Efficient Method for Predicting Rotor/Stator Interaction

Many modern turbomachinery blade failures are attributed to high vibratory stresses arising from the interactions between stationary and rotating blade rows. A number of finite difference methods have been developed to predict the interaction within a coupled rotor-stator pair. However, these methods cannot currently be used efficiently in a design and development stage. An alternative approach by using a frequency-domain potential paneling method was developed to predict the forced responses due to rotor-stator interaction: In this approach, the rotor and stator are decoupled and their forced responses are solved separately. The forced response on the downstream blade row is simulated by a single blade row with an unsteady nonuniform inflow. Lakshminar ay ana's wake model was employed as the unsteady forcing function. The unsteady loading on the upstream blade row due to the downstream blade row is assumed to be purely potential. A pseudounsteady approach is used to avoid wake cutting. The nonlinear perturbation is assumed to be much smaller than the mean loading, and only deterministic unsteadiness is considered. The United Technologies Research Center large-scale turbine, which has been used extensively to study rotor/stator aerodynamic and thermodynamic interactions, is revisited here to demonstrate the present capability. The comparison between the predicted results and measurement is very encouraging. The computational time is much smaller than other similar finite difference calculations.