GB2292775A

GB2292775A - Redirecting fluid flow

Info

Publication number: GB2292775A
Application number: GB9517342A
Authority: GB
Inventors: Kenneth Herbert Haywood; Paul Christopher Haywood; Mark David Haywood; Kim Stephen Haywood
Original assignee: ZETA DYNAMICS Ltd
Current assignee: ZETA DYNAMICS Ltd
Priority date: 1994-09-01
Filing date: 1995-08-24
Publication date: 1996-03-06
Anticipated expiration: 2015-08-24
Also published as: GB9517342D0; GB2292775B

Abstract

A fluid flow device for redirecting and enhancing fluid flow has a plurality of parallel vanes or baffles 1 arranged to form parallel inlets between adjacent vanes or baffles. Each vane or baffle has an upstream planar portion 7 and a downstream planar portion 8 which is at an angle to 125 DEG to 155 DEG to the upstream portion. The width of the inlets is of a similar magnitude to the thickness of the intervening baffle or vane. The fluid flow device causes the incident fluid flow to be deflected by a larger amount than would be expected and causes the flow through each inlet to be cascaded into a unitary flow downstream of the vanes, the velocity and mass flow increasing along the array of vanes. The device may be used in a wide number of applications such as power generation, ventilation of buildings, flares, heat exchange, oil separation, chimneys, fences, wind and sea defence structures and reducing fluid drag resistance on a moving body. <IMAGE>

Description

FLUID FLOW DEVICE The present invention relates to a fluid flow device for redirecting fluid flow. In particular, the device may be used to redirect fluid flow such as gas, air or liquid flow.

It is known that vanes are used extensively for redirecting fluid flow in many engineering applications. For example, a vane may have its leading edge facing into a gas or air stream and it orients with the flow such that the gas or air stream will follow the surface of the vane. The changing profile of the vane directs the flow to the downstream or trailing edge of the vane where the subsequent flow direction is dictated by the surface characteristics of the trailing edge. Also, another example of a vane or baffle is a plate in which fluid flow impinges at an angle to its surface and is diverted according to the angle of the surface to the fluid flow.

The present invention relates to an improved fluid flow device having a configuration which allows redirection and enhancement of an incident fluid flow.

Thus according to the present invention there is provided a fluid flow device comprising a plurality of vanes or baffles, the vanes being arranged substantially parallel to each other so as to form substantially parallel inlets between each vane or baffle characterised in that each vane or baffle has an upstream and a downstream planar portion, the upstream planar portion being at an angle of 1250 to 1550, most preferably 1350 to 1450 to the downstream portion.

It is preferred that the upstream and downstream planar portions are arranged to form a sharp discontinuous edge where they join. The upstream and downstream portions may be formed as an integral single piece of material or may be discrete portions physically joined along the abutting edge.

The width of the inlets is desirably of the same magnitude as the thickness of the intervening baffle or vane.

It is also preferred that all the vanes have their upstream planar portions oriented in substantially the same plane.

In conventional vane or baffle arrays, the vane or baffles act to deflect or direct an incident fluid flow into a desired direction, each individual vane flow being parallel to its neighbour.

The fluid flow device according to the present invention surprisingly causes the incident fluid flow to be deflected by a larger amount than would be expected and also causes the flow through each inlet to be cascaded into a unitary flow downstream of the vanes, the velocity and mass flow increasing along the array of vanes.

The invention will now be described by way of example only and with reference to figures 1 to 12 of the accompanying drawings Figure l(a) and l(b) are diagrammatic views of conventional flow devices using vane arrays showing emergent parallel flows from each vane.

Figure 2(a) shows a diagrammatic view of a single vane for use in the invention and figure 2(b) shows the flow paths for a fluid flow device using an arrangement having four such vanes.

Figures 3(a) to (c) are schematic diagrams showing the effect on incident fluid flow on the fluid flow device positioned in different attitudes to the fluid flow.

Figures 4(a) to (d) are schematic diagrams of fluid flow devices for converting natural wind flow into useful energy.

Figures 5(a) and (b) are schematic diagrams of fluid flow devices used for power generation using water current or tides.

Figures 6(a) and (b) are schematic diagrams of fluid flow devices used for the ventilation of buildings.

Figures 7(a) and (b) are schematic diagrams of fluid flow device used as part of a sea defence structure or for wind protection.

Figure 8 is a schematic diagram of an oil separator using a fluid flow device.

Figures 9(a) and (b) are schematic diagrams of fluid flow devices used as an air deflector for a gas flare and forming part of a pipe flare.

