During the design process of fans and compressors, rapid computation of performance characteristics at various operating points is essential. In view of estimating off-design performance, the prediction of compressible separated flow is needed.

A method has been developed for predicting such flows in 2-D cascades, with varying blade-height, based on an iterative viscous-inviscid interaction approach. Inviscid flow is simulated using a panel method. The effects of compressibility and streamsheet convergence or divergence are taken into account by singularities distributed in the interior of the flowfield.

Viscous flow is simulated using an integral boundary-layer method, till the point of separation. Laminar and transitory separation bubbles are modelled semi-empirically. Separated-flow regions are simulated using a free streamline model.

The method has been systematically compared with available experimental data and has shown very good agreement concerning the prediction of pressure distribution, deviation angle and loss coefficient, from negative to positive stall and for a wide range of Reynolds number and subsonic Mach number. The method is an interesting performance analysis tool due to its rapidity and reliability.

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