EP0155924A2

EP0155924A2 - Air curtaining unit

Info

Publication number: EP0155924A2
Application number: EP85850099A
Authority: EP
Inventors: George Bernhard Dhenstrand
Original assignee: Bahco Ventilation AB
Current assignee: Bahco Ventilation AB
Priority date: 1984-03-21
Filing date: 1985-03-20
Publication date: 1985-09-25
Also published as: SE8401574L; EP0155924A3; SE444975B; SE8401574D0

Abstract

An air stream-generating curtaining unit (1) adapted for being included as one of several curtaining units situated in a row in an air curtaining installation. The unit comprises a fan unit (6) arranged.in a casing (5), the casing having inlets (7) and outlets (8) for a partial curtain forming air stream driven by the fan unit (6) for the air curtain. The outlet (8) of the curtaining unit is provided with a combined silencing and air distribution means having an air supply nozzle (9) which has a substantially rectangular through-flow cross section with long sides extending along substantially the entire curtaining length of the curtaining unit, and with short sides (12) of gradually decreasing length along the flow path of the partial air stream. At least one (13) of both the defining walls of the supply air nozzle which form said long sides has its profile convex shaped in the flow direction of the partial air stream, seen from within the nozzle. Both defining walls (13,14) each define one side of a box (15) filled with porous material exterior to and facing towards the nozzle (9), the box serving in a manner known per se as a resisfve arSd reactive silencer, the only open communication of the box (15) with the supply air nozzle (9) being a pierced portion (16) of the defining wall, this portion being at a distance from the inlet of the nozzle. Adjacent the inlet end there is an unpierced entry portion (17) for the partial air stream. The fan unit (6) has a plurality of fans (19), the outlets (20) of which are distributed in spaced relationship along the longitudinal extension of the inlet cross section of the nozzle (9) while the zones in the cross section of the inlet not utilized for outlets from the fan are blanked off.

Description

The invention relates to an air stream-generating curtaining unit which is arranged to be included as one of several similar curtaining units in an air curtaining installation, which has the curtaining units situated in a row for the common generation of an air curtain in connection with a wall opening. The curtaining unit has a fan unit arranged in a casing. The casing has inlets and outlets for an air stream generated by the fan unit and forming part of the common air curtain.
In air curtaining of this kind, as well as with other types of air curtaining, it is essential to provide a uniform distribution of the air stream along the slot or the like forming the outlet of the casing just mentioned. At the same time, there is often a requirement of a rather low sound level, which restricts the possibilities of achieving, via constrictions of an optional kind, a pressure drop which gives the desired distribution.
The object of the invention is to achieve a curtaining unit which satisfies severe requirements on both flow distribution and quiet operation.
The desired result is obtained by the curtaining unit being given the characterizing features apparent from the following claim 1.
An embodiment of the invention will now be described in detail with reference to the accompanying drawings.

Fig. 1 is a perspective view of a curtaining unit in accordance with the invention.
Fig. 2 schematically illustrates how the curtaining unit of Fig. 1 is included in a transverse draught air curtain.
Fig. 3 is a horizontal section through the curtaining unit in Fig. 1.
Fig. 4 is a vertical section through the curtaining unit according to IV - IV in Fig. 3.
Fig. 5 is a vertical section through the curtaining unit according to V - V in Fig. 3.

