128 摩擦力の作用する柔軟回転軸の振動 : 実験

概要

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A soot blower is used to blow off soot on tubes in a tubular heat exchanger, or a gas heater. High frequency vibrations and noises occurred in operation. The soot blower has a long slender tube called a lance tube, 8 m long and 76.2 mm in diameter, which is put slowly into a gas heater. Steam flows through the lance tube and is discharged at the free end to blow off soot. The lance tube rotates slowly about its axis at 12 rpm. At an intermediate position the lance tube is supported by a support bearing called a lance bearing. A lance tube is put into a gas heater slowly, the dominant frequency decreases and then increases abruptly. From frequency analysis the observed frequencies are the seventh to the ninth natural frequencies. Experimental study is done to clarify the mechanism of the vibration. Backward whirling motion of shaft is observed. Higher modes appear as the gap between the flexible shaft rod and the circular support is reduced. They are considered friction induced self-excited vibrations.
一般社団法人日本機械学会の論文
2003-06-04