Using thermal barriers for driver comfortTags : coatings
We have discussed the use of thermal barrier coatings for many reasons in the past, including mitigating heat transfer to areas of the engine which cost performance, protecting electronic components which can suffer reliability problems when the melting point of the solder is reached, to the reduction of heat transfer to the transmission system from literally red-hot exhaust systems. These are all very important considerations.
Ask any engineer who has worked with the very best cars and drivers what factors are most potent in terms of race performance, and almost all will put the driver further towards the top of his or her list than the engine. As someone who has spent most of his career as a racing powertrain design engineer, it slightly pains me to write this. It should therefore be a priority to look after the driver and, as far as is reasonably possible without costing overall performance, we should consider his or her comfort during the race.
Drivers of closed-cockpit cars are particularly vulnerable to fatigue when the cabin temperature is high. The problem can be so bad that some series mandate the use of driver cooling if the temperature exceeds a certain limit. Even in the relatively mild British summer, driving in the day with no air-conditioning system can sometimes be uncomfortable, even in a T-shirt and shorts. I dread to think what it must be like at Le Mans in a very much hotter car with full fire-proofs and a helmet.
The way to minimise the penalty of having to carry an air-conditioning system on a car is to minimise the amount of heat that needs to be removed from the driver compartment, and this is done by limiting the amount of heat that is transferred to it. By shielding the driver compartment from sources of conducted or radiated heat, we can keep the warm areas of the car warm, and the driver a little cooler. Thermal barrier coatings can be used in this situation and can be applied directly to hot components such as exhausts, heat-shields or onto the chassis on the outer surfaces of the driver compartment.
This includes the obvious areas such as the engine compartment bulkheads and exhaust tunnels, but also the less obvious ones, such as where the transmission cases are close to the driver compartment or where coolant pipes are routed along the underside of the chassis or through the sills. If it is not practical to coat the chassis directly or to fit insulated hard heat shields, thermal barrier coatings have been successfully applied to flexible foils that can easily be formed to fit into tunnels and so on or around certain components.
Where the inevitable compromise lies with the application of thermal barriers to closed-cockpit cars isn’t obvious – we aren’t looking at one-lap performance because adding mass to a car is rarely a cause of lap time reduction. The real benefit comes as the driver tires; the driver can give a better performance for a longer period if he or she feels fresh, comfortable and properly hydrated.
Written by Wayne Ward