The Importance of Thermal Design in Aerospace Electronics
Tom Gregory, Product Manager, 6SigmaET
The demands of the aerospace industry pose a significant challenge for electronics designers. The nature of the industry means that electronics will be subject to unique stressors and will be expected to survive. On top of this, the required life expectancy of products is higher and the accepted rate of failure must be far below that of commercial products.
In fact, the need for high-performance parts with bulletproof reliability cannot be overstated – in the majority of design aspects, it is critical. The difficulty with products that are purpose-built for the aerospace or defense industry is that there are no simple recall procedures or RMA processes. It’s simply not possible to “reboot” a device to clear issues on a missile guidance system during an operation.
When you combine the demand for high reliability with the need for high power – while also reducing the overall device footprint – thermal design in aerospace takes on even greater importance, when compared to other industries. The electronics are tightly packed, highly engineered and densely powered, meaning designers must carefully calculate the product’s heat flow so that it doesn’t negatively impact critical components.
The aerospace industry requires that electronics be highly reliable in order to meet stringent testing standards. These requirements have seen thermal design and heat flow become critical aspects of aerospace electronics design. Designers require the right tools to meet these challenges head-on, without having to compromise on efficiency and without having to sacrifice either size or performance within a product’s final design.
As an example of the pressures that aerospace electronics designers are under when developing their thermal designs, consider US aerospace engineering firm TEN TECH LLC.
TEN TECH, provides design and analysis support for embedded defense and aerospace electronics systems. The team was tasked with the design of a liquid-cooled airborne radar processing chassis. The high-ambient-temperature design was very high-powered, and the requirement was that it be incredibly reliable. In order to meet reliability standards, a little under 3kW had to dissipated out to the (already hot) environment for the electronics to be able to function. Despite this, the product had no cooling mechanism other than the liquid-cooling loop.
The system’s main driver in achieving functionality was its thermal design – and it was a significant challenge. To overcome this, TEN TECH used 6SigmaET’s dedicated thermal simulation tool throughout its design process. The software’s thermal/CFD analysis allowed TEN TECH to better understand the flow and focus of the design so that they could maximize cooling and minimize pressure drop.
This was a big model, with the added complexity of being multi-fluid with liquid cooling cavities, and in total encompassed around 40 million simulation grid cells. The use of a dedicated thermal simulation tool enabled TEN TECH to shorten solve times by 50 percent, compared to general purpose CFD tools. This also meant that they were able to easily simulate several different mission scenarios, corresponding to different altitude, ambient temperature and liquid cooling pump inlet temperature and pressure permutations.
This example highlights the overall importance of thermal design in the aerospace sector and the value that specialised design and simulation tools can deliver to electronics designers. When the demands for reliability and performance are high, there is simply no way to shortcut the design process – designers need the right tools for the job if they are to complete projects efficiently, accurately and safely.
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