2022, Jacob, Stefan, Trigell, Emelie, Mihaescu, Mihai, Åbom, Mats

Numerical solutions of acoustic wave scattering are often used to describe sound propagation through complex geometries. For cases with flow, various forms of the convected equation have been used. A better alternative that includes vortex-sound interaction is instead to use the linearized and harmonic forms of the unsteady fluid flow governing equations. In this paper, a formulation of the linearized equations that include rotational effects, in an acoustic computation using a rotating frame of reference in a stationary geometry, is presented. We demonstrate that rotational effects can be important, e.g., when computing the transmission loss through high-speed compressors. The implementation of the proposed addition to the existing schemes is both simple and numerically inexpensive. The results are expected to have an impact on the research and development related to noise control of high-performance turbo-machinery, e.g., used in automotive or aviation applications at operating conditions that can be represented by steady background flows.

2023, del Moral, Jaime, Montes, Laura, Rico‐Gavira, Victor Joaquin, López‐Santos, Carmen, Jacob, Stefan, Oliva‐Ramirez, Manuel, Gil‐Rostra, Jorge, Fakhfouri, Armaghan, Pandey, Shilpi, Gonzalez del Val, Miguel, Mora, Julio, García‐Gallego, Paloma, Ibáñez‐Ibáñez, Pablo Francisco, Rodríguez‐Valverde, Miguel Angel, Winkler, Andreas, Borrás, Ana, González‐Elipe, Agustin Rodriguez

Icing has become a hot topic both in academia and in the industry given its implications in transport, wind turbines, photovoltaics, and telecommunications. Recently proposed de-icing solutions involving the propagation of acoustic waves (AWs) at suitable substrates may open the path for a sustainable alternative to standard de-icing or anti-icing procedures. Herein, the fundamental interactions are unraveled that contribute to the de-icing and/or hinder the icing on AW-activated substrates. The response toward icing of a reliable model system consisting of a piezoelectric plate activated by extended electrodes is characterized at a laboratory scale and in an icing wind tunnel under realistic conditions. Experiments show that surface modification with anti-icing functionalities provides a synergistic response when activated with AWs. A thoughtful analysis of the resonance frequency dependence on experimental variables such as temperature, ice formation, or wind velocity demonstrates the application of AW devices for real-time monitoring of icing processes.