WO1993000800A1

WO1993000800A1 - Stream water aquarium

Info

Publication number: WO1993000800A1
Application number: PCT/SE1992/000448
Authority: WO
Inventors: Mats E. Henriksson; Karl-Erik Eriksson
Original assignee: Vattenfall Utveckling Ab
Priority date: 1991-07-01
Filing date: 1992-06-18
Publication date: 1993-01-21
Also published as: AU2290792A; SE9102048L; SE9102048D0; SE468697B

Abstract

A stream water aquarium comprises a basin (1) defined by sidewalls (2, 3), end walls (4, 5) and a bottom from which extends upwards a partition (7) which defines an endless stream water path having two elongate channels (8, 8') and two passages (9, 9') therebetween. The basin further includes at least one water-propelling unit (10, 10') imparting to the water a circulating stream motion along the path. A curved screen (11, 11') is mounted at each of the two opposite ends of the basin. This screen is formed with a plurality of small holes or openings through which at least the surface water propelled in the preceding channel is forced to pass before impinging upon the end wall (5) in order to divide the surface water into a plurality of minor partial flows, thus counteracting splashing or wave-formation.

Description

STREAM WATER AQUARIUM

Field of the Invention

The invention relates to a stream water aquarium, especially for studying the behaviour of fishes or other living creatures in streaming water, comprising a basin defined by two side walls, two end walls and a bottom from which extends upwards at least one partition which is shorter than the side walls and which, together with these walls and the end walls, defines an endless stream water path having two elongate channels or channel-like portions and two transverse passages therebetween, said basin including at least one water-propelling unit impart¬ ing to the water a circulating stream motion along said path.

Description of the Prior Art

Prior-art aquariums of this type are so designed that the circulating water will, at the end of each channel, impinge directly upon the end wall, which results in much splashing and considerable wave-formation in the surface water at the two ends of the basin as soon as the water is propelled at some speed. To prevent the water from splash¬ ing over the edge of the basin (open at the top for pur¬ poses of study), it has been necessary to propel the water at a very low speed, e.g. not exceeding 0.5 m/s. Such mediocre circulation of the water highly restricts the possibilities of studying e.g. the natural behaviour of fishes in various types of streaming water. Further, the streaming conditions in such prior-art aquariums become very different in different sections of the basin chan¬ nels, and the propelling speed and the wave-formation at a side wall may thus differ markedly from the correspond¬ ing parameters at the partition. Also, the water stream conditions may vary considerably at different depths. Another serious inconvenience is that the water-propelling unit or units required are mounted within the stream of water in the basin. Thus, the separate water-propelling unit is in the form of a motor-powered impeller incorpo¬ rated in a lattice cage which, although of a hydrodynami- cally suitable design, is fixedly mounted on the bottom of the basin channel and extends up towards the water surface in such a manner that it takes up a considerable part of the space between the partition and the side wall. Thus, the unit forms, in the middle of the stream water path, an obstacle on which the fish may easily get caught and which, in addition, interferes with the stream pattern. Summary of the Invention

The present invention aims at obviating the above inconveniences and providing a stream water aquarium offering better opportunities to all-round studies of the natural behaviour of fishes and other animals in various types of streaming water. A primary object of the inven¬ tion is, therefore, to provide an aquarium in which the water can be propelled at a comparatively high speed with¬ out splashing over or forming undesired waves. According to the invention, this object is achieved by a stream water aquarium having the features recited in appended claim 1. A secondary object of the invention is to provide an aquarium in which the water-propelling unit or units required do not in any way obstruct the water stream. According to the invention, this object is achieved by a stream water aquarium having the features recited in appended claim 5. Other features and advantages of the invention will appear from the following description, the remaining claims and the accompanying drawings illustrat¬ ing a preferred embodiment of the invention. Brief Description of the Drawings In the drawings, FIG. 1 is a part-sectional top plan view of an aquarium according to the invention,

FIGS 2 and 3 are part-sectional longitudinal views of the aquarium of Fig. 1, and

FIG. 4 is an enlarged detail view of a portion of a screen mounted in the basin. Description of the Preferred Embodiment

Fig. 1 shows a basin 1 defined by two side walls 2, 3, two end walls 4, 5, and a bottom 6, from which a cen¬ tral partition 7 extends upwards. The partition 7 is shorter than the side walls so as to define, together with the walls 2-5, an endless stream water path having two substantially straight channels or channel-like portions 8, 8* and two transverse passages 9, 9' therebetween. In practice, the basin may have a length of 10-20 m, suitably 12-15 m, and a width of 3-6 m, suitably 4-4.5 m. Although in the drawings all the walls are straight, this is no requirement. Thus, especially the end walls 4, 5 may have another shape and e.g. be curved. In the embodiment shown, the water is assumed to circulate anticlockwise in a flow path about the partition 7.

In this case, t water in the basin is propelled by two identical units 10, 10', one of which will be described in more detail below. As appears from Fig. 1, the water-propelling unit 10 is arranged at the front or inlet end of the channel 8, as seen in the direction of flow, and the water-propelling unit 10' is similarly arranged at the front end of the channel 8' .

