GB2201733A

GB2201733A - Fluid flow device

Info

Publication number: GB2201733A
Application number: GB08702523A
Authority: GB
Inventors: Kenneth Herbert Haywood; Paul Christopher Haywood; Mark David Haywood
Original assignee: ZETA DYNAMICS Ltd
Current assignee: ZETA DYNAMICS Ltd
Priority date: 1987-02-04
Filing date: 1987-02-04
Publication date: 1988-09-07
Anticipated expiration: 2007-02-04
Also published as: GB8702523D0; GB2201733B

Abstract

A fluid flow device that provides movement of fluid using coanda principles, with the main supply tube (1) having an exit slot and having a threaded, serrated, or grooved surface with the slot cover having direct abutment on this surface, the enclosed area forming the primary fluid jet exit (2). The emerging fluid (3) entrains the surrounding fluid from (5) and the resultant fluid is directed by a fin (4) to the outlet (6). The cover (2) is clip held for speedy cleaning. A design using a smooth supply tube surface is included. Applications include, fluid movers, flow-visualisation and process tanks, therapeutic and health aid, propulsion units and a gas burner. <IMAGE>

Description

FLUID FUM DEVICE The present invention relates to fluid flow devices.

It is known that a stream of fluid emerging from the mouth of a narrow slot under pressure tends to cling to an extended lip or surface of the slot thereby creating a pressure drop in the surrounding fluid. The pressure drop tends to cause a surrounding fluid to flow towards the low pressure region. This physical phenomenom is known as the Coanda effect. This phenomenom has been employed in a number of ways, one of which is disclosed in British Patent No.2055726A.

It is desirable in many applications to produce controlled flows of fluids and these may be provided by use of fluid pumps. However, conventional pumps may produce flow which is too turbulent for applications in, for example, a flow visualisation tank as the total flow of the fluid has to be passed through the pump. However, the present invention uses the Coanda effect to obtain a relatively large flow of a fluid by the use of a much smaller fluid flow through a slot. This enables the production of relatively controlled fluid flow and also enables the mixing of fluids.

Thus according to the present invention, there is provided a fluid flow device comprising a supply tube for a first fluid, the tube having an aperture or slot extending preferably in a longitudinally axial direction, the aperture or slot having means directing emergent fluid flow over the curved surface of the tube, whereby surrounding second fluid is entrained into the first fluid, there also being means downstream of the aperture or slot for facilitating fluid flow away from the tube. The device may have an external housing enclosing the tube and flow directing means, the housing device preferably having a venturi-like or cuniform form. The surrounding second fluid may be the same as or different to the first fluid. The housing may be integral with the device or may form part of a surrounding or ancillary equipment.

The fluid flow device may be used in many flow related applications and it is particularly suitable for providing fluid flows of low turbulence, for the mixing of fluids, for aeration, and for mixing inflammable gases with air for burning. The fluids passing through the device may be gaseous or liquid and the entraining fluid may be the same as or different from the entrained fluid. Thus, for example, water emerging under pressure from the slot may be used to entrain surrounding air or to entrain water or another liquid.

The supply tube is preferably cylindrical in shape, and most preferably has a slot, the direction of the slot being parallel to the longitudinal axis of the aperture. The external or outer surface of the supply tube may be smooth or may have surface features. For example, a preferred surface feature is the presence of threading, serrations, or grooves, the threading, serrations, or grooves being preferably at right angles to the slot length.

The means for directing fluid flow over the curved outer surface of the supply tube may be, for example, a cover plate spaced apart from the slot. In the case of a supply tube having a smooth outer surface the plate may be spaced by a suitable spacing device, preferably which is capable of adjustment to give different widths of gap between the slot and curved plate. In the case of a supply tube having surface features in the form of surface indentations, such as threading, serrations or grooves, there may be sufficient gap formed by direct abutment of a curved cover plate and the tube.

Preferably the curved plate is placed symmetrically over, and overlapping the slot, because the exit area within the threads, serrations or grooves is enclosed by the cover, and it directs the emerging fluid in a pair of equal streams passing above and below the supply tube in the opposite direction to the emergent flow.

