Race engine development shifts gear
08 March 2017
Race engine development shifts gear
Traditionally, race engine development has primarily been centred on maximising the air flow rate of an engine by improving its volumetric efficiency as well as increasing the maximum operating speed. Fuelling was typically rich of stoichiometric and obtaining good combustion was rarely an issue. Over the years Ilmor has built up a vast knowledge about how to optimise these types of engines, using 1D simulation tools as well as empirical testing of hardware. CFD studies were only carried out on rare occurrences as they were costly in terms of time and resources with the systems available at the time.
The situation for engine designers is now rapidly changing. Today, developments in both software and hardware mean that in-cylinder CFD studies can now be completed in only a few hours using relatively inexpensive computers. These advances in the simulation technology have coincided with the shift in emphasis towards fuel efficiency in many of the top level racing series, as well as the general automotive industry.
The new generation of fuel efficient racing engines are optimised in a totally different way to what’s traditionally been the case and it’s resulted in a significant change in how we now work at Ilmor. Improving performance is now largely concerned with optimising the combustion efficiency through the generation of in-cylinder charge motion and turbulence, along with the interaction and mixing of the fuel from the direct injection. Tools such as CONVERGE CFD software, developed primarily for this type of work, can model in-cylinder processes and significantly reduce the workload in preparing models.
Simulation allows us to evaluate many more port, combustion chamber and spray geometries than would have been possible by physically testing hardware. As well as saving time and reducing the prototype parts costs, CFD allows us to visualise the complex flow regimes within the engine, enabling our Engineers to understand the processes in more detail. They can be much more creative and it’s led to several fruitful avenues of development that may have traditionally been missed.
Ilmor takes a fairly pragmatic approach to simulation and we still carry out dyno tests on a number of the hardware configurations. It’s important that CFD simulations correlate with the test data to ensure it’s actually taking us in the right direction. Fully predictive CFD isn’t quite here just yet.
For many customers it is important to demonstrate technology through racing. It’s exciting times ahead for CFD simulation to generate real success both on the road and track.
Rennmotorenentwicklung wechselt den Gang
Traditionellerweise war die Entwicklung von Rennmotoren in erster Linie darauf ausgerichtet, die Luftströmungsrate eines Motors zu maximieren, indem der volumetrische Wirkungsgrad verbessert und die maximale Betriebsgeschwindigkeit erhöht wird. Das Treibstoffgemisch war in der Regel fett und eine gute Verbrennung war selten ein Problem. Im Laufe der Jahre hat Ilmor ein umfassendes Wissen darüber aufgebaut, wie man diese Art von Motoren, mit 1D-Simulation-Tools sowie empirischen Tests von Hardware optimiert. CFD-Studien wurden nur bei seltenen Ereignissen durchgeführt, da diese zeit- und ressourcenintensiv mit den damals verfügbaren Systemen waren. Die Situation für Motorenbauer verändert sich jetzt rasant.
Durch die Entwicklungen sowohl in der Software als auch in der Hardware können heute CFD-Untersuchungen innerhalb von nur wenigen Stunden mit relativ preiswerten Computern abgeschlossen werden. Diese Fortschritte in der Simulationstechnologie sind mit der Verschiebung der Bedeutung der Kraftstoff-Effizienz in vielen der Top-Level-Rennserien, sowie der allgemeinen Automobilindustrie zusammengetroffen.
Die neue Generation der kraftstoffsparenden Rennmotoren wird auf eine völlig andere Art und Weise optimiert, als dies traditionell der Fall war und es hat zu einer deutlichen Veränderung der Arbeitsweise bei Ilmor geführt. Die Leistungsverbesserung betrifft nun weitgehend die Optimierung des Verbrennungswirkungsgrades durch die Erzeugung von Ladungsbewegung und Turbulenz im Zylinder zusammen mit der Wechselwirkung und dem Mischen des Kraftstoffs von der Direkteinspritzung. Werkzeuge wie die CONVERGE CFD-Software, die primär für diese Art von Arbeiten entwickelt wurde, können In-Zylinder-Prozesse modellieren und die Arbeitsbelastung bei der Modellvorbereitung deutlich reduzieren.
