174. Individual blades 171 of energy wheel 170 are caused to rotate around the underwater structure 100 as a result of flow 107. Preferably, a debris deflector 172, such as a series of bars, is provided around the energy wheel 170 or between the energy wheel 170 and the direction of flow 118, as shown in FIG. 8B. The debris deflector 172 prevents debris such as rocks and soil from damaging or eroding the underwater structure 100. As shown in FIG. 8C, the direction of flow 107 as it approaches and enters energy wheel 170 is then altered as the flow 107 exists energy wheel 170, reducing turbulence in the flow 107 and damage to underwater structure 100. Additionally, the energy wheel 170 could be used to generate energy, in a similar manner as discussed above for the fluttering air foil 150.
Referring to FIG. 8C, free stream velocity of fluid in the body of water 120 is denoted as V while velocity induced from the propeller is denoted as V_Pand causes a mixed flow to occur where the free stream is deflected upward or downward accordingly. This flow change will reduce the strength of vortex 182 at the mud line 114 surrounding underwater structure 100 through proper design, and reduce any damaging effect of those vortices cause by flow 107. Preferably, as many as three debris deflectors 172 may be used, orientated at zero degrees from the direction of flow 118, and at 60 degrees on either side of the underwater structure 100.
The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.
While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that other embodiments and implementations are possible within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.

Claims

1. An underwater structure for supporting an above-water structure having an underwater portion immersed for some period of time underneath a water line of a body of water, comprising a turbulence reducing member connected with the underwater portion.

2. The underwater structure of claim 1, wherein the turbulence reducing member is an air foil, a vertical fence, a horizontal fence, a curved fillet, a straight fillet, an articulating air foil, or a fluttering air foil.

3. The underwater structure of claim 1, wherein the turbulence reducing member is a movable turbulence reducing member.

4. The underwater structure of claim 3, wherein the movable turbulence reducing member is capable of rotating to generate energy.

5. The underwater structure of claim 3, wherein the movable turbulence reducing member is an articulating air foil which surrounds the underwater portion of the underwater structure.

6. The underwater structure of claim 1, wherein the underwater structure is an abutment.

7. A turbulence reducing member connected with an underwater water structure for supporting an above-water structure having an underwater portion immersed for some period of time underneath a water line of a body of water, the turbulence reducing member comprising:

a fixed air foil, a vertical fence, a horizontal fence, a curved fillet, a straight fillet, an articulating air foil, or a fluttering air foil, wherein the turbulence reducing member is aerodynamically shaped to break up or reduce the turbulence of a flow of water flowing around the underwater portion, and wherein the flow of water is flowing in a first direction towards the underwater structure.

8. The turbulence reducing member of claim 8, wherein the turbulence reducing member is aligned parallel to or within ±30 degrees, the first direction.

9. The turbulence reducing member of claim 8, wherein the turbulence reducing member includes a fixed air foil with a depth (h) to chord (c) ratio, h/c, of at least 1/5.

10. The turbulence reducing member of claim 8, wherein the turbulence reducing member is a movable turbulence reducing member.

11. The turbulence reducing member of claim 10, wherein the movable turbulence reducing member is capable of rotating to generate energy.

12. The turbulence reducing member of claim 10, wherein the movable turbulence reducing member is an articulating air foil which surrounds the underwater portion of the underwater structure.

13. A method for reducing turbulence around and erosion of an underwater structure for supporting an above-water structure having an underwater portion immersed for some period of time underneath a water line of a body of water, comprising

connecting a turbulence reducing member with the underwater portion, wherein the turbulence reducing member is aerodynamically shaped to break up or reduce the turbulence of a flow of water flowing around the underwater portion, and wherein the flow of water is flowing in a first direction towards the underwater structure; and

aligning the turbulence reducing member with the first direction.

14. The method of claim 13, wherein the turbulence reducing member is an air flow having a head opposed to a tail, and the aligning of the turbulence reducing member further comprises aligning the turbulence reducing member, along a line from the a center point (L₁) of a head of the air foil to an end point (L₂) of a tail of the air foil, to be parallel to or within ±30 degrees of, the first direction.

15. The method of claim 14, wherein the air foil is a fixed air foil, an articulating air foil, or a fluttering air foil.

16. The method of claim 13, wherein the turbulence reducing member is a vertical fence or a horizontal fence.

17. The method of claim 13, further comprising connecting a first edge of a curved fillet with the underwater structure and a second edge of the curved fillet with the turbulence reducing member.

18. The method of claim 13, wherein the turbulence reducing member includes a fixed air foil with a depth (h) to chord (c) ratio, h/c, of at least 1/5.

19. The method of claim 13, wherein the turbulence reducing member is a movable turbulence reducing member.

20. The method of claim 13, further comprising generating electricity with the movable turbulence reducing member.