Fluidic Control of Asymmetric Forces on a Body of Revolution

Fluidic Control of Steering Aerodynamic Forces on Axisymmetric Bodies using a Mid-Body Cavity

“…It was shown previously that the azimuthal distribution of the four actuators around the tail, analogous to the present one, induced practically additive effects from the individual jets, i.e., there was practically no interference among singular effects of each of the jets 15,16 . Here, it is expected that the operation of more than one of the jets would induce a joint rather than additive effect, as they are all issued into the common cavity rather than into the wake.…”

“…This flow alteration generates a predominantly downward lift force that opposes the other two lift sources. Clearly, utilization of Coanda-assisted flow vectoring through the mid-body cavity results in more complex flow dynamics than similar vectoring of the flow at the body's tail, where only one source of the flow asymmetry is generated by the segmented flow turning over the Coanda surface 15,16 . flowing out of the cavity near the rear cavity wall can only weakly penetrate the outer flow and therefore only a weak recirculating bubble is formed which results in a weak symmetry breaking downstream from the cavity edge.…”

“…Therefore, sets of PIV measurements are obtained at specific phases of the harmonic actuation, enabling an insight into the time-resolved spatial dynamics of the flow. Figure 17 shows phase-locked PIV measurements, i.e., averaged flow fields at particular phases of the actuation signal, taken at the onset of actuation by the top jet (τ/T = 0) and after 2,4,6,8,10,12,15,20,30,40, and 50 actuation cycles. After two actuation cycles are completed (Figure 17b), the second vortex issued is observed next to the jet orifice, while the first vortex (both remaining with the same sense of vorticity as in the global flow) is convected to about x/R = 0.3.…”

“…In the earlier work of Abramson et al 15 , they investigated the effects of asymmetric flow actuation on an axisymmetric body of revolution with four, equally-spaced azimuthal synthetic jets issuing from within a backward facing step in the tail. The authors reported saturation of the induced aerodynamic forces with actuation input which depends on the model's tail geometry.…”

“…Furthermore, typical generation of the lift/side force utilizing Coanda-assisted flow vectoring is associated with the drag increase. The present approach builds on the control approach that was developed for the flow control at the body's tail 15,16 and involves both active and passive control elements. The controlled flow is characterized using direct force and PIV measurements.…”