Active Separation Control with Pulsed Jets in a Critically Loaded Compressor Cascade

Hecklau, Martin; Wiederhold, Olaf; Zander, Vincent; King, Rudibert; Nitsche, W.; Swoboda, M.; Huppertz, André

doi:10.2514/6.2010-4252

Cited by 19 publications

(22 citation statements)

References 13 publications

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“…A higher frequency indicated a smaller residence period of circulating flow in the chamber and a shorter oscillation period (Yang et al, 2007). In the airfoil application for separation control, the most effective oscillation frequency of the fluidic oscillator depended on various conditions including freestream conditions (Scott Collis, Joslin, Seifert, & Theofilis, 2004) and amplitude of oscillating jet (Hecklau et al, 2011;Nishri & Wygnanski, 2004).…”

Section: Resultsmentioning

confidence: 99%

Shape optimization of a feedback-channel fluidic oscillator

Jeong

Kim

2017

Engineering Applications of Computational Fluid Mechanics

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In this study, a fluidic oscillator was optimized based on the three-dimensional unsteady Reynolds-averaged Navier-Stokes analysis to enhance peak jet velocity at the outlet and simultaneously reduce pressure drop. A multi-objective genetic algorithm performed the optimization with surrogate modeling. The ratios of the inlet nozzle width and the distance between the splitters to the throat width were chosen as the design variables. And, two objective functions related to peak jet velocity at the outlet and pressure drop through the fluidic oscillator were selected for the optimization. Ten design points were selected in the design space using a Latin hypercube sampling method; the objective functions were calculated by unsteady Reynolds-averaged Navier-Stokes analysis at these design points to construct surrogate models that were used to approximate the objective functions. Two different surrogate models, namely response surface approximation and Kriging models were tested. Pareto-optimal front representing a compromise between the two objective functions was obtained from the multi-objective optimization. The optimization results indicated that a jet velocity-oriented optimum design increased the peak jet velocity ratio at the outlet and the friction factor by 11.18% and 16.82%, respectively, when compared to those of a friction factor-oriented design.

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Section: Resultsmentioning

confidence: 99%

Shape optimization of a feedback-channel fluidic oscillator

Jeong

Kim

2017

Engineering Applications of Computational Fluid Mechanics

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“…Hecklau et al 12 performed an experimental investigation of two different AFC concepts applied to a highly loaded compressor cascade. Pulsed blowing from the sidewalls was used for the suppression of secondary flow structures while the pressure-induced boundary-layer separation in the rear part of the blade was suppressed by means of pulsed excitation out of the slots in the blade's suction surface.…”

Section: Review Of Literaturementioning

confidence: 99%

Open-Loop and Closed-Loop Trailing-Edge Separation Control on a Natural Laminar Flow Airfoil

Gupta

Ansell

2016

54th AIAA Aerospace Sciences Meeting

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Active Unsteady Flow Control experiments were performed on a Natural Laminar Flow, NLF 0414 airfoil at Rec = 1.0 × 10 6 in a 3-ft × 4-ft low-speed, low-turbulence wind tunnel. The NLF 0414 was designed with a region of favorable pressure gradient extending almost 70% of the chord on the upper surface of the airfoil. Aggressive pressure recovery in the aft 30% of the chord near the trailing edge results in the separation of the flow from the airfoil surface at the off-design conditions. The goal of this study was to control boundary-layer separation across the trailing-edge region of the airfoil in an effort to improve the performance beyond the designed angle-of-attack range. Active control of separation was achieved using a series of fast-switching solenoid valves connected to blowing slots at x/c = 0.75 on the upper surface of the airfoil. The airfoil in its baseline configuration was first evaluated to identify the dominant modes in the spectral content of unsteady Cp. Airfoil performance data were then acquired across a parametric range of blowing amplitudes, actuation frequencies and duty cycles in order to understand the effects of variations in the major forcing parameters on the performance of the model. Phase-averaged and phase-locked planar PIV measurements were also acquired across a horizontal plane near the trailing-edge region of the airfoil model in order to examine the spatio-temporal evolution of the flowfield and understand the mechanism responsible for the alleviation of separation as a result of actuation at the different flow control settings. A closed loop controller was developed to vary the actuation parameters in-situ using sensory feedback from the unsteady surface pressure measurements. Adaptive modal decomposition methods were used to identify the frequencies of natural instabilities in the flowfield in real-time. A proportional controller was designed to automatically control the blowing amplitude by estimating the state of the flow and the extent of boundary-layer separation. The closed-loop system was able to simultaneously control the blowing amplitude and the actuation frequency such that a desired value of Cl was obtained.

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“…It was claimed that the functioning jet location varies with the inlet Mach number. Under subsonic flow conditions with large scale separations and strong unsteadiness, the pulsed blowing (Hecklau et al, 2011) or pulsed bleeding (Zhang et al, 2018) have been reported to be more effective in the management of the flow separations and aerodynamic losses reduction. Similarly, spark jet (Yang et al, 2016) and pulsed plasma jet (Narayanaswamy et al, 2012) were applied for the control of the SWBLI features.…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulation of Pulsed Blowing in a Supersonic Compressor Cascade

Meng

Chen

Ding

et al. 2020

JAFM

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Large Eddy Simulation (LES) of a two dimensional supersonic compressor cascade is performed in the current study. It is found that the Shock Wave Boundary Layer Interaction causes a large scale of total pressure losses and presents strong fluctuation features. Thus the pulsed and steady excitation jets are applied to suppress the flow separations and to reduce the total pressure losses. Several impacting parameters, such as jet axial location, jet hole width, jet angle to the local blade surface and jet mass flowrate are chosen based on the primary analysis by the calculations by the Reynolds Averaged Navier-Stokes equations. In addition, based on the results of frequency spectrum and POD analysis, the excitation jet frequency is chosen for the pulsed excitation jet scheme. It is concluded that the pulsed excitation jet scheme achieves a 9.8% reduction of total pressure loss in comparison to the steady excitation jet scheme under the same time-averaged excitation jet mass flow rate. The excitation jets affect both the flow field near the jet hole on the suction surface and the flow field on the pressure surface via the management of the reflection shock wave. In addition, the excitation frequency dominates not only the time-averaged flow field, but also the second and third modes which stand for the unsteady structures in the flow field under the POD analysis. The first mode contains most energy in the flow field and the energy percentage decreases dramatically with the increase of the mode number. In comparison to the steady excitation jet scheme, the pulsed excitation jet scheme gathers more energy to the low orders of the modes, especially the first four modes. With the mixing effect and high dissipation rate of the high-frequency signals, the high-frequency signals shrink in the wake and the flow field builds up more uniformity.

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Active Separation Control with Pulsed Jets in a Critically Loaded Compressor Cascade

Cited by 19 publications

References 13 publications

Shape optimization of a feedback-channel fluidic oscillator

Shape optimization of a feedback-channel fluidic oscillator

Open-Loop and Closed-Loop Trailing-Edge Separation Control on a Natural Laminar Flow Airfoil

Large Eddy Simulation of Pulsed Blowing in a Supersonic Compressor Cascade

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