• Vol 8, No 7 (2017)
  • Mechanical Engineering

The Effect of Frequency Excitation and Cavity Shape Changes on the Vortex Ring Formation of a Synthetic Jet Actuator

Dewi Larasati, Harinaldi , Ramon Trisno

Corresponding email: dewi.larasati.mech.eng.ui.13@gmail.com


Published at : 27 Dec 2017
IJtech : IJtech Vol 8, No 7 (2017)
DOI : https://doi.org/10.14716/ijtech.v8i7.730

Cite this article as:
Larasati, D., Harinaldi., Trisno, R., 2017. The Effect of Frequency Excitation and Cavity Shape Changes on the Vortex Ring Formation of a Synthetic Jet Actuator. International Journal of Technology, Volume 8(7), pp. 1286-1295
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Dewi Larasati - Mechanical Engineering University of Indonesia
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Harinaldi Mechanical Engineering University of Indonesia
Ramon Trisno Mechanical Engineering University of Indonesia
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Abstract
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This paper provides an explanation of the effects of cavity shape and frequency excitation to the vortex formation of the synthetic jet. In order to get comprehensive results, this study will be conducted by both computational and experimental methods.The experiment method prepared by applying hotwire probe on the center point of the synthetic jet orifice, so from here the researcher get the Ux (average airflow velocity from membrane movement)in a low voltage signal, then the data will be transferred to analog data converter within the record speed 10.000 data/s. The cavities shapes that will be applied are half-sphere, tubes, and conical. The diameter varieties of the orifice are 3 mm, 5 mm and 8 mm. the simulation is started by utilizing the flow rate data from the experiment which can be put in the simulation boundary condition. Furthermore, from visual data of flow contour from CFD simulation the qualities vortex ring formation from SJA can be determined. Based on this research result, the formation of vortex ring occurs at the configuration B3, T3, T5, K3 and K5 of the SJA. Meanwhile, the other types of the synthetic jet cavity which have 8 mm of orifice diameter is not producing the vortex ring.

Active Flow Control; Ahmed Body; Airflow Separation; Drag Force ;Vortex Ring

Conclusion

Based on the findings from this research, it can be concluded that 10,000/s is the maximum jet speed generated by the SJA in the frequency range of 110 Hz–130 Hz with an uncertainty of 2% and a data amount of 10,000. The highest velocity jet is produced by K3 (conical cavity) with an orifice diameter of 3 mm. The average jet velocity generated reached 9.98 m/s. The vortex ring formation can be determined by the experiments and the CFD simulation method. Based on the experimental and simulation data, it can be concluded that the vortex ring formation equation calculation results were the same for both methods. Vortex ring formation can occur in B3, T3, T5, K3, and K5 synthetic jet cavities. A vortex ring is not formed on any type of cavity with an orifice diameter of 8 mm. In addition, determination of the occurrence of vortex ring formation can also be evaluated from the equation proposed by Utturkar (2002). The condition of  Re/S2> 1 is indicative for certain frequency excitations to produce a vortex ring. Thus, it can be said that the results from the simulation and experiments conducted in the present study provide some evidence to support the theory of vortex ring formation mentioned by some previous researchers.

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