Optimal control theory and Ferrari’s turbo-electric hybrid

The Department of Engineering Science at the University of Oxford, published an interesting paper in 2014 which appears to shed some light on the deployment of energy-recovery systems in contemporary Formula One.

Entitled Optimal control of Formula One car energy recovery systems, (a free version can be downloaded here), the paper considers the most efficient use of the kinetic motor-generator unit (ERS-K), and the thermal motor-generator unit (ERS-H), to minimise lap-time, given the various regulatory constraints. (Recall that the primary constraints are: 100kg fuel capacity, 100kg/hr maximum fuel flow, 4MJ Energy Store capacity, 2MJ per lap maximum energy flow from ERS-K to the Energy Store, and 4MJ per lap maximum energy flow from the Energy Store to the ERS-K). The paper outlines a mathematical approach to this Optimal Control problem, and concludes with results obtained for the Barcelona track.

In the course of the paper, a number of specific figures are quoted for engine power. For example, the power of the internal combustion (IC) engine under the maximum fuel-flow rate, with the turbo wastegate closed, is quoted as 440kW (590bhp); it is claimed that by having the turbo wastegate open, the power of the IC engine can be boosted by 20kW (~27bhp), but in the process the ERS-H has to use 60kW of power from the Energy Store to power the compressor; and with the wastegate closed, the 20kW reduction in IC power is compensated by the 40kW generated by the ERS-H. (Opening the wastegate boosts IC power because the back-pressure in the exhaust system is reduced).

Running with the wastegate closed is therefore considered to be the most efficient solution for racing conditions. However, the paper also considers qualifying conditions, where the Energy Store can be depleted over the course of a lap without any detrimental consequences:

“In its qualifying configuration the engine is run with the waste gate open for sustained periods of time when maximum engine power is needed. During these periods of time the energy store will be supplying both the MGU-K and the MGU-H, with the latter used to drive the engine boost compressor…In contrast to the racing lap, the waste gate is typically open when the engine is being fully fuelled. On the entry to turns 1, 4, 7 and 10 the waste gate is being closed a little before simultaneously cutting the fuel and the MGU-K.”

Professor of Control Engineering David Limebeer delivered a presentation of the work at a Matlab conference the same year (video here). Another version of the work, Faster, Higher and Greener, featuring Spa rather than Barcelona, was published in the April 2015 edition of the IEEE Control Systems Magazine. In his Matlab presentation, Professor Limebeer also credits Peter Fussey, Mehdi Masouleh, Matteo Massaro, Giacomo Perantoni, Mark Pullin, and Ingrid Salisbury.

After reading their work, I e-mailed Professor Limebeer, and asked if he’d considered collaborating with a Formula One team. I received a slightly odd response. After a further internet search, I found out why. In the November 2014 issue of Vehicle Electronics, David reports “We have done this work with one of the Formula One teams, but we can’t tell you which one.”

Which is totally understandable. University departments have to protect the confidentiality of their work with Formula One teams. Unfortunately, however, the University of Oxford, Department of Engineering Science Newsletter 2013-2014, proudly reveals:

The Ferrari F1 Connection.
Mr Stefano Domenicali, Scuderia Ferrari Team Principal, visited the Department in May 2013 to deliver the annual Maurice Lubbock Memorial Lecture. During this lecture he announced the evolving research partnership between the University and Ferrari.

DPhil Engineering Science students Chris Lim, Giacomo Perantoni and Ingrid Salisbury are working with Ferrari on novel ways to improve Formula One performance. Chris Lim said: “I’m very excited that I’ll be the first student working with Ferrari in the Department’s Southwell Laboratory, under the supervision of Professor Peter Ireland, the Department’s Professor of Turbomachinery. It’s a privilege to work with a prestigious manufacturer such as Ferrari in an industry like Formula One where the application of thermo-fluids has such a large impact”.

Pictured from left to right are: Chris Lim (postgraduate), Ingrid Salisbury (postgraduate), Mr Stefano Domenicali, Giacomo Perantoni (postgraduate) and Professor David Limebeer (supervisor to Giacomo Perantoni and Ingrid Salisbury).

In light of this, then, the figures quoted in these papers can be interpreted as pertaining to Ferrari’s turbo-electric hybrid. The first paper was submitted for publication in late 2013, and the assumptions used there are the same as those used in the 2015 paper, so it appears that Ferrari development data from no later than 2013 was used throughout.

Continue Reading…

Coral reefs and vortices

It seems that counter-rotating vortices are everywhere. The September 2014 edition of the Proceedings of the (US) National Academy of Sciences has published a fascinating study which reveals that coral reefs actively create quasi-steady arrays of counter-rotating vortices.

Corals exist in a symbiotic relationship with algae, which live within the tissue of the coral, and photosynthesise the organic carbon used by the corals to build their calcium-carbonate skeletons. In return, the corals have to provide nutrients for the algae, and remove the excess oxygen produced by photosynthesis.