Figures 10(a) and (b) are schematic diagrams of fluid flow devices forming part of a ground flare stack and as a wind fence for a flare stack Figure 11(a) and (b) are schematic diagrams of fluid flow devices for protecting a domestic chimney pot.

Figure 12 is a schematic diagram of a fluid flow device for reducing flow resistance of a land, sea or air vehicle Figures 1(a) and (b) demonstrate conventional vanes 1 with a fluid flow 2 entering into the leading edge and leaving the trailing edge in the direction 3 as dictated by the plane of the trailing edge.

Contrary to conventional vanes and baffles where the function is to baffle or direct in accordance with the requirement of the trailing edge angle, the present invention uses a fluid flow device comprising a plurality of vanes to redirect an incident fluid flow and to create a unitary enhanced flow. The fluid flow device provides a flow that contrary to the trailing edge angle actually turns a further 40 degrees from an assumed nominal trailing edge angle of 140 degrees between upstream and downstream planar portion and, enables the flow to cascade behind, and parallel to, the line of vanes, increasing its velocity and mass flow as it passes each vane. This enhanced flow may be channeled into a handleable form where its energy may be converted into a number of useful applications.The fluid flow device function is the conversion of an incoming fluid flow, its control and the cascading of the mass flow both parallel to and down its rear face. In addition the fluid flow device has useful kinetic energy and pressure force balancing characteristics; particularly when it is leaning into the flow. The force of the incoming flow can be balanced by the resultant forces created by the processing and redirecting of the energies. The force on the fluid flow device due to the incoming flow can be considerable reduced and when the fluid flow device is in a flow, freely pivoted at its base, the structure may be moved to a leaning forward attitude and stand in a balanced position, without any further retaining support whatever.The harnessing of these energies may, as desired, result in either their destruction or their diversion for a defined use, as outlined in the examples in this document. The fluid flow device uses its fluidic control characteristics to achieve its objective. Unlike the normal function of a pack of vanes, when the flow from each vane, if similarly designed, follows a path parallel to that of the other vanes' downstream direction, the flow from each vane of the fluid flow device cascades into the flow from the adjacent vane following the path parallel to the fluid flow device.

Fig 2(a) shows the shape of an individual vane 1 having upstream and downstream planar portions in the form oftwo straight, flat sided plates 7,8 joined at a nominal angle of 140".

Characteristics of the invention may be observed up to an angle of 155 and down to an angle of 1250. The fluidic operation that provides the fluid flow device's qualities reduces in performance as the angle deviates from the nominal angle. The radius joining the sides should be tight and sharp and not of a gentle curve, for higher efficiency. One portion of the vane forms a bluff surface 7 which faces the incident flow, and the other side forms the trailing edge 8. The nominal setting of the vane's attitude within the fluid flow device is that the bluff surfaces are set in-line and the gap between each vane, measured at the bluff surface is equal to the width of the bluff surface. To alter the characteristics of the quantity of flow, the gap between the vanes may be varied from the nominal width equal to that of the bluff surface.

Under this condition the vortex weakens and the flow down the rear of the fluid flow device is not so positive in its direction although the flow is generally greater. The end of the trailing edge of the vane must line up, approximately, with the next vane, at the edge of the bluff surface.

Without wishing to be bound by any theory, the principle of operation of the fluid flow device may be explained as follows. The vanes 1 are fitted in a parallel array with the bluff surface 7 facing an incoming fluid 2. As the fluid 2 enters the gaps between the vanes, a vortex 4 is created within the confines of the vane sides 7 and 8. The rotating, high velocity fluid, of the vortex, within each vane, creates energy changes of pressure and kinetic rotation which pulls the passing fluid around it and thus to the maximum radial distance possible, which is parallel to the plane of the fluid flow device. The effect is as though the vanes' inclusive angle of a nominal 140 degrees behaves as if it were 180 degrees. The fluid flow 3 runs down the rear of the fluid flow device, cascading as it goes, and increasing in~velocity and mass flow.When the incident fluid flow 2 is at an angle other than perpendicular, the device functions in a similar way with similar performance. The secondary flow is directed down the back of and parallel to, the fluid flow device's plane to a utilisation region.

Figs 3(a), 3(b) and 3(c) show the fluid flow device 1 in different attitudes or orientations. Fig 3(a) is in the vertical plane, although it also shows the plan view of when the fluid flow device is in the sideways attitude; Fig 3(b) is at an angle of 45 , facing away from the incoming primary flow; and Fig 3(c) is at the same angle but facing towards the incoming primary flow 2. The resultant flow becomes a stream of fluid 3 that is directed to the end of the fluid flow device 1. Any orientation of the above fluid flow device structure may be used to send the flow 3 upwards, downwards, sideways, horizontal or angled. A backplate is not necessary for enclosing and channeling the fluid behind the vanes but may be fitted should there be a requirement. The space may be totally open as the stream of fluid is fluidically controlled. On reaching the base, the flow may be redirected and channeled as required, providing a stream of fluid which may be used for various applications..

