ROTORDYNAMIC FORCES DUE TO TURBINE TIP LEAKAGE .2. RADIUS SCALE EFFECTS AND EXPERIMENTAL-VERIFICATION

This paper presents a radius scale actuator disk model, which describe s the flow response to a whirling/spinning rotor in an unshrouded turb ine. At each azimuth, the upstream-downstream flow variables are march ed by the results from a steady blade scale analysis presented in a co mpanion paper, with allowance for mass storage in the stator-rotor reg ion. The new model can accurately predict the magnitude of both direct and cross excitation forces as well as their breakdown into work extr action and pressure effects. The trends versus the mean flow coefficie nt and interblade distance are predicted. While underpredicted, a tren d versus mean rotor tip clearance height is also indicated. Thus, the new model captures the dominant physical effects caused by a whirling/ spinning rotor in an unshrouded turbine.