## 3 Results and Discussion
### Evaporative-Heat-Transfer Characteristics of Helmet Ensembles  
Zonal Heat Transfer Characteristics  
_Frontal zone_: In comparison with the evaporative heat losses of the nude manikin, losses from the frontal zone of Helmets A1, A4 and H1 were not statistically different (\(p>0.05\)). However, plots indicate that the heat flux from the frontal zone of nude head at 3 m/s was, surprisingly, 2% higher than the heat flux from the frontal zone at 6 m/s (Figure 8). During the experiments, it was observed that, at 6 m/s, the fabric used to retain the fluid simulating sweat had dry spots in the frontal zone, which implied a lower surface area with evaporation, and thus lower heat losses in the zone in question. In opposition, at 3 m/s, the fabric was relatively wet, and hence implied more evaporation and higher heat losses than for 6 m/s. The same effect was observed on the fabric for Helmet A1 tests, resulting in higher frontal-region heat fluxes at the lower velocity. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{4}{c}{**(a)**} \\ \hline
**Helmet** & \multicolumn{2}{c}{**Apparent Evaporative Heat Loss (W)**} & \multicolumn{2}{c}{**Cooling Efficiency (\%)**} \\ \hline  & Mean & SD & \\ \hline  & 47.4 & 2.2 & \\ \hline A1 & 46.1 & 0.6 & 97.3 \\ \hline A2 & 37.8 & 0.7 & 79.8 \\ \hline A3 & 42.4 & 1.0 & 89.5 \\ \hline A4 & 44.3 & 0.0 & 93.4 \\ \hline H1 & 44.3 & 0.4 & 93.5 \\ \hline  & \multicolumn{4}{c}{**(b)**} \\ \hline
**Helmet** & \multicolumn{2}{c}{**Apparent Evaporative Heat Loss (W)**} & \multicolumn{2}{c}{**Cooling Efficiency (\%)**} \\ \hline  & Mean & SD & \\ \hline  & 47.3 & 0.8 & 95.4 \\ \hline A2 & 44.6 & 0.8 & 89.9 \\ \hline A3 & 45.5 & 0.7 & 91.7 \\ \hline A4 & 48.0 & 0.8 & 96.7 \\ \hline H1 & 47.4 & 0.6 & 95.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: **(a)** Apparent evaporative-heat-loss values at 3 m/s. (b) Apparent evaporative-heat-loss values at 6 m/s. Figure 7: Apparent evaporative heat loss of helmet ensembles at tested velocities (confidence intervals obtained for a 95% confidence level and a sample size of three). _Parietal zone:_ When covered with helmet, the parietal zone had 2-15% lower evaporative losses when compared to nude manikin. Statistical analysis showed that the parietal region of Helmets A1, A2 and A4 was not statistically different when compared to that of the nude manikin. Heat-flux transfer from the parietal region at 3 m/s was lower than heat flux at 6 m/s for all helmets except for A1 (Figure 8). It could be considered that the high parietal cooling efficiency of Helmet A1 caused the 'dry-fabric effect' as observed in frontal zone resulted in lower power consumption at 6 m/s than at 3 m/s. _Occipital zones:_ The occipital region of Helmets A1, A3, A4 and H1 shows no significant difference when compared to the nude head (\(p>0.05\)). The occipital regions are located on the leeward side of the air flow. Hence, the effect of air speed on this region was not very pronounced, as shown in statistical analysis. However, Helmet A2 showed the lowest heat transfer from the occipital region (8%-31% lower than nude head) for both velocities, and this can be attributed to helmet design (which implies a snug fit in the occipital region). _Ocular, facial and temporal zone characteristics:_ The facial region of the nude manikin with and without helmets showed no significant difference for both velocities (\(p>0.05\)). Interaction between facial region and the helmets was minimal during helmet usage; hence, no difference was observed. Heat-flux values from the ocular region of the thermal manikin with and without helmets showed no significant difference (\(p>0.05\)). However, heat flux values for low air velocity (3 m/s) were found to be 4-12% higher than the heat-flux values for moderate speed (6 m/s). It was assumed that the existence of dry spots in the fabric during the tests at moderate speeds (6 m/s) resulted in low power consumption, as observed in parietal region.