Novel Fluidic Diode for Hybrid Synthetic Jet Actuator

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Jozef Kordík ◽  
Zdeněk Trávníček
Keyword(s):  
Pressure Drop ◽  
Resonant Frequency ◽  
Synthetic Jet ◽  
Volumetric Efficiency ◽  
Operating Frequency ◽  
Working Fluid ◽  
Hot Wire ◽  
Synthetic Jet Actuator ◽  
Fluidic Diode ◽  
Resonance Curves

This paper deals with a new design of a hybrid synthetic jet actuator (HSJA), which is based on a novel fluidic diode. Two fluidic diodes were tested using pressure-drop measurements with air as the working fluid, and their diodicities were evaluated. A greater diodicity was achieved with the new diode design. Two outlet nozzles of the HSJA were tested (shorter and longer), and the velocity resonance curves were evaluated using hot-wire measurements at the outlets of the nozzles. Volumetric efficiency of the HSJA was evaluated as function of the operating frequency. The greatest efficiency was achieved at the second resonant frequency of the actuator with the longer nozzle.

A Synthetic Jet Issuing From a Bio-Inspired Actuator With an Oscillating Nozzle Lip

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Zdeněk Trávníček ◽  
Zuzana Broučková
Keyword(s):  
Momentum Flux ◽  
Flux Measurement ◽  
Experimental Methods ◽  
Synthetic Jet ◽  
Operating Frequency ◽  
Working Fluid ◽  
Hot Wire ◽  
Synthetic Jet Actuator ◽  
Novel Variant ◽  
Flexible Diaphragm

A novel variant of a synthetic jet actuator (SJA) has been designed, manufactured, and tested. The novelty consists in a bio-inspired nozzle whose oscillating lip is formed by a flexible diaphragm rim. The working fluid is air, and the operating frequency is 65 Hz. The proposed SJA was tested by three experimental methods: phase-locked visualization of the nozzle lips, hot-wire anemometry, and momentum flux measurement using a precision scale. The results demonstrate advantages of the proposed SJA, namely, an increase in the momentum flux by 18% compared with that of a conventional SJA.

Analytical and Experimental Investigation of Different Synthetic Jet Actuator Configurations

Aerospace ◽  
2004 ◽  
Author(s):  
Sandra Ugrina ◽  
Alison Flatau
Keyword(s):  
Resonant Frequency ◽  
Smart Materials ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Laser Vibrometer ◽  
Synthetic Jet Actuator ◽  
Exit Nozzle ◽  
Geometry Configuration ◽  
Jet Velocity ◽  
Constant Temperature Anemometer

The ultimate goal of this project is to actively control the flow over a micro air vehicle using smart materials. MAVs are a new type of aircraft operating at Reynolds numbers of about 50,000 that are one to two orders of magnitude lower than encountered in larger aircraft. The intention is to implement smart structures and couple them with fluids to improve the deteriorated aerodynamics of MAVs and help improve efficiency, stability and maneuverability of such vehicles. The actuators used in this work for artificially controlling the boundary layer are piezoelectrically driven synthetic jets. We theoretically investigated and predicted the behavior of the synthetic jet as we changed the geometry and material property parameters of the actuator. Analytical results were then compared to the results obtained from the experiments. It is crucial to be able to accurately design a strong unimorph to be implemented as an active component of a synthetic jet actuator and design the geometry configuration of the cavity that will best couple with the chosen membrane. A condenser microphone, a constant temperature anemometer (CTA) and a laser vibrometer were used to quantify actuator performance. It was observed that the size of the cavity and the size and shape of the exit nozzle were related and the performance of the actuator increased when the structure was tuned such that the resonant frequency of the diaphragm and that of the cavity were close to matching. A square unimorph made of PZT-5H and bonded to a 0.20- mm brass shim maximized jet velocity for the actuators studied. Optimum direction of change in the volume and the dimensions of the nozzle will strongly depend on the resonant frequency of the membrane in use. In this situation, increasing either the volume of the cavity or the thickness of the nozzle made the two frequencies move away from each other producing reduction in jet velocity. Increasing the area of the nozzle, made the structure behave more as needed and was taken as a key parameter for tuning the base geometry of the device.

