Investigation of Three-Dimensional Subsonic Flow in Straight Cascades by Means of Potential Flow Calculations and Experiments

摘要

Calculation methods for three dimensional, incompressible potential flow in straight cascades having arbitrarily shaped end walls are developed. A singularity model was constructed which represents the blades by means of vortex sheet elements and the end walls by means of source sheet elements. This method calculates the influence of blade height and end wall shape on the velocity distribution in the cascade mean section using a small amount of computer time. This model is extended to the three dimensional panel model by means of additionally introduced area sources (panels) and enables the calculation of fully three dimensional flow in the entire passage of the cascade with aerodynamic blade and wall interaction. Both methods are exemplified by means of two compressor cascades and are compared to one another and to quasi three dimensional methods. A parameter study demonstrates the influence of blade height, end wall contraction and end wall shape. A corresponding experiment provides test data on the surface pressure distribution in a passage of a compressor cascade.