Until now, it’s been assumed that corals were dependent upon molecular diffusion alone to achieve the necessary mass transport. A concentration boundary layer exists at the surface of the coral: the concentration of a molecular species produced by the coral (such as molecular oxygen, O2) is highest at the surface of the coral, and a concentration gradient exists in the direction normal to the surface of the coral until the edge of the boundary layer is reached, where the concentration matches the ambient level. This concentration gradient drives outward molecular diffusion.

In the presence of an ambient flow, the boundary layer becomes thinner, increasing the steepness of the concentration gradient, and thereby enhancing the mass transfer rate. However, many parts of many coral reefs often experience periods of very low ambient flow, and there was evidence to believe that mass transfer rates were actually higher than could be explained by the ambient flow conditions. (Here there is a similarity with heat transfer within a bundle of nuclear fuel rods, where the rate of thermal mixing was higher than could be explained by turbulent diffusion and thermal conduction alone).

The research just published has revealed that the cilia (tiny hairlike entities) on the surface of the coral polyps are able to create a pattern of counter-rotating vortices which enhance mass transfer rates even in conditions of stagnant ambient flow (see image below). The counter-rotating vortices seem to be produced by the coordinated sweeping motion of the cilia, with one group of cilia sweeping in direction, and another group sweeping in the opposite direction.

The research revealed that the vortices are able to transport dissolved molecules by ~1mm in ~1sec, under conditions which would otherwise require ~1000secs to traverse the same distance by molecular diffusion alone.

It was also found that the location and shape of one such vortex was stable over the 90min period under which the concentration levels of oxygen were measured. The latter produced the image below, showing that one side of the vortex, flowing towards the surface of the coral, had ambient levels of oxygen, whilst the other side of the same vortex transports the oxygenated water away.

.

Bridgestone MotoGP: Qatar debrief with Shinji Aoki

Repsol Honda’s Marc Marquez won the MotoGP season opener at Qatar’s Losail International Circuit, as the reigning World Champion claimed victory ahead of Movistar Yamaha Racing’s Valentino Rossi and Repsol Honda’s Dani Pedrosa who finished in second and third place respectively.

Weather conditions for the race were cool and humid, with a peak track temperature of 20°C for the … Keep reading

.

Ferrari plan ‘Red’ rally for Michael Schumacher

While Michael Schumacher remains in critical condition, Ferrari have announced via their Facebook page that they would like to host a silent and respectful rally at the hospital in Grenoble to honor the 7-time champion on his birthday Friday January 3rd.

“In these difficult days and on the occasion of his birthday the SCUDERIA FERRARI CLUBS want to show their support for MICHAEL SCHUMACHER, organising tomorrow a silent and respectful event all in Red at the Grenoble University Hospital Center.”

Schumacher remains in critical condition today and the hospital is planning no media updates. That does bring to mind the notion that the hospital does have other patients and duties and should the event garner a large participation, it could be challenging for the hospital to manage.

I would hope the Ferrari clubs will also provide some sort of crowd management and security for the event. We’ve already seen a journalist impersonate a priest in order to try and sneak into Schumacher’s room so having a throng of ardent fans may be a challenge as well.

Having a throng of supporters is most likely appreciated by Corinna but at this moment, the only thing she’s likely to really care about is her husband.

Source: formula1blog.com

Schumacher ‘is in a critical situation’ and ‘fighting for his life’

Doctors assembled this morning to release a statement and update the world on Michael’s condition:

“On his arrival we examined him clinically and realised he was in a serious conditions, in a coma with in fact cranial pressure,” Professor Stephan Chabardes said.

“The brain scan showed a number of pieces of information: some inter-cranial haematoma, but also some cerebral contusions and edema.

“We operated urgently to try and eliminate the haematoma and after the operation, we saw that we were able to eliminate these haematoma. But also, sadly, the appearance of various bilateral lesions, so he was taken to intensive care to try to help him.”

Doctors say that they are working hour-by-hour to help Michael and that it is too early to talk of future prognosis:

“For the moment, we are not able to express ourselves with regard to Michael Schumacher’s future,” Professor Payen added.

“We’re working all together, day and night, at his bedside. But it’s far too early to be able to say anything as far as prognosis is concerned.

“We’re currently not talking about after-effects; we’re talking about treatment and we’re working hour by hour.”

Friends Jean Todt and Ross Brawn have been to the hospital to visit and give their support as well as Schumacher’s friend and physician, Gerard Saillant, who is a leading brain surgeon and who assisted Schumacher when he broke his leg in the 1999 British Grand Prix. Saillant said:

“It’s just as a friend that I’m here, so I can’t answer any questions that are not in my domain,” he said.

“We’re all concerned by his state and it’s been extremely well explained, the doctors can’t tell you anymore.

“It’s not that they don’t want to or are not able to. They are working hour-by-hour and it’s at that level that one can make decisions.”

Via formula1blog

dd