A Method for Testing Cascades with Converging Sidewalls

Cascade tests on a set-up equipped with converging lateral walls are more representative of the flow in a section of actual turbomachine than in those with two-dimensional-flow. The experiment is carried out at mid-span, where it is necessary to know the local area contraction evolution in order to get more representative data: for this purpose, a simple computation method has been developed and successfully applied, as shown by the comparison with experimental data. By means of successive approaches, the side wall shape can be defined so that a given area contraction evolution can be obtained at the center.