The function of the fluid flow device has a wide range of applications, which includes conversion of energy, control of random energy forces, and directing or controlling a fluid flow for its individual qualities or processing; using either a natural or created fluid flow.

Examples of applications to demonstrate the operation of the fluid flow device follow in Figs 4 to 13.

The fluid flow device may be used to convert natural wind into generated power. Fig 4(a) shows a diagrammatic form of a 'static windmill'. The wind 2 is converted into the stream of air 3 that covers the whole of the reverse down-wind side of the fluid flow device 1. This is then channeled into a flow stream 4 through a collector 5 and into an electricity generatorturbine (or other forms of energy conversion) 6 and out through an outlet 7. Fig 4(b) shows a version in the form of a barrier where, similarly to Fig 4(a), the wind 2 impinges on the face of the fluid flow device 1 and is converted to a velocity flow 3 down the reverse side and is collected and redirected as a flow 4 at the base and into an electricity generator 6 and through an outlet 7. Fig 4(c) shows the function of the fluid flow device in single and double sided forms.The double sided version operates with a wind from either side of the structure. The angle of the fluid flow device structures may be other than that at the vertical and 45" is generally a suitable figure for an angled version. Likewise the whole structure may be turned through 90" whereby the vanes would be vertical rather than horizontal, thus directing the flow sideways instead of downwards The fluid flow device is not sensitive to the wind's gusting nor does the wind need to flow perpendicular to the plane of the fluid flow device. The shape of the wind collecting structure is not restricted to that of the example shown as may be seen in 4(d) below. Similarly, the single sided fluid flow device structure of Fig 4(a) could be rotatable to face the wind direction.

Fig 4(d) shows in outline a design of power generator that could be used in an isolated or remote area and it could be both small and portable. The fluid flow device structure may be in various forms such as, for example, a cube or a pyramid, as shown. In each case the fluid flow device 1 directs the wind 2 such that the rear, controlled flow 3 is channeled into the tube 8 through a collector 5 as a high velocity flow 4 and into an electrical generator 6. It is feasible that with the above structures, figure 4(d) being an example, electricity generating solar cells could be integrated into the vane structure to increase the flexibility of the unit and make it more able to take advantage of nature's power supply.

Fig 5 provides an outline of power generation for use in the current of a river or tidal movement in the sea. Fig 5(a) shows both angled and vertical versions of a single fluid flow device. The water current 2 enters the fluid flow device and the flow is redirected into a narrow stream of flow 3 to the collector 5 for onward feed to a power converter. Fig 5(b) shows a double sided version for use with tidal currents. The plane may be turned through 900 so that the flow 3 moves sideways, which could be useful in rivers.

Fig 6 shows how the fluid flow device may be used in ventilation systems. By having an air intake in the form of a fluid flow device 1 the mass of entering air may be converted to a compact, high velocity flow of fresh air into ducting for ventilating the building. The diagram, Fig 6(a), shows the fluid flow device inlet 1 fitted into a wall 6 of a building 7 with the wind 2 entering the inlet 1. The parallel flow 3 is channeled as a mass flow 4 into ducting 5 and distributed as required. This forms a natural draught ventilating system. Fig 6(b) shows a pyramid structure fluid flow device version fitted on a roof 6. The wind 2 impinges on the fluid flow device and the flow 3 is collected at 5 and directed into the duct 8 and into the ventilation system of the building 7.One important variation on this design is that by reversing the direction of the vanes on the fluid flow device 1 the flow 3 is directed upwards and the structure will become an extractor of stale air from the building through the top of the structure 9.

Fig 7 presents the use of the fluid flow device in respect of the control of a random moving fluid that may require a form of energy destruction, damping, controlling, or redirecting. An example of this in water is in respect of coastal protection and in the air examples of use are for the protection of structures, transport, the environment, and life, against the elements particularly the wind.

The fluid flow device has the advantage of not holding back sea water because it is an open barrier and yet it will redirect the mass flow in a more controllable manner as described above.

Depending on its orientation, any random mass flow that hits the vane assembly could be redirected in a safe direction, sideways, upwards and even in the direction from where it came.

