1. Following a detailed literature survey on the state-of-the-art and review of the initially proposed design methodology, a numerical methodology was developed that enables to design a two-component distortion device consisting of a honeycomb screen for the total pressure and a turning vanes assembly for the swirl distortion (see Figure). This type of device is manufacturable with additive manufacturing for maximum flexibility, and is adapted to reproduce complex and realistic patterns with high levels of total pressure distortion and flow angle magnitudes.
Preliminary design tools have been developed for the separate components. An isolated honeycomb total pressure screen was considered to reproduce a canonical total pressure loss pattern with mixed radial and circumferential distortion, as well as an isolated swirl vanes assembly generating two counter-rotating vortices. This has allowed to validate the preliminary design tools developed for each separate component. Next, a multi-fidelity modelling approach was developed for the two-component device, which combines a simplified aerodynamic model of the total pressure screen with detailed steady CFD computations of the turning vanes assembly. This allows to jointly optimise the two components by means of a surrogate-based optimisation (SBO) strategy, thus taking into account their coupling. Four realistic BLI-configuration patterns with high levels of total pressure distortion and flow angles have been considered for the design of the distortion-generating devices for the experimental test campaign. This design exercise has highlighted the capability of the SBO strategy to fine-tune the preliminary components and counter-balance the effect of the downstream propagation on the produced distortion pattern. Clear improvements are obtained on the patterns shapes after the optimisation. The SBO strategy also allows to easily account for various constraints, such as manufacturing constraints, or constraints linked to operability of the destination ground test-rig.
2. In parallel with the numerical developments, the experimental facility has been designed and prepared to test the distortion-generating devices. The VKI R4 high-speed closed-loop test rig has been modified to host a new test section for characterising distortion devices at independently variable Reynolds and Mach numbers. The redesign of the facility was performed in order to ensure that the facility could be operated with an acceptable safety margin while providing the required flow conditions at the measurement section. During the redesign, special attention has been paid on the richness and capabilities of the instrumentation techniques for the test campaign. Both five-hole pressure probe measurements as well as detailed state-of-the-art stereoscopic particle image velocimetry (SPIV) capturing have been foreseen.
3. The two canonical screens, as well as two distinct two-component screens for realistic BLI distortion patterns have been printed using additive manufacturing. For the testing of the isolated canonical screens, SPIV measurements and the five-hole pressure probe measurements have been employed, allowing for the comparison between the two techniques. For the testing of the combined screens reproducing the realistic distortion patterns, probe measurements have been performed at different Mach numbers.
A scientific dissemination of the results is ongoing through the submission of two peer-reviewed publications for the upcoming ASME TurboExpo conference. The experimental facility and measurement capabilities have already been presented during an international conference on Measuring Techniques in Turbomachinery. A further dissemination is planned through the organisation of a Lecture Series at VKI on Aircraft Engine Technologies in Fall 2024.
Further maturation of the ASTORIA methodology as well as the application for experimental large scale test demonstrators are foreseen through the setup of dedicated project proposals for regional, national, and European research calls.
