Military Embedded Systems

Northrop Grumman air-flow-through cooling technique licensed by Curtiss-Wright for VPX systems


April 20, 2012

John McHale

Editorial Director

Military Embedded Systems

Northrop Grumman air-flow-through cooling technique licensed by Curtiss-Wright for VPX systems

ASHBURN, VA. Curtiss-Wright Controls Defense Solutions (CWCDS) engineers are using Air-flow-through (AFT) cooling techniques from Northrop Grumman for use in rugged, military embedded systems. In compliance with the ANSI/VITA 48.5-2010 standard, CWCDS will use the AFT cooling on its VPX systems ? VITA 46/28/65 -- in C4ISR applications such as signals intelligence and radar signal processing.

The AFT design enhances the air-cooling of electronic modules via a compact core style heat exchanger design that improves the cooling efficiency of removable electronic modules like VPX (VITA 46/48) cards. The AFT modules are sealed in rugged shells, which support Two-Level Maintenance, for in-field replacement of individual card assemblies without the need for specialized technicians or removal of the entire sub-system.

The rugged shells eliminate exposure risk from contaminants in the air, which is an occasional problem in systems for military and commercial applications. The AFT design uses sliding air seals at the inlet and outlet of AFT cards. This enables the removal and replacement of modules in the field.

AFT’s thermal path to the cooling air has the least possible resistance, enabling CWCDS’s AFT-cooled chassis to manage thermal densities as high as 200W per system slot. Each AFT card has a heat frame through which the cooling air is passed. On the card’s inlet and exhaust sides of a gasket is mounted inside the chassis that seals the card’s internal air passage to the chassis side walls. These seals keep air from being blown into the chassis while protecting the internal electronics from harsh external environments.

Each high-power component on an AFT board is connected to the AFT heat frame via a conductive, flexible gap pad. This enables cooling air to be brought into close proximity to the device’s high-power components. Due to each individual module’s thermal path being isolated, each card has its own cooling air inlet and exhaust channels, eliminating the need for multiple cards having to share cooling air or thermal interfaces. AFT cooling may be directed to components on the base card as well as to components on high performance mezzanine modules likes XMC cards.

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