Numerical investigation of hypersonic flow with repetitive-pulsed plasma actuators

2017 ◽  
Vol 232 (9) ◽  
pp. 1715-1724
Author(s):  
Chin-Cheng Wang ◽  
Li-Chung Hsu
Keyword(s):  
Circular Cylinder ◽  
Flow Control ◽  
Hypersonic Flow ◽  
High Speed ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Plasma Actuators ◽  
Circular Cylinders ◽  
Pulsed Plasma ◽  
Pulsed Discharges

Repetitive-pulsed plasma actuators have become the key enabler for flights in the hypersonic flow control. A numerical study focuses on the effect of the repetitive-pulsed plasma actuators at Mach 6. The geometric effects of circular, square, and triangular cylinders as well as a sphere on the aerodynamic performance are considered in the present study. For flow over the circular cylinder and sphere, shock control by repetitive-pulsed discharges is investigated, respectively. The baseline results are successfully validated with the theoretical and published numerical values for flow past a circular cylinder at Mach 6. Without flow control, results show that the shapes of the triangular cylinder and sphere have much smaller high-pressure regions compared to that of the square and circular cylinders. With repetitive-pulsed plasma, the time-average drag reduction has been reduced by a maximum of 0.8% and the stagnation pressure ratio is reduced by 2.1% for Mach 6 flow over a circular cylinder. Thus, this research shows a great benefit of repetitive-pulsed discharges to the state-of-the-art in high-speed flight design.

Experimental Investigation of Tip Clearance Flow in a Transonic Compressor With and Without Plasma Actuators

2014 ◽  
Vol 137 (4) ◽  
Author(s):  
S. Saddoughi ◽  
G. Bennett ◽  
M. Boespflug ◽  
S. L. Puterbaugh ◽  
A. R. Wadia
Keyword(s):  
Flow Control ◽  
High Speed ◽  
Plasma Actuator ◽  
Tip Clearance ◽  
Plasma Actuators ◽  
Tip Clearance Flow ◽  
Transonic Compressor ◽  
Low Aspect Ratio ◽  
Clearance Flow ◽  
Design Speed

Blade tip losses represent a major performance penalty in low aspect ratio transonic compressors. This paper reports on the experimental evaluation of the impact of tip clearance with and without plasma actuator flow control on performance of an U.S. Air Force-designed low aspect ratio, high radius ratio single-stage transonic compressor rig. The detailed stage performance measurements without flow control at three clearance levels, classified as small, medium, and large, are presented. At design-speed, increasing the clearance from small to medium resulted in a stage peak efficiency drop of almost six points with another four point drop in efficiency with the large clearance (LC). Comparison of the speed lines at high-speed show significantly lower pressure rise with increasing tip clearance, the compressor losing 8% stall margin (SM) with medium clearance (MC) and an additional 1% with the LC. Comparison of the stage exit radial profiles of total pressure and adiabatic efficiency at both part-speed and design-speed and with throttling are presented. Tip clearance flow-control was investigated using dielectric barrier discharge (DBD) type plasma actuators. The plasma actuators were placed on the casing wall upstream of the rotor leading edge and the compressor mapped from part-speed to high-speed at three clearances with both axial and skewed configurations at six different frequency levels. The plasma actuators did not impact steady state performance. A maximum SM improvement of 4% was recorded in this test series. The LC configuration benefited the most with the plasma actuators. Increased voltage provided more SM improvement. Plasma actuator power requirements were almost halved going from continuous operation to pulsed plasma. Most of the improvement with the plasma actuators is attributed to the reduction in unsteadiness of the tip clearance vortex near-stall resulting in additional reduction in flow prior to stall.

Development of localized arc filament RF plasma actuators for high-speed and high Reynolds number flow control

2010 ◽  
Vol 49 (2) ◽  
pp. 497-511 ◽  
Author(s):  
J.-H. Kim ◽  
M. Nishihara ◽  
I. V. Adamovich ◽  
M. Samimy ◽  
S. V. Gorbatov ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Flow Control ◽  
High Speed ◽  
High Reynolds Number ◽  
Plasma Actuators ◽  
Rf Plasma ◽  
Reynolds Number Flow ◽  
Number Flow ◽  
High Reynolds

scholarly journals Passive Flow Control for Drag Reduction on a Cylinder in Cross-Flow Using Leeward Partial Porous Coatings

Fluids ◽  
2021 ◽  
Vol 6 (8) ◽  
pp. 289
Author(s):  
Imogen Guinness ◽  
Tim Persoons
Keyword(s):  
Flow Control ◽  
Numerical Study ◽  
Cross Flow ◽  
Circular Cylinders ◽  
Porous Coating ◽  
Leeward Side ◽  
Porous Coatings ◽  
Passive Flow Control ◽  
Passive Flow ◽  
The Impact

This paper presents a numerical study on the impact of partial leeward porous coatings on the drag of circular cylinders in cross-flow. Porous coatings are receiving increasing attention for their potential in passive flow control. An unsteady Reynolds-averaged Navier–Stokes model was developed that agreed well with the numerical and experimental literature. Using the two-equation shear stress transport k−ω turbulence model, 2D flow around a circular cylinder was simulated at Re = 4.2×104 with five different angles of partial leeward porous coatings and a full porous coating. For coating angles below 130∘, the coating resulted in an increase in pressure on the leeward side of the cylinder. There was a significant reduction in the fluctuation of the pressure and aerodynamic forces and a damping effect on vortex shedding. Flow separation occurred earlier; the wake was widened; and there was a decrease in turbulence intensity at the outlet. A reduction of drag between 5 and 16% was measured, with the maximum at a 70∘ coating angle. The results differed greatly for a full porous coating and a 160∘ coating, which were found to cause an increase in drag of 42% and 43%, respectively. The results showed that leeward porous coatings have a clear drag-reducing potential, with possibilities for further research into the optimum configuration.

