| 1. |
- Da Ronch, A., et al.
(författare)
-
A framework for constrained control allocation using CFD-based tabular data
- 2011
-
Ingår i: AIAA Aerosp. Sci. Meet. Incl. New Horiz. Forum Aerosp. Expos.. - Reston, Virigina : American Institute of Aeronautics and Astronautics. - 9781600869501
-
Konferensbidrag (refereegranskat)abstract
- This paper describes a framework for control allocation problem using Computational Fluid Dynamics (CFD) aerodata, which is represented by a multidimensional array of dimensionless coefficients of aerodynamic forces and moments, stored as a function of the state vector and control-surface deflections. The challenges addressed are, first, the control surface treatment for the automated generation of aerodata using CFD and, second, sampling and data fusion to allow the timely calculation of large data tables. In this framework, the generation of aerodynamic tables is described based on an efficient sampling/data fusion approach. Also, the treatment of aerodynamics of control surfaces is being addressed for three flow solvers: TORNADO, a vortex-lattice method, and two CFD codes, EDGE from the Swedis Defence Agency and PMB from the University of Liverpool. In TORNADO, the vortex points located at the trailing edge of the flaps are rotated around the hinge line to simulate the deflected surfaces. The transpiration boundary conditions approach is used for modeling moving flaps in EDGE, whereas, the surface deflection is achieved using mode shapes in PMB. The test cases used to illustrate the approaches is the Ranger 2000 fighter trainer and a reduced geometry description of Boeing 747-100. Data tables are then generated for the state vector and multiple control surface deflections. The look-up table aerodata are then used to resolve the control allocation problem under the constraint that each surface has an upper and lower limit of deflection angle.
|
|
| 2. |
- Eliasson, Peter, et al.
(författare)
-
IMPROVING STALL CHARACTERISTICS OF UCAV WING WITH VORTEX GENERATORS
- 2022
-
Ingår i: 33rd Congress of the International Council of the Aeronautical Sciences, ICAS 2022. - : International Council of the Aeronautical Sciences. ; , s. 2990-2998
-
Konferensbidrag (refereegranskat)abstract
- Recent Unmanned Combat Air Vehicle (UCAV) configurations have not-so-slender wings with moderate leading-edge sweepangles of 45◦ to 60◦. Planforms vary from pure delta to diamond and even lambda more or less blended wing bodies with a relatively small thickness ratio at the inner wing/fuselage region. The performance and low-observable signature considerations require a compromise between a small radar cross-section and lifting surface shapes for long range and sufficient agility. The airflow is governed largely by the progression of vortices shed from the wing leading edge which interact and produce non-linear aerodynamics. Like early swept wing fighters like the Saab 32 the UCAV may exhibit undesirable flying characteristics over part of the envelope with tip stall and pitch-up. Such problems were mitigated by vortex control "devices" like leading edge fences and notches which violate the low observable requirement. The AVT-181 SACCON is a well studied case. We attempt to improve its stalling characteristics by mimicking the leading edge fence action by a configuration of very small vortex generators and study their effect by CFD.
|
|
| 3. |
- Jungo, Aidan, et al.
(författare)
-
Benchmarking New CEASIOM with CPACS adoption for aerodynamic analysis and flight simulation
- 2018
-
Ingår i: AIRCRAFT ENGINEERING AND AEROSPACE TECHNOLOGY. - : EMERALD GROUP PUBLISHING LTD. - 1748-8842. ; 90:4, s. 613-626
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose The purpose of this paper is to present the status of the on-going development of the new computerized environment for aircraft synthesis and integrated optimization methods (CEASIOM) and to compare results of different aerodynamic tools. The concurrent design of aircraft is an extremely interdisciplinary activity incorporating simultaneous consideration of complex, tightly coupled systems, functions and requirements. The design task is to achieve an optimal integration of all components into an efficient, robust and reliable aircraft with high performance that can be manufactured with low technical and financial risks, and has an affordable life-cycle cost. Design/methodology/approach CEASIOM (www.ceasiom.com) is a framework that integrates discipline-specific tools like computer-aided design, mesh generation, computational fluid dynamics (CFD), stability and control analysis and structural analysis, all for the purpose of aircraft conceptual design. Findings A new CEASIOM version is under development within EU Project AGILE (www.agile-project.eu), by adopting the CPACS XML data-format for representation of all design data pertaining to the aircraft under development. Research limitations/implications Results obtained from different methods have been compared and analyzed. Some differences have been observed; however, they are mainly due to the different physical modelizations that are used by each of these methods. Originality/value This paper summarizes the current status of the development of the new CEASIOM software, in particular for the following modules: CPACS file visualizer and editor CPACSupdater (Matlab) Automatic unstructured (Euler) & hybrid (RANS) mesh generation by sumo Multi-fidelity CFD solvers: Digital Datcom (Empirical), Tornado (VLM), Edge-Euler & SU2-Euler, Edge-RANS & SU2-RANS Data fusion tool: aerodynamic coefficients fusion from variable fidelity CFD tools above to compile complete aero-table for flight analysis and simulation.
