Méthodes de tracé des turbomachines hydrauliques

Design methods for hydraulic turbomachines

Société NEYRPIC

Abstract

There are three basic conditions for modern hydraulic turbomachine design : 1) higher output, 2) more compact dimensions and lower cost, and 3) better performance. To meet these requirements, designers must be thoroughly familiar with modern theory and the application of detail corrections established by experimental model research, and thus be able to optimise both hydraulic and economic features of turbomachine components. Stay vane, guide vane and runner blading designs are optimised by consideration of quasi three-dimensional blading grid theory, starting out from irrotational flow conditions over an axisymmetric surface and flow continuity conditions in the elementary turbine (Fig. 1). In applying these calculated results (for an ideal fluid) the designer must rely on experimental data. The final design must meet all hydraulic, mechanical stress and (sometimes) economic requirements. The same applies to the volute, design of which is based on both experimental and theoretical calculation data. Optimisation of the diffuser on the other hand is based exclusively on experimental model data (exploratory flow measurement). Component geometry, especially of rotor bladings, is determined by mathematical design procedure, whereby both hydraulic and mechanical conditions can be taken into account in establishing an optimal design, and which ensures very much earlier availability of manufacturing drawings of the bladings. A brief summary of present-day turbomachine performance data in this report adds substance to Authors' calculation and test data, which they are applying in their current design procedure.