2244. New Moment Balance Machine for Turbine Blade Measurement

Paper

Abstract

Balance is a major factor in determining the reliability and service life of turbine rotors used in jet engines or power plants. The task of balancing a completed rotor can be greatly simplified if the individual blades are first measured and sorted according to static unbalance moment. They are then assembled in the rotor in such a way as to compensate for hub unbalance, resulting in an assembly that is approximately balanced. Final balance is then done on a horizontal spin balance machine. Space Electronic has designed a special static balance machine to measure turbine blade moment. Previously this task has been accomplished using knife edge and load cell technology that was developed in the 1950?s. Our machine combines force rebalance with flexure pivots to result in sensitivity and accuracy that is at least 20 times better than the existing state of the art. This paper discusses the various steps in the process of balancing a turbine rotor. the new Space Electronics machine is described in detail. Fixturing is a limiting factor in blade moment measurement. We discuss some of the problems and propose some novel solutions.