MODELING OF VARIABLE AERODYNAMIC FORCES IN TURBINE BASED ON EXPERIMENTAL DATA

Effective methods of vibration diagnostics of a turbomachine’s flow duct are necessary for efficient condition based maintenance. Modern equipments provide extended opportunities for vibration measurements. However, there are few adequate models of high frequency vibration. A majority of the existing diagnostic techniques are limited within the low frequency range. This paper suggests the variable forces model intended for high frequency vibration diagnostics. For modeling of variable forces acting on the vane the test series are performed using a two-stage air test turbine. High frequency signals of total pressure and casing vibration are measured in order to investigate the airflow and vibration structure generated by the blades. Parameters of the blade wake are investigated and the wake’s dual nature is determined. Harmonic and random components of blade wakes are related to specific blade aerodynamic features as well as upstream airflow characteristics. Air duct failures are simulated with upstream static and rotating disturbances. The model of flow velocity oscillation, which acconts for both harmonic and random features of blade wakes is presented. Dynamic forces acting on a single vane are also modeled based on the model of blade wakes.QC 2012011