The means downstream of the slot for facilitating fluid flow away from the supply tube, may take the form of a fin attached to the surface of the tube opposite or radially at 180 degrees to that of the slot to provide fluidic streamlining, simulating the round supply tube as a fully streamlined profile. It is also envisaged that the fin is integral with tube and it gives direction to the flow.

The housing of the device may enclose the tube and flow directing means. The housing preferably has a venturi or cuniform-like shape, the cross-sectional area of the fluid flow device being greater at the fluid inlet than at the fluid outlet. The housing preferably extends over the means downstream of the slot for facilitating fluid flow away from the tube to the slot or most preferably upstream of the slot.

The fluid flow device has a metal or plastic supply tube of generally cylindrical shape which is capable of being connected to a supply of a fluid such as water possibly through a feedpipe. The tube has a slot extending longitudinally over most of its length.

In the case of a smooth surface, the slot has an associated cover which is spaced apart from and lying over the slot so as to form a pair of outlet gaps for water emerging from the supply tube.

In the case of the supply tube having surface features in the form of external threading, serrations, or grooves, the slot cover sits on the peaks of the threads, serrations, or grooves, thereby giving control of the gap width which is the space between the cover and the threads. The cover is in the form of a plate having an area sufficient to overlap the slot. The covers longitudinal edge needs to touch the tips of the threads, serrations or grooves with an appropriate shape, but is preferably shaped to follow the contour of the external surface of the tube. The cover may be fixed in position, but is preferably removable by the use of spring or screwed clips. The use of clips enables ease of removal of the cover so as to allow the removal of foreign matter which may cause blockage or disruption of the fluid flow.

The threads, serrations, or grooves, may have various profiles dependent on the application and include 'V"-shape, curved, square or acme. The pitch of the threads or shape of serrations or grooves used is dependent on the quantity of fluid and the pressure of the fluid in the tube. They may cover the local area around the slot only, the remainder of the surface being smooth Alternatively, the tube has a smooth outer surface and the slot cover is supported at the required gap separation from the slot.

The cover may be fixed in position, but is preferably removable, to allow removal of foreign matter, by the use of spring or screw clips.

The device may be made of various materials, of which stainless steels, brasses, or plastics are most suitable, either separately or in combination.

The invention also includes tanks such as flow visualisation tanks comprising a fluid flow device as hereinbefore described and fluid mixers such as aerators or oxygenators comprising a fluid flow device as hereinbefore described, a therapeutic and health device for use in a bathing situation, a propulsion unit, and a burner comprising a fluid flow device as herein described.

The invention will now be described by way of example only and with reference to the accompanying drawings.

Fig 1 (a) is a perspective view of a fluid flow device for moving fluid according to the invention which shows the thread, serration, or groove form of a supply tube. Fig 1 (b) is a section across A-A and fig 1 (c) shows a section across the slot assembly B-B.

Fig 2 (a) is a perspective view of a fluid flow device for moving fluid according to the invention which shows the smooth surfaced version of supply tube, as fig 1. Fig 2 (b) is a section across A-A and fig 2 (c) shows a section across B-B the slot assembly.

Fig 3 (a) shows a perspective view of a fluid flow device for moving fluid in accordance with the invention without the outer housing as in figs 1 and 2, but with guide templates for fitting into a housing in a situation as demonstrated in fig 4. Fig 3 (b) shows a view of the device from arrow A as fitted into such a situation such as fig 4.

Fig 4 (a) shows a perspective view of a flow visualisation tank fitted with a fluid flow device in accordance with the invention in fig 3. Fig 4 (b) shows diagramatically through section A-A the fluid movement within the tank.

Fig 5 (a) shows a cross-sectional view of a bath with the portable fluid device which is designed as a therapeutic and health aid and in accordance with the invention. Figs 5 (b), (c) and (d) shows diagramatic views of the three major positions of effective operation of the device.

Fig 6 (a) is a diagramatic view of the fluid flow device in accordance with the invention applied to the function of an inboard drive unit. Fig 6 (b) shows the application as an outboard drive unit. Figs 6 (c) and (d) show views from arrow B of two attitudes of the fluid flow device on the outboard drive unit. Fig 6 (e) shows a diagramatic view of the inboard fluid flow device from the direction of arrow A.

