APPLICATIONS

AUTOMOTIVE | ELECTRONICS | FANS AND PUMPS

ELECTRONICS

REFRIGERATION (Contributed by Toshiba Co., Ltd.)

It is often preferable to model just the P-Q characteristics of a cooling fan, instead of solving the detail shape, in CFD applications of electric devices. On the other hand, most of fan-analyses are carried out without any modeling but with just a fan itself; other electric components are analyzed separately, although the assembled package is the environment of real machinery. This is done so in order to save the number of mesh elements, computation time, and also man-hours. However, the large scale computations for whole assembled components including a fan can be done easily in SC/Tetra without concerning time and troubles. In this analysis, an axial fan attached to the electronics compartment of a refrigerator for cooling and defrosting, is considered to reduce the noise level without changing the flow rate. The results of computation for the two fans compared here, with three and five blades respectively, indicate that the five-blade fan causes a less disturbed pressure field than the three-blade fan. It implies that the five-blade cooling fan runs more quietly. Afterwards, a production model of the compartment was actually tested and the noise level reduction has been confirmed.

POWER UNIT

The thermo-fluid analysis using CFD has become very effective for the design of electronics devices along with experiments, since the internal circulation is the key issue in electronics cooling. Here is an example of electric devices on a power supply board. The analysis was performed for the whole power unit as the computational domain, although only the board with heat sources is shown here. It can be noticed that the surface temperature of one particular capacitor (marked with asterisk sign) becomes higher than that of the other capacitors. The cause can be inferred from the flow pattern over the power unit visualized using the oil flow display function. Clearly, the flow passage is so narrowed that the circulation cooling does not work well, despite the fact that the capacitor is surrounded by heat sources. These analyzed results have been confirmed by the experimental measurement; the temperature distributions qualitatively agree well, as shown in the figure.