|
|
| 4. |
- Mengmeng, Zhang
(författare)
-
Contributions to Variable Fidelity MDO Framework for Collaborative and Integrated Aircraft Design
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis develops computational tools for early stages of the aircraft design process. The work focuses on a framework which allows several design teams concurrently to develop a baseline concept into a configuration which meets requirements and whose aerodynamics has been assessed by flight simulation. To this end, a data base format suggested by the German Aerospace Center DLR was adopted in the CEASIOM system, developed in the EU 6th Framework Program, enabling more accurate transonic analysis and tabulation of forces and moments as well as control surface authority assessment. Results from simple, fast models are combined with computationally expensive full CFD results by co-Kriging to speed up productionof the aero-data for flight simulation.Non-linear optimization methods in wing design play an increasingly important role together with computational aerodynamics. High performance computing enables the use of high-fidelity non-linear flow predictions in optimization loops. It is argued that the optimization tools should allow the engineer to influence the process by setting up suitable target pressure distributions for the shape to approach, combined with steps to minimize drag under suitable constraints on geometry, forces, and moments. The simulation framework incorporated into CEASIOM was applied to a number of configurations, conventional as well as un-conventional, such as an a-symmetric twin prop, a canard-configured transonic cruiser, and a novel chinrudder concept for transonic airliners. Aerodynamic shape design by the developed methods was applied to the standard M6 benchmark wing, a joined-wing concept, a wing-tip, and a blended wing-body.
|
|
| 5. |
- Mengmeng, Zhang, 1985-, et al.
(författare)
-
Enhancement of CEASIOM with Rapid-Meshing Tool for Aircraft Conceptual Design
- 2012
-
Ingår i: Aerotecnica Missili & Spazio, The journal of Aerospace Science, Technology and Systems. - : Associazione italiana di Aeronautica e Astronautica. - 2524-6968. ; 91:3/4, s. 79-85
-
Tidskriftsartikel (refereegranskat)abstract
- This paper details the development and application of the RDS-SUMO-CEASIOM-EDGE rapid-CFD tool. It uses theRDS CAD model as geometry for automated meshing and CFD analysis to produce an aero-data base for control andstability analysis. It is applied to two non-conventional design proposals, an asymmetric twin-prop aircraft and anairliner with rear Open Rotor propulsion, retractable canard, and a “chin-rudder” instead of vertical tail. For bothconfigurations,yaw control is problematic, and the stability and control analysis is used to assess control surface sizing and stabilityaugmentation system.
|
|
| 6. |
- Mengmeng, Zhang, 1985-, et al.
(författare)
-
Transonic airfoil and wing design using inverse and direct methods
- 2015
-
Ingår i: 53rd AIAA Aerospace Sciences Meeting. - Kissimmee, Florida : American Institute of Aeronautics and Astronautics. - 9781624103438
-
Konferensbidrag (refereegranskat)abstract
- A hybrid inverse/direct-optimization method for subsonic/transonic airfoil and wing shape design is presentedwith application to a range of airfoil and wing cases, in preparation for the test cases defined for the Special Sessionof SciTech 2015. The method is hybrid in the sense that it combines the traditional inverse design technique witha gradient-based procedure to approach the optimum aerodynamic surface. This paper emphasizes the first part, thedevelopment of SCID, the Surface Curvature Inverse Design method, the theory upon which it is based, includingmany of the details involved with shocks, smoothing and cross flow. The application of SCID to wing design posesmany challenges, and how they are met is discussed in the context of a number of inverse design test cases for airfoilsand wings. But it also includes results from the adjoint optimization and compares them. The procedure workswell for airfoils and the twist optimization for wings. The real benchmarks for our hybrid approach are the threeOptimization Discussion Group design problems. Solutions are presented for the drag minimization of the airfoil testcases along with the wing twist optimization problem, and conclusions are drawn from the results obtained. A swept-back transonic wing is designed by SCID with encouraging results, showing that SCID works fine with wings. Workhas started on the drag minimization of the CRM wing in transonic flight, and final results will be presented in a futurepaper.
|
|
| 7. |
- Mialon, Bruno, et al.