Fig 7 (a) shows a perspective view of a burner in accordance with the invention with the fin modified to provide turbulence. Figs 7 (b) and (c) show outline views from the direction of arrow A without and with the housing respectively. Figs 7 (d) to (j) show various examples of configurations, with the fluid flow device burner shown in solid lines and the feed pipe in broken lines.

Fig 1 shows the device in a standard form with the threaded, serrated, or grooved supply tube (1) for moving fluid. The primary fluid flow leaves the slot (2) and follows the tube curve (3) towards the fin (4). The fin (4) simulates fluidically a tapered tail to the tube and simulates a streamlined rear of the feed tube and gives direction to the flow. The combination of momentum exchange and pressure depression results in the primary flow pulling through the secondary flow from the inlet of the integral housing(8). The primary fluid enters the supply tube (1) by the feed tube (7) with the pressurised primary flow being supplied by a pump (not shown).

Fig 2 shows the device in a standard form with the smooth surfaced supply tube for moving fluid. The primary fluid flow leaves the slot (2) and follows the tube curve (3) towards the fin (4). The fin (4) simulates fluidically a tapered tail to the tube, and simulates a streamlined rear of the feed tube and gives direction to the flow. The combination of momentum exchange and pressure depression results in the primary flow pulling through the secondary flow from the inlet of the integral housing (8). The primary fluid enters the supply tube (1) by the feed tube (7) with the primary flow being supplied by a pump (not shown).

Fig 3 shows the device for moving a fluid in a form which does not have an integral housing as in figs 1 and 2 above. The device in which the supply tube (1) can be of either the former described in figs 1 and 2, has two formers to act as guides (2) on either side of the supply tube (1). These formers guide the device into an external housing (3)-that may be part of another body such as process tank or flow-visualisation tank as illustrated in fig 4.

Fig 4 shows a flow-visualisation tank which consists of an outer water-tight tank body (1) in which there is a flow-visualisation, working table (2) which may or may not have a weir (3). An extension (4) of the table (2) drops down to the tanks fluid device housing section (5) which is an integral part of the tank. Slid into this housing section (5) is the fluid device (6) which is of the form shown in fig 3. The tank is filled with water to a level which may be as shown (7). The device is powered by a pump (8) through a connecting tube (9). This pump (8) is shown as an immersible pump but this could be an external pump connected through appropriate tubes to the fluid device. The water is circulated by the device (6) in the direction as shown by the arrows (10) from the outlet.The area above the working table (2) is able to be used for experimentation in fluids using, as an example, hydrogen bubble flow visualisation. The use of this technique provides a smooth flow over the table (2) because only a small percentage of water goes through the turbulence of the pump (8) the water moves through the whole width of the tank (1) in one slug. The technique is appropriate to many processes and for circulating or mixing in a tank (without the table (2)) the device could be in a vertical mode.

Fig 5 shows an application of the device to a therapeutic or health aid for use in a situation such as a domestic bath or pool. In the illustration, the fluid device (1) is designed as shown in Fig 1 or Fig 2 except that the feed tube is a continuation of the supply tube and has a dual role of a handle (2) so that the user in the bath can hold it if he/she wishes to direct the flow, which will be described. The fluid device (1) is connected by a tube (3) in this case to a low voltage immersion pump (4) which is fastened to a service harness (5). This arrangement for a pressurised water supply could alternatively be to an externally fitted pump of either low voltage or suitably protected standard mains voltage .The harness (5) has a facility for locking the handle (2) of the device (1) into a fixed position, without the bather having to hold it, at any height within the height or length of the harness (5). Figs 5 (b), (c), and (d) show three specific functions of the device.

Fig 5 (b) shows a position of the device (6) when it is totally submerged within the bath's water. This could be either hand-held, or fixed on the harness. The device (1) provides a moving jet of water that is directed at the bather, and provides a therapeutic effect. This both provides circulation around the bather, and a direct jet as described.

