Globally unique experimental and simulation techniques result in CO2 savings equivalent to removing 109, 000 cars from the road every year
When challenged with the requirement to reduce CO2 emissions without compromising vehicle performance, researchers at Bath worked with Ford to develop globally unique experimental and simulation techniques, to achieve the challenging targets set whilst also significantly shortening the vehicle development process.
“The challenging brief set by Ford called for an innovative, yet sustainable approach to future product development processes, something our system-level approach and facilities enabled us to embrace. Combining our expertise in bridging the gap between real driving conditions and the accuracy and repeatedly of the lab environment contributed to Ford achieving an outstanding CO2 saving across their EcoBoost fleet whilst also substantially strengthening their product development processes.”
Professor Chris Brace, IAAPS Academic Director
Increasing regulation called for improved product development processes
The automotive industry has been under pressure to shorten its product development processes whilst also adhering to increased regulatory requirements on CO2 emission reductions. Within this complex environment, Ford needed to deploy new product development techniques across its Ford Focus fleet that would deliver significant CO2 reductions without compromising vehicle performance. In 2013, while planning the development of its revised EcoBoost engine to meet new CO2 and performance targets, Ford asked the University of Bath to apply their expertise in highly downsized engine systems to better understand and model the complex engine boosting system.
Novel Experimental and Simulation System Development
The research at Bath began in 2014. Specifically, the Bath team studied how non-steady energy transfers from a highly pulsating exhaust flow affect the performance of a novel mixed-flow turbocharger. A subsequent aim was to incorporate the new techniques into an improved development process.
Extending the use of digital development tools
As laid out by the Automotive Council, over the next decade the automotive industry needs to adopt new development practices to shorten product development from 5 years to 18 months, under increasing regulatory pressure. This requires a change from today’s practice, where around 95% of product verification is achieved experimentally, to an end state where 95% of the process is digital. The challenge is enormous and will require much better digital models of complex powertrain systems.
A key obstacle is the lack of accuracy in simulation of the dynamic performance of turbochargers, commonly leading to overly optimistic design choices that later result in unacceptable performance deficiencies in real world use. Existing design techniques for engine development use simple models of turbocharger performance based on datasets captured experimentally under steady flow conditions. True dynamic performance cannot be assessed until much later in the development process when the engine and turbocharger are fitted into a vehicle. Evaluations of dynamic performance in the vehicle at this stage occur late in the vehicle development programme, when any changes are enormously expensive.
To provide greater insight into dynamic performance at an early stage in the process, the Bath team designed a technique to move from steady state to dynamic real time data. They developed a novel experimental system that could be used to study the behaviour of the turbocharger under pulsed air mass flow and high-speed pressure fluctuations, realistically recreating the phenomena seen in an engine. The University of Bath team, led by Professor Sam Akehurst and Dr Colin Copeland, designed, built and demonstrated the first facility of this type in the world.
The exhaust pressure pulses caused by individual engine cylinder firing events were recreated by a novel hot gas pulse generator. Changing the frequency of the valve events simulated changing engine speed. To achieve robust, high fidelity measurement of the critical temperature and pressure fluctuations at the turbine inlet required the development of a high-speed mass flow sensing system using a novel, 3D printed, metal pitot tube architecture, complementing data from more traditional sensors. Similar challenges were overcome when quantifying unsteady turbine efficiency, which required the ability to measure the time-resolved mass flow rate at high speed. Full-scale engine studies further refined the technique to ensure correlation of the process with real-world behaviour across all operating conditions.
The data and insight gained were used to develop new dynamic simulation methods that predict the behaviour of the complete engine/turbocharger system under realistic dynamic conditions. The simulation was used to model system behaviour, demonstrating that the required dynamic performance was achievable. Additionally, the simulation provided an early warning of a control instability leading to flow disturbances that would render vehicle performance unacceptable. This was achieved at a point in the programme at least a year in advance of when such issues would normally be evident in vehicle testing. This led to a strong pull through for the research from Ford, who wished to use the improved experimental methods and computer model to allow fast, accurate understanding of how airflow influences the behaviour of turbomachinery. This in turn allowed CO2and fuel economy benefits to be realised with lower risk of delays and changes late in the vehicle development programme.
Recognised as ‘Globally Unique’
This new capability, developed by the team at Bath, has been recognised by the Government’s Technology Strategy Board as globally unique, and the technique has been patented (GB2536760A·2016-09-28). To make the improved understanding delivered by this research more widely available and to reduce the cost and time required to apply it, the University of Bath then used data and insights from the laboratory simulations to support the development of a high fidelity, computer-based dynamic model of airflow within a turbocharger.
The techniques developed by the Bath team have been incorporated into the product development process used by Ford to develop the revised 1 litre EcoBoost and subsequent engines. This has improved the quality and speed of the development process and enabled evaluation of performance issues at least a year earlier than previously possible using the incumbent product development approach.
As stated by Ford:
“The Bath team developed a novel pulsating flow experimental test facility to characterise and optimise the turbocharger. This facility was so effective and unique that Ford Motor Company filed a patent to secure its IP, with Akehurst and Copeland as named inventors. (DE102016121974 and GB2536760).”
The adoption of this novel approach to Ford’s development processes has allowed outstanding reach for the impact, initially to include additional Ford engine programmes. Its subsequent adoption by engine and system designers at other companies has further contributed to the automotive industry’s strategic goal of greater deployment of virtual product development processes, by improving the fidelity of the analysis to a level not normally achieved until the physical hardware is available in a vehicle.
Exceptional UK and Global CO2 Reductions
Passenger cars represent the 60.2% of EU road transport CO2 emissions, themselves equivalent to 21.6% of all EU’s CO2 emissions. The Ford Fiesta is the 4th best-selling passenger car in Europe, first in the UK. Therefore any improvements that can be made have outstanding international reach due to the huge number of vehicles affected.
The primary impact of the University of Bath research was to develop and apply a novel research technique that allowed Ford’s objectives to be met through precise but significant changes to turbocharger design and engine calibration, allowing their CO2 reduction strategy to enter high volume production. The programme passed Ford’s ‘Judgement Gateway’ in August 2016, meeting or exceeding all targets for fuel economy, CO2, pollutant emissions and refinement. Engine production began in November 2017 with fitment planned for the Fiesta, the Focus (the UK’s second best-selling vehicle) and seven other Ford models.
As noted by Ford:
“as a consequence of Bath’s research… the ACTIVE programme demonstrated a 13% improvement in vehicle fuel economy with 9% due to the engine technologies. The engine went into mass production in 2017 and is now available across a wide range of the Ford vehicle portfolio, to date more than 300,000 engines have been produced utilising the technology developed, peak demand for the engine family is expected to be around 1.4M vehicles per annum. This would equate to approximately 200,000tonnes of reduced CO2 for a single year of production.” Furthermore, “around 1.4 million new Ford vehicles each year emit less CO2 and pollutants because of this work, delivering an annual, cumulative CO2 saving equivalent to taking 109,000 average cars off the road every year.”
Delivering sustainable, global impact
The impact delivered by the research with Ford has outstanding international significance in CO2 terms alone. More efficient engines also offer the driver improved fuel economy, roughly equivalent to the percentage CO2 reduction, saving money for the business or individual operating the vehicle and reducing the need for fossil fuels.
The University of Bath work contributed to Ford winning the 2019 global Engine of the Year award following assessment by 70 specialist judges from 31 countries.
Ford of Britain Chairman, Graham Hoare stated that:
“Bath directly contributed to fundamental research to improve the performance and integration of… our 1 Litre EcoBoost engine, which was voted best Sub 150PS engine in 2019”.