1,720,994 research outputs found
Dataset for Efficient Infinite-swept Wing Solver for Steady and Unsteady Compressible Flows
No full textSupporting material:
Franciolini, M. et al (2017). Efficient infinite–swept wing solver for steady and unsteady compressible flows. Aerospace Science and Technology, 1-25.
The database contains data in support of the above manuscript. In particular, grid files and solution files that were used for the generation of the figures are made available. A toolbox that implements in Matlab a Discrete Fourier Transform algorithm is also shared. Each subfolder contains a README.dat file.</span
Data-driven Optimisation of Closure Coefficients of a Turbulence Model
No full textSupplementary material for "Data-driven Optimisation of Closure Coefficients of a Turbulence Model" by Da Ronch et al.</span
Rapid calculation of unsteady aircraft loads
No full textAn efficient multi–fidelity aerodynamic solver for unsteady flow problems,combining the unsteady vortex lattice method and Navier–Stokes solver for the infinite–swept wing problem, is presented. The new flow solver is able to correctly reproduce the loads of the three–dimensional Navier–Stokes unsteady, non–linear loads around a representative wing configuration, at a computational cost of a two–dimensional Navier–Stokes computation. Numerical details of the unsteady vortex lattice method solver, developed for this purpose, and its verification are presented. The coupling algorithm of multi–fidelity solver is described, followed by its demonstration around swept–wing configurations. It is demonstrated that the newly developed framework reproduces the loads of a three–dimensional unsteady Navier–Stokes computation, with the speed–up upto 290–times for the same accuracy
Fast aerodynamic calculations based on a generalised unsteady coupling algorithm
No full textAn aerodynamic model for applications to external flows is formulated that provides a great trade–off between computational cost and prediction accuracy. The novelty of the work is the ability to deal with any unsteady flow problem, irrespective of the frequency of motion and motion kinematics. The aerodynamic model, baptised FALCon, combines an in–house unsteady vortex lattice method with an infinite–swept wing Navier–Stokes solver. The two specialised methods are orchestrated by an unsteady coupling algorithm that represents our main research contribution. The paper gives the formulation and algorithmic implementation. FALCon is demonstrated on three test cases of increasing complexity in flow physics, up to flow conditions well outside its validity range. On average, FALCon achieves a computational speed up of a factor of about 50, compared to a full Navier–Stokes run, while capturing relevant flow physics: three–dimensional, viscous, compressible and unsteady phenomena
Wing twist optimisation using aerodynamic solvers of different fidelity
No full textComputational fluid dynamics has become the method of choice for aerodynamic shape optimisation. However, the computational cost poses challenges for the routine use of high-fidelity flow solvers in the early phase of aircraft design. In this paper, a benchmark wing twist optimisation problem is investigated using two aerodynamic solvers of different fidelity. The first solver is the open-source SU2 software, and the second is an efficient hybrid solver which couples a linear vortex lattice method with an infinite-swept wing solver. Numerical details of two optimisation frameworks are presented. It is demonstrated that the hybrid solver can accurately reproduce the aerodynamic loads on the three-dimensional wing. Optimisation results show that both optimisations can effectively minimise the induced drag by recovering a nearly elliptical lift distribution. In comparison to SU2 optimisation, the hybrid approach achieves a speed-up of two orders of magnitude
Sensitivity and calibration of turbulence model in presence of epistemic uncertainties
No full textThe solution of Reynolds-averaged Navier-Stokes equations employs an appropriate set of equations for the turbulence modelling. The closure coefficients of the turbulence model were calibrated using empiricism and arguments of dimensional analysis. These coefficients are considered universal, but there is no guarantee this property applies to test cases other than those used in the calibration process. This work aims at revisiting the calibration of the closure coefficients of the original Spalart-Allmaras turbulence model using machine learning, adaptive design of experiments and accessing a high-performance computing facility. The automated calibration procedure is carried out once for a transonic, wall-bounded flow around the RAE 2822 aerofoil. It was found that: a) an optimal set of closure coefficients exists that minimises numerical deviations from experimental data; b) the improved prediction accuracy of the calibrated turbulence model is consistent across different flow solvers; and c) the calibrated turbulence model outperforms slightly the standard model in analysing complex flow features around additional test cases (ONERA M6 wing, axisymmetric transonic bump, forced sinusoidal motion of NACA 0012 aerofoil). A by-product of this study is a fully calibrated turbulence model that leverages on current state-of-the-art computational techniques, overcoming inherent limitations of the manual fine-tuning process
