低圧軸流送風機の共鳴騒音に関する研究 : 丸棒の位置、回転数および翼先端形状の影響

抄録

Resonance tone is minimized by reducing the tip clearance, say less than about 1 mm. Even in these conditions it occurs with a sufficiently high level if a rod is attached near the leading edge on the suction surface of the blade, as well as if a part of the blade tip is cut off. The fundamental resonance frequency, f, is about 60 70% of the blade passing frequency and is correlated by a Strauhal number as f = S_t. W_D, where S_t = 0.2 and W is the relative velocity. D is the characteristic length, which is without exception equal to the integer multiple of 0.0078 t, where t is the blade pitch.