How To Analyse A Flugzeugflugfl\U00Fcgels In 3D Cda

Transcription

1 cfd analyse eines flugzeugflügels bei mach 7 Zum Start der Entwicklung unseres Entwurfswerkzeuges werden wir die Ergebnisse des Workshops Speculative Patterns aus dem Entwurfsprojekt 51,9 N mit der Software Ecotect und WinAir testen. Die numerische Strömungsmechanik (englisch: computational fluid dynamics, CFD) ist eine Methode der Strömungsmechanik, die strömungsmechanische Probleme approximativ mit numerischen Methoden löst. Die numerische Strömungsmechanik bietet eine kostengünstige Alternative zu Windkanal-Versuchen, die oft als Werkzeug zum Design von Flugzeugen verwendet wird. Aufgabe: Jede der Gruppen des Entwursprojektes hat die Aufgabe bekommen, ein digitales Modell Ihrer Studie zu erstellen. Erstellen Sie anhand dieser Modelle eine CFD-Analyse in Ecotect (gem. Anleitung). Modus: Gruppenarbeit (min 2er Gruppen, max 3er Gruppen) Abgabe: Erstellen Sie 6 Schnitte durch die Simulation Ihres Modells und erstellen Screenshots gem. Abbildung. Schicken Sie diese Screenshots bis Dienstag, 12. April, Uhr als gezipptes Archiv an die -Adresse: teamdigital@fh-muenster.de. Horizontale Schnitte Vertikale Schnitte

2 how to get_ ecotect: (free for students) winair: steps_ 1. import.dxf to ecotect 2. define analysis grid 3. create cfd data 4. export cfd data to winair and run calculations 5. load winair output file and discuss results info_ for this tutorial, I used Rhino 4 SR9, Ecotect Analysis 2011 and WinAir 1.4b

3 export - set the units in your 3d programm to meters - export as.dxf by using the following options (example from rhino) When you use other CAD software, be aware that you export meshes and not only curves!

4 ecotect analysis 3d editor visualise page climate settings display settings visualisation settings shadow settings analysis grid settings export manager 3d editor: - select, move, and modify objects visualise page: - switch here to display results (perspektive view) climate settings - you can load diffrent climate locations. (only effects sun, shadows and climate) - no effect on wind simulations display settings: - settings for groundplane, axis, view settings,... visualisation settings: - set forground, background color, - outline, sketchiness, transperency,... shadow settings: - daily sun path or annual sun path - set shadow range, animate shadows over a specific time analysis grid settings: - grid settings (sizes, cells, position) - importent for calculations export manager: - export cfd data to winair

5 1. import to ecotect Goto: File > Import > 3D CAD Geometry choose your.dxf file 2. import options 3. open in ecotect

6 2. define analysis grid Be sure, that all objects are selected under 3d editor and go to analysis grid Goto: analysis grid > Auto-Fit Grid to Objects... Type to Fit: Around Fit Grid to Selected Objects or All Visible Objects Axial Offset = for XY-axis Now the analysis grid should fit to the selected objects

7 2. define analysis grid extend analysis grid in XYZ axis for wind simulations it is importent that the analysis grid is lager then the model. goto: analysis gird > Grid Managment... extendet analysis grid The maximum number of cells is limited to (Number of Cells 70 * 70 * 50 < ) Make the grid size a little bit bigger, that all volumes are in the grid. (Factor ) If nessesary, shift the start position of the grid. The Number of Cells affects the calculation time in Winair. goto: analysis gird > Adjust Grid Extents > Manually Adjust Grid Extents Check that the z-axis of the analysis grid is large enough to allow the air to circulate over. You also need to provide a good amount of space beyond your objects for air to circulate past. z-axis

8 3. create cfd data Be sure, that all the same objects are selected. Goto: analysis grid > calculations > CFD Cell Blockages > Perform Calculation... All surfaces will be marked by the dense of the analysis grid

9 4. export cfg data to winair Goto: Export Manager > Winair 4(cfd) > Export Model Data... Important: Save the file under C:\Winair\ Blockages: Boundaries Wind Settings: When the wind speed is to low, you don t see so much effects in the results. (Recommendation: m/s) Wind Direction: 0 = +X axis = North 45 = South-West Wind Befor you Start: Set Computer time to XX.XX.2006 Winair Location: C:\WinAir\winAIR4.exe Check Run WinAir Application... Check Auto-Start Calculation

10 4. winair calculation WinAir running... WinAir ready load winair resluts to ecotect Goto: analysis grid > calculations > load CFD Data > Load OUTPUT File... Location: C:\WinAir\OUTPUT

11 5. display results Goto: Visualise and switch under DATA & Scale to Air Flow Rate or Flow Vector Goto: move analysis grid XY or XZ or YZ shift the slider to move the grid

12 5. display results