## 1 Introduction
[PERSON] [22] analyzed the performance of the surrounding oscillating foil structure under different frequencies and local deformation amplitudes, finding that, at lower frequencies, the leading edge vortex exhibited greater connectivity with the suction side, while, at higher frequencies, there were fewer shedding vortices on the suction side. [PERSON] [23] proposed a C-shaped oscillating foil system and concluded that there was a stable oscillation range for pitching and heaving damping coefficients that could yield a steady energy output. Researchers have used various methods to perturb the trailing edge flow field of oscillating foils, aiming to optimize their energy harvesting efficiency by increasing their lift. [PERSON] [24] first studied the effect of Gurney flaps on the NACA airfoil and found that a 1.25% of c Gurney flap could enhance lift while reducing drag. [PERSON] [25] optimized an underwater oscillating foil with flaps and stabilizers and found that modifying the flow through them could greatly enhance lift, while shifting the peak pressure position could reduce the moment on the flap. [PERSON] [26] observed a 28% efficiency increase compared to traditional blades when they explored the energy harvesting potential of vertical-axis tidal turbines using blades with fixed and oscillating flaps. [PERSON] [27] improved efficiency by installing a smaller auxiliary oscillating foil beneath the main foil, increasing lift. [PERSON] [28] applied an improved Gurney flap to an oscillating foil to enhance lift for energy harvesting and revealed that pitching motion consumed energy at all heights of the Gurney flap. [PERSON] [29] increased lift and synchronized heaving motion by using a type of adaptive Gurney flap, improving the energy harvesting capacity of the oscillating foils. [PERSON] [30] found that placing a bluff body upstream significantly enhanced efficiency via two mechanisms. [PERSON] [31] improved energy extraction from an oscillating hydrofoil by adjusting the height and motion period of a movable Gurney flap. These works provide a valuable reference for further research [32] into techniques for enhancing the efficiency of energy harvesting through oscillating foil mechanisms. In synthesizing the existing literature, our survey reveals a multifaceted landscape in the domain of oscillating foil energy harvesting. The primary themes explored encompass the optimization of motion parameters, the alternative deformations of foil shapes, and methods for perturbing the trailing edge flow field to enhance lift and energy harvesting efficiency. However, these methods alter the original shape of the foil, such as Gurney flaps [33], trailing edge flaps [34], and spoilers [35], which may have negative effects on its structural integrity, processing complexity, applicability, and safety [36]. Notably, these discussions form the backdrop against which our research proposal unfolds. Our focus on a tail edge cylindrical spoiler structure is motivated by the simplicity and practicality it introduces, preserving the original foil shape while innovatively enhancing vorticity generation. This unique contribution addresses gaps in the current literature by presenting a comprehensive analysis of the flow parameters, optimization methods, and applicability of this novel approach. Based on this innovative flapping foil flow control structure, we have developed a comprehensive set of methods for analyzing the influence of flow parameters, optimization, and applicability. We have established a parametric research model featuring a cylindrical spoiler structure on the trailing edge of the foil. By comparing aerodynamic parameter profiles, pressure distributions, and flow field characteristics, we have evaluated the impact of the trailing edge cylindrical spoiler structure on energy harvesting performance.