Fig 7(a) shows an example of the use of a fluid flow device in a sea defence structure. The force of the sea 2 enters the fluid flow device 1 and is directed parallel to the fluid flow device 1 in the flow direction 3. Depending upon the variability of the random forces involved, the flow 3 will be thrown at various distances 4 in front of the assembly, thus helping to oppose the primary force of the sea. Alternatively, as stated, it could be directed either to the left or right, parallel to the protection area by turning the fluid flow device sideways, through 90 degrees. With the fluid flow device fitted sideways in water i.e. at 90" to the example shown, it could , for example, be used for protecting a river bank or for the control of flood water forces.

Fig 7(b) shows an example of the use of a fluid flow device in a wind protection structure in which wind is diverted from the entrance to a tunnel. The wind 2 is deflected by the fluid flow device 1 away from the entrance of the tunnel 5 with the deflected wind 3 being thrown upwards. The force of the deflected wind 3 will also influence the wind that is higher than the fluid flow device.

The fluid flow device may be used similarly in many situations from simple applications such as a fence for domestic purposes to highly complex applications in environmental protection situations.

In respect of Fig 8, the fluid control and manipulation that the fluid flow device provides has applications within the petroleum industry and other processing operations. In oil separation the control of the processing that the fluid flow device provides is very effective. For example, in a production oil separator the liquid liquid and liquid/gas separation may be controlled through the fluid flow device: in the liquid by improving the velocity profile in the liquid channel to ensure a maximum retention time, and destroy turbulence within it; and in the gas phase the fluid flow device is able to help control foam and remove liquid particles. In the case of a floating platform or boat, the rhythmic movement of the liquid can be controlled by the fluid flow device. The overall result is to enhance performance. Fig 8 shows an outline of an oil separator, as may be used on an oil production platform at sea. The large cylindrical pressure vessel contains a series of internal fittings, such as inlet, coalescers, baffles and weir, with the purpose of enabling the entering crude oil to be separated from contained water, gas and any solids. In the diagram the flow enters at the inlet 5. Internal components are represented by baffles 12, coalescer 11, demister 13, weir 14, oil outlet 6, water outlet 8, gas outlet 7, and a fluid flow device 1 is fitted in the liquid phase 10 and another fluid flow device 15 is fitted in the gas stream 16.In the liquid phase the fluid flow device 1 will take the flow 2 which will represent the inlet flow in the form that may be either within the considered inlet assembly or having left it and being in the inlet zone depending upon the design that integrates the fluid flow device as desired. In the form shown the fluid flow device 1 is at the downstream edge of the inlet zone. The flow 2 which is three phase, enters the fluid flow device 1 and is converted into flow 3 at 90 degrees, and directed upwards, to the line of the entering flow. This action activates separation and controls the liquid flow 10 into both calmness and an even velocity profile and ultimate improvement in efficiency. In the case of the fluid flow device 15 the gas flow 16 enters the structure and is directed downwards at 90 degrees to a plate 16 that acts as a wetting plate and redirector.In so doing liquid particles separate out of the gas stream and foaming is arrested. Alternatively, in applications such as the above the flow 3 may be directed as desired.

Fig 9 (a) shows the fluid flow device in the form of an air deflector for use on a gas flare 8 in that when the prevailing wind 2 approaches the stack 5 the wind 2 is then re-directed upwards by the fluid flow device 1 as stream 3 to support the air supply to the flare flame 6. In general, the prevailing wind blows the burning gas downstream. With a strong wind hitting the fluid flow device 1 the updraught will help neutralise the force of the wind directly on the flare and feed more oxygen to the flame to improve combustion efficiency and prevent pollution. The various types of flare would have the fluid flow device made to suit the design and this would mostly be just below the burning area, free of excess heat.It is, however, conceivable that the fluid flow device could be in close proximity to the heat source or even form part, in terms of the outer section, of a combustion chamber. The construction of the assembly would most likely be made up of multiple fluid flow devices, in the shape of a triangle, square, polygon or circle. Fig 9(b) shows an outline of a simple pipe flare 8 with the fluid flow device 1 fitted around the stack 7.

Fig 10(a) shows the fluid flow device 1 aiding the uplifting of wind on a ground flare stack 7 to assist the exhaust fumes 6 rise rather than that which may occur when the wind blows the exhaust downstream towards the ground or even back into the stack. The wind 2 strikes the fluid flow device 1 and is directed upwards 3 to vector with the wind above the stack. Fig 10(b) shows the fluid flow device 1 used as a wind fence to protect the inlet to the burners.

The gusting wind would be controlled to allow a smooth supply of air to the spread of burners within the structure. The wind 2 enters the fluid flow device fence 1 and the flow which for different designs within the stack may be fitted for either upwards or downwards flow becomes controlled.

