Characterization of the Unsteady Aerodynamics of Optimized Turbine Blade Tips through Modal Decomposition Analysis

Abstract

The present research focused on the analysis of the leakage flows developing from advanced blade tip geometries. The aerodynamic field of a contoured blade tip and of a high-performance rimmed blade were investigated against a baseline squealer rotor. Time-resolved numerical predictions were combined with high-frequency pressure measurements to characterize the tip leakage flow of each tip design. High spatial and temporal resolution measurements provided a detailed representation of the unsteady flow in the near-tip region and at the stage outlet. Numerical computations, based on the nonlinear harmonic method, were employed to assess the unsteady blade row interactions and identify the loss generation mechanisms depending on the tip design. The space- and time-resolved flow field was analysed by modal decomposition to identify the main periodicities of the near-tip and outlet flow and classify the most relevant sources of aerodynamic unsteadiness and entropy generation across the stage.

A novel method for the natural frequency estimation of the jet engine turbine blades based on its dimensions

“…There are also other experimental methods for natural frequency estimation, an example is Estimation of Turbine Blade Natural Frequencies from Casing Pressure and Vibration Measurements where the authors described experimental frequency identification by using the casing pressure [ 15 ]. There can be found a large number of different methods for natural frequency estimation that are meant for various purposes [ [16] , [17] , [18] ]. There are many methods that are used for natural frequency estimation, however, each of them requires a huge amount of time in terms of the testing set up, etc.…”