Considerations for the design of a second generation induction driven transonic wind tunnel

Abstract

The considerations for the design of a high Reynolds number 1.5m X 1.5m transonic wind tunnel to be operated up to 5 atm abs stagnation pressure are discussed. The wind tunnel has a closed return circuit, driven by high pressure air injector system. This design results in low initial costs and significant reduction in the operating costs. The experimental data obtained from the GOcm x 80cm induction driven wind tunnel is used as the basis for the present design. The injector design is based on an empirical relation between the test section Mach number and the injector pressure. The effects of circuit characteristics on the injector efficiency, the injector location, test section turbulence and noise levels as well as the flow quality are discussed. The measurements in the GOcm x 80cm wind tunnel indicate that the mass efficiency of the induction driven tunnel (IDT) will be 2 to 7 times better than that of an equivalent blow down (BDT) one. The measured noise level in the present IDT is less than 1% AC prms and the turbulence level is between 0.5% to 1%. These levels are comparable to those realized in various continuous compressor driven transonic wind tunnels and are well below the corresponding values measured in various BDT ones.