Experimental Investigation of Separation Control Part 2:  Zero Mass-Flux Oscillatory Blowing

Greenblatt, David; Paschal, Keith B.; Yao, Chung-Sheng; Harris, J. E.

doi:10.2514/1.19324

Cited by 87 publications

(79 citation statements)

References 10 publications

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“…Although the oscillatory control initiates an earlier reattachment from the baseline state, the pressure drag is increased, due to the C p values immediately after separation. The increase is pressure drag with oscillatory control is also seen in the low Mach number LES and experiments [5]. Table 2 summarizes the performance of the lower and higher Mach number controlled flows in terms of pressure drag and reattachment location.…”

Section: B Control At Higher Mach Numbermentioning

confidence: 84%

“…Despite the discrepancy in C p just after separation, the average separation-bubble length in Fig. 17 is only slightly overpredicted by the LES and is 5.1% longer than that documented in the experiments [5]. The velocity profiles of the oscillatory-control flow are compared with the PIV data in Fig.…”

Section: A Control At Low Mach Numbermentioning

confidence: 99%

“…Oscillatory forcing just before the separation point has been experimentally shown to decrease the size of the separated region and, if enough momentum is added, to decrease the drag on the model [5]. The alternating blowing and suction does not delay separation, but rather forms large-scale vortices that accelerate the flow's reattachment to the wall.…”

Section: A Control At Low Mach Numbermentioning

confidence: 99%

“…When the endplates were temporarily removed the new C p curve was consistently a better match to the CFD results presented at the workshop [4]. Since the controlled cases are performed with endplates, corresponding experimental C p results from Greenblatt et al [4,5] are rescaled by increasing the reference pressure by 0.0365%. This value is obtained by adjusting p 1 of the baseline case with endplates until the C p curve was aligned with the no-endplate baseline case.…”

Section: Simulation Detailsmentioning

confidence: 99%

“…The wall-mounted hump was also a test case at the CFD Validation of Synthetic Jets and Turbulent Separation Control workshop held at NASA Langley Research Center (LaRC) [3]. The workshop provided a separate set of experimental data of the baseline and controlled flow including additional data from pressure taps, particle image velocimetry (PIV), and oil-film flow visualization along the surface of the hump [4,5]. The welldocumented experiments from both groups provide a database that can be used for the development of computational fluid dynamics (CFD) techniques capable of simulating separation and control.…”

mentioning

confidence: 99%

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Compressible Large-Eddy Simulation of Separation Control on a Wall-Mounted Hump

Franck

Colonius

2010

AIAA Journal

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Compressible large-eddy simulations of turbulent flow over a wall-mounted hump with active flow control are performed and compared with previous experiments. The flow is characterized by the unsteady separation before the steep trailing edge, which naturally reattaches downstream of the hump to form an unsteady turbulent separation bubble. The low Mach number large-eddy simulation demonstrated a good prediction of surface pressure coefficient, separation-bubble length, and velocity profiles compared with experiments. The effect of compressibility on the baseline flow is documented and analyzed and is found to increase the separation-bubble size, due to a reduced growth rate. Control is applied just before the natural separation point via steady suction and zero-net-mass-flux oscillatory forcing, and steady suction is shown to be more effective in decreasing the size of the separation bubble and pressure drag for the control parameters investigated. Controlled flow at a compressible subsonic Mach number is applied, and found to be slightly less effective than the same control parameters at low Mach numbers.

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Section: B Control At Higher Mach Numbermentioning

confidence: 84%

Section: A Control At Low Mach Numbermentioning

confidence: 99%

Section: A Control At Low Mach Numbermentioning

confidence: 99%

Section: Simulation Detailsmentioning

confidence: 99%

mentioning

confidence: 99%

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Compressible Large-Eddy Simulation of Separation Control on a Wall-Mounted Hump

Franck

Colonius

2010

AIAA Journal

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The application of passive air jet vortex-generators to stall suppression on wind turbine blades

2016

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An experimental study was performed to assess the feasibility of passive air jet vortex-generators to the performance enhancement of a domestic scale wind turbine. It has been demonstrated that these simple devices, properly designed and implemented, can provide worthwhile performance benefits for domestic wind turbines of the type investigated in this study.In particular, this study shows that they can increase the maximum output power coefficient, reduce the cut-in wind speed and improve power output at lower wind speeds while reducing the sensitivity to wind speed unsteadiness. A theoretical performance analysis of a 500 kW stall-regulated wind turbine, based on blade element momentum theory, indicates that passive air jet vortex-generators would be capable of recovering some of the power loss because of blade stall, thereby allowing attainment of rated power output at slightly lower average wind speeds.

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