DESIGN OF GUIDE VANES FOR MINIMIZING THE PRESSURE LOSS IN SHARP BENDS

A guide-vane section was designed with the aim of minimizing the pressure drop for flow in a 90-degrees corner. A central part of the design process was to use potential flow calculations in order to obtain a vane geometry such that the velocity distribution on the suction side replicates that of a chosen single airfoil (Wortmann FX60-100) at the angle of attack for maximum lift/drag in a straight free stream. The choice was based on proven good drag characteristics at low Reynolds numbers. For the design of the pressure-side velocity distribution advantage was taken of the expansion in the middle part of the cascade to obtain a high pressure coefficient on the pressure side, as compared to the single airfoil case. Vanes were built and tested in a special-purpose wind tunnel. The two-dimensional pressure-loss coefficient, as measured downstream of a five-vane corner, was found to be as low as 0.036, which is about one-fifth of that for traditional 1/4-circle-shaped vanes.