Post-stall flow control on an airfoil by local unsteady forcing. I - Lift, drag, and pressure characteristics

Wu, J.; Lu, Xi‐Yun; Denny, Andrew G.; Fan, Mingming; Wu, Jing

doi:10.2514/6.1997-2063

Cited by 9 publications

(4 citation statements)

References 22 publications

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“…Some numerical investigations concerning lift increase using synthetic jets were reported in the litterature, solving time-accurate Reynolds-Averaged Navier-Stokes equations. Wu et al [14] investigated poststall lift enhancement for a NACA 0012 airfoil using a normal suction/blowing jet located at 2.5% of the chord and found that lift increase in the post-stall regime can be achieved, as was reported in experiments.…”

Section: Introductionmentioning

confidence: 73%

Simulation and optimization of stall control for an airfoil with a synthetic jet

Duvigneau

Visonneau

2006

Aerospace Science and Technology

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This study concerns the simulation and optimization of stall control, using a synthetic jet. The flow is simulated by solving unsteady Reynolds-averaged Navier-Stokes equations with a near-wall low-Reynolds number turbulence closure. The flow around a NACA 0015 airfoil, including a synthetic jet located at 12% of the chord, is studied for a Reynolds number Re = 8.96 10 5 and for angles of attack from 12 to 24 degrees. The optimization of the control parameters (momentum coefficient, frequency, angle w.r.t. the wall) is intended, by coupling an automatic optimization algorithm with the flow solver. A significant improvement of the control efficiency is obtained (maximum lift increased of 34% and stall delayed from 19 • to 22 • w.r.t. the initial controlled flow). A Physical analysis of the flow is performed to characterize the optimal control process found.

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Section: Introductionmentioning

confidence: 73%

Simulation and optimization of stall control for an airfoil with a synthetic jet

Duvigneau

Visonneau

2006

Aerospace Science and Technology

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“…Flow over airfoils at high angles of attack and its control is quite complicated due to the flow separation that leads to vortex shedding from both the leading and trailing edges of the airfoil (Wu et al [85]). Secondary and tertiary separations from the middle part of the airfoil upper surface may also be induced, which makes the airflow field inherently unsteady.…”

Section: Numerical Simulation Of Flow Over the Naca 0015 Airfoilmentioning

confidence: 99%

“…The resulting model The applications of the AIC on validation data are useful in determining when to stop adding parameters to a model. However, the use of this criterion alone would not always result in an optimal model (Wu et al [85]). Figure 7a shows those BIC indices for both estimation and validation series are of higher values than AIC indices.…”

Section: Narmax Identification Of Flow Over An Airfoilmentioning

confidence: 99%

NARMAX Identification Based Closed-Loop Control of Flow Separation over NACA 0015 Airfoil

Obeid

Ahmadi

Jha

2020

Fluids

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A closed-loop control algorithm for the reduction of turbulent flow separation over NACA 0015 airfoil equipped with leading-edge synthetic jet actuators (SJAs) is presented. A system identification approach based on Nonlinear Auto-Regressive Moving Average with eXogenous inputs (NARMAX) technique was used to predict nonlinear dynamics of the fluid flow and for the design of the controller system. Numerical simulations based on URANS equations are performed at Reynolds number of 106 for various airfoil incidences with and without closed-loop control. The NARMAX model for flow over an airfoil is based on the static pressure data, and the synthetic jet actuator is developed using an incompressible flow model. The corresponding NARMAX identification model developed for the pressure data is nonlinear; therefore, the describing function technique is used to linearize the system within its frequency range. Low-pass filtering is used to obtain quasi-linear state values, which assist in the application of linear control techniques. The reference signal signifies the condition of a fully re-attached flow, and it is determined based on the linearization of the original signal during open-loop control. The controller design follows the standard proportional-integral (PI) technique for the single-input single-output system. The resulting closed-loop response tracks the reference value and leads to significant improvements in the transient response over the open-loop system. The NARMAX controller enhances the lift coefficient from 0.787 for the uncontrolled case to 1.315 for the controlled case with an increase of 67.1%.

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“…Embora jatos sintéticos tenham fluxo de massa líquido nulo, eles transferem quantidade de movimento ao fluido ambiente. No trabalho do WU et al (1997) A sensibilidade do escoamento recolado e a sustentação restabelecida, para uma determinada freqüência de excitação também é demonstrada na simulação numérica do DONOVAN et al (1998) (1998) reafirmam que um escoamento separado pode ser manipulado efetivamente através de injeção e sucção periódicos de baixo nível próximo ao bordo de ataque. A excitação pode modular a evolução das estruturas de vórtices dentro da camada cisalhada separada e promover a formação de vórtices de sustentação concentrados, que giram e interagem com vórtices no bordo de fuga, e assim alteram o escoamento estolado global.…”

Section: 12) a Utilização Dos Meios Ativos De Controle De Escoamentounclassified

Estudo dos efeitos de um jato sintético simulado numericamente no atraso da separação de uma camada limite sobre um aerofólio hipotético

Mello¹

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A realização deste trabalho tem como objetivo fundamental estudar os efeitos dos atuadores de jato sintético no escoamento de uma camada limite desenvolvida sobre uma placa plana e um aerofólio hipotético. A interação dos jatos sintéticos com um escoamento transversal pode conduzir a uma aparente modificação da forma aerodinâmica de corpos rombudos e, dessa forma, fornecer uma maneira de controle da separação na camada limite. Estudos recentes demonstram que tipos diferentes de escoamentos podem ser produzidos pelo atuador dependendo da oscilação da membrana. Um método numérico para solução das equações de Navier-Stokes incompressíveis bidimensionais na formulação vorticidade-velocidade é utilizado neste trabalho. As equações governantes são discretizadas utilizando-se métodos de diferenças finitas compactas de sexta ordem para as derivadas espaciais. A equação de Poisson para a componente da velocidade normal é resolvida por um método iterativo de sobre-relaxação em linhas sucessivas usando um esquema com malha composta para acelerar a convergência. Os resultados de simulações com diferentes valores de freqüência, amplitude e comprimento de fenda foram verificados através de uma análise de Fourier temporal. Através desta análise é verificado qual a melhor situação para se atrasar a separação da camada limite.Palavras-chave: jato sintético, controle ativo de escoamento, atraso da separação, camada limite de Blasius, camada limite de Falkner-Skan.

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Post-stall flow control on an airfoil by local unsteady forcing. I - Lift, drag, and pressure characteristics

Cited by 9 publications

References 22 publications

Simulation and optimization of stall control for an airfoil with a synthetic jet

Simulation and optimization of stall control for an airfoil with a synthetic jet

NARMAX Identification Based Closed-Loop Control of Flow Separation over NACA 0015 Airfoil

Estudo dos efeitos de um jato sintético simulado numericamente no atraso da separação de uma camada limite sobre um aerofólio hipotético

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