GB2111125A - Apparatus for inducing fluid flow by Coanda effect - Google Patents

Abstract

An apparatus for inducing air flow for ventilation purposes in mines, refineries and the like hazardous environments comprises a first tubular body 1, which defines the air flow duct A, having a mouth 2 which is flared to form a venturi shape and which defines an annular lip 3. A second body 4 is coaxially located around the first body 1 and secured by a screw threading 5 which permits relative axial movement by rotation of body 4 about body 1. The body 4 has a tapered inlet 7 forming a venturi surface with mouth 2 and a lip 8 which defines, with lip 3, an annular coanda slot 9 communicating with chamber 10 fed with pressure gas. Gas flow out of slot 9 induces flow through the body in direction A. <IMAGE>

Description

SPECIFICATION Apparatus for inducing fluid flow by Coanda effect This invention relates to an apparatus for inducing fluid flow by Coanda effect whereby flow of air, such as for ventilation in aggressive environments, may be induced using a high energy flow. Specification G.B. 863124 discloses an apparatus mainly intended for inducing flow in gas turbine power units using a convergent-divergent venturi passage requiring an insert neck. Specifications 1411083 and 1403188 disclose apparatus primarily for dilution of internal combustion engine exhaust gases.

It is an object of this invention to provide an apparatus of the kind described which is of simplified construction wherein the Coanda slot is adjustable and readily capable of calibration.

According to this invention there is provided an apparatus for inducing fluid flow by Coanda effect comprising a tubular first body defining a fluid flow duct and having a flared mouth with an annular lip, a second body coaxial with the first body and secured thereto in an axially movable manner, the second body having a tapered inlet with an inwardly directed annular lip forming, with the lip of the first body, an annular Coanda slot, said slot communicating with an annular chamber defined between the first and second bodies with the chamber having an inlet connection for flow inducing fluid medium which is fed under pressure through the Coanda slot.

Preferably the first and second bodies are secured together through a screw threaded coupling permitting accurate relative axial movement whereby the dimension of the Coanda slot may be set. The coupling will preferably include a locking means, such as a set screw.

The first body may include an internal threading at the end opposite the mouth for connection with an exhaust funnel duct.

An embodiment according to this invention is shown by way of example in the accompanying drawing showing an axial section through a preferred construction of apparatus.

In the drawing an apparatus for inducing air flow for ventilation purposes in mines, refineries and the like hazardous environments comprises a first tubular body 1, which defines the air flow duct A, having a mouth 2 which is flared to form a venturi shape and which defines an annular lip 3. A second body 4 is coaxially located around the first body 1 and secured by a screw threading 5 which permits relative axial movement by rotation of body 4 about body 1. The two bodies may be locked together by set screws 6.

The second body 4 has a tapered bell mouthed inlet 7, which is shaped to form a venturi surface coextensive with the mouth 2.

The inlet 7 has an inwardly directed annular lip 8 which forms, with the lip 3 of the first body 1, a Coanda slot 9 which is annular. The slot 9 is in communication with an annular chamber 10 defined between the two bodies 1 and 4 and the chamber has an inlet connec tion 11 provided in a lower extension part of the body 4.

The body 1 has an internal screw threading 1 2 at the rear which serves for connection with a funnel shaped ducting 1 3.

Compressed air is fed into the chamber 10 through connection 11. This air is circulated I around the chamber and escaped through the slot 9 to cause a vacuum in front of the slot which induces the flow of ambient air creating an output flow or air in excess of the input.

The amount of air that is induced is deter mined by the width of the slot which can be adjusted by means of thread 5, and the width of the slot is measured by the use of feeler gauges. When the correct gap setting is reached the body 4 is locked by screws 6.

The funnel 1 3 is fitted to the body 1 for directing the flow of air and there is also provision for an electrical earth point at 1 4.

1. An apparatus for inducing fluid flow by Coanda effect comprising a tubular first body defining a fluid duct and having a flared mouth with an annular lip, a second body coaxial with the first body and secured thereto in an axially movable manner, the second body having a tapered inlet with an inwardly directed annular lip forming, with the lip of the first body, an annular Coanda slot, said slot communicating with an annular chamber defined between the first and second bodies with the chamber having an inlet connection for flow inducing medium which is fed under pressure through the Coanda slot.

2. An apparatus in accordance with Claim 1, wherein the first and second bodies are secured together through a screw threaded coupling permitting accurate relative axial movement whereby the dimension of the Coanda slot may be set.