Atmospheric-pressure pulsed plasma actuators for flow control: shock wave and vortex characteristics

2019 ◽  
Vol 28 (6) ◽  
pp. 064001 ◽  
Author(s):  
Cheng Zhang ◽  
Bangdou Huang ◽  
Zhenbing Luo ◽  
Xueke Che ◽  
Ping Yan ◽  
...  
Keyword(s):  
Shock Wave ◽  
Flow Control ◽  
Atmospheric Pressure ◽  
Plasma Actuators ◽  
Pulsed Plasma ◽  
Control Shock

On the Development of Localized Arc Filament Plasma Actuators for High Speed Flow Control

2009 ◽  
Author(s):  
Jin-Hwa Kim ◽  
Munetake Nishihara ◽  
S Keshav ◽  
Igor Adamovich ◽  
Mo Samimy ◽  
...  
Keyword(s):  
Flow Control ◽  
High Speed ◽  
Plasma Actuators ◽  
High Speed Flow ◽  
Speed Flow ◽  
Filament Plasma

Characterization of Localized Arc Filament Plasma Actuators Used for High-speed Flow Control

2007 ◽  
Author(s):  
Yurii Utkin ◽  
Saurabh Keshav ◽  
Jin-Hwa Kim ◽  
Jeff Kastner ◽  
Igor Adamovich ◽  
...  
Keyword(s):  
Flow Control ◽  
High Speed ◽  
Plasma Actuators ◽  
High Speed Flow ◽  
Speed Flow ◽  
Filament Plasma

A Numerical Study of Geometrical Effects on the Strouhal Number of a Circular Cylinder

2008 ◽  
Author(s):  
Farzan Kazemifar ◽  
Mehdi Molai ◽  
Bahar Firoozabadi ◽  
Goodarz Ahmadi
Keyword(s):  
Circular Cylinder ◽  
Strouhal Number ◽  
Vortex Shedding ◽  
Numerical Study ◽  
Circular Cylinders ◽  
Percentage Reduction ◽  
Blade Angle ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency ◽  
Geometrical Effects

In this paper, reducing the Strouhal number of a circular cylinder is studied numerically. Two-dimensional numerical simulations of flow over a normal circular cylinder and various modified circular cylinders are carried out using FLUENT® soft ware. Two small blades are attached to a circular cylinder and the effects of variation of the blades length and the blade angle are studied numerically. The blade angle is chosen 2α = 0°, 30°, 90°, 120° and 150°. The blades length is chosen l/d = 0.125, 0.25, 0.375. Effects of blade angles and blade lengths were studied for both 2α = 0° and 150°. Results show that increasing in blade lengths decreases the Strouhal number. Moreover, as the blade angle was increased from zero to 90°, the percentage reduction in Strouhal number decreased; however, as the blade angle was further increased from 90° to 150°, the percentage reduction in Strouhal number increased. Although the modifications studied here decrease the vortex shedding frequency they make the vortices shed from the cylinder farther and stronger hence increasing the magnitude of the fluctuating forces.

Stability Improvement of a Turbocharger Centrifugal Compressor by a Nonaxisymmetric Vaned Diffuser

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Xinqian Zheng ◽  
Zhenzhong Sun ◽  
Tomoki Kawakubo ◽  
Hideaki Tamaki
Keyword(s):  
Flow Field ◽  
Flow Control ◽  
Centrifugal Compressor ◽  
Flow Separation ◽  
Static Pressure ◽  
Control Method ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Vaned Diffuser ◽  
Positive Effects

The nonuniformity of the flow field induced by a nonaxisymmetric volute significantly degrades the stability of a turbocharger centrifugal compressor. In this paper, a nonaxisymmetric vaned diffuser is investigated as a nonaxisymmetric flow control method using both three-dimensional computational fluid dynamics (CFD) and experiment. The numerical study first focuses on the relationship between the flow field and the static pressure distortion, and the steady CFD results indicate that the positive static pressure gradient in the rotating direction facilitates flow separation in the vaned diffuser and induces a nonuniform flow field. A nonaxisymmetric flow control method with variable stagger and solidity of the vaned diffuser is developed to suppress the flow separation, and the guideline of the method suggests narrowing flow passages where the flow separates or closing diffuser vanes upstream of flow separations. Steady CFD also presents the flow field of the investigated turbocharger centrifugal compressor with volute, and flow separation is found in the flow passages near the volute tongue. Under the guidance of the nonaxisymmetric flow control method, several nonaxisymmetric vaned diffusers are designed to make the flow field uniform, which are believed to be beneficial for compressor stability. Finally, an experiment is carried out to validate the positive effects of the nonaxisymmetric vaned diffuser for stability improvement. The test data show that Non-AxisVD (with a nonaxisymmetric vaned diffuser) extends the stable flow range (SFR) of the compressor by 26% compared with the AxisVD (with an axisymmetric vaned diffuser), at the cost of acceptable decreases in the maximum total pressure ratio and peak efficiency.

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