Effect of jet width and momentum coefficient of active control over NACA0012 airfoil using synthetic jet

2018 ◽  
Vol 36 (4) ◽  
pp. 1443-1449
Author(s):  
Mohamed C. Saadi ◽  
Lakhdar Bahi
Keyword(s):  
Active Control ◽  
Synthetic Jet ◽  
Momentum Coefficient ◽  
Naca0012 Airfoil

Active Control of Unsteady Cavitating Flows Over Hydrofoil

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Maria Grazia De Giorgi ◽  
Donato Fontanarosa ◽  
Antonio Ficarella
Keyword(s):  
Active Control ◽  
Leading Edge ◽  
Suction Side ◽  
Synthetic Jet ◽  
Thick Sheet ◽  
Dimensionless Frequency ◽  
Ambient Conditions ◽  
Local Pressure ◽  
Vapor Cavity ◽  
Momentum Coefficient

Abstract A preliminary two-dimensional (2D) numerical investigation of the active control of unsteady cavitation by means of one single synthetic jet actuator (SJA) is presented. The investigation involves the cloud-cavitating flow of water around a NACA 0015 hydrofoil with an angle of attack of 8-deg and ambient conditions. The SJA locates on the suction side at a distance of 16% of the chord from the leading edge; it has been modeled by means of a user-defined velocity boundary conditions based on a sinusoidal waveform. A Eulerian homogeneous mixture model has been used, coupled with an extended Schnerr–Sauer cavitation model and a volume of fluid interface tracking method. As first, a sensitivity analysis allowed to evaluate the influence of the main control parameters, namely, the momentum coefficient Cμ, the dimensionless frequency F+, and the jet angle αjet. As a result, the best performing SJA configuration was retrieved at Cμ=0.0002, F+=0.309, and αjet=90 deg, which led to a reduction of both the average vapor content and the average torsional load in the measure of 34.6% and 17.8%. The analysis of the coupled dynamics between vapor cavity–vorticity and their proper orthogonal decomposition (POD)-based modal structures highlighted the benefit of the SJA lies in preventing the growth of a thick sheet cavity, which causes the development of the highly cavitating cloud dynamics after the cavity breakup. This is mainly due to an additional vorticity close to the hydrofoil surface just downstream the SJA, as well as a local pressure modification close the SJA during the blowing stroke.

scholarly journals Control of a Round Jet Intermittency and Transition to Turbulence by Means of an Annular Synthetic Jet

Actuators ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 185
Author(s):  
Zuzana Antošová ◽  
Zdeněk Trávníček
Keyword(s):  
Reynolds Number ◽  
Active Control ◽  
Flow Regimes ◽  
Velocity Profiles ◽  
Synthetic Jet ◽  
Transition To Turbulence ◽  
Jet Flows ◽  
Maximal Effect ◽  
Hot Wire ◽  
Round Jet

This paper deals with active control of a continuous jet issuing from a long pipe nozzle by means of a concentrically placed annular synthetic jet. The experiments in air cover regimes of laminar, transitional, and turbulent main jet flows (Reynolds number ranges 1082–5181). The velocity profiles (time-mean and fluctuation components) of unforced and forced jets were measured using hot-wire anemometry. Six flow regimes are distinguished, and their parameter map is proposed. The possibility of turbulence reduction by forcing in transitional jets is demonstrated, and the maximal effect is revealed at Re = 2555, where the ratio of the turbulence intensities of the forced and unforced jets is decreased up to 0.45.

