1 / 29

Aerodynamic analysis of a two-man bobsleigh

Centro Interdipartimentale di Fluidodinamica e Idraulica Università di Udine. Aerodynamic analysis of a two-man bobsleigh. A.Soldati, S. Filippi, G. Miclet, M. Campolo, M. Andreoli, G. Moretti. Sport Aerodynamics- CISM course – Udine, 3-7 September 2007.

gabby
Download Presentation

Aerodynamic analysis of a two-man bobsleigh

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. Centro Interdipartimentale di Fluidodinamica e Idraulica Università di Udine Aerodynamic analysis of a two-man bobsleigh A.Soldati, S. Filippi, G. Miclet, M. Campolo, M. Andreoli, G. Moretti Sport Aerodynamics- CISM course – Udine, 3-7 September 2007

  2. A typical bobsleigh race … from inside!

  3. Push off stretch Starting area Main track Decelerating area Finish line …the track… Torino, Italy, Cesana Pariol track, 2006 Winter Olympics Course length: 1,435 m Difference in height : 114 m Bends: 19

  4. …the importance of men & bob aerodynamics… From 0 to 40 km/h Average speed: 50-110 km/h Top speed: 140 km/h

  5. …and typical performances What can we do to go faster?

  6. Motivation and Objectives • Evaluate aerodynamic performances (drag and lift forces) of italian team two-man bobsleigh using numerical analysis • Identify and test design modifications which may improve aerodynamic performances

  7. Steps of work CFD optimization & Virtual testing Model 1, …, Model n Reverse engineering CAD model Scaled Prototype & Wind tunnel testing Meshing technique CFD model CFD solver Full scale Prototype & field testing Performance index

  8. Research cooperation Aerodynamical optimization (M.V. Salvetti, UNIPI) Wind tunnel tests (G. Gibertini, PoliMi) Technical consultancy Design Rule/Constraint (I. Ferriani, Nazionale Italiana Bob) Multidisciplinary team University of Udine Coordination (G. Miclet) Fluid dynamic analysis/optimization (A. Soldati) Technical partners Reverse engineering/Prototyping (MarMax, UD) Reverse engineering/fast prototyping (S. Filippi) RANS CFD solver (CD Adapco, TO) Carbon/Kevlar shells (CS Canoe, PN)

  9. 1. From real object to design: reverse engineering

  10. “Virtual” Italian 2-men bobsleigh Pilot Brakeman Wings Chute Nose Bumpers

  11. 2. Virtual model: check of allowed dimensions (FIBT rules) Shape optimization of shell will be constrained by external vincula!

  12. 3. Discretization for CFD analysis TARGET: • simulate the flow around the bobsleigh • evaluate the forces (drag/lift) acting on the solid surface ASSUMPTIONS: • Steady state • Ideal gas • Turbulent flow (k-epsilon model + wall treatment)

  13. 4. Computational domain & boundaries Free shear/wall outlet Simulation data • Box dimensions (4.5m x 2.5m x 1.5m) • Height from bottom: 50 mm • Air relative velocity: 39 m/s (140 Km/h) • Wall velocity: 39 m/s (140 Km/h) Straight track Inlet Bends

  14. 5. Results: velocity field & streamlines

  15. From qualitative analysis of flow…

  16. … to quantitative evaluation of forces! Pressure/shear distribution over surface  Drag: 121 N (pressure) + 21.8 N (shear) (Lift : 320.4 N) Identification of “critical” regions

  17. World championship ’07 (Cortina d’Ampezzo, Italy) Need ideas to improve design? Look at competitors!

  18. Can we exploit any ground effect to improve performances? Observation 1: bobsleights have variable distances from bottom wall USA GERMANY RUSSIA Low “h” (50 mm) High “h” (70 mm) Airfoil Bobsleight International rules: h ≤ 100 mm

  19. h=50 mm h=70 mm - 4% - 5% Simulation results: Higher distance smaller drag …but drag reduction is not significant!

  20. USA GERMANY ITALIA Observation 2: bobsleights have variable nose shapes Rounded nose Triangular nose Pentagonal nose Best performing!* *Ref.: Advanced bobsleigh design: Part 2, aerodynamic modifications to a two-man bobsleigh, by F Motallebi, P Dabnichki* and D Luck, Department of Engineering, Queen Mary, University of London, London, UK

  21. Restart from good design to make it better: evaluation of German bobsleigh Reverse engineering from sequence of photos

  22. GERMANY ITALIA Italian vs German bobsleigh Nose shape Bumpers and wings Shell curvature & Men position

  23. Simulation data Box dimensions (4.5m x 2.5m x 1.5m) Height from bottom: 70 mm Air relative velocity: 39 m/s (140 Km/h) Wall velocity: 39 m/s (140 Km/h) GER ITA Computational domain & boundaries outlet Free shear/wall Straight track Inlet Bends

  24. Results: velocity field & streamlines

  25. GER ITA Streamline comparison H=70 mm, v=140km/h

  26. … and quantitative evaluation of forces! Pressure/shear distribution over surface  Drag: 113 N (pressure) + 19.8 N (shear) (Lift : 165.7 N) Identification of “critical” regions

  27. h=50 mm h=70 mm h=70 mm Comparison of performances …but we know we can do better!

  28. … other design modifications implemented Shape of wings Chute Aerodynamic profile of shell Better shape Rounded boumpers Flat bottom Rounded boumpers

  29. … and final result! Still to be tested • in lab to confirm results of CFD simulations • in the field … to win next bob championship

More Related