GB2342079A

GB2342079A - Thrust vectoring nozzle using coanda surface

Info

Publication number: GB2342079A
Application number: GB9816260A
Authority: GB
Inventors: Thomas Smith
Original assignee: S & C Thermofluids Ltd
Current assignee: S & C Thermofluids Ltd
Priority date: 1998-07-27
Filing date: 1998-07-27
Publication date: 2000-04-05
Anticipated expiration: 2018-07-27
Also published as: GB9816260D0; GB2342079B

Abstract

A thrust vectoring nozzle comprises a circular inlet duct 1, a bearing surface 2, a circular to rectangular transition duct 3, two Coanda surfaces 4 which are planar across the major axis of the rectangular outlet of the nozzle, and side plates 5 which are able to rotate about a pivot 6. The thrust of the nozzle can be deflected by rotating the side plates 5, causing flow on the uncovered Coanda surface to separate while preventing separation on the covered surface. The nozzle can be vectored by additional rotation of the bearing surface 2 about the major axis. Alternatively, the side plates 5 and Coanda surfaces 4 may be an integral assembly. Uses described include for aircraft or where the fluid is water.

Description

1 2342079 PATENT APPLICATION ROTATING COANDA SURFACES FOR THRUST VECTOR

This invention relates to the use of rotational nozzle systems in conjunction with Coanda vectoring of thrust to produce full 3D vectoring capability.

A previous patent application has discussed the possibility of making use of the fact that flow which normally remains attached to a surface in accordance with the Coanda effect can be forced to separate if the side plates bounding that surface are removed. The particular vector within the plane of the Coanda surface can be controlled through the location for the extent to which the side plates are removed. Thus it is possible to achieve thrust vector control for one axis of a geometry, say pitch or yaw on an aircraft. However, it is often the case that one requires a universal vectoring capability which can be utilised between being fully pitch and fully yaw with any position in between. In such circumstances it may well be the case that the full engine thrust in any given direction is required at the particular vector angle.

The present invention describes a technique by which the single plane thrust vector can be aided by the use of rotation to obtain the required fully 3D vector. This technique involves the principle that the duct supplying the flow from which the thrust is being obtained is at some point circular before travelling through a transition duct to a more 2 dimensional rectangular type of shape, just upstream of the Coanda surface. Just prior to the start of the transition duct, the circular duct can be mounted in a bearing arrangement which allows that part of the duct to rotate relative to the upstream part which may be connected to the main propulsion system, say, a jet engine. By rotating the transition duct and the 2 dimensional or flat Coanda surface mounted onto it the vector which comes off the 2 dimensional Coanda surface at a particular angle can be directed to give the combined pitch/yaw vector in any 3D region. If the Coanda surface is double sided, i.e. some of the flow comes out on one side, and some of the flow on to an opposite side, then the full vector range can be achieved within 180 degrees rotation of the transition duct. If a single side is used then it may be necessary to produce up to 360 degrees of rotation.

This invention is more clearly described by way of an example wherein Figures 1&2 show a complete 3 dimensional thrust vectoring Coanda arrangement. This comprises, 1) a circular inlet duct, 2) a bearing surface arrangement for the circular duct, 3) a circular to rectangular transition duct split into two halves, 4) two Coanda surfaces which are planar across the major axis of the rectangular outlet section of the Coanda nozzle, 5) side plates which span the sides of the nozzle and which are able to rotate about the pivot, 6). In the normal on axis thrust arrangement the side plates are positioned centrally so that the flow separates just after the crest of the Coanda surface and the flow travels axially or parallel with the axis of the duct. For full deflection in the plane of the Coanda surface, the side plates are rotated such that one side of the Coanda surface is completely exposed which allows flow to separate from that surface and achieve a thrust close to a thrust vector for that half of the flow equal to the angle which is made by the exit plane of the exhaust duct with the duct axis At the same time the plate on the opposing surface fully covers the Page2of2 24July1998 2, sides of the Coanda surface thus preventing any separation and encouraging exhaust flow to remain attached all the way around the Coanda surface until it is deflected in the same trajectory as the flow leaving the opposite surface. Thus a vector is obtained in the 2D plane of the nozzle. By then rotating the whole assembly of the transition duct at the Coanda surface about the bearing surface, the 2d plane in which the vector exists can be rotated to point in a different azimuth. Variations within the scope of this invention are possible, e.g. the working fluids can be, compressed air, gas turbine exhausts, internal combustion engine exhausts of all types and can also include water and other types of fluids. A further invention within the scope of this arrangement is that instead of rotating the side plates relative to the Coanda surface, the side plates and the Coanda surface can be made integral, and the whole of the integrated assembly can be moved relative to the original access of rotation. In such cases it may be necessary to cut back the length of the down stream part of the Coanda surface as this is now redundant.

Page 2 of 2 24 July 1998 Rotating Coanda Thrust Vector Nozzle CLAIMS

1. A nozzle comprising a circular duct which conveys fluid from an inlet plane to an exit plane to produce a jet of the fluid, also known as the primary flow, into a surrounding fluid, also known as the secondary flow, this action causing a reaction force on the nozzle which can be transmitted to any object to which the nozzle is attached, said reaction force also being known as the thrust of the nozzle, and surfaces downstream of the nozzle exit plane such that the jet can be deflected through control of the entrainment of secondary flow into the primary flow and attachment of the primary flow to said surfaces according to the Coanda effect, the deflection of the primary fluid allowing the said thrust to be given a vector angle relative to the axis of the duct, said duct being in two coaxial parts such that one part is able to rotate relative to the other part, the purpose of which is to allow the vector produced using the Coanda effect to be rotated to any given angle about the nozzle axis.

2. A nozzle according to claim 1 in which only a single surface downstream of the exit plane is used to achieve vector.

3. A nozzle according to claim 1 in which two or more surfaces are used downstream of the exit plane.

4. A nozzle according to claim 1 in which the circular cross-section duct transitions to a none circular cross-section downstream of the position where the two coaxial parts can rotate relative to each other.

5. A nozzle according to claim 4 in which the transition produces an exit plane cross-section of the duct which matches the cross-section of the downstream Coanda surface.

6. A nozzle according to claim 1 in which the duct splits into two or more separate ducts downstream of the position where the two coaxial parts can rotate relative to each other.

7. A nozzle according to claim 6 in which the separate, split ducts transition to a shape at the exit planes of each duct which matches the cross section of the corresponding Coanda surface.

8. A nozzle according to claim 1 and 6 in which the Coanda surfaces are axisymmetric.

9. A nozzle according to claims 1 to 7 in which the Coanda surface or surfaces are planar.

10. A nozzle according to all of the preceding claims in which the fluid is the exhaust from a combustion process.

G 11. A nozzle according to claim 10 in which the combustion process is that of a gas turbine engine.

12. A nozzle according to claim 10 in which the combustion process is that of a rocket motor.

13. A nozzle according to claim 11 in which the combustion process is that of a piston engine.

14. A nozzle according to claim 1 in which the fluid is a liquid such as water (including sea water).

15. A nozzle according to claim 1 which is attached to a gas turbine engine.

16. A nozzle according to claim I which is attached to a marine propulsion system.

17. A nozzle according to claim 1 in which the Coanda surfaces can move relative to the duct.

18. A nozzle according to claim 1 which used in connection with the propulsion and/or control of an aircraft or missile.

19. A nozzle substantially as hereinbefore described with reference to and shown by Figure 1.

20. A nozzle substantially as hereinbefore described with reference to and shown by Figure 2.