Thermal Management Solutions for Network File Server Used in Avionics Applications

Abstract

In the modern era of commercial aviation there is an increasing need for establishing on-aircraft networks that interconnect legacy avionics systems for the purpose of data collection, health monitoring, and software management. At the heart of these networks are flightworthy file servers that perform similar functions to servers used in ground-based IT infrastructures. However, the size, weight, and power constraints for airborne servers are significantly more challenging than the constraints placed on groundbased equipment. As a result, the critical goals in the development of aircraft network systems are reducing the size and weight, maximizing the performance and reliability, and reducing cost. One of the main challenges includes dissipating high power in small packages within a confined space. This makes thermal management a critical component of the overall LRU (Line-Replaceable Unit) design. In addition, passive cooling systems are often required in place of internal fans in order to improve long-term reliability of the system. This presents another set of challenges, such as optimizing the airflow provided by the aircraft in the electronics compartment. This paper will present some of the critical elements of thermal management such as heat sinking, component placement, thermal interface materials, thermal vias, thermal links, heat spreader, packaging approaches and cooling strategies. The design and optimization of this system are based on analytical solutions, conjugated heat transfer and experimental results. Thermal management solutions must enable reliable operation under various environmental conditions: ground operation, flight operation, high operating temperature and loss of cooling air. Each environmental condition has different parameters for coolant airflow rate, effect of the surroundings, and ambient and coolant air temperature. Cooling airflow analyses were performed using CFD (Computational Fluid Dynamics). We have identified multiple approaches to remove heat from the critical components through optimization of the components and subsystems. These same approaches also serve to increase the system's performance and reliability.