Unsteady Pressure Field Investigation of an Axial Fan—Inlet and Outlet Unsteady Pressure Field Measurement

Abstract

The unsteady pressure characteristics at inlet and outlet of an axial fan were measured in this study. A 1.829 m (6 ft) diameter axial fan was operated at 1770 rpm in a laboratory. The unsteady pressure field was obtained at three axial positions each with seven radial locations. The results showed that there was a relatively long response time for pressure drop both in the inlet and outlet during fan start-up. The measurements also showed that, due to the vortex shedding from the trailing edge of each fan blade, the fan outlet pressure oscillation frequency was related to the fan operating frequency. A theoretical analysis was also conducted in order to understand the measurements. The unsteady pressure measurements helped improve the fan performance and contributed to the understanding of the vibrational behavior of the fan unit. The complete set of the measurements obtained can be used as a database for computational fluid dynamics (CFD) codes validation and modeling.