(författare)
-
Validation of numerical prediction of dynamic derivatives : The DLR-F12 and the Transcruiser test cases
- 2011
-
Ingår i: Progress in Aerospace Sciences. - : Elsevier BV. - 0376-0421 .- 1873-1724. ; 47:8, s. 674-694
-
Forskningsöversikt (refereegranskat)abstract
- The dynamic derivatives are widely used in linear aerodynamic models in order to determine the flying qualities of an aircraft: the ability to predict them reliably, quickly and sufficiently early in the design process is vital in order to avoid late and costly component redesigns. This paper describes experimental and computational research dealing with the determination of dynamic derivatives carried out within the FP6 European project SimSAC. Numerical and experimental results are compared for two aircraft configurations: a generic civil transport aircraft, wing-fuselage-tail configuration called the DLR-F12 and a generic Transonic CRuiser, which is a canard configuration. Static and dynamic wind tunnel tests have been carried out for both configurations and are briefly described within this paper. The data generated for both the DLR-F12 and TCR configurations include force and pressure coefficients obtained during small amplitude pitch, roll and yaw oscillations while the data for the TCR configuration also include large amplitude oscillations, in order to investigate the dynamic effects on nonlinear aerodynamic characteristics. In addition, dynamic derivatives have been determined for both configurations with a large panel of tools, from linear aerodynamic (Vortex Lattice Methods) to CFD. This work confirms that an increase in fidelity level enables the dynamic derivatives to be calculated more accurately. Linear aerodynamics tools are shown to give satisfactory results but are very sensitive to the geometry/mesh input data. Although all the quasi-steady CFD approaches give comparable results (robustness) for steady dynamic derivatives, they do not allow the prediction of unsteady components for the dynamic derivatives (angular derivatives with respect to time): this can be done with either a fully unsteady approach i.e. with a time-marching scheme or with frequency domain solvers, both of which provide comparable results for the DLR-F12 test case. As far as the canard configuration is concerned, strong limitations for the linear aerodynamic tools are observed. A key aspect of this work are the acceleration techniques developed for CFD methods, which allow the computational time to be dramatically reduced while providing comparable results.
|
|
| 8. |
|
|
| 9. |
- Zhang, Mengmeng, et al.
(författare)
-
Aerodynamic Design Considerations and Shape Optimization of Flying Wings in Transonic Flight
- 2012
-
Ingår i: 12th AIAA Aviation Technology, Integration, and Operations (ATIO) Conference and 14th AIAA/ISSM17 - 19 September 2012, Indianapolis, Indiana. - Reston, Virigina : American Institute of Aeronautics and Astronautics. - 9781600869303 ; , s. 1-17
-
Konferensbidrag (refereegranskat)abstract
- This paper provides a technique that minimize the cruise drag (or maximize L/D) fora blended wing body transport with a number of constraints. The wing shape design isdone by splitting the problem into 2D airfoil design and 3D twist optimization with a frozenplanform. A 45% to 50% reduction of inviscid drag is nally obtained, with desired pitchingmoment. The results indicate that further improvement can be obtained by modifying theplanform and varying the camber more aggressively.
|
|
| 10. |
- Zhang, Mengmeng, et al.
(författare)
-
Aerodynamic wing shape optimization based on the computational design framework CEASIOM
- 2017
-
Ingår i: Aircraft Engineering. - : Emerald Group Publishing Ltd.. - 0002-2667. ; 89:2, s. 262-273
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose - A collaborative design environment is needed for multidisciplinary design optimization (MDO) process, based on all the modules those for different design/analysis disciplines, and a systematic coupling should be made to carry out aerodynamic shape optimization (ASO), which is an important part of MDO. Design/methodology/approach - Computerized environment for aircraft synthesis and integrated optimization methods (CEASIOM)-ASO is developed based on loosely coupling all the existing modules of CEASIOM by MATLAB scripts. The optimization problem is broken down into small sub-problems, which is called "sequential design approach", allowing the engineer in the loop. Findings - CEASIOM-ASO shows excellent design abilities on the test case of designing a blended wing body flying in transonic speed, with around 45 per cent drag reduction and all the constraints fulfilled. Practical implications - Authors built a complete and systematic technique for aerodynamic wing shape optimization based on the existing computational design framework CEASIOM, from geometry parametrization, meshing to optimization. Originality/value - CEASIOM-ASO provides an optimization technique with loosely coupled modules in CEASIOM design framework, allowing engineer in the loop to follow the "sequential approach" of the design, which is less "myopic" than sticking to gradient-based optimization for the whole process. Meanwhile, it is easily to be parallelized.
|
|
