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Review Article Volume 10 Issue 2
Active control of base drag through experimental investigation of a hybrid synthetic jet system: a comprehensive review
Afsana Hossain Asha, Ambareen Khan, Sher Afghan Khan
Received: April 06, 2026 | Published: April 17, 2026
Citation: Asha AH, Khan A, Khan SA. Active control of base drag through experimental investigation of a hybrid synthetic jet system: a comprehensive review. Aeron Aero Open Access J. 2026;10(2):69-74. DOI: 10.15406/aaoaj.2026.10.00251
Abstract
Aerodynamic drag, particularly base drag generated by low-pressure wake regions, significantly impacts the fuel efficiency and emissions of bluff-bodied vehicles. While active flow control (AFC) methods like synthetic jets offer dynamic drag reduction, their practical application is often hindered by unproven net energy efficiency and limited integration with real-world vehicle geometries. This study experimentally investigates a novel hybrid aerodynamic system that synergistically combines recessed base cavity geometry with an array of piezoelectric synthetic jet actuators. The research aims to quantify the system’s efficacy in reducing base drag and, critically, to evaluate its net energy balance. Experiments were conducted on a scaled square-back Ahmed body model fitted with the hybrid system in a closed-circuit wind tunnel with moving ground simulation. Flow-field diagnostics were performed using particle image velocimetry (PIV) and direct force and base-pressure measurements. Results demonstrated that actuation tuned to the natural wake frequency (St ≈ 0.21) produced a 30% reduction in the recirculation zone, a 38% increase in base pressure, and an 11.2% net drag reduction. Crucially, the aerodynamic power saved exceeded the electrical power input to the actuators by a factor of 3.9, yielding a positive Net Energy Efficiency Ratio (NEER). This work concludes that a frequency-tuned hybrid synthetic jet system is a viable, energy-positive concept for reducing base drag. The study contributes a validated methodological framework for assessing AFC net efficiency and provides empirical evidence for the performance gains achievable through coupled activepassive design, offering a pathway toward sustainable transport aerodynamic solutions.
Keywords: base drag reduction, synthetic jet, hybrid aerodynamic system, net energy efficiency, ahmed body, wind tunnel experiment
©2026 Asha, et al. This is an open access article distributed under the terms of the, which permits unrestricted use, distribution, and build upon your work non-commercially.