Fig 11 introduces a domestic type wind-protecting chimney pot. Fig 11(a) shows a standard form where the central flue pipe 7 is surrounded by a fluid flow device, which in this case is a circular one 1 but which could be of octagonal or any similar shape to facilitate design. Radial baffles 5 may be fitted between the flue pipe and the fluid flow device. Fig 11(b) shows a modified version which includes a rotating cowl 9 activated by a wind vane 8 to ensure that the blank cowl is on the downwind side. The cowl may take two forms of rotating section: either the vanes occupy half of the circumference with the other half having a blank surface forming a cowl and the whole outer-section rotates or the cowl rotates independently of the fluid flow device section which is fixed and totally surrounds the inner pipe.The wind 2 impinges upon the fluid flow device 1 and the upstream flow 3 both protects and directs the chimney fumes.

Fig 12 shows a simple outline of the fluid flow device fitted in front of a moving body which could be of any sort of transport on land, sea, air or space. It will affect the resistance and drag characteristics on the body. The diagram is symbolic of any position on a moving body as it is possible to manipulate pressures and velocities for various purposes. It provides an alternative way in solving problems which at present are associated with using normal fluid dynamics principles and streamlining. In the diagram, with the body 4 moving through, for example air, the relative, moving air 2 enters the fluid flow device 1 which is in an attitude for neutralising the forces of the incoming flow 2. The secondary flow 3 is thrown upwards and forwards and the fluid flow device 1 takes the major forces off the body 4, which is able to glide through the air in a calmer environment.

A characteristic of the fluid flow device is that in certain attitudes it is able to receive a flow of fluid and redirect it whilst the balancing pressure or thrust forces on the structure are considerably reduced. It is possible to freely pivot the base of the fluid flow device and angle the structure towards the flow and receive the full force of the fluid flow, and stand freely without support. It has, therefore, a neutralising effect on the normally expected stress load on the structure, resulting from a mass flow. Applications where this characteristic may be considered are in respect of situations where the fluid flow device is subject to heavy thrust fluid dynamic loads. Typical of this is in the subject of coastal defences where the loads are heavy and irregular, and similarly in situations such as those associated with oil platforms. The condition when the neutralising balance of the loads is at a peak is when the fluid flow device is angled towards the flow. Protection of any object fastened behind the fluid flow device is by the deflection of the flow and by reduced stress loads on the retaining structures.It is this same characteristic that is important to the moving body. When considering all of the previous examples of the applications of the fluid flow device these characteristics must be remembered as an important claim of this invention.

Claims

1. A fluid flow device comprising a plurality of vanes or baffles, the vanes being arranged substantially parallel to each other so as to form substantially parallel inlets between each vane or baffle characterised in that each vane or baffle has an upstream and a downstream planar portion, the upstream planar portion being at an angle of 1250 to 1550 to the downstream portion.

2. A fluid flow device according to claim 1 in which the upstream planar portion is at an angle of 1350 to 1450 to the downstream portion.

3. A fluid flow device according to claim 1 or claim 2 in which the upstream and downstream planar portions are arranged to form a sharp discontinuous edge where they join.

4. A fluid flow device according to any of claims 1 to 3 in which the upstream and downstream portions are formed as an integral single piece of material or in which they are discrete portions physically joined along an abutting edge.

5. A fluid flow device according to any of the preceding claims in which the width of the inlets is of a similar magnitude to the thickness of the intervening baffle or vane.

6. A fluid flow device according to any of the preceding claims in which all the vanes have their upstream planar portions oriented in substantially the same plane.

7. A fluid flow device as hereinbefore described and with reference to figures 2 to 12 of the accompanying drawings.

8. A composite fluid flow device comprising a plurality of fluid flow devices as claimed in any of the preceding claims.

9. A method of redirecting fluid flow comprising the steps of (a) directing a fluid flow on to the inlet face of a fluid flow device according to any of claims 1 to 8 and (b) passing the fluid flow emerging from the fluid flow device to a utilisation region.

10. A power generator comprising a fluid flow device according to any of claims 1 to 8.

11. A power generator comprising a fluid flow device according to claim 9 in which the fluid flow is tidal flow, wave flow or river flow.

12. A ventilation system comprising a fluid flow device according to any of claims 1 to 8.

13. An oil separation system comprising a fluid flow device according to any of claims 1 to 8.

14. A wind or sea protection structure comprising a fluid flow device according to any of claims 1 to 8.

15. A flare system comprising a fluid flow device according to any of claims 1 to 8.

16. A chimney system comprising a fluid flow device according to any of claims 1 to 8.

17. A means for reducing fluid drag resistance on a moving body comprising a fluid flow device according to any of claims 1 to 8.