TS-85 Study on the Noise Reduction in a Turbofan(Session D-1 Control of Unsteady Flow and Noise)

概要

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Aerodynamic noise generated by a fan is generally classified into rotating noise and turbulent noise. We conducted a study to reduce rotating noise without diminishing performance, by reshaping the tongue of the turbofan casing. The tongue shape was modified to minimize rotating noise in consideration of the delivery flow from the impeller vane. It was clarified that breaking the simultaneity of the interference of the flow by modifying the shape of the tongue yields a noise reduction effect. In addition, it was found that if the angle difference between the angle of side plate and the tangential angle at the top of the nozzle is not appropriate, the separation inside the side plate is increased. As a result, the rotating noise is increased by interference between the tongue and the separation flow from the vane. By realizing the optimum angle difference between the angle of the side plate and tangent at the top of the nozzle, the rotating noise was further reduced.
公益社団法人日本ガスタービン学会の論文
1999-11-14