Imbalance between Centrifugal Force and Pressure Gradient around a Blade Row

Abstract

It is important to know the deviation from the two dimensional flowfield in an axial-flow fan. In general, the centrifugal force and pressure gradient in radial direction in the flowfield around a blade row designed as a free vortex design do not balance except in the far field. Imbalance between the two forces was calculated based upon a two-dimensional potential-fiow theory. The calculations of the flow inside and outside a blade passage were carried out by the method of conformal mapping. Imbalance of a large scale over one blade pitch was found to dominate over the other ones of small scales and this was also found to be large in magnitude especially near the leading edge of the blade. It is highly probable that the effect has a nonnegligible influence on turbomachine characteristics.