His call is bracing but melodious, although once he sets to work on a blade, the noise of grindstone on metal brings out the old women with their beloved worn-out cleavers.
Then there's increasing the number of rotor blades. This helps because each additional blade carries less of the weight of the helicopter, and thus produces less noise.
增加旋翼桨叶数量也是一种方法,这使得每片桨叶负载的直升机重量降低了,因此产生的噪音更小。
3
It has been found that wake loss of the blade has a great impact on the performance and stability of Turbomachinery, and also has been recognized as one of main noise sources of Turbomachinery.