Aero-acoustic wind tunnel has fan that is arranged in closed current return tube in which free cross-sectional area is suddenly changed according to specific amount of change in outer periphery of free cross-sectional area

摘要

The wind tunnel (1) has a measuring section (6) that is arranged between a nozzle (3) and a collector (2). A closed current return tube (4) is extended from the side of the collector up to the nozzle. A fan (5) is arranged in the current return tube in which free cross-sectional area is suddenly changed by 25% change in outer periphery of the free cross-sectional area. The free cross-sectional area is suddenly changed by changing the outer periphery of free cross-sectional area by 40-60 wt%.