In accordance with the invention, a curved screen 11, 11' is mounted at each of the two opposite ends of the basin, more precisely in the area in front of the end wall 5 and 4, respectively. As appears from Fig. 2, the lower edge 12 of each screen is located below the water surface, while the upper edge 13 is located above the water sur¬ face. Considering that the level of the water surface may vary, e.g. between the levels Nl and N2 shown in Fig. 2, the screen should be comparatively high. In th embodiment shown, the screen th extends from essentially the same level as the upper edges of the basin walls 2-5 down to a cover or bottom plate 14 forming part of the bottom 6. The screen is formed with a plurality of small holes or open¬ ings 15 (see Fig. 4), through which the propelled water is forced to pass before impinging upon the end wall located behind. In practice, the screen 11 conveniently is a per¬ forated metal sheet with elongate holes 15 whose longitu¬ dinal extension is horizontally oriented. Tests have shown that the individual hole 15 ideally is an elongate rec- tangle measuring 25 x 2 mm and having rounded, suitably semicircular, ends, the hole area being 25-45%, suitably 30-40% and preferably about 34%. When, as preferred, the hole area is 34%, the remaining metal-sheet area amounts to 66%. Advantageously, the curved metal sheet 11 has a substantially semicircular shape, and the ends 16, 16' of the metal sheet are connected to the side walls 2, 3 of the basin at points which are so remote from the adja¬ cent end walls that the metal sheet is maintained in its entirety at a certain distance from the end wall. It should be observed that the partition 7 has, at each of its two opposite ends, a so-called flow-turning nose 17 in the form of a continuous, non-perforated metal sheet having a progressively curved shape and serving to conduct the streaming water round the wall end in gentle streams, i.e. without giving rise to any appreciable tur¬ bulence.

The water propelled substantially linearly in the channel 8 will impinge upon the curved metal sheet 11 before reaching the end wall 5. Thus, some of the water will pass through the holes 15 dividing it into a plura¬ lity of minor partial flows, while the main part of the flow is guided along a curved path through the passage between the channels by the curved metal-sheet portions surrounding the holes. This ensures that the streaming water will not directly and with full force impinge upon the end wall 5, thus avoiding splashing and wave-forma¬ tion.

As shown in Fig. 2, the bottom plate 14 does not extend all the way up to the end wall 4, but ends on a level with the screen 11', thereby forming a free passage 31. At least the main part of the water taken in to the space 32 between the screen 11' and the end wall 4 via the holes 15 in the screen can be conducted, through this com¬ munication passage 31, down to the water-propelling unit 10 arranged below the bottom plate 14.

The water-propelling unit 10 includes an operative component in the form of an impeller or a vane wheel 18 driven by a submersible motor 19, suitably of a type per¬ mitting continuous variation of the speed of the motor and, consequently, of the rotational speed of the impel¬ ler 18. Further, the impeller 18 is arranged within or adjacent to a cylindrical tube 20 which gradually merges into an elongate, rectangular portion 21. This portion ends in a grating-equipped outlet 22 in the bottom of the basin. An inlet 23, also equipped with a grating, is arranged in the bottom of the basin for taking in water to the water-propelling unit 10. This inlet is at least partly formed in the bottom plate 14 covering the water-propelling unit 10. In the embodiment shown, the inlet includes two comparatively large-size openings 23' and 23" which both are covered by gratings and the first of which is formed in the horizontal bottom plate 14, while the second extends obliquely from a rear edge 24 down to a front edge 25 which is located on a lowe level. More precisely, the front edge 25 adjoins ε _r- tion of the channel bottom that is covered by a layer 26 of stone or the like, the upper surface of this layer being located on a level below the two bottom plates 14 at the ends of the basin. In practice, the opening 23" may have the same width as the associated channel, and be comparatively long, e.g. about 5-10% of the length of the channel (in practice about 1 m), whereas the opening 23' may be slightly narrower. A relatively large proportion of the streaming water, e.g. 30-35%, may be taken in through the inlet 23 formed by the openings 23' and 23". This water is then, by the water-propelling unit, drawn through the transverse passage below the bottom plate 14 and given a speed increment by the impeller 18, whereupon it is conducted through the outlet duct 20, 21 to the outlet 22, where the emerging water by ejector action entrains the streaming water above the bottom plate 14 and speeds it up.

It should be observed that the outlet opening 22 is formed in an upright, slightly inclined transitional por¬ tion 27 between the bottom plate 14 and the layer of stones 26, such that the force with which the water rushes out through the opening receives a large horizontal compo¬ nent. As appears from Fig. 1, the outlet 22 is narrower than the channel 8. In practice, the width of the outlet 22 may be but approximately half the width of the channel. To provide optimum streaming conditions in the channel, the outlet 22 is thus offset in relation to the centre of the channel, more precisely in such a manner that the cen¬ tre of the outlet is closer to the partition 7 than to the side wall 3.

