Wind Tunnel Design with Expanding Corners

Abstract

A wind tunnel may comprise: a flight chamber; a plurality of diffusers; a plurality of expanding corners, wherein the plurality of expanding corners comprises a first expanding corner and a second expanding corner; and a return, the return configured to have disposed therein a fan operatively coupled with a motor.

What is claimed is: 
     
         1 . A recirculating vertical wind tunnel comprising:
 a vertical flight chamber;   a plurality of diffusers;   a plurality of corners, wherein the plurality of corners comprises a first expanding corner and a second expanding corner, each of said first expanding corner and second expanding corner comprising an inlet having an inlet cross sectional area defining an inlet plane and an outlet having an outlet cross sectional area defining an outlet plane, the inlet plane being substantially perpendicular to the outlet plane, wherein the ratio of the inlet cross sectional area to the outlet cross sectional area defines an expansion ratio that is between about 1.10 and about 3.0;   a return to house a fan operatively coupled with a motor; and   a netting device positioned at an upstream end of said vertical flight chamber.   
     
     
         2 . The recirculating vertical wind tunnel of  claim 1 , wherein the expansion ratio of at least one of said first and second expanding corners is between 1.10 and 1.50. 
     
     
         3 . The recirculating vertical wind tunnel of  claim 2 , wherein the expansion ratio of each of the first expanding corner and the second expanding corner is between 1.10 and 1.50, the expansion ratio of the first expanding corner being less than the expansion ratio of the second expanding corner. 
     
     
         4 . The recirculating vertical wind tunnel of  claim 1 , wherein the air pressure within the vertical flight chamber during operation is substantially equalized with the air pressure outside the recirculating wind tunnel. 
     
     
         5 . The recirculating vertical wind tunnel of  claim 1 , wherein the netting device is coupled to a net frame at the upstream end of said vertical flight chamber via a plurality of cables, each of said plurality of cables having a first distal end and a second distal end,
 wherein a head end unit is coupled to the first distal end and a receiving end unit is coupled to the second distal end,   wherein the head end unit couples the first distal end to a first connection point on said net frame and comprises a first compression spring and a tensioning bolt that is adjustable in length, and   wherein the receiving end unit couples the second distal end to a second connection point on said net frame and comprises a second compression spring.   
     
     
         6 . The recirculating vertical wind tunnel of  claim 1 , wherein the vertical flight chamber has a circular cross section and a substantially constant area along the vertical flight chamber's length. 
     
     
         7 . The recirculating vertical wind tunnel of  claim 1 , wherein the vertical flight chamber has a circular cross section that diffuses along the vertical flight chamber's length. 
     
     
         8 . The recirculating vertical wind tunnel of  claim 6 , wherein the inner diameter of vertical flight chamber is about 14 feet. 
     
     
         9 . The recirculating vertical wind tunnel of  claim 1 , wherein the length of vertical flight chamber is between about 25 and 35 feet. 
     
     
         10 . The recirculating vertical wind tunnel of  claim 6 , wherein the vertical flight chamber comprises a breather slot. 
     
     
         11 . The recirculating vertical wind tunnel of  claim 1 , wherein the plurality of corners comprises a third expanding corner and a fourth expanding corner, each of the third expanding corner and the fourth expanding corner being installed substantially below ground. 
     
     
         12 . The recirculating vertical wind tunnel of  claim 1 , further comprising a plurality of internally-cooled internal turning vanes operatively coupled with a ground-coupled heat exchanger. 
     
     
         13 . The recirculating vertical wind tunnel of  claim 1 , further comprising, on an inner surface of the recirculating vertical wind tunnel, an acoustically transparent layer positioned between a layer of perforated sheet metal and a layer of sound absorbing material. 
     
     
         14 . The recirculating vertical wind tunnel of  claim 11 , wherein the mean average expansion ratio of the third expanding corner and the fourth expanding corner is greater than the mean average expansion ratio of the first expanding corner and the second expanding corner. 
     
     
         15 . The recirculating vertical wind tunnel of  claim 1 , wherein the plurality of diffusers comprises (1) a first diffuser having a circle to quadrilateral transition positioned between said vertical flight chamber and said first expanding corner and (2) a second diffuser positioned between said first expanding corner and said second expanding corner. 
     
     
         16 . The recirculating vertical wind tunnel of  claim 1 , wherein air traveling through the recirculating vertical wind tunnel is cooled using fluid from a ground-coupled heat exchanger, whereby the fluid is brought into intimated contact with a portion of an exterior wall of said recirculating vertical wind tunnel. 
     
     
         17 . The recirculating vertical wind tunnel of  claim 1 , wherein the vertical flight chamber is fabricated from one or more transparent panels to permit a substantially unrestricted view of activities taking place in the vertical flight chamber. 
     
     
         18 . A vertical wind tunnel system for skydiving simulation, the vertical wind tunnel system comprising:
 a fan operatively coupled with a motor;   a vertical flight chamber fabricated from one or more transparent panels;   a plurality of diffusers;   a plurality of expanding corners comprising a first expanding corner, a second expanding corner, a third expanding corner, and a fourth expanding corner,
 each of said first, second, third, and fourth expanding corners comprising an inlet having an inlet cross sectional area defining an inlet plane and an outlet having an outlet cross sectional area defining an outlet plane, the inlet plane being substantially perpendicular to the outlet plane, wherein the ratio of the inlet cross sectional area to the outlet cross sectional area defines having an expansion ratio of that is between about 1.10 to about 1.50, and 
 wherein the return is configured to have disposed therein the fan; and 
   a return.   
     
     
         19 . The vertical wind tunnel system of  claim 18 , wherein the mean average expansion ratio of the third expanding corner and the fourth expanding corner is less than the mean average expansion ratio of the first expanding corner and the second expanding corner. 
     
     
         20 . The vertical wind tunnel system of  claim 18 , further comprising a netting device positioned at an upstream end of said flight chamber, the netting device being coupled to a net frame via a plurality of cables, each of said plurality of cables having a first distal end and a second distal end,
 wherein a head end unit is coupled to the first distal end and a receiving end unit is coupled to the second distal end,   wherein the head end unit couples the first distal end to a first connection point on said net frame and comprises a first compression spring and a tensioning bolt that is adjustable in length, and   wherein the receiving end unit couples the second distal end to a second connection point on said net frame and comprises a second compression spring.   
     
     
         21 . The vertical wind tunnel system of  claim 18 , wherein at least one of said plurality of diffusers utilizes a conical-angle expansion between 2.0 and 4.0 degrees.