A temporally-separated dual-plane stereoscopic particle image velocimetry (PIV) technique is utilized to investigate the dynamics of periodically-excited vortices in a swirling flame under four experimental conditions. The time-averaged results under the unexcited condition are analyzed to verify the accuracy of the method. For the excited conditions, Q criteria is used to extract and classify the vortex structures within the swirling flame. It is found that under different excitation frequencies of the same amplitude, the outer vortex rings (OVRs) and the inner vortex rings (IVRs) show opposite rotational characteristics. While the excitation frequency has little influence on the central vortices induced by the swirler, the amplitude does have a great influence on the development trajectory of the central vortices. Furthermore, the amplitude and phase of oscillation velocities in three directions are successfully decomposed by using sine curve fittings at each point. A periodic acceleration and deceleration process is observed only in the axial direction. Besides the acoustic wave, it is found that the vortex rings (both OVRs and IVRs) also contribute to the axial velocity oscillations.
|Experimental Thermal and Fluid Science
|Published - Apr 30 2022
Bibliographical noteKAUST Repository Item: Exported on 2022-05-16
Acknowledgements: Supported by National Natural Science Foundation of China (52076137, 91941301) and National Science and Technology Major Project of China (2017-III-0004-0028).
ASJC Scopus subject areas
- Chemical Engineering(all)
- Mechanical Engineering
- Nuclear Energy and Engineering
- Fluid Flow and Transfer Processes
- Aerospace Engineering