It should here be pointed out that the water taken in to the water-propelling unit 10 comes not only from the inlet 23 but also from the space 32 behind the screen 11' . Also, it should be noted that the side walls of the basin are mainly manufactured of plates 28 of a transpa¬ rent material, such as glass. The basin has an inlet 29 for supplying fresh water, as well as an outlet 30 for draining water. In practice, control equipment (not shown) for adjusting e.g. the level of water in the basin is con¬ nected to both the inlet and the outlet.

The advantages of the invention are obvious. Since the screens counteract splashing and wave-formation in the basin, the water can be propelled at a comparatively high speed by the effective water-propelling units. Thus, tests have shown that a propelling speed of 1.5-2.0 m/s is possible. The speed is rapidly adjustable between dif¬ ferent desired values by means of the continuously-vari- able-speed driving motors. Since the water-propelling units are arranged below the bottom of the basin, the water available for the fishes or laboratory animals is completely free from obstacles, which makes it much easier to study the behaviour of the animals in stream¬ ing water of all sorts.

Claims

1. A stream water aquarium, especially for study- ing the behaviour of fishes or other living creatures in streaming water, comprising a basin (1) defined by two side walls (2, 3), two end walls (4, 5) and a bottom (6) from which extends upwards at least one partition (7) which is shorter than the side walls (2, 3) and which, together with these walls and the end walls (4, 5), defines an endless stream water path having two elongate channels or channel-like portions (8, 8') and two trans¬ verse passages (9, 9') therebetween, said basin including at least one water-propelling unit (10, 10') imparting to the water a circulating stream motion along said path, c h a r a c t e r i s e d in that a curved screen (11, 11' ) is mounted at each of the two opposite ends of the basin in the area in front of an end wall (4, 5), said screen having its lower edge located below the water sur- face and its upper edge located above the water surface and being formed with a plurality of small holes or open¬ ings (15) through which at least the surface water pro¬ pelled in a preceding channel (8, 8') is forced to pass before impinging upon the end wall in order to divide the surface water into a plurality of minor partial flows, thus counteracting splashing or wave-formation adjacent to said end wall.

2. An aquarium as claimed in claim 1, c h a r a c ¬ t e r i s e d in that the openings (15) in the screen (11) are elongate and have their longitudinal extension horizontally oriented.

3. An aquarium as claimed in claim 1 or 2, c h a r ¬ a c t e r i s e d in that the screen is a perforated metal sheet (11), the hole area of which amounts to 25-45%, suitably 30-40% and preferably about 34%, of the total area of the screen.

4. An aquarium as claimed in any one of the preced¬ ing claims, c h a r a c t e r i s e d in that the curv¬ ed screen or metal sheet (11) has a semicircular shape, the ends (16, 16') of the screen being connected to the side walls (2, 3) of the basin at points which are so remote from the end wall that the screen will be main¬ tained in its entirety at a distance from said end wall.

5. An aquarium as claimed in any one of the preced¬ ing claims, c h a r a c t e r i s e d in that the water-propelling unit (10, 10') is arranged below a bot¬ tom wall (14) of the basin and is connected to a grating- equipped inlet (23) located in front for taking in to the unit some of the water streaming in the basin, as well as to a grating-equipped outlet (22) located behind for recycling at a higher propelling speed the water taken in to the water in the basin.

6. An aquarium as claimed in claim 5, c h a r a c ¬ t e r i s e d in that a water-propelling unit (10, 10*) is arranged in the area of each of the two ends of the basin, and that the water inlet (23) for each separate unit is disposed at a rear end of one channel (8' ), while the outlet (22) for the same unit is disposed at a front end of the other channel (8), as seen in the direction of flow of the water.

7. An aquarium as claimed in claim 5 or 6, c h a r ¬ a c t e r i s e d in that the inlet (23) extends through¬ out the entire width and a considerable part of the length of the associated channel (8' ), thereby forming a large- size bottom opening covered by a grating, whereas the out- let (22) is in the form of an opening covered by an up¬ right, optionally inclined grating and located between the bottom wall (14) covering the water-propelling unit (10) and a channel bottom (26) situated on a lower level than said bottom wall.

8. An aquarium as claimed in claim 7, c h a r a c ¬ t e r i s e d in that the outlet opening (22) is narrower than the channel (8) and is located with its centre closer to the partition (7) than to the side wall (3).

9. An aquarium as claimed in any one of claims 5-8, c h a r a c t e r i s e d in that the water-propelling unit (10) comprises an impeller (18) which is powered by a submersible, continuously-variable-speed motor (19) and which is arranged within or adjacent to a cylindrical tube (20) gradually merging into a rectangular, elongate por¬ tion (21) forming the outlet opening (22).

10. An aquarium as claimed in any one of claims 5-9, c h a r a c t e r i s e d in that the space which is situated between the individual screen (11, 11') and the end wall (4, 5) located behind and to which water passes through the holes (15) of the screen, communicates with the water-propelling unit (10, 10') for conducting at least some of said water to this unit.