Conference_programme: 2.1 - Aeroacoustics
Lecture: Experimental investigation of the off-design sound emission of low-pressure axial fans with different fan blade skew
Author(s): Krömer Florian, Becker Stefan
Summary:
The design of low-pressure axial fans usually relies on design parameters for a specific operating points, such as the volume flow rate and the pressure rise. However, in complex ventilation systems, these design parameters are often hard to anticipate at the time the fan design needs to be selected. This often leads to an off-design operating point of the axial fan, which in turn affects both the aerodynamics and the aeroacoustics of the fan.\nFor investigating the impact of off-design operating conditions on the aerodynamic and aeroacoustic characteristics of low-pressure axial fans, an experimental study was made with a forward- and a backward-skewed fan that had similar design parameters. For these fans, the characteristic curves and the sound emission were studied. On the one hand, the investigations were made at matching rotational speeds of both fans, which led to non-matching operating conditions at some regions along the characteristic curves. On the other hand, the rotational speed of one fan was adjusted to ensure matching operating conditions with identical pressure rise and volume flow rate at all investigated operating points.\nThe characteristic curves show that with matching rotational speeds, the forward-skewed fan achieves a higher pressure rise in the stall region and the backward-skewed achieves a higher pressure rise at even lower volume flow rates. With matching rotational speeds, the forward-skewed fan has a lower sound emission in the range of the design volume flow rate and in the stall region, whereas the backward-skewed fan has a lower sound emission at very low and very high volume flow rates. This effect is even greater under matching operating conditions.\nBased on these findings, the forward-skewed fan is the best choice as long as the actual operating point does not differ excessively from the design point and clean inflow conditions can be guaranteed.
Corresponding author
Name: Mr Florian Krömer
e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Country: Germany
