Enhancing boiling heat transfer is of great significance for the thermal management of high heat flux electronic devices. To address the limited heat transfer efficiency of conventional cooling methods and the insufficient understanding of bubble detachment mechanisms in existing studies on vibration-enhanced boiling, this study proposes enhancing saturated pool boiling heat transfer by driving a flexible surface by oscillating a flexible surface with piezoelectric ceramic actuator. An experimental platform consisting of a boiling system, a vibration excitation system, a temperature control system, and a synchronized visualization system was established. Under atmospheric-pressure saturated pool boiling conditions, the no-vibration case was used as the baseline, and f = 100 Hz was selected as a representative vibration frequency to systematically investigate the effects of flexible plate vibration on boiling heat transfer performance, bubble base diameter, detachment time, and bubble detachment mode. Synchronized high-speed imaging and data acquisition were employed to extract key dynamic parameters throughout bubble growth, retraction, and detachment. In addition, a bubble force balance model was used to analyze the enhancement mechanisms of bubble detachment under different motion phases of the flexible plate.

The experimental results show that flexible plate vibration can significantly improve saturated pool boiling heat transfer performance. Compared with the no-vibration case, the boiling heat transfer curve shifts upward at f = 100 Hz, with the heat transfer coefficient increasing by up to 28.52% and the bubble detachment diameter decreasing by up to 44.33%. These results indicate that flexible surface vibration promotes rapid bubble detachment at a smaller size, thereby enhancing surface rewetting and liquid replenishment. Further analysis reveals that the effect of vibration on bubble detachment is not governed by a single mechanism, but instead exhibits a distinct coupling relationship with heat flux density. At low heat flux density, the bubble growth rate is relatively low, allowing the three-phase contact line to respond promptly to the periodic displacement of the flexible plate. In this regime, bubble detachment remains primarily governed by buoyancy, with vibration serving as a weak disturbance. At high heat flux density, however, rapid bubble growth significantly intensifies the lagged response of the contact line. The periodic inertial force introduced by flexible plate vibration further amplifies bubble interfacial deformation, leading to kinematic incompatibility and necking instability at the bubble base, which ultimately triggers rapid bubble detachment.

Furthermore, two typical phase-dependent mechanisms by which flexible plate vibration promotes bubble detachment are identified. When a bubble detaches during the rebound stage of the flexible plate, the additional inertial force generated by the upward motion of the plate modifies the bubble force balance and reduces the critical condition required for detachment. When a bubble detaches during the descending stage of the flexible plate, the downward deformation of the plate increases the liquid replenishment space beneath the bubble, strengthens the shear effect of the liquid on the gas-liquid neck, and accelerates neck contraction and rupture. These findings demonstrate that flexible surface vibration not only enhances boiling heat transfer performance but also enables active regulation of bubble dynamics by controlling the bubble detachment phase, contact line response, and liquid replenishment process. This study provides experimental evidence and mechanistic insight into boiling heat transfer enhancement using flexible oscillating surfaces, offering a reference for the design of active boiling enhancement technologies in high heat flux thermal management.