Numerical Investigation of Influence of Entropy Wave on the Acoustic and Wall Heat Transfer Characteristics of a High-Pressure Turbine Guide Vane

Abstract

<jats:p>As an indirect noise source generated in the combustion chamber, entropy waves are widely prevalent in modern gas turbines and aero-engines. In the present work, the influence of entropy waves on the downstream flow field of a turbine guide vane is investigated. The work is mainly based on a well-known experimental configuration called LS89. Two different turbulence models are used in the simulations which are the standard k-ω model and the scale-adaptive simulation (SAS) model. In order to handle the potential transition issue, Menter’s ð-Reθ transition model is coupled with both models. The baseline cases are first simulated with the two different turbulence models without any incoming perturbation. Then one forced case with an entropy wave train set at the turbine inlet at a given frequency and amplitude is simulated. Results show that the downstream maximum Mach number is rising from 0.98 to 1.16, because the entropy waves increase the local temperature of the flow field; also, the torque of the vane varies as the entropy waves go through, the magnitude of the oscillation is 7% of the unforced case. For the wall (both suction and pressure side of the vane) heat transfer, the entropy waves make the maximum heat transfer coefficient nearly twice as the large at the leading edge, while the minimum heat transfer coefficient stays at a low level. As for the averaged normalized heat transfer coefficient, a maximum difference of 30% appears between the baseline case and the forced case. Besides, during the transmission process of entropy waves, the local pressure fluctuates with the wake vortex shedding. The oscillation magnitude of the pressure wave at the throat is found to be enhanced due to the inlet entropy wave by applying the dynamic mode decomposition (DMD) method. Moreover, the transmission coefficient of the entropy waves, and the reflection and transmission coefficients of acoustic waves are calculated.</jats:p>

Effect of clocking on entropy noise generation within an aeronautical high pressure turbine stage

“…For pressure turbine stages, an experimental assessment on the indirect noise generation (for the same turbine stage numerically studied in this paper) can be found in the work from Knobloch et al [13] and describes the main outcomes of the European Project RECORD. Numerical simulations based on LES approach, for entropy noise prediction of turbine guide vane were performed by Hu et al [14] and by Winkler et al [15], while a realistic turbine stage was studied by Becerril et al [16]. This work reports on the natural continuation of previous studies by the authors who already presented an in-depth experimental [17] [18] and numerical study of hot streak propagation [19] and entropy wave evolution [20] within an high pressure turbine stage installed in the test rig at the Politecnico di Milano.…”