FLOW BEHAVIOR AROUND STAYVANES AND GUIDEVANES OF A FRANCIS TURBINE

The three-dimensional computation of steady and incompressible interna l flows is of interest ill numerical simulations of turbomachinery, an d such simulations are currently under investigation, from inviscid to viscous flow analyses. First, surface pressure distributions have bee n measured for the stayvanes and the guidevanes of a Francis turbine. They are presented to verify the numerical results. Second, both invis cid and viscous three-dimensional flow analyses have been made, so as to predict the flow behavior in the same domain. Comparison of the mea sured pressure distributions to the predicted pressure distributions h as been made to study the usefulness of the present simulations. it ca n be pointed out that a global analysis which includes a runner flow p assage except runner blades, is necessary to predict the three-dimensi onal flow characteristics and that inviscid flow analysis has the capa bility of good prediction for flow without separation. Viscous flow an alysis gives similar results, though it is necessary to investigate fu rther the improvement of prediction accuracy. Flow characteristics aro und the stayvanes and the guidevanes are also discussed.