News stories from March 2017

The hidden valley: Ilmor takes the motorsport powertrain lead

29 March 2017

In deepest Northamptonshire, one of motorsport’s greatest names is blending traditional engineering knowhow with state of the art simulation techniques, Chris Pickering discovers

The Chevolet Indycar V6 engine is developed by Ilmor. Driving round the outskirts of Brixworth you wouldn’t necessarily know it was a place of global significance. But this unassuming corner of Northamptonshire marks the northern tip of Motorsport Valley – the strip of central and southern England that’s home to some 75 per cent of the world’s top-level motorsport R&D companies.

In many ways, Ilmor Engineering typifies this industry. Based in a quiet industrial estate on the eastern edge of the village, it’s responsible for engines that have dominated the likes of Formula One and IndyCar yet you’d hardly know it was there. It’s also evolving; embracing new techniques and moving into neighbouring industries such as aerospace and defence.

Ilmor can trace its roots back to another great UK motorsport institution. Company founders Paul Morgan and Mario Illien met while they were working as engineers at Cosworth, just down the road in Northampton. They hatched a plan to produce their own engines and founded Ilmor in partnership with US motorsport mogul Roger Penske in 1984.

 Initially, the company focused on the IndyCar series – a quintessentially American form of racing where British companies have had a defining impact ever since Lotus showed up in the 1960s. This remains a hugely important market for Ilmor, which produces the Chevrolet engines used in around half the current grid. Elsewhere, the company retains a significant presence in Formula 1.

Back in the late nineties it engineered the McLaren-Mercedes V10s that powered Mikka Hakinnen to his back-to-back F1 World Championships. This was the continuation of a fruitful partnership with Mercedes-Benz, which had begun with a phenomenally successful IndyCar engine earlier that decade. It culminated in 2005 when the German giant completed a buyout of the company and created Mercedes-Benz High Performance Engines. 

Paul Morgan, a keen collector of historic aircraft, was killed in 2001 when his Hawker Sea Fury overturned on landing. Following the buyout, however, his fellow co-founders bought the non-F1 parts of the business back from Mercedes, along with the Ilmor name. The two companies now face each other – literally – over the road, but they’re completely independent. They even compete against each other on the track, albeit indirectly with Ilmor carrying out behind the scenes work for a well-known F1 team.

Throw in a liberal sprinkling of NASCAR, World Rally Championship and GT racing projects and you have one of the most versatile – and active – motorsport powertrain companies in the world. Even so, it pays to diversify. “Motorsport is good when it’s good, but it can be quite seasonal,” explains Ian Whiteside, chief engineer for Ilmor’s Advanced Projects group. “We need cutting edge facilities with plenty of capacity to support our racing programmes, but we also need to ensure there’s enough work to keep them busy during the off-season. We try and fill that with racing parts for external companies, along with prototype work for other industries like automotive OEM, aerospace, defence and marine.”

These facilities include a state of the art machine shop, a comprehensive metrology suite and just about every conceivable powertrain testing rig. The building is home to no less than seven different engine dynamometers, including a 20,000 rpm F1 dyno designed and built in-house. Elsewhere, there are more than half a dozen smaller rigs that cater to sub-assemblies and specific components, ranging from valvetrain parts to fuel injectors. Embracing the digital domain Ilmor is a company that places huge emphasis on empirical testing, but the past few years have also seen a dramatic increase in the amount of simulation work carried out. In particular, the company has invested significantly in its CFD capabilities, with the addition of a new 32-core computing cluster and a dedicated in-cylinder combustion modelling package. “Historically we’ve relied heavily on physical testing, usually starting off with a handful of port designs on the flow bench,” Whiteside explains. “In recent years we’ve used rapid prototyping to speed things up, but essentially we’d still pick a handful of RP parts that looked promising on the rig and then manufacture them in metal to test them on the dyno. There’s only a finite number of parts that you can try with this approach and it does get quite expensive.” Aside from the cost constraints, there’s also a fundamental limitation on how much information you can glean from physical testing, he says: “Charge motion is vital to understanding combustion. We do have the facility to measure turbulence on our flow rig and we have an injector rig where we can look at spray patterns with a high speed camera, but these static tests are never truly representative of the real engine. Likewise, while you can measure the results on the dyno that doesn’t necessarily help you to understand the physics that’s produced the effect. In simulation, however, you can look at the root cause.”

While external CFD is more or less universal in motorsport, in-cylinder combustion modelling is still a relatively new field. Modelling the ports on their own creates similar limitations to flow bench testing; even if the correlation is perfect between the CFD and the rig, it doesn’t necessarily reflect what’s happening in the real engine. On the other hand, it’s notoriously tricky to accurately model a full cylinder with moving geometry. Ilmor has turned to the Converge CFD code developed by US company Convergent Science. This uses a radically different approach to generating the mesh that defines the geometry of the simulation. Instead of relying on a manual mesh, Converge automates the process, based on user-defined parameters. Its makers claim this improves the repeatability of the mesh – removing the degree of manual artistry previously involved – and hence providing more consistent results. More importantly, though, Converge regenerates the mesh at each time step throughout the simulation. That may sound time-consuming, but by reducing the cell density in less critical areas of the mesh and increasing it in others – for instance, following the flame front as it propagates out across the cylinder – Convergent Science claims it has achieved a step change in the speed-to-accuracy trade-off. It also means the simulation can represent moving geometry, such as valve and piston motion, without incurring the deformation errors that arise from distorting a static mesh.

This proved to be the tipping point for Ilmor, Whiteside explains: “We still use the flow rig for correlation, but we now use CFD for most of the development work. The first major project we tackled with Converge was the revised cylinder head for the 2016 IndyCar engine. We think we saved around six to eight weeks in terms of development time and arguably got to a better solution. There’s undoubtedly a cost saving too. By screening the designs in the virtual world we probably only manufactured half the number of physical prototypes that we would have done previously. There is a degree of investment in the software, admittedly, but our licence costs less than a single rebuild on an IndyCar engine and it cuts down on running costs too.” In-cylinder CFD is just one part of the shift towards digital development. Ilmor also extensively uses 1D simulation codes like GT Power to model engines at a systems level, often coupling them to the more detailed 3D models.

Other programmes within the GT Suite are also used extensively to analyse things like the torsional vibration and tribology. Elsewhere, the manufacturing process has also been heavily digitised. Once a design is released it is assigned a part number and sent to a central server in read-only form. The manufacturing department picks up this file and uses it to set up the machining operations. Meanwhile, the planning and procurement area of the business establishes a record of the same part number, which goes through a scheduling program to determine when it can be manufactured. “It was quite a lengthy exercise to get this system up and running, but it’s a huge benefit now,” explains Whiteside. “We have much greater control of the work going through the machine shop. Each of the machines is linked to the scheduling system and each part has a job code assigned to it with a bar code, so they get scanned on and scanned off the machine to keep everything updated.” This software also informs the inspection department that there will be parts on the way, where the CMM machines can be programmed in advance using the central CAD model. Finally, the stores are notified of the incoming parts, so each individual component can be given a serial number, which is then used to track it throughout the rebuild life of the engine.

At Ilmor, every stage of the engineering process now features some degree of digitisation, from initial R&D concepts through to managing the service schedule of completed engines. Much of this is part of a gradual trend, admittedly, but there have been step changes, such as the adoption of in-cylinder CFD. Combined, they help to keep this sleepy little corner of Northamptonshire an unexpected focal point for global powertrain development.

By Chris Pickering 17th January 2017 borrowed from The Engineer

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.