Some tests on compressor cascades of related aerofoils having different positions of maximum camber

Abstract

One of the major variables defining the shape of any blade is its position of maximum camber, and there are several indications that its choice considerably effects the performance of the cascade. Tests have therefore been carried out on a series of aerodynamically equivalent cascades in which the position of maximum camber was varied systematically. The tests covered a full incidence range up to choking. From the results and consideration of other work the following conclusions were reached. (1) Bringing the position of maximum camber forward gives a wider working range and a higher choking mass flow. (2) Moving the position of maximum camber back gives a higher work capacity and a higher drag critical Mach number. (3) With the present design rules there can be little doubt that the best all-round performance is obtained with blades having their positions of maximum camber 50 per cent of the chord from the leading edge provided adequate throat area Call be provided with this design. (4) With improved methods of design it is anticipated that the performance for the other positions of maximum camber could be improved, but even so the best combination of large working range and good high-speed performance appears to occur for a blade having its position of maximum camber as in (3) above. These conclusions apply to the two-dimensional performance of a cascade of blades : in an actual compressor the results may have to be modified to accommodate the three-dimensional nature of the flow.