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A Test Bed to Examine Helmet Fit and Retention and Biomechanical Measures of Head and Neck Injury in Simulated Impact
Published on: September 21, 2017
Heat transfer variations of bicycle helmets
P A Brühwiler1, M Buyan, R Huber
1Empa, St. Gallen, ETH Zürich, Zürich. Switzerland. paul.bruehwiler@empa.ch
Journal of Sports Sciences
|August 3, 2006
Summary
This study quantifies bicycle helmet ventilation, finding significant optimization potential. Helmet design details and hair impact heat transfer, with some vents negatively affecting airflow.
Area of Science:
- Biomechanics
- Thermal Engineering
- Sports Science
Background:
- Bicycle helmets balance impact protection with crucial ventilation.
- Understanding ventilation principles is key to improving helmet design.
Purpose of the Study:
- To quantitatively assess the ventilation efficiency of various bicycle helmets.
- To investigate the influence of design features and hair on thermal comfort.
Main Methods:
- Utilized a thermal headform in a climate-regulated wind tunnel to measure heat transfer.
- Employed flow visualization in a water tunnel to analyze airflow patterns.
- Studied the effects of design elements (vent placement, channel length) and hair presence.
Main Results:
- Observed up to 30% variation in heat transfer (scalp) and 10% (face) among helmets.
- Identified instances where vents negatively impacted forced convection.
- Found weak correlations between vent area, head tilt, and heat transfer.
- Demonstrated that hair significantly reduces heat transfer (up to 8x for scalp).
Conclusions:
- Significant potential exists for optimizing bicycle helmet ventilation.
- Helmet design details and the presence of hair are critical factors in thermal regulation.
- A simple analytical model aids in understanding forced convection in helmets.
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