REDUCING THE DISCHARGE SIDE NOISE EMISSION IN RADIAL FLOW FANS WITH ABSORBENT COVER INSIDE THE SPIRAL CASING

The discharge noise emission in radial flow fans may be reduced by providing a sound absorbing inner cover for the spiral casing. The literature is fairly brief on the aspects of constructing such fans with covered walls. This paper summarises the results of tests, which give an insight into the effect of the variables and show solutions to certain constructional problems. On the basis of the tests it is possible to propose an absorbing structure with a good noise reduction effect, which is also economical to make. The experimental machines used made it possible to apply many variations of quality and quantity in the absorbing material and of the position and shape of same in the absorbing structure