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Electronic systems play a key role in the high reliability and safety of modern aircrafts. Components have become smaller and faster leading to an increase in power density and making thermal management a more vital part of the overall design. This paper will demonstrate how thermal transient testing combined with computational fluid dynamics (CFD) can help balance these design constraints and ensure that critical devices will work safely within their prescribed temperature limits. The first part of the paper will focus on the thermal characterization of a component using a continuous measurement method known as the static method per JEDEC51-1 standard. This data provides an insight of the overall component thermal performance and it can also be translated to structure function which helps with detecting potential internal thermal bottlenecks, such as a die attach material.

This paper discusses a streamlined approach for characterizing the heat flows from the combustion chamber to the engine coolant, engine oil circuit and the ambient. The approach in this paper uses a built-in flow and heat transfer solver in the CAD model of the engine to derive heat transfer coefficients for the coolant-block interface, oil-block interface and the block-ambient interface. These coefficients take into account the changing boundary conditions of flow rate, temperatures, and combustion heat to help characterize the complex thermal interactions between each of these sub-systems during the warm-up process. This information is fed into a larger system model of the engine to get a more accurate prediction of the engine warm-up and the effect of various fuel economy improvement strategies being evaluated. One of the key benefits shared in this paper is the practicality of the process that can be replicated on every production vehicle simulation model.

This paper contains a brief description of the numerical approach used to simulate the flow of cavitating liquids that was implemented in FloEFD™ software. Some computational results obtained using this approach are presented. The calculations used 3D Navier-Stokes equations coupled with the k-e turbulence model and equilibrium cavitation model. It is assumed that this process occurs at a fixed temperature (so-called isothermal cavitation). The validity of this assumption is confirmed by numerous test data. Since the liquids heat capacity is large enough to neglect the heat generated in the phase transition, it practically doesn't change the liquids temperature. This approach allows a minimized number of required thermodynamic properties of the liquid.

With the change of luminaires from incandescent bulbs to Light Emitting Diodes (LED), we all know that the concept of thermal management for this application is now redundant and new ways of thinking need to be established. While incandescent bulbs mostly radiate (~83%) and dissipate (~12%) heat loss and do not face thermal challenges related to the light source, LEDs mostly transfer their heat loss (~60-85%) by conduction and are sensitive to the thermal management. Therefore the efficiency of a 100W incandescent bulb is ~5% while the efficiency of LEDs is ~15-40%. The main thermal challenges with LEDs are to maintain a high color stability and life expectancy. LEDs in the automotive industry need to have lifelong durability. With LEDs being not only more efficient, but also valuable in terms of higher visibility and therefore higher safety, the Economic Commission for Europe (ECE) set the Day-time running lamp (DRL) as mandatory from 2011 for all new models of cars.