1 / 16

Dynamic simulation of parachutes with fluid-structure interactions

Dynamic simulation of parachutes with fluid-structure interactions. Inflation problems - Aims. Parachutes: decelerate, stabilize, lead the descent of charges Opening => crucial point Aim: simulation models including parachute stable descent with FSI, suspension lines modelling,

kyros
Télécharger la présentation

Dynamic simulation of parachutes with fluid-structure interactions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Dynamic simulation of parachutes with fluid-structure interactions

  2. Inflation problems - Aims • Parachutes: decelerate, stabilize, lead the descent of charges • Opening => crucial point • Aim: simulation models including • parachute stable descent with FSI, • suspension lines modelling, • drag force, • dynamic forces • unfolding • interaction between parachutes • Relevance: • unaccessibles results by testing • fabric and maters fit • different sails • design to avoid accidents http://www.paraflite.com/Intruder%20Canopy%20Summary.htm

  3. http://www.irvinaerospace.com/range.html http://www.mtu-net.ru/mosseev/ • CEVAP : up to 2003 • SINPA http://www.pcprg.<com • Parks College: Jean Potvin& Gary Peek Existing works • Irvin Aerospace simulations: Antony Taylor – LS-DYNA • MTU simulations : Yuri Mosseev MONSTR-2.2

  4. Coupling method:Lagrangian structure embedded in ALE fluid http://www.lstc.com/

  5. Coupling method: moving grid with fluid advection in interaction with a structure http://www.dynaexamples.com/ALE_Souli/Bird/index.php?example=Bird_B&topic=figures

  6. Coupling method: Simplified Arbitrary Lagrangian-Eulerian • Arbitrary Lagrangian-Eulerian formulation  algorithm that perform automatic rezoning • Stop calculation when mesh distortions become too high • Smooth the mesh • Remap the solution through advection methods • ALE time step • Lagrangien time step • Advection step : • transport of element-centered variables • Momentum transport and velocity update • Eulerian calculations: total smoothing http://www.dynaexamples.com/ALE_Souli/Bird/index.php?example=Bird_B&topic=figures

  7. Coupling method: Advection for simplified ALE • Advection of element-centered variables (density, iternal energy, stress tensor, history variables) : node based • Default: second order Van Leer MUSCL scheme • Monotone Upwind scheme for conservation laws • Remap assumptions • Topology of the mexh is fixed (only for partial rezoning) • Mesh motion during a step is less than the characteristic lengths of surrounding elements : Courant condition (f=transport volume between adjacent elements=purely geometrical) • Replace the piecewise constant distribution of variables with e higher order interpolation function • In 3D: • Momentum advected instead of velocities at nodes • Half Index Space Algorithm: overcomes dispersion & keeps velocity monotonicity http://www.dynaexamples.com/ALE_Souli/Bird/index.php?example=Bird_B&topic=figures

  8. Methodology Feasability ¼ model Validation full model

  9. Parachutes modelling Double thickness: 0,12 mm Φhole 18 cm • ¼ model  1800 membranes • 700 beams •  390 kg/m3 fabric anisotropic •  240 kg/m3 beams Φspan 10 m Full cross model  2000 membranes 1700 beams/seatbelts 6mx7m :80000 fluid elements Full round model  hemispherical => theoritical flow fields & drag force 6mx7m :350000 fluid elements

  10. V [m/s] 50 20 6 T[s] 0.1 0.2 2.5 Air modelling : feasabilityro=1.29 kg/m3 – perfect gaz 50000/60000 elements

  11. Results: feasability Suspension lines needed Inflation possible provided folding & contacts: refine mesh Ribbons, hinges, suspension lines: model not validated Mesh domain too small for drag forces/ CPU too long Mesh size ok Air flow for stable descent: unstable deformations Penalty method instead of momentum ¼ model => unsufficient for pendulum movements Parachute Air FSI

  12. Wrong pressure Correct pressure Drag forces: Theory  9700 N Computed 10150 N +5% Drag coefficients: Theory = 1.42 Computation  1.4 14mx14m 50000 elements 24  7 h CPU Pression imposée 1013 PRESSION MOYENNE 1013 hPa Vitesse imposée Air modelling : validationro=1.225 kg/m3 – perfect gaz 6mx7m: 350000 fluid elements: 24h CPU

  13. Hydrostatic tension Ambiant elements Results Suppression of Oscillations Fine mesh: high gradients and velocities / Coarse mesh : monotonic flow For v=65m/s, computed drag  theory drag +25%

  14. Impossibles Loops of seatbelts Impossibles mesh penetrations Real deformed shape Computed shape Limitations

  15. Features & Improvements P=a*V+b*V2

  16. Conclusions / aims • Development of deformable parachute modelling with FSI computations for transported material and operational mission design : first step to compute dynamic forces during inflation • Progressive density for fluid mesh: computation save without loss of quality & no refinement needed during computation • Suspension lines, ribbons and hinges: correct deformation • drag forces are acceptable on first order : to be improved when porosity will be correctly handled: multiphysics/mutliscale • Interactions/clustering, closing of parachutes, skirt crush • Perspectives: • porosity => coupling algorithms • folding / inflation => contact algorithms

More Related