水力ターボ機械の実オイラーヘッドに及ぼす寸法効果

抄録

The effect of difference between discharge flow angles from model runners and prototype ones on the actual Euler's head and the efficiency of hydraulic turbo-machines are discussed by using the scale effect formula used at present. Then discharge flow angles from the flat plate cascades similar to the runner vanes of models and prototypes are decided under consideration of boundary layer thickness which changes with Reynolds number and surface roughness. The discharge flow angle difference Δα between models and prototypes and the increase in efficiency en from the efficiency step-up formula are estimated as follows: Francis Turbine (N_SQ= 62):Δα= 0.047°, Δη= 0.17% Francis Pump-turbine (N_SQ= 33):Δα= 0.079°, Δη= 0.10% The same as above (pump op.):Δα= 0.079°, Δη=0 Kaplan Turbine (N_SQ =109):Δα=0.017°, ΔΔ=0.27% where N_SQ is the discharge specific speed.