Abstract: Further study on interturbine guide vanes is necessary, as they account for up to 40% of the total head loss in hydraulic turbine mode. Among interstage guide vanes available, the runner type is good in hydraulic performance, because it integrates guide vanes and return guide vanes together and its flow passage is relatively independent. Based on the theory of hydraulic prime mover, this paper describes new designs of runner-type vanes that match the turbine mode, with the concept of flow loop running through the whole design procedure of a hydraulic turbine runner. An optimization algorithm of orthogonal tests is adopted to design orthogonal test schemes for four main factors: guide blade angle φ, guide blade outlet angle , return guide blade width , and the maximum diameter of the flow passage outer wall; and each is tested at four levels. Influence of each factor on guide blade performances are evaluated through CFD calculations and comparative analysis of the performances in different schemes. On this basis, we achieve a guide blade design of higher efficiency; its hydraulic performance, blade surface pressure distributions, and blade internal flow patterns are analyzed. The results of range analysis show that among the influences of different parameters on efficiency, is the largest and the smallest; on water head, is the largest and φ the smallest. Though optimizing the model, its efficiency is increased by 5.83% at the design point, applied head increased by 7.15%, and interstage guide vane loss reduced by 1.16%. And water flows in the blade passages are more stable. Thus, the optimized model meets the requirements of energy recovery from the high residual pressure liquid in hydraulic turbines, providing a useful design and optimization approach for the runner-type guide vanes of hydraulic turbines.

Key words: turbine-mode hydraulic turbine, runner type guide vane, orthogonal experiment, efficiency, water head