Reduced Order Clearance Models for Gas Turbine Applications

This paper describes a reduced order model (ROM) developed to predict changes in gas turbine tip clearance – the radial distance between the end of the blade and the stator case. The clearance is estimated by modeling the growth of the sub-components during engine operating conditions. Gas turbine clearances vary significantly during different engine startup and shutdown conditions because of time constant mismatch between interacting sub-components (e.g. rotor and stator). The ROM is developed based on full-fidelity finite element simulation data and can predict the clearance variation as a function of engine thermodynamic conditions. As a result of their real-time execution capability, these models can be used for preliminary design, clearance control, and operational variation studies. The methodology is demonstrated on transient high-pressure compressor stator growth and high-pressure turbine transient clearance data.