Low turbulence wind tunnel stilling chamber

A wind tunnel for high energy laser applications comprising:

• a test chamber for containing a model support, said model support being capable of fixing a test model to be subjected to illumination with a high energy laser beam, said test chamber being in fluid communication on its downstream side with fluid exhaust means and with a primary flow nozzle on its upstream side, said nozzle being in fluid communication on its upstream side with a means for providing a controllable source of fluid at elevated pressures to be supplied to said test chamber, wherein the improvement comprises:
• an improved curved elongated settling chamber interposed between said nozzle and said source of fluid at elevated pressure, said settling chamber having a gradual turning radius to permit the fluid flow through the tunnel to follow the turning of the settling chamber and prevent turbulence;
• a transverse aerodynamic window providing for the entrance of said laser beam, said window being located in the low velocity flow turning region of said settling chamber;
• and
• a turbulent sonic free-jet coincident with said window wherein fluid flow through said settling chamber is uniform and smooth allowing said laser beam to impinge on said test model without beam distortion or degradation.