Active Flow Control on Vertical Tail Models

Abstract

Active flow control (AFC) subscale experiments were conducted at the Lucas Wind Tunnel of the California Institute of Technology. Tests were performed on a generic vertical tail model at low speeds. Fluidic oscillators were used at the trailing edge of the main element (vertical stabilizer) to redirect the flow over the rudder and delay or prevent flow separation. Side force increases in excess of 50% were achieved with a 2% momentum coefficient (C μ) input. The results indicated that a collective C μ of about 1% could increase the side force by 30-50%. This result is achieved by reducing the spanwise flow on the swept back wings that contributes to early flow separation near their tips. These experiments provided the technical backdrop to test the full-scale Boeing 757 vertical tail model equipped with a fluidic oscillator system at the National Full-scale Aerodynamics Complex 40-by 80-foot Wind Tunnel, NASA Ames Research Center. The C μ is shown to be an important parameter for scaling a fluidic oscillator AFC system from subscale to full-scale wind tunnel tests. The results of these tests provided the required rationale to use a fluidic oscillator AFC configuration for a follow-on flight test on the Boeing 757 ecoDemonstrator. Nomenclature

Flow Control in Wings and Discovery of Novel Approaches via Deep Reinforcement Learning

“…Fluidic actuators placed at a tail of an aircraft were simulated using unsteady RANS and validated by means of experimental results by Shmilovich et al [44]. More recently, Andino et al [45] tested fluidic actuators in a generic tail at low speeds and demonstrated that a modest increase in the momentum coefficient can result in important increments of the side force. Whalen et al [46] presented wind-tunnel test results of the AFC of the vertical tail of a Boeing 757 equipped with sweeping jet actuators; a significant increase in the side force at a maximum rudder deflection of 30 • was observed.…”

Flow Control in Wings and Discovery of Novel Approaches via Deep Reinforcement Learning

“…Fluidic actuators placed at a tail of an aircraft were simulated using unsteady RANS and validated by means experimental results by Shmilovich et al [44]. More recently, Andino et al [45] tested fluidic actuators in a generic tail at low speeds and demonstrated that a modest increase of the momentum coefficient can result in important increments of the side force. Whalen et al [46] presented wind-tunnel test results of the AFC of the vertical tail of a Boeing 757 equipped with sweeping jet actuators; significant increase in the side force at maximum rudder deflection of 30 • was observed.…”

Editorial for the Special Issue on “Fluidic Oscillators—Devices and Applications”

“…One of the most prominent research areas is focused on using fluidic oscillators for active flow control. These devices have been shown to prevent flow separation over a highly deflected surface, thereby significantly increasing the aerodynamic performance of aircraft [11][12][13]. It is hypothesized that fluidic oscillators are more efficient than steady jets and require less mass flow, because the jets' sweeping motion provides greater lateral impact, thereby allowing for increased jet spacing and fewer jets needed.…”