Measurement of Nonsteady Forces in Three Turbine Stage Geometries Using the Hydraulic Analogy

Abstract

Experimental results for the nonsteady forces and nonsteady torques acting at the e.g. of an instrumented moving turbine blade have been obtained. Three different turbine stage geometries have been tested in this manner. The data described was obtained using a rotating model turbine stage consisting of a row of stationary inlet nozzles and a rotating blade row. The hydraulic analogy was used to stimulate the two-dimensional gasdynamic flow through the three stage geometries in turn. The free-surface horizontal flow of water across the rotating water table then represents the gas flow through the stage. Results for the nonsteady forces and torques in the tangential, axial, and torsional directions are presented as dimensionless force ratios or dimensionless torque ratios in each instance. Charts of results are presented for various stage pressure ratios, for practical ranges of stage velocity ratios. Typical results and observed trends are discussed in detail, and a summary table of observed nonsteady excitation values is presented.