Die Simulation ermöglicht es uns, viel mehr Kanal-, Brennraum- und Sprühgeometrien auszuwerten, als dies durch physikalisches Testen von Hardware möglich wäre. Neben der Zeitersparnis und der Reduzierung der Kosten für die Prototypenteile ermöglicht CFD die Visualisierung der komplexen Strömungsabläufe im Motor und ermöglicht es unseren Ingenieuren, die Prozesse detaillierter zu verstehen. Dadurch können sie viel kreativer sein und zudem hat es zu einigen fruchtbaren Entwicklungswegen geführt, die traditionell vermisst worden wären.
Ilmor nimmt einen ziemlich pragmatischen Ansatz für die Simulation und trotzdem führen wir noch etliche Prüfstandtests an einer Reihe von Hardware-Konfigurationen aus. Es ist wichtig, dass CFD-Simulationen mit den Testdaten übereinstimmen, um sicherzustellen, dass es uns tatsächlich in die richtige Richtung bringt. Völlig prädiktive CFD ist noch nicht ganz realistisch.
Für viele Kunden ist es wichtig, technischen Fortschritt durch Rennsport zu demonstrieren. Es wird spannend wie mit CFD - Simulationen Erfolge in Zukunft auf der Straße als auch auf der Rennstrecke erzielt werden können.
Apprentice of the Year
12 January 2017
Patrick Morgan continued his family’s long standing association with Ilmor when he visited recently to present the Apprentice of the Year award and trophy to James Flannigan from the Inspection department.
James has been with Ilmor for almost two years and during that time has become an important member of the Inspection department’s team. James attends Northampton College once a week where he is studying for a BTEC qualification (L3 Technical Services Quality). As part of James’ work in the Inspection department he is learning to run and programme the CMM (Co-ordinate Measuring Machine) which allows the checking of components against drawing specifications.
21 December 2016
Ilmor Engineering wish you a very happy Christmas.
Please note that we are closed from Friday 23 December 2016 at 16.00 and will reopen in the new year on Monday 2 January 2017.
Power Train Test Upgrades
20 October 2016
Ilmor Engineering is one of those companies that largely chooses to fly underneath the radar. Its customers include some of the biggest names in motorsport and beyond, ranging from NASCAR teams to aircraft manufactures. And yet you could quite easily drive past the company’s Northamptonshire headquarters in the UK without even noticing it.
Across the road sits the factory where Mercedes makes its all—conquering Formula 1 engines. That too was part of the Ilmor empire until the German brand completed its purchase of the group in 2005. The rights to the name and the non-F1 side of the business were promptly sold back to its original owners and since then the two have gone on as separate entities.
Ilmor has diversified over the years into OEM automotive, marine and defence but motorsport remains the backbone of the business. These days it’s perhaps best known for developing and manufacturing the Chevrolet IndyCar engines but the company also works with Roush Yates Racing Engines on the Ford NASCAR program, not to mention Renault on its F1 units. Add to that a number of GT and World Rally Championship projects and it’s obvious Ilmor is doing a lot behind the scenes.
The unremarkable–looking industrial unit that forms its UK base is home to 85 staff and array of test facilities. There’s a bank of seven dynamometers, including an in-house designed F1 dyno capable of more than 20,000rpm – due to be retired shortly for a new Apicom FR500BRV eddy current unit. Alongside it sit three Schenck D700 water brakes, two Apicom FR1000S eddy current dynos and an AVL Elin EBG P22 transient AC dyno run in tandem with an Apicom FR500BRVS eddy current brake.
