New Computational Fluid Dynamics methodology enables more efficient drivetrain
design, reducing drag losses by up to 30%
Leamington Spa, UK, 27th February 2018 – Driveline engineering consultancy, Drive System Design (DSD), has partnered with software specialists Altair and FluiDyna to develop and enhance a novel computer modelling technique, nanoFluidX, that significantly improves the analysis of lubrication flow. The approach utilises Smoothed Particle Hydrodynamics (SPH) methodology and increases the accuracy of analysis while reducing the simulation time from weeks to just a few days, when compared to traditional methods.
DSD is using nanoFluidX to improve electric vehicle (EV) range by reducing losses in the drivetrain, identified as the largest energy draw on the battery pack at steady speeds up to approximately 80km/h (50mph); even bigger than the vehicle’s aerodynamic drag. Improving efficiency at these lower speeds is essential to achieve worthwhile improvements in ‘real world’ driving range.
“Bearing, gear and seal losses are well understood by the industry; the interaction between rotating components and the transmission lubricant however has been too complex to explore within a typical project timescale,” explained Matt Hole, Head of Design Engineering, Drive System Design. “Practical tests using transparent casings have some value but it is difficult to visualise what is going on deep within the rotating components. The hardware lead times can also be prolonged; Finite Volume CFD (Computational Fluid Dynamics) analysis typically involves extensive run times, with each test point requiring several weeks’ computing just to generate a couple of seconds of real time data.”
DSD has overcome these difficulties working alongside Altair and FluiDyna to further develop and enhance the software to make it suitable to solve drag and fluid visualisation in transmission applications. In a recent project DSD used nanoFluidX to optimise an EV planetary transmission design.
“Using nanoFluidX enabled us to accurately visualise and analyse the behaviour of the transmission lubricant and its interaction with the rotating assemblies,” said Hole. “The improved understanding meant we could develop a highly optimised, passive lubrication system, iterating the design with specifically targeted improvements. In all, we reduced drag losses by almost 30 percent while maintaining satisfactory lubrication of all the transmission elements.”
Better visualisation allowed DSD to improve thermal management by increasing the oil volume without incurring high churning and windage losses. Instead, a segregated oil cavity was created within the transmission case, from which oil is directed by baffles to strategic areas, such as the planet bearings and pins which are often very difficult to lubricate reliably.
“nanoFluidX offers a level of interaction with, and analysis of, the results that is not available with conventional testing, and those results can be achieved in a much shorter time frame than is possible with either physical testing or fixed volume CFD approaches,” said Hole. “It means we can achieve a much higher level of design optimisation within the timescale of a typical customer program.”
Drive System Design will demonstrate its use of the software in conjunction with its development engineering when the company exhibits at the Future Powertrain Conference in Solihull, UK, on Wednesday 28th February and Thursday 1st March (Stand 27). Visitors to DSD’s stand will see an ultra-compact, highly efficient electric drive unit, recently developed on behalf of a global manufacturer, demonstrating the benefits of the methodology.
Drive System Design (DSD) is an award winning engineering consultancy specialising in the engineering, development, test and control of electrified and conventional driveline systems.
The company’s staff have experience working with vehicle manufacturers and Tier 1s around the world, designing new technologies and solving problems to make their products more competitive. They have the engineering, test, analysis and project management skills necessary to deliver projects to demanding timescales. Working closely with its customers through technical centres in Europe and North America, DSD is recognised as a world leading expert in driveline refinement, efficiency improvement and hybrid and electric vehicle transmissions. DSD is ISO 9001 and ISO 14001 certified.
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