Numéro : 1910 - Year : 1982
Two-dimensional flow calculation in a diffuser
B.COURBET, Ingénieur de Recherches à l' ONERA
The diffuser is a key element in centrifugal compressors and other fluid machinery. Large improvements have been achieved in this area thanks to the experimental data gathered by several authors. Nevertheless, calculation methods are far less advanced than technical practice. The lack of understanding of complicated physical phenomenons (i,e. rapid boundary-layer growth and possible transitory stall) is the origin of this situation.
The present paper describes the first stages of development of a computational method for the calculation of diffuser flows. Owing to the difficulties of the problem, this first attempt has been restricted to two-dimensional, channel-type geometries Fluid flow equations are discredited in space through a staggered grid technique and integrated in time by a second order implicit method. Reynolds stresses are taken into account through an algebraic eddy-viscosity model and preinte grated wall functions. An orthogonal coordinate system generation technique allows the treatment of arbitrary smooth channel geometries.
The first computational results are relatively consistent with experimental data for mode rate divergence angles. More systematic tests should allow an improvement of the method.
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