Fig 5 (c) shows a position of the device (7) when it is either handheld or fixed to the harness (5) at the surface ofthe water. In this situation, which is most likely to have half the inlet in water and half in air, the primary flow directs the water with an injection of air and thus creates bubbles within the water with a particularly therapeutic effect on the bather. In addition, the smallest amount of 'bubble bath' additive to the water creates a considerable amount of soapy bubbles and can give a very luxurious bathing effect.

Fig 5 (d) shows a position of the device (8) which is when it is held out of the water, solely in the air, with only the primary flow of liquid operating, and an amount of air being sucked in and the device (8) then provides a form of shower unit that the bather can use.

Overall, 'the device is a very flexible, therapeutic and luxurious aid to a bather, which is highly economic in energy output. No heating of the water is necessary because the device (1) takes the water from the bath and continually recirculates what it requires.

The device (1) as demonstrated in Fig 5, also has applications using the same technique in other fields, where for example, aeration is required as with the device (7) in fig 5 (c). Although not required in the bath application of the fig 5, it is possible to have the unit below the surface as in Fig 5 (d), but with an air extension pipe as part of the device (1) so that air is mixed with the liquid with the object of providing aeration of a liquid.

Fig 6 shows the application of the device (1) as a fluid propulsion unit, and is shown in fig 6 (a) as an inboard propulsion unit, and in fig 6 (b) as a outboard propulsion unit. The fluid power is provided by either immersion or inboard pumps, drawn by electrical or liquid fuel power or by heated water to produce steam as the primary flow. SIn fig 6 (c) and (d), an horizontal and vertical attitude is shown, respectively. The units in the figs 6 (a) and (b) are shown in boats, but can also be suitable as positioning units on barge-type vehicles or rigs. The system is perfect for bow thrusters. Performance levels of 105N thrust/KW to 140N thrust/KW have been recorded in development testing.

Fig 7 (a) shows the device in its function as a burner with the threads, serrations, or grooves, of the supply tube (1) being fed from the slot and cover (2) which is at the bottom of the supply tube (1). Depending upon the thread, serration, or groove size, the outlet sizes for the primary flow which in this case is an inflammable gas or vapour, can operate at any range of pressure.

The direction and burning of the gas and subsequent exhaust draws in the air around it. The fin (3) is modified from the simple straight form by adding an oblique shape to provide vortices and thus turbulence in the mixing of the gas and the secondary air flow that supports combustion. This design can be without an integral housing as in fig 7 (b), or with an integral housing which is shown in fig 7 (c) depending upon the application. Various configurations of this burner are shown in figs 7 (d) to 7 (j), with the burner supply tube being shown by the continuous lines (4) and the feed tubes by the broken lines (5). This type of burner is particularly effective in the oil industry's flare applications.

The same type of design with standard fin is suitable for steam application in flaring work.

Claims

1. A fluid flow device comprising of a supply tube with longitudinal slot with the surrounding area of the slot having a threaded, serrated, or grooved surface which by having a cover fitted over and slightly wider and longer than the slot, and touching the threaded, serrated, or grooved tips, provides an exit area for a first fluid to move tangentially on to the tube and thus clinging to the threaded, serrated, or grooved tube surface causing a secondary fluid to move past it due to momentum exchange and pressure suction; the cover being quickly removable being retained by springs or retaining clips for cleaning.

2. A fluid flow device comprising of a supply tube with longitudinal slot with a smooth surrounding area with a cover fitted over slightly wider and longer than the slot and having distance piece settings to give a longitudinal gap to provide for a first fluid to move tangentially on to the tube, and thus clinging to the smooth surface causing a second surrounding fluid to move past it due to a momentum exchange and pressure suction; the cover being quickly removable being retained by springs or retaining clips for cleaning.

3. A fluid flow device according to claims 1 and 2 in which the direction of flow from the slot is guided by a fin fitted radially at 180 degrees or as required from this slot to provide fluidic streamlining, simulating the supply tube as a fully streamlined profile, whilst the supply tube may be of circular cross-section with the resultant strength for high pressure fluids.

4. A fluid flow device according to the preceding claims which provides a Coanda fluid drive device with or without a housing for fluid moving or mixing applications.

