THE PREDICTION OF PRESSURE FLUCTUATIONS OF A FRANCIS TURBINE

摘要

The pressure fluctuations were predicted inside draft tube, in the front of runner, guide vanes, stay vanes, and at spiral case inlet by using three-dimensional unsteady turbulent flow simulation through the whole passage of a Francis hydraulic turbine. The calculated pressure fluctuations were compared with test data of model turbine experiment, which showed that the calculation could be used to simulate the pressure fluctuation in draft tube well. And the helical vortex rope in draft tube was analyzed to get the principle of its production and spread. Then the calculated results of the whole passage were analyzed, which demonstrated that the unsteady vortex rope in draft tube, rotor-stator interaction between guide vanes and runner were two main factors bringing the pressure fluctuations in turbine.