| 摘要 |
PROBLEM TO BE SOLVED: To reduce aerodynamic sound generated from a recessed part with a bar foamed on an object exposed to high speed air flow. SOLUTION: When air flow F flows in a direction crossing a bar body Q within the recessed part P formed on the surface S of the object, inclined surfaces R and R are substantially face-symmetrically formed in both regions which face to the air flow F and become leeward side and windward side of air flow F, of an inside surface of the recessed part P and the position of the bar body Q is set on not the surface S of the object but on a depth side of the recessed part P. Disturbance of air flow which flows into the recessed part P and collides with the inside surface on the leeward side is suppressed by making the inside surface on the leeward side as an inclined surface and thereby an aerodynamic sound level is lowered. Since the inclined surfaces R and R are substantially face-symmetrically formed across the bar body Q, the formation is effectively applied to reducing of aerodynamic sound also when air flow F flows in both of reverse and normal directions. Therefore, this structure is effective especially for reducing noise in a reciprocating operating object such as a rolling stock.
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