From Geometric Regulation to Intelligent Design: A Review on Performance Improvement of Dual-Feedback Fluidic Oscillators

Fluidic oscillators (FOs) are self-excited jet-generating devices without moving parts that convert steady fluid supply into oscillatory jets through inherent flow instabilities. Among various FO configurations, dual-feedback fluidic oscillators (DFFOs) have attracted extensive attention due to their simple structure, high reliability, stable oscillation characteristics, and broad applications in active flow control, heat transfer enhancement, and fluid mixing. However, conventional trial-and-error-based optimization methods are limited by strong parameter coupling and trade-offs among multiple performance objectives, such as oscillation frequency, jet deflection angle, and energy efficiency. This review systematically summarizes recent advances in performance enhancement strategies for DFFOs from the perspective of “from geometric control to intelligent design”. The effects of multi-scale geometric regulation, including macroscopic structures, internal microstructures, and manufacturing-related factors, are discussed. Advanced optimization approaches, including active control, novel configurations, inverse design, and data-driven methods, are further reviewed. Particular attention is given to additive manufacturing challenges and DFFO performance under multiphase flow conditions, including erosion, particle deposition, atomization, and mass transfer. Finally, future perspectives are proposed regarding multi-physical coupling, intelligent optimization, and engineering applications. This review provides a comprehensive reference for the cross-scale performance enhancement and intelligent design of DFFOs.