New pressure-based methods for quantifying radiator airflow

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New pressure-based methods for quantifying radiator airflow

Ng, E Y / Watkins, S / Johnson, P W

The high complexity of vehicle front-end design, arising from considerations of aerodynamics, safety and styling, causes the airflow velocity profile at the radiator face to be highly distorted, leading to potentially reduced airflow volume for heat dissipation. A review of the existing experimental techniques for quantifying radiator airflow indicates that currently the most commonly used methods in the automotive industry are propeller based, despite the fact that the accuracy is in doubt, especially when documenting detailed airflow distributions. Two relatively new techniques, including a four-hole dynamic pressure (Cobra) probe and a new pressure-based technique, are presented in this paper. The Cobra probe featured a head size of 1.2 mm and was used to document flow fields in proximity to a section of radiator core in a wind tunnel. The results show that the flow field at the radiator core exit was extremely complex, consisting of jets and wakes. In an investigation of the effect of airflow maldistribution on radiator heat-transfer performance, a newly developed pressure-based technique was implemented for the measurement of radiator airflow distribution. This technique, based on relating local airflow pressure drop through the radiator core to local velocity, is also discussed in the paper. The advantages of the technique over the existing methods include simplicity, robustness and relative insensitivity to air temperature thus making the technique suitable for use in complex, thermally stratified flow fields.