Optimal Sensor Arrangement for Asymmetric Vortex State Estimation on a Slender Body at High Incidence

Fagley, Casey; Porter, Chris; Seidel, Jürgen; Farnsworth, John; McLaughlin, Thomas

doi:10.2514/6.2012-3046

Cited by 7 publications

(6 citation statements)

References 10 publications

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“…[18][19][20] Figure 6 shows the time history of three different simulations using different time steps. For reference, pressure data from the companion experimental campaign is shown for a corresponding step input.…”

Section: A Transient Forcing Validationmentioning

confidence: 99%

“…[18][19][20] In the experiments, the plasma actuator has a minimum threshold in voltage before the air will break down and create a jet of air tangential to the body. Therefore it is difficult to judge if the reversal in side force for low momentum addition is a real phenomena due to such a small disturbance, the result of forcing at 30 • to the surface, or a computational artifact.…”

Section: B Open-loop Simulationsmentioning

confidence: 99%

“…The Reynolds number based on the base diameter was 156, 000, which matches the corresponding experimental setup. [18][19][20] All simulations were unsteady with a time step set to 5.0 × 10 −6 seconds and five Newton sub-iterations; this yielded an average CFL number of approximately four. The center of the coordinate system is at the nose of the model.…”

Section: Setupmentioning

confidence: 99%

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Closed Loop Flow Control of a Tangent Ogive at a High Angle of Attack

Porter

Fagley

Farnsworth

et al. 2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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The flowfield around an axisymmetric forebody at a moderate angle of attack (40 • < α < 60 • ) produces a significant side force as the result of an asymmetric pressure distribution around the body resulting from an asymmetric vortex flow state. Numerical studies of open-loop control using mass-blowing slots near the tip of the model have shown proportional control of the side force by varying the momentum coefficient of the blowing slots. From the open-loop simulations, a prediction-error minimization method (PEM) was used to develop a linear time invariant (LTI) model which captures the dynamics of the side force response to different mass flow rates applied to the port or starboard actuator. Based on the model, a PI controller was developed for reference tracking a prescribed side force profile. The development of the LTI model, and corresponding controller simulations of the closed-loop system are presented to illustrate the models capabilities as well as its limitations. The ability to track a prescribed reference signal based on the LTI model and corresponding PI control scheme is shown. The results indicate that the bandwidth of the controller is limited to frequencies below half the convective frequency due to the convective time delay as well as the actuator and sensor placement. Finally, the closed-loop controller simulations are compared to Navier-Stokes feedback simulations.

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Section: A Transient Forcing Validationmentioning

confidence: 99%

Section: B Open-loop Simulationsmentioning

confidence: 99%

Section: Setupmentioning

confidence: 99%

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Closed Loop Flow Control of a Tangent Ogive at a High Angle of Attack

Porter

Fagley

Farnsworth

et al. 2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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“…4. The sensor placement was determined through an optimal genetic algorithm as documented by Fagley et al, 22 however the placement was slightly modified from the optimal results due to constraints in the physical model. Each of the pressure transducers had a range of ±2 psi (±13.8 kPa), a sensitivity of approximately 160 mV/psi (23.2 mV/kPa), and resonate frequency of 60 kHz.…”

Section: B Experimental Setupmentioning

confidence: 99%

The Transient Response of a von Karman Ogive to Open Loop Plasma Actuation

Farnsworth

Fagley

Porter

et al. 2012

6th AIAA Flow Control Conference

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The transient response of the asymmetric vortex regime on a von Kármán ogive to open loop plasma actuation was experimentally studied. The von Kármán ogive studied had a fineness ratio of 3.5 and was instrumented with a moment balance and four pressure transducers to quantify the transient response of the vortex state on the ogive body. Two single dielectric barrier discharge (SDBD) plasma actuators were incorporated in the model near the nose of the ogive. The experiments were carried out for a Reynolds number of 156,000 and at an angle of attack of 50 • , where the unforced flow state showed significant side force (i.e. vortex asymmetry). Open loop plasma actuation showed adequate control authority to change the direction as well as alter the magnitude of the side force. Triangular and square modulated waveforms were used to understand the transient dynamics. Asymmetric vortex dynamics displayed a relatively proportional change in each the side force and differential pressure coefficients with plasma input voltage. A hysteresis was present in the measurements when the actuation was turned off. A step input quantified the delay and rise times for the flow field to respond to the plasma actuation. The delay time in the pressure coefficients is related to the convective time from the actuation location to the pressure measurement location. The rise time was constant at each measurement location and changed with actuation being turned on and off. C (l,m,n) Moment coefficients (roll, pitch, yaw) C P Pressure coefficient C (x,y,z) Force coefficients (axial, side, normal) D Diameter f r Fineness ratio, L cone /D L af t Aft body length L cone Nose cone length M Mach number q NomenclatureWind tunnel dynamic pressure ReReynoldsWind tunnel free-stream velocity α Angle of attack ∆C P Differential pressure coefficient, port -starboard θ Circumferential angular position τ c Normalized local convective time, x/(U ∞ t * ) τ d Normalized delay time before the signal reaches 10% of steady-state, t d /t * τ r Normalized rise time for the signal to change from 10% to 90% of steady-state, t r /t *

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“…The flow state estimation technique laid out in Fagley et al [2012b], is experimentally verified by the following technique. The estimated side force,Ĉ y , as described by Eqn.…”

Section: Experimental Validationmentioning

confidence: 99%

Flow Control

Fagley¹

2013

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Optimal Sensor Arrangement for Asymmetric Vortex State Estimation on a Slender Body at High Incidence

Cited by 7 publications

References 10 publications

Closed Loop Flow Control of a Tangent Ogive at a High Angle of Attack

Closed Loop Flow Control of a Tangent Ogive at a High Angle of Attack

The Transient Response of a von Karman Ogive to Open Loop Plasma Actuation

Flow Control

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