Aerodynamic Interaction between Two Speed Skaters Measured in a Closed Wind Tunnel
Team pursuit is a relatively new event in international
long track speed skating. For a single speed skater the aerodynamic
drag will account for up to 80% of the braking force, thus reducing
the drag can greatly improve the performance. In a team pursuit the
interactions between athletes in near proximity will also be essential,
but is not well studied. In this study, systematic measurements
of the aerodynamic drag, body posture and relative positioning
of speed skaters have been performed in the low speed wind
tunnel at the Norwegian University of Science and Technology, in
order to investigate the aerodynamic interaction between two speed
skaters. Drag measurements of static speed skaters drafting, leading,
side-by-side, and dynamic drag measurements in a synchronized and
unsynchronized movement at different distances, were performed.
The projected frontal area was measured for all postures and
movements and a blockage correction was performed, as the blockage
ratio ranged from 5-15% in the different setups. The static drag
measurements where performed on two test subjects in two different
postures, a low posture and a high posture, and two different distances
between the test subjects 1.5T and 3T where T being the length of the
torso (T=0.63m). A drag reduction was observed for all distances and
configurations, from 39% to 11.4%, for the drafting test subject. The
drag of the leading test subject was only influenced at -1.5T, with
the biggest drag reduction of 5.6%. An increase in drag was seen
for all side-by-side measurements, the biggest increase was observed
to be 25.7%, at the closest distance between the test subjects, and
the lowest at 2.7% with ∼ 0.7 m between the test subjects. A clear
aerodynamic interaction between the test subjects and their postures
was observed for most measurements during static measurements,
with results corresponding well to recent studies. For the dynamic
measurements, the leading test subject had a drag reduction of 3%
even at -3T. The drafting showed a drag reduction of 15% when being
in a synchronized (sync) motion with the leading test subject at 4.5T.
The maximal drag reduction for both the leading and the drafting
test subject were observed when being as close as possible in sync,
with a drag reduction of 8.5% and 25.7% respectively. This study
emphasize the importance of keeping a synchronized movement by
showing that the maximal gain for the leading and drafting dropped to
3.2% and 3.3% respectively when the skaters are in opposite phase.
Individual differences in technique also appear to influence the drag
of the other test subject.
 G. J. van Ingen Schenau The influence of air friction in speed skating,
Journal of Biomechanics, vol 15, no 6. Elsevier, 1982. pp. 449-458.
 J. J. De Koning and G. J. van Ingen Schenau Performance-determining
factors in speed skating, Biomechanics in sport: Performance
enhancement and injury prevention. Olympic encyclopaedia of sports
medicine, vol 9. 2000. pp. 232-246.
 L. Sætran and L. Oggiano, Skin suit aerodynamics in speed skating, Sport
Aerodynamics. Springer, Vienna, 2008. pp. 93-105.
 A. D’Auteuil, G. L. Larose and S. J. Zan The effect of motion on wind
tunnel drag measurement for athletes, Procedia Engineering, vol 34.
Elsevier, 2012. pp. 62-67.
 S. Leirdal, L. Sætran, K. Roeleveld, B. Vereijken, S. Br˚aten, S. Løset
and G. Ettema Effects of body position on slide boarding performance
by cross-country skiers, Medicine and science in sports and exercise, vol
38, no 8. 2006. pp. 1462-1469.
 Winter Olymnpics Pyeong Chang 2018, Speed skating results - Men’s
team pursuit. https://www.olympic.org/pyeongchang-2018/speed-skating/
mens-team-pursuit. Accessed: 2019-01-02.
 N. Barry, J. Sheridan, D. Burton and N. Brown The effect of spatial
position on the aerodynamic interactions between cyclists, Procedia
Engineering, vol 72. Elsevier, 2014. pp. 774-779.
 B. Blocken, T. Defraeye, E. Koninckw, J. Carmeliet and P. Hespel, CFD
simulations of the aerodynamic drag of two drafring cyclist, Computer
& Fluids, vol. 71, Elsevier, 2013. pp. 435 - 445.
 N. Barry, D. Burton, J. Sheridan, M. Thompson and N. Brown
Aerodynamic drag interaction between cyclists in a team pursuit, Sports
Engineering, vol 18, no 2. Springer, 2015. pp. 93-103.
 P. Bradshaw Experimental Fluid Mechanics, 2nd ed., Pergamon Press:
Oxford, UK, 1970.
 K. Cooper Bluff-body blockage corrections in closed-and
open-test-section wind tunnels, In Wind Tunnel Wall Correction
(AGARD-AG-336), BFR Ewald, ed., Advisory Group for Aerospace
Research and Development, North Atlantic Treaty Organization,
Neuilly-sur-Seine Cedex, France, 1998.
 D. Sumner Two circular cylinders in cross-flow: a review, Journal of
Fluids and Structures, vol 26, no 6. Elsevier, 2010. pp 849-899.