5. A fluid flow device in accordance to any of the preceding claims which with an appropriately designed tank forms a flow visualisation tank for fluid movement analysis such as hydrogen flow-visualisation.

6. A fluid flow device according to any of the preceding claims in which if combined with tanks or pipes or channels or process apparatus, can move, mix or aerate fluids.

7. A fluid flow device according to any of the preceding claims in which it is applied as a therapeutic and health aid used for a domestic or other form of bath or pool for the benefit of the bather.

8. A fluid flow device according to any of the preceding claims in which it is applied to boat or vehicle propulsion or manouvering applications.

9. A fluid flow device according to any of the preceding claims in which it is applied to a burner for inflammable gaseous or vapourous fluids or a steam provider.

10. A fluid flow device as hereinbefore discussed with reference to figs 1 to 7 of the accompanying drawings.

Amendments to the claims have been filed as follows CLAIMS A A fluid flow device comprising a supply tube for a first fluid, the tube having an aperture or slot, the aperture or slot having fixed means directing emergent fluid flow over the curved outer surface of the tube whereby surrounding second fluid is entrained into the first fluid, there also being means downstream of the aperture or slot for facilitating fluid flow away from the tube.

2. A fluid flow device according to claim 1 in which the device has an external housing enclosing the tube and flow directing means.

3. A fluid flow device according to claim 2 in which the housing extends over the means downstream of the aperture or slot for facilitating fluid flow away from the tube to the slot or to a position upstream of the slot.

4. A fluid flow device according to claim 2 or claim 3 in which the housing has a venturi-like form or a cuniform form.

5. A fluid flow device according to any of claims 2 to 4 in which the housing is integral with the device.

6. A fluid flow device according to any of claims 2 to 5 in which the housing is part of a surrounding or ancillary equipment.

7. A fluid flow device according to any of the preceding claims in which the supply tube is cylindrical in shape and has a slot, the direction of the slot being parallel to the longitudinal axis of the tube.

8. A fluid flow device according to any of the preceding claims in which the external or outer surface of the supply tube is smooth or has surface features.

9. A fluid flow device according to claim 8 in which the surface features comprise threading, grooves or serrations.

10. A fluid flow device according to claim 9 in which the surface features have a "V"-shaped, curved, square or acme profile.

11. A fluid flow device according to claim 9 or claim 10 in which the threading, grooves or serrations are at right angles to the slot length.

12. A fluid flow device according to any of the preceding claims in which the fixed means directing emergent fluid flow over the curved outer surface of the tube is adapted to provide a variable outlet gap between said means and the supply tube.

13. A fluid flow device according to claim 12 in which the means for directing fluid flow over the curved surface of the supply tube is a curved plate spaced apart from the slot.

14. A fluid flow device according to claim 13 in which the curved plate is spaced apart from the slot by an adjustable spacing means.

15. A fluid flow device according to claim 13 or claim 14 in which the curved plate is placed symmetrically over and spaced apart from the slot.

16. A fluid flow device according to any of the preceding claims in which the means for directing fluid flow over the curved surface of the supply tube is rapidly assembled and disassembled.

17. A fluid flow device according to any of the preceding claims in which the means for directing fluid flow over the curved surface of the supply tube comprises retaining springs or clips or the like for rapid assembly and disassembly.

18. A fluid flow device according to any of the preceding claims in which the means downstream of the slot for facilitating fluid flow away from the supply tube takes the form of a fin attached to the surface of the tube opposite to that of the slot or radially at 180 degrees to that of the slot.

19. A fluid flow device according to claim 18 in which the fin is integral with the tube.

20. A fluid flow device as hereinbefore described and with reference to the accompanying drawings.

21. A flow visualisation tank comprising a fluid flow device according to any of the preceding claims.

22. An aerator or oxygenator comprising a fluid flow device according to any of the preceding claims.

23. A therapeutic or health aid comprising a fluid flow device according to any of the preceding claims.

24. A vehicle propulsion device comprising a fluid flow device according to any of the preceding claims.

25. A burner device comprising a fluid flow device according to any of the preceding claims.