UNSTEADY FLUID FORCES ON A BLADE IN A CROSS-FLOW TURBINE

The internal flow in a cross-flow turbine is nonuniform because the wa ter passes through only part of the runner. Therefore, the unsteady fl uid forces act on a blade through rotation. Experimental and theoretic al studies for determination of fluid forces on the blade in a cross-f low turbine are conducted. In the experiment, the tangential and radia l forces are measured on a test blade using strain gauges and slip rin gs. On the other hand, in the theoretical study, they are calculated n umerically using the unsteady momentum theory. The calculated results are compared with experimental data and good agreement is demonstrated . Furthermore, the maximum forces are found to occur immediately befor e the blade leaves the nozzle exit in both the experimental and theore tical results.