US3916772A - Device at supply air means with throttling member - Google Patents

Abstract

Apparatus for supplying air from a high-pressure air duct to a room, for ventilation of the room. Air from the high-pressure source is passed through a set of nozzles spaced across the cross section of a flow chamber, the apertures of the nozzles being mutually spaced apart by a distance d and the aperture nearest the sidewalls of the chamber being spaced therefrom by substantially d/2. The length of the fluid chamber is at least 3 times d, and a grating is provided across its outlet end. In one embodiment, an adjustably-sized aperture is provided in a sidewall of the chamber near the nozzles to control the quantity of secondary air pulled into the chamber from the room, and hence the velocity of flow into the room. In another embodiment the chamber is a telescoping tube, adjustable to change the chamber length. The apparatus enables a smooth, nearly homogeneous, flow of air into the room, while permitting control of the velocity of air flow into the room, and without materially reacting on the high-pressure source of air.

Description

Lindestriim et al.

Nov. 4, 1975 DEVICE AT SUPPLY AIR MEANS WITH THROTTLING MEMBER [75] Inventors: Lars-Erik Lindestriim,

Kristinehamn; Birger L'arkfeldt, Odens J o-Barnarp, both of Sweden [73] Assignee: Aktiebolaget Svenska Flaktfabriken,

Nacka, Sweden [22] Filed: Apr. 22, I974 211 Appl. No.: 462,778

[30] Foreign Application Priority Data May 7, 1973 Sweden 06408/73 [52] US. Cl. 98/38; 28/40 C [51] Int. Cl. F24F 13/08 [58] Field of Search 98/40 N, 40 C, 38, 40 D, 98/108 [56] References Cited UNITED STATES PATENTS 2,783,979 3/1957 Blum 98/38 X 2,872,859 2/1959 Kennedy 98/38 3,327,607 6/1967 Newell et al 98/40 D 3,422,888 l/l969 Coleman et al 98/40 N Primary Examiner-William E. Wayner Attorney, Agent, or Firm-Howson and Howson [57] ABSTRACT Apparatus for supplying air from a high-pressure air duct to a room, for ventilation of the room. Air from the high-pressure source is passed through a set of nozzles spaced across the cross section of a flow chamber, the apertures of the nozzles being mutually spaced apart by a distance d and the aperture nearest the sidewalls of the chamber being spaced therefrom by substantially d/2. The length of the fluid chamber is at least 3 times d, and a grating is provided across its outlet end. In one embodiment, an adjustably-sized aperture is provided in a sidewall of the chamber near the nozzles to control the quantity of secondary air pulled into the chamber from the room, and hence the velocity of flow into the room. In another embodiment the chamber is a telescoping tube, adjustable to change the chamber length. The apparatus enables a smooth, nearly homogeneous, flow of air into the room, while permitting control of the velocity of air flow into the room, and without materially reacting on the high-pressure source of air.

U.S. Patent Nov. 4, 1975 Fig.7

DEVICE AT SUPPLY AIR MEANS WITH TI-IROTTLING MEMBER This invention relates to a device for use with an air means comprising a throttling member with flow apertures of equally spaced-apart relationship, said throtply means without affecting the pressure drop or the flow of primary air. It was found possible by means of the device according to the invention to provide suitable throwing lengths for different depths of the ventilated rooms or to vary the throwing length as a function of the difference in temperature, or also at a so-called VAV-installation to maintain the throwing length at varying flows.

The device according to the invention is primarily characterized in that it comprises a flow chamber between the aforesaid throttling member and the outlet to the ventilated room, said chamber having a length sufficiently great, preferably 3 times the aforesaid relative spacing of the flow apertures, that the air jets from said apertures are spread into to one homogeneous air stream prior to the outflow out of the flow chamber. An advantageous embodiment of the device is characterized in that the flow chamber comprises an external pipe with a grating which is mounted movably on an internal pipe surrounding said throttling member. A preferred embodiment of the device is characterized in that the flow chamber is a single pipe surrounding said throttling member and provided with an opening to the ventilated room in the wall of the flow chamber near said throttling member, said opening being variable for adjusting the intended co-ejected air flow from the ventilated room and, thereby, the throwing length of the supply air means.

The invention is described in greater detail in the following, with reference to the accompanying drawing showing by way of example two embodiments of the supply air means, in which the invention is applied.

FIG. 1. shows a one-duct apparatus located adjacent a window-wall and connected to a primary air passageway, the apparatus being provided with a throttling member and a grating, and

FIG. 2 shows a supply air passageway through a wall terminating with a throttling member and a grating.

