16:00
High order methods
Chair: Daniella Raveh
16:00
30 mins
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Effect of Turbulent Wedges on the Steady and Unsteady Aerodynamics of a Forward Swept Laminar Wing
Michael Fehrs, Christoph Kaiser
Abstract: Within the LuFo VI/2 project ULTIMATE, steady and unsteady wind tunnel tests in the European Transonic Windtunnel on a forward swept laminar wing configuration are conducted. The wind tunnel data are used to validate intermittency-based transition models in high Reynolds and transonic Mach number flows. This article presents a comparison of experimental data from the first steady wind tunnel campaign with coupled CFD-CSM computations. In the wind tunnel, turbulent wedges develop on the wing surface due to surface imperfections or surface contamination. Once these known turbulent wedges are included in the CFD-CSM simulation, a more precise computation of the aerodynamics of the wind tunnel model is possible. Additionally, the effect of the turbulent wedges on the unsteady aerodynamics is demonstrated
for an unsteady pitching wing.
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16:30
30 mins
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Numerical Analysis of the Unsteady Wing-Tailplane Interaction in Two-Dimensional Flows
Kristopher Davies, Michael Fehrs
Abstract: The buffet phenomenon is commonly associated to the self-induced unsteady motion of a shock as a result of an interaction with the separated boundary layer on a wing in transonic conditions. Another unsteady flow phenomenon linked to separated flows is the so-called horizontal tailplane (HTP) buffet. Contrary to shock buffet, HTP buffet is an externally induced unsteadiness and is the consequence of turbulent structures convecting from the separated wing to the tailplane. This leads to fluctuations of the pressure distribution (buffet) and structural vibrations (buffeting) of the HTP. However, the dominating flow mechanisms and the critical frequency range causing HTP buffet are insufficiently understood.
This work aims to study the flow interaction between the (separated) wing, its wake, and the tailplane in more detail. In this context, potential critical flight conditions in terms of HTP buffet need to be identified. This requires a variation of flow parameters, in particular the Mach number, Reynolds number, and angle of attack. Potentially, a multitude of flight conditions have to be considered, which requires a compromise between justifiable computing times and an adequate capturing of the most relevant unsteady flow effects. For this reason, this analysis is performed based on unsteady RANS simulations using a Reynolds Stress Model (RSM). This study is initially focussing on two-dimensional flows and is a prerequisite to understand similar effects on a more complex industrial configuration. In order to reproduce a realistic configuration of the wing and tailplane, the applied geometry is extracted based on the NASA Common Research Model (CRM) at a constant spanwise position.
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17:00
30 mins
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A CFD/CTD/CSD based aero-thermo-elastic framework for full-vehicle scale analysis
Liang Ma, Zhiqiang Wan, Xiaozhe Wang, Keyu Li, Chang Li, Longfei He
Abstract: Due to the significant multidisciplinary coupling mechanism inherent in hypersonic flight mission, unnecessary and wasteful trade-off in vehicle performance will be cost if complex load distribution and aerodynamic heating effect are neglected at the early stage of design. This paper establishes an CFD/CTD/CSD based aero-thermo-elastic framework for analysis of the full-vehicle scale. The loose coupling strategy is chosen in this framework to reveal the specific efforts of each disciplinary, and the RBF-TFI method is introduced for mesh deformation. This study is carried on the rudders assembled on a hypersonic missile, with the high-fidelity aerodynamic data of the full-vehicle model extracted by CFD and only the component deformation of the rudders extracted by FEM. This paper demonstrates the aero-thermo-elastic effects of those factors concealed by engineering algorithms, with the influence mechanism revealed from the results discussed.
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17:30
30 mins
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Adaptive Euler - efficient and predictive aerodynamics: validation and prototype development toward aeroelasticity
Johan Jansson, Kristoffer Wingstedt, Rebecca Durst
Abstract: We describe the Adaptive Euler methodology, and results from the High Lift Prediction Workshops with focus on the current HLPW5, showing good validation and high efficiency [1]. Adaptive Euler is first principles FEM simulation with adjoint-based adaptive error control, realized with automated discretization from mathematical notation in our FEniCS [8] framework. We describe a prototype extension of the methodology to aeroelasticity also with adjoint-based adaptive error control, such methods are highlighted as having “great potential” in the field of aeroelasticity in [7]
We show that by the Adaptive Euler by the scientific method in our reproducible Digital Math framework predicts drag, lift, pitch moment and pressure distribution in close correspondence with experiments in the 4th and 5th High Lift Prediction Workshops, with very high efficiency, estimated to 100x faster and cheaper than RANS, the industry standard for efficient aerodynamics, corresponding to appx. 100 core hours on a commodity computational resource.
The guiding incentive for this work is to develop an efficient and versatile tool for aeroelasticity modeling with the Adaptive Euler methodology. Such a product is highly sought after and is motivated in part by the CFD Vision 2030 set by NASA and the Certification by Analysis 2040 Vision set by Boeing. The consequences of this would include–but are not limited to–the eventual development of a full fluid-structure interaction (FSI) framework that may be used for applications in aerospace engineering. As such, we present numerical simulations designed to test benchmark problems in the field of aeroelasticity. These problems are chosen based on their relevance to current challenges and potential for extension, and the results are compared to experimental data when available. We view these simulations as critical building blocks towards the development of a full Adaptive Euler framework for aeroelasticity.
References
[1] Jansson, J., Johnson, C., & Scott, R. (2022). Predictive Euler CFD-Resolution of NASA Vision 2030. In AIAA AVIATION 2022 Forum (p. 3589).
[2] Johan Jansson (jjan@kth.se), Claes Johnson, L. Ridgway Scott, Rebecca Durst, Predictive Aerodynamics: Adaptive Euler Real Flight Simulation http://digitalmath.tech/hiliftpw4-aiaa
[3] http://digimat.tech/paper-euler-short/
[4] Certification by Analysis Vision 2040 https://ntrs.nasa.gov/citations/20210015404
[5] Daumas, L., Chalot, F., Forestier, N., & Johan, Z. (2009). Industrial use of linearized CFD tools for aeroelastic problems. IFASD, 54, 21-25.
“The Galerkin/least-squares (GLS) formulation introduced by Hughes and Johnson, is a full
space-time finite element technique …”
[6] Cirrent (2024) Aeroelasticity Prediction Workshop: https://aiaa-dpw.larc.nasa.gov/
[7] Hulshoff, S. J. (2013). Aeroelasticity. Lecture notes Aerodynamics Master Track, TU Delft.
[8] Logg, A., Mardal, K. A., & Wells, G. (Eds.). (2012). Automated solution of differential equations by the finite element method: The FEniCS book (Vol. 84). Springer Science & Business Media.
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