Evaluation of Experimental Forced Response Data of a Turbine Stage with Respect to different Stator Blade Damages : Verification of the Superposition Principle for Unsteady Pressure Distribution

This thesis work is based on the evaluation of experimental forced response data of a turbine stage with respect to different excitation sources. Six stator blade configurations are considered with three types of damage blades, i.e. triangular, rectangular and quadrilateral damages arranged at different positions around the circumference of the stator ring. Post processing routines are developed to evaluate the forced response data of all the sensors attached to the rotor disk for all configurations and at different stator positions. Methods for averaging of the pressure data have been proposed. Unsteady pressure distribution around blade surface is computed using the forced response from each sensor mounted on the blade. Important task is to verify the principle of superposition for configuration 05 and 06 by taking into account the single damage pattern from configurations 02-04. This principle has been verified in this thesis. A method has been proposed for the scaling of the unsteady pressure distribution for different damage sizes of same type based on some size parameter, based on which forced response for any size of damage blade can be deduced. Finally, the thesis concludes with a detail sensitivity study and discussion of the results together with proposed future work