Multivariable Control in a Critically Loaded Compressor Cascade

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

doi:10.1260/1756-8250.2.4.219

Cited by 7 publications

(3 citation statements)

References 21 publications

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“…As both systems behave rather similarly, it could be expected that with similar approaches in controller synthesis rather similar control laws are obtained. As in other setups [32], a cascaded control architecture turns out to be important to improve the results. Spending a higher effort in mathematical modeling of the process in the first place pays out with a more aggressive or a more robust but still aggressive controller, as it is seen for the glider.…”

Section: Comparisonmentioning

confidence: 94%

Flight and Wind-Tunnel Tests of Closed-Loop Active Flow Control

King

Heinz

Bauer

et al. 2013

Journal of Aircraft

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Closed-loop active flow control is applied in wind-tunnel tests to an industry-relevant civil aircraft half-model designed by Airbus and in full-scale free-flight experiments with a Stemme S10 glider. The focus of this contribution is on closed-loop control. Moreover, it is shown that our approach can be used for very different setups. For this, the modeling of the dynamic responses of the two systems and the synthesis of robust controllers are compared. For the highly three-dimensional wind-tunnel model, differential pressures are used as surrogate control variables as a correlation with the lift can be described by a lookup table. Two control inputs, pulsed blowing, and two output variables are exploited. In the glider study, with a profile that experiences a mostly two-dimensional flow, an approximate pressure gradient is used instead as a single output to avoid the necessity of such a lookup table. Active flow control is done again, exploiting pulsed blowing. For the controller synthesis, both in the single-input singleoutput and in the multivariable cases, the same approach is used, showing its versatility. In both setups, the closedloop controllers succeed in adjusting the control inputs such that changing reference signals are followed, and the influence of disturbances are attenuated. For the civil aircraft model, completely new landing scenarios can be proposed using the closed-loop controller. Nomenclatureactuation frequency, Hz F L = lift force, N Gjω = frequency response K = Controller _ m = mass flow, kg∕s p = pressure, Pa q = dynamic pressure, Pa Re c = Reynolds number with respect to c S = sensitivity T = complementary sensitivity u = control input, V u, u jet = amplitude of control input, V u ∞ = freestream velocity, m∕s x = nondimensional coordinate y 1 = model parameter, V∕m y 2 = model parameter, V W = weight δ F = flap angle, deg φ = phase, deg ω = angular frequency, rad∕s Subscripts i = model number ref = reference

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Section: Comparisonmentioning

confidence: 94%

Flight and Wind-Tunnel Tests of Closed-Loop Active Flow Control

King

Heinz

Bauer

et al. 2013

Journal of Aircraft

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“…Robust controllers act conservatively to respect neglected nonlinearities in this linear approach, and thus limit the achievable bandwidth. In many AFC applications [3,59,61,62], this conservatism can be reduced significantly by postmultiplying the controller with the inverse of the nonlinear static gain of the plant. By this, the H ∞ controller acts on a seemingly linear plant, at least from the steadystate point of view.…”

Section: Closed-loop Controlmentioning

confidence: 99%

Alleviating Unsteady Aerodynamic Loads with Closed-Loop Flow Control

Williams

King

2018

AIAA Journal

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The practical benefits and issues related to controlling unsteady loads in gusting flows with active flow control actuators are discussed. Recent methods used to model the response of flight and road vehicles to unsteady flow disturbances, as well as modeling approaches for the dynamic effects of active flow control, are presented in the framework of a feedforward/feedback control architecture. Limitations of the achievable control performance are discussed. For instance, the lift reversal and the delay time required for the lift increment to reach its maximum value are responsible for limiting the bandwidth that can be achieved with active flow control of separated flows. An estimate of the practical gust bandwidth that can be controlled with aircraft is made.

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“…On highly loaded compressor cascades, Wiederhold et al 6 used jet flows to suppress the development of boundary layers on the blade surfaces and reduce blockages in the cascade passages. The results showed that when the jet flow rate was 0.5% of the main flow rate, the static pressure ratio increased by more than 10%.…”

Section: Introductionmentioning

confidence: 99%

Corner separation control in compressor stators with jets from the blade leading edge

Zheng

Zhou

2023

Advances in Mechanical Engineering

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Corner separation occurs easily in highly loaded compressor stators. This paper proposes a novel slot inside the stator blade, with the slot inlet located at the blade leading edge and the slot outlet located at the suction surface, by using the momentum of the incoming flow to form a high velocity jet to control the development of the boundary layer on the blade suction surface. For 3D compressor cascades, the influence of the key geometrical slot parameters on the flow fields in the slot and cascade passage and the aerodynamic performance of the cascade were investigated with a numerical method. Then, the stator blades in a highly loaded compressor stage were slotted to improve the flow in the stator blade passages. The main results can be summarized as follows. The use of slotted blades in the cascade effectively suppresses corner separation. When the cascade inlet velocity is high or the inlet flow is at a positive attack angle, the separation control effect improves. In the highly loaded compressor stage, slotted stator blades considerably reduced the flow loss at the stator corner, and the stage efficiency increased over the entire flow rate range. Furthermore, two cascades with unslotted and slotted blades were tested. The experimental and numerical results were consistent, demonstrating that the total pressure loss coefficient of a cascade can be effectively reduced by slotting the blades in the cascade.

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Multivariable Control in a Critically Loaded Compressor Cascade

Cited by 7 publications

References 21 publications

Flight and Wind-Tunnel Tests of Closed-Loop Active Flow Control

Flight and Wind-Tunnel Tests of Closed-Loop Active Flow Control

Alleviating Unsteady Aerodynamic Loads with Closed-Loop Flow Control

Corner separation control in compressor stators with jets from the blade leading edge

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