High bypass ratio fan noise research test vehicle

A most critical factor in establishing noise levels from a high bypass ratio turbofan engine is the choice of fan design. Although a great deal of research work has been done in support of noise reduction programs for low bypass ratio two-stage fan engines, the single-stage fan without inlet guide vanes has been the subject of relatively limited noise research. To provide noise research capability, a fan test rig vehicle was designed and fabricated for the conduct of noise studies on single-stage high bypass ratio fans. This fan test rig is free turbine driven with a remote mounted JT3 engine providing the hot gas supply to the modified JT3D drive turbine. Flexibility has been incorporated into the design of this rig to allow fans of different designs to be tested over a range of speed and operating conditions, and a wide variety of design and installation features to be evaluated, which are pertinent to the noise output from advanced engine and nacelle designs.