Surface to air
Michael Augustin, senior aerodynamicist at Horiba-MIRA, considers the challenges facing India’s carmakers as well as the opportunities they have to improve the efficiency and safety of their vehicles through aerodynamics.
India has been a production and manufacturing base for the global automotive industry for many years. Traditionally hampered by inadequate infrastructure, increased investment in recent times and its impact on expanding the road network in the country is ensuring a brighter future for industry in India.
Further, with the Union Budget 2016-17 allocating a humungous Rs 97,000 crore to roads and highways development, it won’t be very long before a number of roads in the country enable smooth and speedy motoring. This in turn means car manufacturers will need to keep up, ensuring their vehicles are designed for more efficient and faster roads and vehicle aerodynamics will become more important as manufacturers will need to account for vehicles traveling at higher speeds.
A stronger future
In fiscal 2014-15, the automotive sector in India grew by eight percent. In fact, it now accounts for seven percent of the country’s gross domestic product. Despite this growth, India is hampered by insufficient infrastructure. Congestion and pollution remain a challenge for many Indian cities, with infrastructure development unable to keep up with the rapid growth of the urban population. However, recent tranches of investment, including India’s National Highways Development Project injecting $45 billion into infrastructure over the next three years, means the country will soon see faster and more efficient road networks. With 1.9 percent of the nation’s roads carrying 40 percent of India’s total traffic, this improvement will ensure drivers can get to their destinations faster, more efficiently and safer.
A case for improved aerodynamics
With investments in the Indian road network and improved infrastructure, road users will begin to experience a new way of driving – one where the importance of efficiency will rise in tandem with the increase in speeds. Efficient vehicles rely on accurate aerodynamic testing, to ensure the way the vehicle moves is not disproportionately impacted by drag.
Currently, aerodynamic development in India relies largely on Computational Fluid Dynamics (CFD), a simulation technique that attempts to simplify the real flow conditions by using a computer to create a 3-D mesh (or grid) to break down the overall flowfield into small zones. Within each small zone (or cell), the CFD software solves the underlying laws of fluid dynamics for a defined set of boundary conditions, using turbulence models (flow approximations with limited applicability) and other mathematical techniques that are selected by the CFD engineer.
The advent of relatively cheap and powerful computers has increased the speed of CFD computations from many weeks to a few hours in recent times; the windfall of cheap and plentiful computational power has also been put to good use in alternative ways – in the attempt to improve the accuracy of the CFD predictions. Instead of solving the equations faster, but retaining lower quality results, CFD engineers have tended to ‘spend’ their improved access to computational power by increasing the complexity of the underlying physics and increasing the number of cells in the mesh – all in the valiant aim to increase accuracy.
Whilst CFD is an essential part of development with particular strategic benefits early in the design cycle, where styling themes are not fixed and large scale changes are both practical and cheap to implement; CFD simply cannot ‘compete’ with wind tunnel testing once the styling is more mature and other technical factors become dominant.
Wind tunnels are able to quickly and accurately quantify the key aerodynamic forces including lift, side-force and drag, which in turn create the pitching, rolling and yawing moments that act on the vehicle’s body and impact on the way a vehicle moves.
For vehicles to be as aerodynamic as possible, vehicle makers must intelligently combine computer aided simulation, wind tunnel development and real-world validation in precise quantities and at the right juncture. Each of these three tools provide distinct and discreet technical, developmental and commercial advantages at different times in the development-cycle. When combined correctly, their data streams correlate to deliver the confidence that the technical development process is robust and that future vehicle programmes will deliver the projected levels of performance improvement. No coincidence either, this virtuous circle also delivers the highest return on investment.
Whilst leading Indian brands have been highly successful in developing vehicles for local markets, competing on the world stage and exporting global-specification vehicles in volume has yet to be fully exploited. To do so, they must adopt similar testing practices to the likes of Ford, GM and Toyota. Collaboration with experts in areas like aerodynamics will be essential to driving down the overall cost and accelerate the effectiveness of aerodynamic development programmes. Partnering with established experts will enable vehicle manufacturers in India to take advantage of this ready pool of expertise and de-risk progress in this strategically significant attribute area.
The competition in the automotive sector in India is very healthy. Increased awareness of the importance of vehicle attributes (e.g. ride and handling, safety and NVH) is being driven by educated consumers who have access to global vehicles for comparison and a boom in automotive media i.e. magazines and TV shows. This increasingly demanding marketplace provides an opportunity for Indian manufacturers to collaborate with engineering experts, such as Horiba MIRA, to design and develop competitive vehicles.
Horiba MIRA has been present in India for over 20 years; in the past three years its Indian technical centre has been situated in Pune. There are a large number of R&D centres based in India – and in Pune specifically – so being in the heart of this is essential. Horiba MIRA India has the ability to deliver projects in ride and handling, safety, durability, thermofluids and design. However, through linking in with Horiba MIRA’s wider services, including use of the full scale wind tunnel, the business is able to deliver full vehicle engineering including testing and homologation, controls and electronics, electric and hybrid vehicle engineering, intelligent transport systems, functional safety, unmanned ground vehicles and, of course, aerodynamics.
The future of aerodynamics
The automotive industry has much to learn from aeronautics. One such technology, originally used by aeronautics engineers, is Particle Image Velocimetry (PIV). First developed in 1984 in Germany and now an industry-recognised reliable technique for measurement, PIV is being adopted by the automotive industry. Formula 1 teams, for example, use this optical technique to optimise the aerodynamic performance of their cars, with the ability to shave a valuable hundredth of a second off a lap time.
PIV works by tracking displacements of small particles without having to use intrusive equipment, providing much more accurate and reliable data. The basic principle of PIV involves using the stereoscopy technique to record the motion of microscopic particles that follow the airflow around an object (e.g. a car). Image processing methods are then used to establish the particle motion, and hence determine the three-component velocity field in the planar region of investigation.
More importantly, PIV can provide the experimental data necessary to the validation of an increasing number of high quality numerical flow simulations.
A new vision
Wing mirrors – a basic necessity in all vehicles and a relatively small external addition to a car can disproportionately increase the drag of the vehicle by around 6 per cent. In response, vehicle manufacturers are developing prototypes without wing mirrors, instead replacing them with cameras linked to a screen on the car’s dashboard. Whilst this may seem alien to some, they do provide additional vision and provide relief for those navigating narrow streets, where the removal of these winged protuberances gives the driver an additional foot of room, and increase forward field of vision.
Regardless of the take-up of this technology, it is evident that aerodynamics is continually being looked at as a way to improve efficiency of modern vehicles, and therefore must be taken seriously.
With the automotive industry careering towards greater efficiency, aerodynamics will become an ever more important part of the vehicle’s development lifecycle. Indian automotive manufacturers must keep pace with global development and develop robust testing practices to ensure their vehicles do not get left behind. Though a useful tool, CFD must be used in conjunction with physical tests in wind tunnels, making use of new technologies such as PIV, to ensure vehicles are developed to be aerodynamically efficient the first time round.
Horiba MIRA’s active R&D activity is addressing the challenges facing the automotive and commercial vehicle markets in India. This includes the need to reduce carbon consumption, improve activity and advanced passive safety systems to address the rising global casualty rates on our roads, and look at the potential of rapidly increasing levels of intelligence that can be deployed in vehicles. All of these technologies will come to the Indian market over the next few years, and indeed some already are. As this happens, collaboration with engineering expertise will be essential for Indian manufacturers to ensure they compete on the global automotive marketplace.
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