# US 4,398,415 A · Swing link flexible wind tunnel nozzle

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- Number: US 4,398,415 A
- Document ID: US4398415A
- Status: Granted
- Kind: A
- Application number: 06/329,443
- Filed: 1981-12-10
- Granted: 1983-08-16
- Earliest claimed: 1981-12-10
- Assignees: The United States of America as represented by the Secretary of the Air Force
- Inventors: James L. Jacocks; Henry L. Henderson
- Web page: https://patentgrep.com/patent/US4398415A

## CPC

- G01M 9/04: Details
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR

## Abstract

A flexible duct for conveying a gaseous flow, with the duct useable as the flexible nozzle in a wind tunnel. The duct includes a flexible plate member which is attached at the downstream end to a frame support member, with the upstream end of the flexible plate member being slideable and pivotable upon a member attached to the frame support member. A plurality of swing link members in spaced-apart relationship are pivotally connected at one end to the flexible plate member, and pivotally connected at the other end to a translatable and rotatable cradle-like member which is supported by crank members from the frame support member. An actuator is used to selectively move the cradle-like member. The resultant movement of the cradle-like member causes the flexible plate member to deflect, resulting in predetermined contours (and profiles) of the flexible plate member. If the duct is used as the flexible nozzle of a wind tunnel, this contouring of the flexible plate member allows generation of a large range of uniform velocities at the downstream exit end of the duct which is in communication with the testing section of the wind tunnel. Unlike the Pierce invention which was very restricted in the range of velocities attainable, this duct can be used to provide a large range of uniform velocities including supersonic.

## Claims

### Claim 1

A flexible duct for conveying a gaseous flow, comprising:
a. means having a changeable contour for defining a wall of said duct; and
b. means, operably connected to said wall defining means for changing said contour of said wall defining means wherein this means includes: a cradle-like member connected to said wall defining means, said cradle-like member being capable of translatable and rotatable movement; and, means for applying a load to said cradle-like member in order to cause said movement of said cradle-like member to take place thereby changing said contour of said wall of said duct.

### Claim 2 (depends on 1)

A flexible duct for conveying a gaseous flow as defined in claim 1 wherein said wall defining means comprises a flexible plate member.

### Claim 3 (depends on 2)

A flexible duct for conveying a gaseous flow, as set forth in claim 2, wherein said means for changing said contour of said flexible plate member further includes:
a. a support frame member having a first end to which a first end of said flexible plate member is attached; and
b. means attached to a second end of said support frame member for supporting a second end of said flexible plate member in a manner that permits free rotation and translation thereof with respect to said second end of said frame member.

### Claim 4 (depends on 3)

A flexible duct for conveying a gaseous flow, as set forth in claim 3, wherein said means for applying a load to said translatable and rotatable cradle-like member includes:
a. a plurality of crank members pivotally supporting said cradle-like member from said support frame member; and
b. means, operably associated with said cradle-like member, for actuating said cradle-like member, with this means including an actuator.

### Claim 5 (depends on 4)

A flexible duct for conveying a gaseous flow, as set forth in claim 4, wherein said means for changing said contour of said flexible plate member further includes a pluralty of swing link members each having a first end and a second end, with said first end of each of said swing link members pivotally connected to said flexible plate member, and with said second end of each of said swing link members pivotally connected to said cradle-like member.

### Claim 6 (depends on 5)

A flexible duct for conveying a gaseous flow, as set forth in claim 5, wherein said duct has a downstream exit for said gaseous flow, and wherein said duct is connected at said exit to the entrance of a test section of a wind tunnel, thereby said duct structurally functions as the flexible nozzle of said wind tunnel.