Referring to the drawing, 1 designates a air supply means and 2 a throttling member with a number of flow apertures 3. 4 is a flow chamber and 5 designates an outlet therefrom. According to FIG. 1, the flow chamber is a rectangular passageway or'a single pipe 7, which adjacent the plane through the throttling member is provided with a movable cover 8, by means of which the opening 9 can be varied by the reversible movement of the cover in the direction of the arrow 10 can be varied. From the passageway 12 supply air is delivered in the form of primary air at a certain rate and tries to co-eject secondary air from the room 6. If this is prevented by the movable cover 8 closing the opening 9 and the flow chamber 4 being given a certain minimum length, the airjets of the throttling member 2 will fill up the entire crosssection of the flow chamber 4, and a minimum speed of the flow out of the mouth 5 of the chamber is obtained. This minimum speed can be determined by calculation as the ratio between the primary air flow and the cross-sectional area of the chamber 4. When now the cover 8 is opened increasingly wider, a certain amount of secondary air is taken along in the suction from the room 6, and the speed in the mouth of the flow chamber increases to the ratio between the flows of primary air plus secondary air and the aforementioned cross'sectional area. The coejected flow from the room 6 was found to depend on the width of the opening 9 and on the pressure drop over the throttling member 2.

The present invention is based on the understanding of that, in order to ensure a good functioning of the device, Le. a so-called short circuit, the length of the flow chamber constantly is to be maintained sufficiently great that the condition L a 3 d is met where d according to above and in the claims designates the spacing between the flow apertures'S of the throttling member 2. In the embodiment shown in FIG. 2, secondary air from the room 6 will be sucked into the chamber 4a, for example in the direction of the smaller arrow, where the air is mixed with primary air supplied from the passageway 12a and is ejected, for example in the direction of the larger arrow. The invention renders it possible that air supply means with a relatively high pressure drop can have a short throwing length, which implies the possibility of adjusting the throwing length within certain limits in order to bring about an optimum flow pattern in a room. It may be pointed out that a change in the throwing length according to above has no effect (reaction) on the primary air system.

We claim:

1. Apparatus for supplying a flow of primary air from a high-pressure air source to a room by way of an outlet to the room, comprising:

a plurality of adjacent, generally parallel ejecting nozzles each having a flow aperture for directing primary air supplied thereto generally along the same direction;

means for supplying primary air from said source to each of said nozzles to produce from said flow apertures a flow of primary air which is substantially constant despite changes in air-flow conditions downstream of said apertures;

an enclosed flow chamber for receiving said primary air from said apertures and having an outlet end through which air from said chamber is delivered to said room outlet, and a grating across said outlet end;

said flow chamber comprising two telescopicallyarranged tubes, one supporting said grating and one surrounding said apertures, so as to permit adjustment of the length of said chamber by telescoping one of said tubes with respect to the other said tube, thereby to adjust the throw length of the air stream from said outlet end to said room without substantial reaction on said air supply source;

the length of said flow chamber being sufficient that secondary air from said room is sucked into said chamber at the edges of said grating and mixed with said primary air to form a substantially homogeneous ventilation air current into said room.

2. The apparatus of claim 1, wherein the centers of adjacent ones of said apertures are spaced from each other by the same mutual distance d and the internal length of said chamber from said nozzles to said grating is at least about 3d.

3,916,772 3 4 3. The apparatus of claim 2, in which the distance nearest adjacent ones of said apertures is about d/2. from the sidewalls of said chamber to the centers of the

Claims (3)

1. Apparatus for supplying a flow of primary air from a highpressure air source to a room by way of an outlet to the room, comprising: a plurality of adjacent, generally parallel ejecting nozzles each having a flow aperture for directing primary air supplied thereto generally along the same direction; means for supplying primary air from said source to each of said nozzles to produce from said flow apertures a flow of primary air which is substantially constant despite changes in air-flow conditions downstream of said apertures; an enclosed flow chamber for receiving said primary air from said apertures and having an outlet end through which air from said chamber is delivered to said room outlet, and a grating across said outlet end; said flow chamber comprising two telescopically-arranged tubes, one supporting said grating and one surrounding said apertures, so as to permit adjustment of the length of said chamber by telescoping one of said tubes with respect to the other said tube, thereby to adjust the throw length of the air stream from said outlet end to said room without substantial reaction on said air supply source; the length of said flow chamber being sufficient that secondary air from saId room is sucked into said chamber at the edges of said grating and mixed with said primary air to form a substantially homogeneous ventilation air current into said room.

2. The apparatus of claim 1, wherein the centers of adjacent ones of said apertures are spaced from each other by the same mutual distance d and the internal length of said chamber from said nozzles to said grating is at least about 3d.

3. The apparatus of claim 2, in which the distance from the sidewalls of said chamber to the centers of the nearest adjacent ones of said apertures is about d/2.

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