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A Study on Formation and Evolution of Synthetic Jet using Stereo Particle Image Velocimetry

Main objectives : To characterize the synthetic jet generated from a circular orifice by varying the actuation frequency and the Reynolds number using particle image velocimetry (PIV) as synthetic jets have potential applications in flow control and cooling of miniature devices. Other objectives were: developing experimental facilities (wind tunnel, water tunnel, electronic cooling and blast wave attenuation) using particle image velocimetry (micro PIV in fluidic devices to Supersonic flow over objects).

What was achieved :

  • The effect of different orifices diameters (15 and 25 mm) on the evolution of synthetic jet is studied using PIV, high speed flow visualizations and hot wire anemometry measurements. The reduction in orifice diameter increases the instantaneous velocity of the discrete vortices for a given actuation frequency and the cavity size.
  • The effect of actuator frequencies on synthetic jet evolution has been studied. The velocity and vorticity field during formation and evolution of discrete vortex rings generated at different actuation frequencies are obtained using particle image velocimetry. The jet velocity near the orifice exit increases with increase in actuation frequencies.
  • The results obtained with particle image velocimetry are verified with hotwire anemometry velocity measurements. The discrete vortices generated for lower frequencies (up to 50 Hz) travel a long distance along the downstream direction before collapsing into a turbulent structure. The vortex rings generated for higher frequencies break into a turbulent jet at a lesser distance compared to a low-frequency jet. The time history of synthetic jet velocity measured for various actuation frequencies at different axial distances using hot wire anemometry showed that the mean velocity of the jet increases with increase in actuation frequencies.
  • The cooling effectiveness of synthetic jet is studied by varying the actuation frequency and the nondimensional spacing using thermal imaging camera. The temperature field obtained using a thermal imager showed that the effectiveness of synthetic jet increases with  increase in actuation frequencies.
Project Number:
OLP 201912
Project Type:
Project Date:
01/03/2013 to 31/12/2015
Cost of the Project:
81.65
Sponsoring Agency:
CSIR
Deliverables:

Deliverables :

Envisaged Achieved
Advancement of knowledge One SCI paper published
One paper is accepted in international
conference
The developed technology will be used for flow control and heat transfer enhancement

One proposal has been  formulated to ISRO through respond program for flow control using synthetic jet.

A preliminary cooling effectiveness study of the synthetic jet has been performed using thermal imaging camera. We will formulate a proposal on miniature electronic component cooling using synthetic jet.

What Next?  The synthetic jet experimental facility and the particle image velocimetry system will be used for studying the heat transfer enhancement by analyzing the flow field using thermal imager and PIV. The thunder (miniature) actuators will be used for generating the synthetic jet at high  frequencies up to 700 Hz for studying the transition and flow control over the delta wing at the higher angle of attacks.

The developed experimental facility with particle image velocimetry, high-speed flow visualization, and multichannel hotwire anemometry will be used for various fluid dynamic activities of the institute such as flow field evaluation of fish fin in a water tunnel and quadrotor configuration of the flying robot, drag measurements over various objects in low-speed wind tunnel.

A proposal is being prepared for studying the characteristic of delta wing at subsonic speed using particle image velocimetry which will be submitted to ISRO India. A proposal titled "Development of blast wave generator for studying the blast wave attenuation and the interaction of blast wave with bunkers, wedge and circular disc and the related acoustics" is already submitted to DST India for financial support.


Last updated : 26 Oct, 2017