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In this study, we developed the defrost performance evaluation technology using the multi-objective optimization method based on the CFD. The defrosting is one of the key factors to ensure the drivers’ safety using the forced flow having proper temperature from HVAC during drive. There are many factors affecting the defrost performance, but the configurations of guide-vane and discharge angles in the center DEF(defrosting) duct section which are main design factors of the defrost performance in automotive, so these were set to the design parameters for this study. For the shape-optimization study, the discharge mass flow rate from the HVAC which is transferred to the windshield and the discharge areas in the center defrost duct were set to the response parameters. And then, the standard deviation value of mass flow rate on the selected discharge areas checking the uniformity of discharge flow was set to the objective function to find the optimal design.

Numerical simulations are widely used to predict the performance of products in the automotive development process. In particular, ventilation and defrost performances of automotive HVAC system are developed according to design variables and environmental conditions based on CFD (Computational Fluid Dynamics). Recently, as improvement on both computer hardware performance and analysis technology continues, the usage of simulation has been increasing accordingly. However, the cost of software license also increases in such development environments. In this paper, we introduce our CFD program with OpenFOAM, which is the free, open source CFD software, to simulate flow characteristics of ventilation and defrost in automobile. This program includes self-developed GUI similar to commercial CFD code, two-layer realizable κ-ε turbulence model to secure numerical stability, and fluid film model to check the defrost phenomena with time dependence from OpenFOAM libraries.

In this paper an effective technology of virtual thermal test of disc brake with several advanced analytic techniques was presented. With the virtual thermal test process, thermal performance of brake system could be easily evaluated without any possibility of great errors that used to happen in the past. In addition to the classical result of CFD, this virtual thermal test produced several valuable applications such as thermal deformation of rotor, optimization of thermal performance and estimation of braking distance.

There have been many kinds of simplifications and limitations in evaluating the thermal performance of disc brake when using the analytic technologies which were established before. But now new technology of virtual test with several advanced analytic techniques was developed to evaluate the thermal performance without any possibility of great errors that used to happen for the earlier time-consuming analyses. As a result, it was estimated that the new virtual test technology could afford to replace the physical dynamo test since the reliability of virtual test technology was reasonably verified with the existing data measured in dynamo test.