| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce the mutual interference noise of moving blades, in the jet fan for a road runnel ventilation requiring the same blow out wind speed, even at either one of normal/reverse rotation times. SOLUTION: The number of moving blades 5a, 5b of respective impellers 3a, 3b is made different and the number of the moving blade of one impeller which is larger than that of the other is except the natural number times of the latter and the installation interval of the moving blades 5a, 5b is constituted to be constant at the respective impellers 3a, 3b. Therefore, as the frequency of speed variation of the slip stream of a first step moving blade is not matched with the rotation frequency of a second step moving blade, the interference noise generated by these interference can be reduced. Thus, the noise of the jet fan for a road tunnel ventilation can be reduced and the silencer length can be shortened and simplified.</p> |
