Controlling flow separation over a curved ramp using vortex generator microjets

Razzaghi, Mohammad Javad Pour; Masoumi, Yasin; Sani, Seyed Mojtaba Rezaei; Huang, Guoping

doi:10.1063/5.0122831

Cited by 8 publications

(2 citation statements)

References 31 publications

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“…Reducing flow separation and recirculation in this simplified model holds significant implications for industrial flow applications. The potential of passive devices such as vortex generators [41][42][43] and active devices such as microjet actuators [44][45][46][47][48][49] to the effective ramp separation control have been successfully demonstrated in the state-ofthe-art experiments and numerical simulations. The current research adopts a smooth backward-facing ramp profile initially proposed in [40].…”

Section: Separation Control On a Smooth Ramp Using Hybrid Passive And...mentioning

confidence: 99%

Enhancing Flow Separation Control Using Hybrid Passive and Active Actuators in a Matrix Configuration

Li,

Zhang

2024

Aerospace

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Efficient control of flow separation holds significant economic promise. This study investigates flow separation mitigation using an experimental platform featuring a combination of passive and active actuators arranged in a matrix configuration. The platform consists of 5 × 6 hybrid actuator units, each integrating a height-adjustable vortex generator and a micro-jet actuator. Inspired by the distributed pattern of V-shaped scales on shark skin, these actuator units are strategically deployed in a matrix configuration to reduce flow separation on a backward-facing ramp. Distributed pressure taps encircling the hybrid actuators monitor the flow state. Parametric analyses examine the effect of different control strategies. By adopting appropriate passive and active actuation patterns, effective pressure recovery on the ramp surface can be achieved. The most significant flow control outcome occurs when the actuators operate under combined active and passive excitation, harnessing the benefits of both control strategies. Particle image velocimetry (PIV) results confirm a notable reduction in flow separation under the best-controlled case. These findings suggest a promising future for flow control devices employing combined passive and active actuation in matrix-like configurations.

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Section: Separation Control On a Smooth Ramp Using Hybrid Passive And...mentioning

confidence: 99%

Enhancing Flow Separation Control Using Hybrid Passive and Active Actuators in a Matrix Configuration

Li,

Zhang

2024

Aerospace

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“…Common boundary layer control technologies include boundary layer blowdown, vortex generator, flow channel, and microjet control [5][6][7][8][9]. Pour et al [10] introduced a fluid microjet into the boundary layer to increase fluid momentum and numerically analyzed the control of a separation bubble behind a ramp. Reese et al [11] experimentally considered the control of flow separation over a NACA-0025 airfoil using microjet actuators, and the experimental results are presented for a novel approach to nonlinear model predictive control.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Boundary Layer Control and Pressure Performance for Low Reynolds Flow with Chemical Reaction

Xu,

Gu,

Gao

et al. 2023

Applied Sciences

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This study examines boundary layer control and pressure recovery in low Reynolds number supersonic flow with chemical reactions in a chemical laser system. Our work prescribes a novel boundary layer control method for the optical cavity of a chemical laser system, and a design of a supersonic diffuser is compared and proposed to make a stable flow for the system. The flow characteristics of a low Reynolds number and internal reaction heat release were analyzed. Three types of experimental pieces were designed to passively control the boundary layer in the optical cavity. An active booster-type supersonic diffuser is proposed to study the pressure recovery problem of a low Reynolds number and chemical reaction supersonic flow generated by an optical cavity. A supersonic chemical reaction platform (SCRP) was established to conduct experimental research on boundary layer control and docking the active booster supersonic diffuser with the SCRP. The experimental results indicate that increasing the boundary layer pumping capacity within a certain range can reduce both the boundary layer thickness and the pressure on the optical cavity while simultaneously enhancing the SCRP energy power. The supersonic diffuser based on active gas pressurization can create the necessary conditions for the normal chemical reaction and improve the ability of the SCRP to resist high back pressure and airflow disturbance. Moreover, the chemical reaction energy release was full and stable with the docking of supersonic diffuser test pieces, resulting in energy power increases, which could be a significant improvement for the design of chemical laser systems.

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Numerical study of microjet and heat flux effects on flow separation and heat transfer over a ramp

et al. 2023

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The control of flow and heat transfer has recently been of great interest to engineering researchers in light of computational technology advances. Microjets are used as control solutions to avoid flow separation and increase heat transfer. The present study evaluates a microjet over a ramp at microjet velocity ratios (jet to inflow velocity) of = 1, 2, and 4 and heat flux ratios (heat flux to based heat flux) of = 1, 2, and 3 to examine the flow separation area and heat transfer improvement numerically. The numerical velocity and temperature gradients were compared to earlier numerical and experimental works. Then, the flow over the ramp was analyzed at the aforementioned microjet velocity and heat flux ratios. Moreover, streamlines, bed pressure, fluid temperature, and bed Nusselt number were evaluated. It was found that a microjet with the optimal velocity could not only diminish the separation bubble but also improve heat transfer. A rise in the velocity ratio from 2 to 4 led to a nearly 33% decrease in the separation bubble and an approximately 20% rise in the Nusselt number. In addition, the microjets enhanced heat transfer by up to 50%.

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Controlling flow separation over a curved ramp using vortex generator microjets

Cited by 8 publications

References 31 publications

Enhancing Flow Separation Control Using Hybrid Passive and Active Actuators in a Matrix Configuration

Enhancing Flow Separation Control Using Hybrid Passive and Active Actuators in a Matrix Configuration

Experimental Investigation on Boundary Layer Control and Pressure Performance for Low Reynolds Flow with Chemical Reaction

Numerical study of microjet and heat flux effects on flow separation and heat transfer over a ramp

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