Effects of Operating Frequency of a Synthetic Jet and Cross Flow Velocity on the Heat Transfer Enhancement in a Micro-Channel

2013 ◽  
Author(s):  
Mark E. Zschirnt ◽  
Ann Lee ◽  
Guan H. Yeoh
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Cross Flow ◽  
Synthetic Jet ◽  
Operating Frequency ◽  
Micro Channel ◽  
Transfer Enhancement ◽  
Synthetic Jet Actuator ◽  
Micro Channels

Current devices have been reported to approach 1 MW/m2 so that current heat dissipation devices will not be able to cope with increasing heat flux. It has therefore been proposed that in order to manage the ever-increasing heat rejection demands, it will be necessary to have cooling fluid flowing through micro-channels in the microchip itself. Since laminar flow is likely to result for reasonable pressure drops in these micro-channels, the heat transfer rate will need to be enhanced if this approach is to be successfully used. Synthetic jets, which are the main focus of this research, generate vortex structures which disrupt the flow. They have, therefore, been proposed as a means of providing mixing, thereby augmenting the heat transfer potential of the fluid in the micro-channel. A two-dimensional computational model has been developed to investigate the cooling effect of a synthetic jet interacting with a turbulent cross-flow in a micro-channel. Validation of the hydrodynamics feature of the flow was done by comparing numerical results against existing experimental results. A parametric study was performed on a fixed geometry by using a constant wall temperature to investigate the effect of operating frequency of the synthetic jet actuator coupling with different flow rates in the micro-channel. The operating frequencies of the jet were simulated at 1000 Hz, 1500 Hz and 2000 Hz while the cross flows vary from 0 to 10 m/s. In general, the flow structures in the micro-channel were shown to be greatly disrupted when the synthetic jet actuator was turned on. However, the heat transfer enhancement due to the operation of the synthetic jet reduces as the cross flow increases. The frequency of the diaphragm oscillation has a large influence on the distance between the adjacent vortices and therefore on the average flow rate in the micro-channel. The near wall Nusselt Number was calculated in order to compare the effects of operating frequency of the jet and flow rate in the micro-channel. The jet Reynolds number was increased by 50% when the actuator frequency was increased from 1000 Hz to 1500 Hz while the heat transfer enhancement was increased by 21%. Further increment of actuator frequency from 1000 Hz to 2000 Hz resulted in a doubled jet Reynolds number while the heat transfer enhancement was improved by 66%. The heat transfer enhancement showed greater improvement when the actuator operating at 2000 Hz.

scholarly journals Research on Cavitation of the Rotating-Sleeve Distributing Flow System Considering Different Cam Groove Profiles

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2139
Author(s):  
Shanxiao Du ◽  
Jichao Hong ◽  
Hongxin Zhang ◽  
Qinghai Zhao ◽  
Tiezhu Zhang ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Flow System ◽  
Volumetric Efficiency ◽  
Piston Pump ◽  
Operating Frequency ◽  
Cavitation Model ◽  
Pump Chamber ◽  
Orthogonal Experiments ◽  
Simulation Results ◽  
Further Development

Reciprocating piston pumps are widely used in various fields, such as automobiles, ships, aviation, and engineering machinery. Conventional reciprocating piston pump distributing flow (RPPDF) systems have the disadvantages of a loose structure and low volumetric efficiency, as well as affected positively by the operating frequency. In this paper, a novel rotating-sleeve distributing flow (RSDF) system is presented for bridging these drawbacks, as well as structurally improved to overcome the inoperable and challenging problems in oil intake and discharge found in the experiment. Moreover, the Singhal cavitation model specifically for the RSDF system and four-cam groove profiles (CGPs) is established. To find the most suitable CGP to reduce the RSDF’s cavitation, the cavitation of the RSDF system was investigated, combining with simulations by taking into account the gap among the rotating sleeve, the pump chamber, and experiments on four presented CGPs. Simulation results based on vapor volume fraction, cavitation ratio, and volumetric efficiency show that the linear profile’s cavitation is the weakest. Finally, the correctness of the simulation is verified through orthogonal experiments. This research is of great significance to the further development of the RSDF system; more important, it has great potential to promote the reform of the RPPDF method.

scholarly journals Cephalopod‐Inspired Swimming Robot Using Dielectric Elastomer Synthetic Jet Actuator

2020 ◽  
Vol 22 (4) ◽  
pp. 2070014
Author(s):  
Chao Tang ◽  
Wentao Ma ◽  
Bo Li ◽  
Mingliang Jin ◽  
Hualing Chen
Keyword(s):  
Dielectric Elastomer ◽  
Synthetic Jet ◽  
Synthetic Jet Actuator
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