Investigation on the dynamic response characteristics of the pressure drop oscillation at the non-uniform heat flux

The microchannel heat sink is one of the most promising approaches to addressing the heat dissipation of the non-uniform heat flux for semiconductor chips. The pressure drop oscillation is usually encountered in the microchannel heat sink, while the effect of the non-uniform heat flux on its dynamic response characteristics remains poorly understood. To address this gap, three configurations of non-uniform heat flux are designed, which are a single hotspot of Group # 1, double hotspots of Group # 2, and triple hotspots of Group # 3, respectively. Meanwhile, the uniform heat flux serves as the baseline case for comparison. The calculated results exhibit that the limit cycle displays a nonmonotonic feature in both Group # 1,1 and Group # 1,2, indicating a substantial nonlinear characteristic. In addition, a significant reduction in oscillation amplitude is observed in the non-uniform configurations (Group #1,2 and Group #1,3) compared to the uniform baseline. Meanwhile, the oscillation frequency is reduced in Group #1,1 and Group #1,2, while it is elevated in Group #1,3. The oscillation amplitude is attenuated in all double hotspots configurations except Group # 2.3, The oscillation frequency, by contrast, is elevated across all cases except Group # 2.3. Specifically, the enhancement effect of the oscillation frequency decreases by 35.0% as the mass velocity increases from 20 kg/m²s to 40 kg/m²s in Group # 2.4. Triple hotspots exhibit a pronounced reduction in the oscillation amplitude relative to the baseline case. Furthermore, the oscillation amplitude exhibits a decrease as the heating source distribution becomes more concentrated toward the centre. Finally, the effect of the non-uniform heat flux on the instability region is investigated and found that multiple hotspots facilitate a shrinkage in the unstable region, although it also induces two distinct unstable domains. Moreover, the instability region of the microchannel heat sink can be furtherly reduced by decreasing the spatial concentration of the heating source.