Active Control of Unsteady Cavitating Flows in Turbomachinery

2019 ◽  
Author(s):  
Maria Grazia De Giorgi ◽  
Antonio Ficarella ◽  
Donato Fontanarosa
Keyword(s):  
Active Control ◽  
Synthetic Jet ◽  
Hydrodynamic Performance ◽  
Transfer Model ◽  
Thick Sheet ◽  
Dimensionless Frequency ◽  
Pulsation Frequency ◽  
Local Pressure ◽  
Vapor Cavity ◽  
The Impact

Abstract A preliminary 2D numerical investigation of the active control of unsteady cavitation by means of one single synthetic jet actuator (SJA) is presented. The SJA has been applied to hinder the intrinsic instabilities of a cloud cavitating flow of water around a NACA 0015 hydrofoil with an angle of attack of 8° and ambient conditions. It has been placed inside the inception region at a distance of 16% of the chord from the leading edge. Concerning the numerical approach, a Eulerian homogeneous mixture/mass transfer model has been used, in combination with an extended Schnerr-Sauer cavitation model and a Volume of Fluid (VOF) interface tracking method. The synthetic jet has been modeled by means of a user-defined velocity boundary conditions based on a sinusoidal waveform. A sensitivity analysis has been first performed in order to evaluate the influence of the main control parameters, namely the momentum coefficient Cμ, the dimensionless frequency F+ and the jet angle αjet. By combining the cavitating vapor content and the impact on the hydrodynamic performance, the best performing SJA configuration has been retrieved. Then, a deeper analysis of the vapor cavity dynamics and the vorticity field has been conducted in order to understand the modification of the main flow produced by the synthetic jet. The best SJA configuration was observed at Cμ = 0.0002, F+ = 0.309 and αjet = 90°, which led to a reduction of both the average vapor content and the average torsional load in the measure of 34.6% and 17.8% respectively. A reduction of the average pulsation frequency of the pressure upstream confirmed the beneficial effect of the SJA. The analysis of the coupled dynamics between vapor cavity-vorticity and their POD-based modal structures highlighted that the benefit of the SJA lies on preventing the growth of a thick sheet cavity which tends to cause the development of the highly cavitating cloud dynamics after the cavity breakup. This is mainly due to an additional vorticity close to the hydrofoil surface just downstream the SJA, as well as a local pressure modification close the SJA during the blowing stroke.

scholarly journals Active Control for Lifted Flame using a Speaker-Driven Synthetic Jet

2006 ◽  
Vol 72 (715) ◽  
pp. 901-908 ◽  
Author(s):  
Kakuji OGAWARA ◽  
Tatsuo NISHIMURA ◽  
Daisuke KUWAHARA ◽  
Masayuki KITAZAWA ◽  
Yoshikazu ISHIDA
Keyword(s):  
Active Control ◽  
Synthetic Jet ◽  
Lifted Flame

Active control of a free jet using a synthetic jet

2008 ◽  
Vol 29 (4) ◽  
pp. 967-984 ◽  
Author(s):  
David A. Tamburello ◽  
Michael Amitay
Keyword(s):  
Active Control ◽  
Synthetic Jet ◽  
Free Jet

Vortex Shedding Control on a Three-Dimensional Ground Vehicle With Synthetic Jets

2016 ◽  
Author(s):  
Wenshi Cui ◽  
Zhigang Yang ◽  
Guojun Wang ◽  
Hua Zhou
Keyword(s):  
Vortex Shedding ◽  
Excitation Frequency ◽  
Three Dimensional ◽  
Synthetic Jet ◽  
Space Distribution ◽  
Ground Vehicle ◽  
Synthetic Jet Actuators ◽  
Synchronization Phenomenon ◽  
Momentum Coefficient ◽  
Jet Actuators

The study is mainly focused on the influence of the vortex shedding control of a three-dimensional ground vehicle by using synthetic jet actuators based on Large-eddy simulation. Excitation parameters for synthetic jet actuators, such as the excitation frequency, momentum coefficient and jet location, have an influence on vortex shedding control process, which lead to different unsteady flow phenomenon, vortex shedding frequency value and space distribution in the wake. Vortex shedding suppression and vortex-synchronization phenomenon have an influence on the pressure. Under present momentum coefficient, the excitation frequency plays an important role in the occurrence of vortex-synchronization phenomenon behind vertical base. As the momentum coefficient increase, the vortex-synchronization zone expands.

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