Parametric Study of Synthetic-Jet-Based Flow Control for Performance Enhancement of a Vertical Stabilizer

Abstract

The performance enhancement of a vertical tail using synthetic jet actuators may allow for a decrease in tail size, which would result in a reduction of the drag, weight, and fuel consumption of the airplane. The potential for enhancement was investigated during wind tunnel experiments with a 1/19 th scale wind tunnel model of a Boeing 767 vertical tail at a Reynolds number of 350,000. The model was instrumented with twelve finite span synthetic jet actuators placed slightly upstream of the rudder hinge-line with the objective of controlling the separation that commences over the rudder when it is deflected to high angles. The synthetic jets were capable of increasing the side force coefficient by up to 0.17 or 34% above the unactuated level. Stereo Particle Image Velocimetry (Stereo PIV) was used to understand the interaction of the synthetic jets with the flow over the rudder, primarily focusing on the inboard portion of the rudder. The Stereo PIV data revealed the complicated, highly three-dimensional nature of the baseline and actuated flow fields. Timeaveraged measurements showed ridges of reduced velocity and valleys of increased velocity in the iso-surfaces of total velocity that were created by the jets. The ridges were believed to be a result of an interaction between the synthetic jets' clockwise edge vortices and the crossflow. The counterclockwise edge vortices were associated with regions of higher velocity indicating that they were more beneficial for flow separation control relative to the counterclockwise vortices. This suggested that in this application the synthetic jet flow control system could be made more effective at augmenting side force by configuring the jet orifices in such a way to reduce the strength of the clockwise edge vortices and enhance the counterclockwise vortices they generate. Nomenclature A j= cross-sectional area of the synthetic jet orifice, m 2 AR = jet orifice aspect ratio b = span, m b' = local distance from the root to the tip of the model in a direction of constant x'/c', mm C b = synthetic jet blowing ratiochord perpendicular to the stabilizer leading edge, m = mean aerodynamic chord, m 2 = mean aerodynamic rudder chord, mm C µ = synthetic jet area-based momentum coefficient f = synthetic jet's carrier frequency, Hz F + = reduced carrier frequency l = length of the jet orifice, m n = number of jets Re = Reynolds number based on mean aerodynamic chord S = tail trapezoidal reference area, m 2 T = period of synthetic jet driving frequency, s U j = averaged jet exit velocity, m/s u j (t) = phase-averaged synthetic jet velocity, m/s U* = normalized velocity perpendicular to the hinge-line U ∞ = freestream velocity, m/s * = normalized total velocity w = width of the jet orifice, m x = streamwise direction (parallel to the freestream) x' = local distance from the leading edge in the direction perpendicular to the leading edge, m x* = normalized distance perpendicular to the rudder hinge-line y* = normalized distance perpendicular to the rudder surface z = spanwise direction...

Performance Enhancement of a Vertical Tail Model with Sweeping Jets

“…AFC on VTP with synthetic jets has also been studied both experimentally [22]- [24] and numerically [25]- [26]. A side force increment of 18% was obtained for C μ = 0.7% and a non-dimensionalized rudder deflection angle δ* equal to 0.5 [22].…”

“…AFC on VTP with synthetic jets has also been studied both experimentally [22]- [24] and numerically [25]- [26]. A side force increment of 18% was obtained for C μ = 0.7% and a non-dimensionalized rudder deflection angle δ* equal to 0.5 [22]. Different types of synthetic jet actuation have been compared and it was concluded that a purely sinusoidal waveform was more effective up to a deflection angle δ* = 0.8 but for higher angles, a pulse-modulated waveform at reduced frequency close to one was more effective while reducing the power by 80%.…”