Formula One – 2014 and beyondTags : exhausts
There are huge changes afoot in Formula One. The rules that initially gave us the incredibly high-revving V8 engines heralded a period of relatively little change; the engines were described as ‘frozen’ but there were always little opportunities for performance development, which meant that engines were responsible for some pretty major increases in car performance.
In recent years, many of the performance increases have come from exhausts and the associated mapping and engine control changes that have accompanied them. We have known about the mass flow and energy contained in exhaust flows for a long time. Blown diffusers were used sporadically in the past, but in recent years we saw a return to the use of exhaust gases for aerodynamic benefit, with blown floors and rear wings and the use of the Coanda effect.
The regulations for 2014 inhibit such developments for two main reasons. The first is a result of the drastic changes to the basic engine type and its use. The 2.4 litre V8s are replaced with a 1.6 litre V6 which is turbocharged and which has a fuel flow limit that imposes both a maximum instantaneous mass flow rate and a maximum total fuel use in a race. The limit on fuel mass flow rate limits the exhaust mass flow rate and therefore the amount of work the exhaust gas can do on a rear wing, for example.
The rules also encourage teams to use as much of the energy in the exhaust gas as possible to generate electrical energy to be used for propulsion; the less energetic the flow exiting the tailpipe, the less work can be extracted from it. There will always be a temptation to try to exploit the exhaust gas to do something useful, but it will be much less effective than in the past.
The second reason is that the exhaust flow is going to be less effective in improving car performance, because the exhaust exit position, direction, shape and cross-sectional area are more tightly controlled, giving less latitude for doing something clever to gain performance. For instance, the tailpipe diameter must be between 97.7 and 138mm. Given a reduced mass flow rate compared to 2013, the resulting cross-sectional areas could give a tenfold reduction in exhaust gas velocity, making any extraction of useful work much harder.
The previous incarnation of the rules prevented the weird and wonderful exhausts that were used to ‘blow the floor’, but gave us exhaust exits that were submerged into the sidepods and angled downwards, still providing significant gains. The tailpipe diameters and lengths were not chosen to optimise engine performance, but to provide aerodynamic benefits, probably coming with a small engine performance penalty.
In addition to the significant ‘blunting’ of a whole area of car performance, the exhaust will be very different in its general architecture. The exhausts will be joined to a single turbocharger assembly that will be linked to a turbo-generator which will provide energy, not only for propulsion but to accelerate the turbocharger itself. Gone will be the days of turbo-lag: the reshaping of Formula One regulations will give us turbocharged engines with the transient response that we might expect from a naturally aspirated engine, and markedly improved efficiency.
Written by Wayne Ward