In a bid to reduce the build costs associated with the first three Astute Class submarines, the Royal Navy’s latest class of fleet submarines, Aish Technologies were invited to participate in a team to rethink designs for for the mission systems, which includes Combat Management, Sonar, Optronics etc. Part of Aish’s solution was to provide a new electronics cabinet, called the Common Enclosure. The existing mission systems fit made use of the Naval Equipment Practice (NEP) enclosure, a standard cabinet that had been designed in the 1980’s that was extremely expensive to build and incorporated outdated and hard to source manufacturing techniques. Modern electronics density meant that its chilled-water cooling system couldn’t cope with the removal of wild heat from the five 19” sub-racks: the highest of the stack of sub-racks had become unusable due to the stovepipe effect of heated air being blown through it from below.

Aish’s design aim was to improve heat removal, increase the electronics capacity and reduce the cost of the enclosure. By applying some innovative thinking and using in-house Computational Fluid Dynamics modelling to track and refine the cooling system, the solution for the new cabinet has proved a radical departure from the old NEP and, indeed, from most electronics enclosures of any kind.

The problem was how to get rid of the stovepipe effect of the NEP’s cooling system and replace it with a system where the cooling airflow was restricted to no more than two sub-racks. Aish’s radical solution was to turn the sub-racks through 90° so that the electronics cards are mounted horizontally. Naval equipment is tested for shock and vibration in three axes, so it is immaterial which way the cards are mounted. This layout has allowed us to provide three separate cooling circuits, each with two sub-racks; each circuit has its own air/water heat exchanger and fan assembly.

This has given us space and cooling capacity for six fully-populated 19” sub-racks within the same space envelope and footprint of the NEP, effectively a 50% increase. Mounting points, connector panels and chilled water connections are in the same place as the NEP, enabling the new Common Cabinet to replace the NEP without any changes to ship’s infrastructure. And, crucially, the cost of the Common Console shows a very healthy reduction over the NEP.

The result is so impressive that Aish Technologies was presented with a BAE Chairman’s Silver Award for Innovation. The award is a very welcome recognition of the ability and expertise of Aish’s Engineering staff, and is another indication of the way that Aish Technologies’ flair for innovation has added value for its customers

The Common Console is currently being rolled out across the Astute Class.

common enclosure