Periodic Reporting for period 3 - ASTORIA (Advanced Steady and unsTeady distORtion sImulAtor)
Reporting period: 2022-10-01 to 2023-08-31
To accelerate the path towards a net-zero carbon emission target by 2050, great efforts are made to develop more efficient and novel aircraft engine architectures. Advanced engine configurations such as Ultra High Bypass Ratio (UHBR) engines with short nacelle layouts, Blended Wing Bodies (BWB), or Boundary Layer Ingestion (BLI) configurations experience much higher levels of flow distortion at the fan inlet compared to current configurations. Since engine performance, operability, and vibration can be drastically affected by the non-uniformity of the inlet flow, extensive testing is an essential part of the design process in order to assess engine-airframe incompatibilities. This requires devices that can accurately and flexibly recreate complex total pressure and swirl distortion cartographies in test environments.
The Clean Sky 2 project ASTORIA has focused on developing and testing of radically new design methodologies for such distortion generating devices. Its objective was to develop a set of numerical and experimental tools and associated methodologies allowing sound and reliable parametric studies aiming at replicating and understanding the impact of a wide variety of distortion patterns. To achieve this, ASTORIA's main targets were:
1. The development of a unique methodology for the design of optimised tailored multicomponent distortion simulator devices able to provide the required combined total pressure and swirl steady pattern at a specific distance from the generator.
2. To provide a proof of concept for the design of unsteady patterns distortion simulators.
3. To validate steady and unsteady patterns design methodologies through extensive experimental testing in precisely controlled conditions.
4. To implement the validated methodology within a highly modular and flexible software tool set.
Through strong numerical/experimental synergies, ASTORIA's key results include the development and application of the screen design methodology for realistic and complex distortion generating devices and the delivery of the software toolset for the screen design. The analysis of the experimental results and the back-to-back comparison with numerical simulations have allowed to validate the design methodology and to confirm the ability of the coupled strategy to reproduce the targeted distortion patterns. Valuable lessons to further improve the design methodology as well as to enhance a tailored measurement campaign for turbomachinery components under distortion have been identified and will be addressed and applied in future projects.
The Clean Sky 2 project ASTORIA has focused on developing and testing of radically new design methodologies for such distortion generating devices. Its objective was to develop a set of numerical and experimental tools and associated methodologies allowing sound and reliable parametric studies aiming at replicating and understanding the impact of a wide variety of distortion patterns. To achieve this, ASTORIA's main targets were:
1. The development of a unique methodology for the design of optimised tailored multicomponent distortion simulator devices able to provide the required combined total pressure and swirl steady pattern at a specific distance from the generator.
2. To provide a proof of concept for the design of unsteady patterns distortion simulators.
3. To validate steady and unsteady patterns design methodologies through extensive experimental testing in precisely controlled conditions.
4. To implement the validated methodology within a highly modular and flexible software tool set.
Through strong numerical/experimental synergies, ASTORIA's key results include the development and application of the screen design methodology for realistic and complex distortion generating devices and the delivery of the software toolset for the screen design. The analysis of the experimental results and the back-to-back comparison with numerical simulations have allowed to validate the design methodology and to confirm the ability of the coupled strategy to reproduce the targeted distortion patterns. Valuable lessons to further improve the design methodology as well as to enhance a tailored measurement campaign for turbomachinery components under distortion have been identified and will be addressed and applied in future projects.
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.
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.
The development and validation of the methodology to design these distortion generating devices directly contribute to the development and testing of novel engines and innovative aircraft-engine integrations. In line with the specific role of the LPA IADP in Clean Sky 2, the results of ASTORIA support TRL6 testing for large-scale integrated demonstrator platforms to mature breakthrough technologies and facilitate "virtual testing" by creating, establishing, maturing, and calibrating tools and numerical simulations. The resulting tools and lessons learnt have already been exploited by the Walloon Region project WINGS and can support design and testing challenges within Clean Aviation or other innovative projects that contribute to achieving Europe's Green Deal objectives.