The Effect of Orifice Diameter Variations of Conical Cavity Synthetic Jet Actuator on the Drag Reduction of the Reversed Ahmed Body Model

This paper presents a numerical unsteady analysis of a SJA impact on a car wake flow. First, for the optimal reduced frequency F+, the influence of the Cμ on the mean aerodynamic drag reduction 〈Cd〉 is observed. A spectral analysis of the vortex shedding coming from the upper and the lower part of the car and of the drag coefficient is then presented for different Cμ values. Preliminary results suggest that maximum drag reduction is obtained when most energy in the wake comes from the actuator forcing frequency rather than the natural vortex shedding frequencies of the two contributions. This work is completed by a phase locked analysis of the synthetic jet actuator local effect on the turbulent boundary layer just before the flow separation. For the fixed optimal F+, different Cμ values are compared. The streamwise velocity profiles seem to show that maximal efficiency of the control is obtained when the synthetic jet injected momentum is introduced in the logarithmic sub-layer part of the turbulent boundary layer.

Download Full-text

An Active Radial Countercurrent Heat Sink Driven by a Synthetic Jet Actuator

10.1115/imece2001/epp-24701 ◽

2001 ◽

Author(s):

Jelena Vukasinovic ◽

Ari Glezer

Keyword(s):

Heat Transfer ◽

Heat Sink ◽

Jet Impingement ◽

Ambient Air ◽

Synthetic Jet ◽

Synthetic Jets ◽

Heat Transfer Analysis ◽

Orifice Diameter ◽

Synthetic Jet Actuator ◽

Extended Surface

Abstract The performance of a low-profile radial countercurrent heat sink driven by an integrated synthetic jet actuator is investigated experimentally. A packaged thermal test die is cooled using an array of synthetic jets normally impinging on the extended surface. A power dissipation of 50 W is accomplished at the nominal case temperature of Tc = 70 °C. The heat sink design is driven by the flow and heat transfer analysis of normal jet impingement in a confined flow geometry consisting of two parallel circular plates having a diameter that is typically an order of magnitude larger than the spacing between the plates. The velocity and temperature distributions are measured using particle image velocimetry and arrays of thermocouple sensors. A jet actuator is integrated into one of the plates and cools a test heater attached to the opposite surface. The jet draws its makeup air from ambient, impinges on the heater, and ultimately rejects the heat to ambient. This introduces a radial countercurrent flow in the gap between the plates that includes a layer of hot air dispensed along the top plate and a layer of cooler ambient air entrained along the jet exit plane. When the jet is activated the heater temperature drops substantially. Although the global heat transfer coefficient decreases with decreasing gap height, flow pathlines show that the jet can still entrain cool air from ambient and effect substantial cooling even when the spacing between the plates is of the order of the jet orifice diameter.

Download Full-text

Effects of capacitance on a plasma synthetic jet actuator with a conical cavity

Sensors and Actuators A Physical ◽

10.1016/j.sna.2018.04.038 ◽

2018 ◽

Vol 276 ◽

pp. 284-295 ◽

Cited By ~ 6

Author(s):

Mengxiao Tang ◽

Yun Wu ◽

Hongyu Wang ◽

Di Jin ◽

Shanguang Guo ◽

...

Keyword(s):

Synthetic Jet ◽

Conical Cavity ◽

Synthetic Jet Actuator

Download Full-text

Characterization of plasma synthetic jet actuator with Laval-shaped exit and application to drag reduction in supersonic flow

Physics of Fluids ◽

10.1063/5.0064533 ◽

2021 ◽

Vol 33 (9) ◽

pp. 096104

Author(s):

Wei Xie ◽

Zhenbing Luo ◽

Lin Hou ◽

Yan Zhou ◽

Qiang Liu ◽

...

Keyword(s):

Supersonic Flow ◽

Drag Reduction ◽

Synthetic Jet ◽

Synthetic Jet Actuator

Download Full-text

A Simple Passive Device for Drag Reduction over a Three Dimensional Ahmed Body Model

10.32393/csme.2020.1248 ◽

2020 ◽

Author(s):

Naseeb Ahmed Siddiqui ◽

Martin Agelin-Chaab

Keyword(s):

Drag Reduction ◽

Three Dimensional ◽

Passive Device ◽

Body Model ◽

Ahmed Body

Download Full-text

Helmholtz Resonance Frequency of the Synthetic Jet Actuator

Applied Sciences ◽

10.3390/app11125666 ◽

2021 ◽

Vol 11 (12) ◽

pp. 5666

Author(s):

Paweł Gil ◽

Joanna Wilk ◽

Michał Korzeniowski

Keyword(s):

Resonance Frequency ◽

Cross Section ◽

Synthetic Jet ◽

Orifice Diameter ◽

Helmholtz Resonance ◽

Synthetic Jet Actuator ◽

Synthetic Jet Actuators ◽

Cross Section Area ◽

Section Area ◽

Jet Actuators

This paper presents the results of experimental investigations of 108 geometrical configurations of a loudspeaker-driven synthetic jet (SJ) actuator. The considered cases of the SJ actuator were characterized by a high coupling ratio. The experiment was performed to determine the impact of geometry on the Helmholtz resonance frequency. Geometrical parameters of the orifice diameter, orifice length, and cavity volume were changed within a wide range. The dependences of electrical and flow parameters that characterized the synthetic jet actuators as a function of the excitation frequency were also identified. The main goal of the research was to identify the optimal mathematical formula of the model to calculate the Helmholtz resonance frequency in the case of synthetic jet actuators. To determine the model that was characterized by the best fit of the experimental results, an additional geometrical dimensionless parameter, representing the ratio of the orifice cross-section area to the cross-section area of the cavity, was introduced. A significant impact of this parameter on the effective orifice length was noted. Based on the research findings, a model was obtained for which the results of the experiment were in the error range of ±6% for 95% of the measurement data. The obtained model is an improved version of the classical model used in the description of the resonance frequency in the case of a synthetic jet actuator. The model enables highly accurate determination of the Helmholtz resonance frequency at which the maximum synthetic jet actuator parameters occur.

Download Full-text