Each cell is fed with its own stream of inlet air, with independent control of temperature, pressure and humidity. This largely to provide fixed environmental conditions, rather than full climatic testing but one of the cells does have a neat trick in the form of a large compressor that mimics the effect of a turbocharger or supercharger. This provides up to 8 bar of boost, allowing engines to run in a forced induction mode without the associated hardware.
“At any one time we’re typically using four of those dynos for internal use and hiring out the remainder” says Ian Whiteside, chief engineer of advanced projects at Ilmor. “They’re fed by a 42,000-liter tank above ground or one of five 9,000-liter subterranean tanks, which can be loaded with anything from aviation fuel to methanol”.
The company is currently in the process of switching over its dynamometer control systems to the REO-dEC platform. There’s also a Horiba MEXA 7170D emissions measurement system and a total of four AVL IndiSet analysis machines for high-speed data acquisition.
At the high-performance end of the spectrum, the biggest challenge is actually getting cylinder pressure transducers to survive, explains Whiteside: “On our Formula 1 and IndyCar work we’re really pushing the capability of the sensors. Even using the highest quality 300 bar sensors from AVL and Kistler, their lifespan ranges from a few hours down to a single knock event. They tend to have a bit of concussion after that!”
Less brutal, but no less important, is Ilmor’s off-engine rig. This is another in-house designed device developed for testing engines or components in a motored state. It is powered by a 46kW electric motor, which provides enough torque for large-capacity road engines and even th4e big NASCAR V8s.
Some of the most interesting work carried out on this rig revolved around valvetrain development. Whiteside explains. Just down the corridor, the company has a single-valve rig, which enables valve and spring motion to be examined in even greater details – something that is particularly critical in NASCAR engines, which rev to higher than 9,000rpm with pushrod actuation and mechanical springs.
“It’s interesting, because the valve doesn’t always move in the way you think it’s going to move”, says Whiteside. “NASCAR valvetrains are designed to allow lofting – where the follower parts company with the camshaft to achieve higher lift. Getting it to come off is quite simple but getting it to go back down is a bit trickier! On the single-valve rig it’s also quite difficult to get the right lubrication on the rockers and the push rods during the test, so we could only run that for a few seconds at a time”.
A number of techniques are used for capturing the details of this valve motion. One option is to bounce a laser beam off the face of the valve, explains Whiteside, while another is to cut a series of serrations onto the valve to be picked up by an eddy current sensor embedded in the valve guide. High-speed video is another method, often used in conjunction with a tracking system that picks up the motion of coloured dots placed on the components.
Further down the facility lies the injector flow rig, which is routinely used for characterizing the injectors on the firm’s IndyCar engines. Quite unusually, it features a rate tube, which can capture will be open 12:00-15:00he injector flow on a crank angle basis, as opposed to averaging it out over a longer time period.
“With this rig, we can look at how the mass flow changes as the injector opens and closes. That’s really useful for comparing the repeatability of injectors, but it’s also good for looking at the performance as the injector ages”, notes Whiteside.
TIME AND MONEY
Although the airflow rig is still used for correlation purposes, most of the development work has been carried out in CFD since the company underwent a major overhaul of its simulation capabilities in 2015. It now has a new 32-core computing cluster, running the converge CFD code from Convergent Science.
Developed with in-cylinder combustion modelling firmly in mind, this package contains a variety of different features designed to improve the speed to accuracy balance of the CFD simulations. It’s Ilmor Engineering’s first foray into the world of in-cylinder simulation and, according to Whiteside, the results have been impressive.
“One of the first major projects we did using Converge was the revised IndyCar cylinder head for the start of this season”, he reveals. “We saved six to eight weeks in terms of development time – a reduction of around 50% - and arguably got to a better solution as a result of using simulation. By screening the designs in the virtual world, we also saw a 75% reduction in our prototype build costs”.
Embracing an increasingly digital age is one of the things that keeps Ilmor at the cutting edge of engine development and means there’s surely a lot more come from this company.
Taken from Automotive Testing Technology International September 2016