Dataset for Sensitivity Assessment of Optimal Solution in Aerodynamic Design Optimisation using SU2
No full textThe database contains data in support of the manuscript 'Sensitivity Assessment of Optimal Solution in Aerodynamic Design Optimisation using SU2' (https://doi.org/10.1016/j.ast.2018.08.012). In particular, grid files and solution files that were used for the generation of the figures are made available. Each subfolder contains a README.dat file.</span
Fast identification of transonic buffet envelope using computational fluid dynamics
No full textPurpose – The paper presented a numerical method based on computational fluid dynamics that allows investigating the buffet envelope of reference equivalent wings at the equivalent cost of several two-dimensional, unsteady, turbulent flow analyses. The method bridges the gap between semi-empirical relations, generally dominant in the early phases of aircraft design, and three-dimensional turbulent flow analyses, characterised by high costs in analysis setups and prohibitive computing times.Design/methodology/approach – Accuracy in the predictions and efficiency in the solution are two key aspects. Accuracy is maintained by solving a specialised form of the Reynolds–averaged Navier–Stokes equations valid for infinite-swept wing flows. Efficiency of the solution is reached by a novel implementation of the flow solver, as well as by combining solutions of different fidelity spatially.Findings – Discovering the buffet envelope of a set of reference equivalent wings is accompanied with an estimate of the uncertainties in the numerical predictions. Just over 2,000 CPU hours are needed if it is admissible to deal with an uncertainty of ±1.0 deg in the angle of attack at which buffet onset/offset occurs. Halving the uncertainty requires significantly more computing resources, close to a factor 200 compared with the larger uncertainty case.Practical implications – To permit the use of the proposed method as a practical design tool in the conceptual/preliminary aircraft design phases, the method offers the designer with the ability to gauge the sensitivity of buffet on primary design variables, such as wing sweep angle and chord to thickness ratio.Originality/value – The infinite-swept wing, unsteady Reynolds–averaged Navier–Stokes equations have been successfully applied, for the first time, to identify buffeting conditions. This demonstrates the adequateness of the proposed method in the conceptual/preliminary aircraft design phases
Dataset for Fast Identification of Transonic Buffet Envelope using Computational Fluid Dynamics
No full textSupplementary material for "Fast Identification of Transonic Buffet Envelope using Computational Fluid Dynamics" by Drofelnik et al. published in Aircraft Engineering and Aerospace Technology.</span
Data-driven optimisation of closure coefficients of a turbulence model
No full textThe solution of the Reynolds-averaged Navier-Stokes equations employs an appropriate set of equations for the turbulence modelling. The closure coefficients of the turbulence model were calibrated using empiricism and arguments of dimensional analysis. These coefficients are considered universal, but there is no guarantee this property applies to test cases other than those used in the calibration process. This work aims at revisiting the universality of the closure coefficients of the original Spalart-Allmaras turbulence model using machine learning, adaptive design of experiments and accessing a high-performance computing facility. The automated calibration procedure is carried out once for a transonic, wall-bounded flow around the RAE 2822 aerofoil. It was found that: a) an optimal set of closure coefficients exists that minimises numerical deviations from experimental data; b) the improved prediction accuracy of the calibrated turbulence model is consistent across different flow solvers; and c) the calibrated turbulence model outperforms slightly the standard model in analysing complex flow features around the ONERA M6 wing. A by-product of this study is a fully calibrated turbulence model that leverages on current state-of-the-art computational techniques, overcoming inherent limitations of the manual fine-tuning process
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