The Ring of Fire for in-Field Sport Aerodynamic Investigation

Conference Paper (2018)
Author(s)

A.M.C.M.G. Spoelstra (TU Delft - Aerodynamics)

Wouter Terra (TU Delft - Aerodynamics)

A Sciacchitano (TU Delft - Aerodynamics)

Research Group
Aerodynamics
Copyright
© 2018 A.M.C.M.G. Spoelstra, W. Terra, A. Sciacchitano
DOI related publication
https://doi.org/10.3390/proceedings2060221
More Info
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Publication Year
2018
Language
English
Copyright
© 2018 A.M.C.M.G. Spoelstra, W. Terra, A. Sciacchitano
Research Group
Aerodynamics
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Abstract

A novel measurement system, the Ring of Fire, is deployed which enables the aerodynamic drag estimation of transiting cyclists. The system relies upon the use of large-scale stereoscopic PIV and the conservation of momentum within a control volume in a frame of reference moving with the athlete. The rider cycles at a velocity of approximately 8 m/s, corresponding to a torso based Reynolds number of 3.2 × 105. The measurements upstream and in the wake of the athlete are conducted at a rate of 2 kHz within a measurement plane of approximately 1000 × 1700 mm2. The non-dimensional, ensemble-averaged streamwise velocity fields compare well to literature and the ensemble-averaged drag area shows a rather constant value along the wake with an uncertainty of 5%. A comparison with wind tunnel force balance measurements shows discrepancies which may be partly attributed to the bike supports and stationary floor in the wind tunnel measurements. The 25% drag difference measured between a rider in upright and time-trial position, however, matches literature well.