3. An apparatus in accordance with Claim 2, wherein the coupling has a locking means to secure same against axial movement.

4. An apparatus in accordance with any preceding Claim, wherein the first body in cludes an internal threading at the end oppo site the mouth for connection with an exhaust funnel duct.

5. An apparatus for the purpose herein set forth and substantially as described and illus trated in the drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Apparatus for inducing fluid flow by Coanda effect This invention relates to an apparatus for inducing fluid flow by Coanda effect whereby flow of air, such as for ventilation in aggressive environments, may be induced using a high energy flow. Specification G.B. 863124 discloses an apparatus mainly intended for inducing flow in gas turbine power units using a convergent-divergent venturi passage requiring an insert neck. Specifications 1411083 and 1403188 disclose apparatus primarily for dilution of internal combustion engine exhaust gases. It is an object of this invention to provide an apparatus of the kind described which is of simplified construction wherein the Coanda slot is adjustable and readily capable of calibration. According to this invention there is provided an apparatus for inducing fluid flow by Coanda effect comprising a tubular first body defining a fluid flow duct and having a flared mouth with an annular lip, a second body coaxial with the first body and secured thereto in an axially movable manner, the second body having a tapered inlet with an inwardly directed annular lip forming, with the lip of the first body, an annular Coanda slot, said slot communicating with an annular chamber defined between the first and second bodies with the chamber having an inlet connection for flow inducing fluid medium which is fed under pressure through the Coanda slot. Preferably the first and second bodies are secured together through a screw threaded coupling permitting accurate relative axial movement whereby the dimension of the Coanda slot may be set. The coupling will preferably include a locking means, such as a set screw. The first body may include an internal threading at the end opposite the mouth for connection with an exhaust funnel duct. An embodiment according to this invention is shown by way of example in the accompanying drawing showing an axial section through a preferred construction of apparatus. In the drawing an apparatus for inducing air flow for ventilation purposes in mines, refineries and the like hazardous environments comprises a first tubular body 1, which defines the air flow duct A, having a mouth 2 which is flared to form a venturi shape and which defines an annular lip 3. A second body 4 is coaxially located around the first body 1 and secured by a screw threading 5 which permits relative axial movement by rotation of body 4 about body 1. The two bodies may be locked together by set screws 6. The second body 4 has a tapered bell mouthed inlet 7, which is shaped to form a venturi surface coextensive with the mouth 2. The inlet 7 has an inwardly directed annular lip 8 which forms, with the lip 3 of the first body 1, a Coanda slot 9 which is annular. The slot 9 is in communication with an annular chamber 10 defined between the two bodies 1 and 4 and the chamber has an inlet connec tion 11 provided in a lower extension part of the body 4. The body 1 has an internal screw threading 1 2 at the rear which serves for connection with a funnel shaped ducting 1 3. Compressed air is fed into the chamber 10 through connection 11. This air is circulated I around the chamber and escaped through the slot 9 to cause a vacuum in front of the slot which induces the flow of ambient air creating an output flow or air in excess of the input. The amount of air that is induced is deter mined by the width of the slot which can be adjusted by means of thread 5, and the width of the slot is measured by the use of feeler gauges. When the correct gap setting is reached the body 4 is locked by screws 6. The funnel 1 3 is fitted to the body 1 for directing the flow of air and there is also provision for an electrical earth point at 1 4. CLAIMS

1. An apparatus for inducing fluid flow by Coanda effect comprising a tubular first body defining a fluid duct and having a flared mouth with an annular lip, a second body coaxial with the first body and secured thereto in an axially movable manner, the second body having a tapered inlet with an inwardly directed annular lip forming, with the lip of the first body, an annular Coanda slot, said slot communicating with an annular chamber defined between the first and second bodies with the chamber having an inlet connection for flow inducing medium which is fed under pressure through the Coanda slot.

2. An apparatus in accordance with Claim 1, wherein the first and second bodies are secured together through a screw threaded coupling permitting accurate relative axial movement whereby the dimension of the Coanda slot may be set.

3. An apparatus in accordance with Claim 2, wherein the coupling has a locking means to secure same against axial movement.

4. An apparatus in accordance with any preceding Claim, wherein the first body in cludes an internal threading at the end oppo site the mouth for connection with an exhaust funnel duct.

5. An apparatus for the purpose herein set forth and substantially as described and illus trated in the drawing.