(Re)designing resistors with Computational Fluid Dynamics
01/10/2018 Cressall Resistors
The design of the much-loved Mini Cooper dates back to the 1950s and has elegantly withstood the test of time to become the British icon it is today. If you asked Mini Cooper engineers, they would tell you that there are several generations of Minis, but the average person would probably say there's only one Mini. Product redesigns can often go unnoticed despite, significant improvements and updates.Here, Damiano Natali, research and development engineer at Cressall Resistors, explains how Computational Fluid Dynamics (CFD) helps refresh legacy product designs.
CFD combines the principles of Fluid Mechanics with numerical algorithms to analyse the behaviour of a fluid (like air or water) and the forces they exert.
Like structural and electromagnetic packages, CFD is one of the Computer Aided Engineering (CAE) technologies that has flourished in the last decade. CAE allows manufacturers to understand their products better and improve product performance faster and with fewer resources. CAE is used in factory settings in a wide range of stages: from first design and proof of concept through to the development and verification of a product.
By providing a reliable and accurate digital simulation of how a resistor will perform in a given situation, the manufacturer can identify potential drawbacks and improvements early in the design process.
Moreover, CAE tools allow engineers to perform simulations on existing products without having to design, set up and maintain a highly complex testing rig and to experiment with changing different parameters to find the optimum design. In turn, this translates into time and cost savings for Cressall's clients.
Wind/wave force on enclosures
The brittle nature of ceramic post insulators is a continuous challenge. As well as providing electrical insulation, post insulators play a fundamental part in the structure of the enclosure. Post insulators need to withstand the impact of the journey from factory to site, the installation and strong winds throughout their lifetime, especially for offshore or near coast projects such as wind farms.
By using CFD, Cressall's design engineers can assess the maximum wind force that an enclosure can be subjected to - ensuring that the product is fit for its environment.
Natural air convection
Because power resistors reach high temperatures in service, the cooling mechanism's design is critical. The principle cooling method is defined by the exact application of the resistor and its location. The three methods used are natural or forced air convection or forced water cooling.
For each method, CFD allows engineers to understand and refine the cooling system's performance.
By experimenting with different set-ups, design engineers can identify the best solution and maximise the power rating that can be assigned to the resistor.
EV2 water-cooled resistors
The EV2 water cooled resistor has a very high-power density, enabling Cressall to offer a compact, water-cooled solution. Its accurate design, using CFD, is aimed at streamlining and reducing all possible pressure drops, meaning customers can use smaller pumps and save energy.
Recently, Cressall was asked to reduce the pressure drop in one of the systems where an EV2 water-cooled resistor was installed. The customer was limited by the amount of pressure available from the pumping system and the minimum flow rate required by the EV2 modules could not be reached. Using CFD, Cressall was quickly able to replicate system bottle-neck and identify improvements.
Cressall designed a new assembly to fit these customer requirements. The design went directly into production following a simple proving test without time-consuming iterative physical testing and delivered in-line with the customers maintenance schedule.
The applications of CFD are almost endless, but the bottom line is that the software enables designers to pin-point specific performance of new products and improvements to established designs with confidence. It allows Cressall Resistors to meet the bespoke requirements of customers, making its products more precise and reliable, while also minimising design and test costs for clients.
Just like the Mini, the proof of good design is its ability to withstand the test of time. By using computer-aided engineering, Cressall Resistors is creating bespoke, reliable products, refining the classic design of the electrical resistor and bringing it into the era of smart manufacturing.
For more information, please contact:
Andrew Keith
Cressall Resistors
Evington Valley Road
Leicester
LE5 5LZ
Tel: +44 (0)1162491739
Email: andrew.keith@cressall.com
Web: www.cressall.com
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