Prediction of Sound Pressure Level of Turbulent Noise for a Radial Flow Fan : Effects of Inner Diameter of the Impeller, Span Length, Volute angle of the Casing and Number of the Blades

We investigated the effects of the span length, the inner diameter of impeller, the number of blades, the volute angle on the turbulent noise and discussed the turbulent noise in relation to the flow condition around rotor blades ; the wake width and the relative velocities. Moreover, we examined the validity of predicted equation of turbulent noise for a radial fan. As a result it was concluded as follows. (1) The turbulent noise became high as the span length became long, (2) The 120 blade impeller was most low for the turbulent noise among 60, 120, 180 blade impellers. (3) The turbulent noise was low and the flow rate region of low noise was wide as the inner diameter was small. (4) If the wake width and the relative velocity were given, the turbulent noise can be estimated from equation (1) and (2) over the whole flow rate containing the low flow rate region