Effect of Tunnel Configuration and Testing Technique on Cascade Performance

An investigation has been conducted to determine the influence of aspect ratio, boundary-layer control by means of slots and porous surfaces, Reynolds number, and tunnel end-wall condition upon the performance of airfoils in cascades. A representative compressor-blade section (the NACA 65-(12)(10) of aspect ratios of 1, 2, and 4 has been tested at low speeds in cascades with solid and with porous side walls. Two-dimensional flow was established in porous-wall cascades of each of the three aspect ratios tested; the flow was not two-dimensional in any of the solid-wall cascades. Turbine-blade sections of aspect ratio 0.83 were tested in cascades with solid and porous side walls and blade sections of aspect ratio 3.33 were tested in cascades with solid wall. No particular advantage was observed in the use of porous walls for the turbine cascades tested.