The inlet flow of centrifugal blower were quantitatively visualized using particle image velocimetry. Because the centrifugal blower system is one of the key parts of EV battery cooling system, the quantitative information of flow field of centrifugal blower is important to design and optimize the cooling system. Two types of inlet parts were used in this study. One is the straight inlet and the other is a bended one. The results showed the flow asymmetry exists in the straight model due to the pressure difference in the blower. In case of the bended one, the separation bubble and the increase of head loss appeared compared with the straight model.
The separated shear flows developed from the vertical fence was manipulated by using the vortex generator jets located in front of the fence. The experiments were carried out in a circulating water channel and the vertical fence was submerged in the turbulent boundary layer. The Reynolds number based on the height of fence and free stream velocity was 2000. DPIV method was used to measure the instantaneous velocity fields around a vertical fence. The mean properties were calculated using the ensemble average method. The obtained results were compared with uncontrolled fence flow. From the results, we found the vortex jets can alter the upstream flow and change the separation bubble behind the fence. As the jet speed increases, the suppression of separation bubble become stronger and the spanwise variation of separation bubble exists.
Plate-fin heat exchanger is a kind of compact heat exchangers with a good performance in heat transfer. It is widely used in various engineering fields such as aerospace, chemical and biomedical industries. Quantitative and qualitative flow visualization study were performed using the water model of commercial plate-fin heat exchanger with header angles of 30 o. The Reynolds number was 100. Conventional digital particle image velocimetry was used to measure the instantaneous velocity fields of the header region and the flow visualization using dye injection and hydrogen bubble method were applied to capture the qualitative flow characteristics. The results showed the existence of separation flow region at the junction area and the bottom wall of the exit region.
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