The curtaining unit 1 is disposed for being included as one of several similar units in an air curtaining installation, which has the curtaining units situated in a row for commonly generating an air curtain. Fig. 2 schematically illustrates an example of such an arrangement of two curtaining units, one on top of the other, for the formation of a curtain with a transverse draught. On the side of the passage opening opposite to the curtaining units there is a return deflection screen 2 for the curtaining air stream. The deflected air stream is directed towards a catcher screen 3 joined to the curtaining unit. Both screens 2, 3 are made up from articulately connected wall elements with windows 4.
Each curtaining element 1 comprises a casing 5 (Figs. 1 and 3 - 5) which inter alia enclose, a fan unit 6 supplying its part of the air stream forming the air curtain. The casing 5 has an inlet 7, open in several directions, and an outlet 8 for this partial air stream.
The outlet 8 of the curtaining unit 1 has the shape of a slit or slot, and is provided with a combined air silencer and air distribution means with an air supply nozzle 9. This air supply nozzle, opening out in the outlet 8 has a substantially rectangular through-flow cross section with long sides 10 extending along the curtaining unit's substantially entire curtain-forming length 11 and with short sides 12 which have varying length, from a greatest length at the incoming end of the nozzle to a least length at the outlet 8 thereof. One defining wall 13 of the nozzle, forming one of the long sides 10 in the through-flow cross section, has its profile extending in the flow direction of the partial air stream provided with a convex shape seen from the inside of the supply air nozzle. This wall 13 and the opposing defining wall 14 of the nozzle each define a side of a box 15 filled with sound insulating porous material, one on either side of the nozzle. Each box 15 is intended to serve as a combined resistive and reactive silencer and its only open communication with the nozzle 9 is via a perforated portion 16, which is centrally situated on the respective defining wall 13, 14, these walls being otherwise unpierced. There is thus obtained an unpierced entry portion 17 for the partial air stream to the nozzle. There are also unpierced end portions 18 on the walls 13, 14 adjacent the inlet 8. The unpierced convex entry portion is favourable both from the aspects of sound and flow technology, and from the distribution point of view this enables the use of a fan unit 6 with two centrifugal fans 19 situated at rather a large distance from each other, the casing outlets 20 of which are directly connected to the inlet end of the nozzle 9:
The convex profile of the defining wall 13 described above may be curved for the whole of its length, with a radius of curvature increasing continuously from the entry portion 17 towards the outlet 8, or with substantially only the entry portion in a convex curve and its remaining part linear. In the first- mentioned case, the profile at the nozzle outlet may suitably be a tangent to a line parallel to the profile of the opposing wall 14.
In the illustrated embodiment the defining wall 14 is illustrated as being flat. This embodiment is based on the fans 19 being of centrifugal type and that they are provided with spiral casings 21 with the resulting air stream characteristic for such casings. The flat defining wall is in this case arranged nearest the respective rotational axis 22 of the fans. In Fig. 3 there is furthermore illustrated adjacent this wall and fan outlets a cylindrical insert 23 serving to improve the air stream configuration in the nozzle-=9. This insert extends throughout the entire width of the nozzle along one of the long sides 10 according to Figs. 4 and 5, although only a portion of the insert is indicated.
The inlet opening of the nozzle 9 is blanked off to the extent it has not been used by the fan outlets 20. The walls 24 thus obtained form, together with the outer walls of the casing, a fan chamber having a back wall 25 situated in spaced relation to the remaining walls, and carried by rails 26 at its corners to form the inlet 7 of the fan chamber. The entire fan chamber is clad with sound-insulating material and a pair of baffles 27 provided with insulation material are also arranged at the inlet openings.
In a fan configuration different from the one illustrated, the nozzle may suitably be formed with two mutually opposing walls formed as the illustrated wall 13, i.e. the flat wall 14 replaced by a convex wall. Furthermore, the curtaining unit may have one or more further outlet slits (not shown) parallel to the outlet slit 8 and each formed with a nozzle of the kind described. Instead of the cylinder 23 a member with a cross section in the form of a tear-drop may be arranged to connect up with the wall 14, as indicated in Fig. 3 by dashed lines extending the shape of the cylinder 23. The curtain installation illustrated in Fig. 2 is also suitably provided with an (unillustrated) roof, covering the passage between both curtaining units 1 and the catcher screen 3 on one side and the return deflection screen 2 on the other side.

Claims

1. Air stream generating curtaining unit (1) adapted for inclusion as one of several like curtaining units in an air curtaining installation, the curtaining units being situated in a row for common generation of an air curtain in connection with a wall opening, the curtaining unit consisting of a fan unit (6) arranged in a casing (5), which has inlets (7) and outlets (8) for a partial curtain-forming air stream caused by the fan unit (6), characterized in that the outlet (8) of the curtaining unit is provided with a combined sound insulating and air distributing means with a supply air nozzle (9) which has a substantially rectangular through-flow cross section with long sides (10) extending along substantially the entire curtaining length (11) of the curtaining unit, and with short sides (12) having gradually decreasing length along the flow path of the partial air stream at least one (13) of both defining walls (13, 14) of the supply air nozzle forming said long sides (10) in the through flow cross section having its profile in the flow direction of the partial air stream formed substantially convex, seen from the inside of the nozzle, both side defining walls (13, 14) each also defining a side of a box (15) filled with porous material, outside of and facing towards the nozzle (9), said box serving in a manner known per se as a resistive and reactive silencer, the only open communication of the box (15) with the nozzle (9) being a pierced portion (16) of the defining wall at a distance from the inlet end of the nozzle, there being adjacent the inlet an unpierced entry portion (17) for the partial air stream the fan unit (6) also having a plurality of fans (19), the outlets (20) of which are distributed in spaced relationship along the longitudinal extension of the inlet cross section of the nozzle (9), while the zones in the inlet cross section not utilized for such fan outlets (20) are blanked off.

2. Curtaining unit as claimed in Claim 1, characterized in that at least one (13) of the said defining walls (13, 14) has the entry portion (17) curved convex on the inside of the nozzle (9) while the remaining portion (16, 18) of the defining wall in the flow direction of the partial air stream is substantially flat.

3. Curtaining unit as claimed in Claim 2, characterized in that one (14) of said both defining walls (13, 14) is substantially entirely flat.

4. Curtaining unit as claimed in Claim 3, characterized in that the fan unit (6) includes two centrifugal fans (19) directly driven by a common motor situated between them, the fans having spiral casings (21), each of which opens directly into the inlet end of the nozzle (9), the flat defining wall (14) being situated closest to the rotational axis of the fans (19).