Thermoacoustics Gallery
Gurpreet Singh and Sathesh Mariappan, Indian Institute of Technology, Kanpur, India;
Balasubramanian Singaravelu, SASTRA University, Thanjavur, India, presented at ICSV24, London, 23-27 July 2017

Experiments are performed in a Rijke type combustor to study vortex-acoustic lock-on from the dynamical systems perspective. At low air flow rates, presence of both vortex shedding and acoustic modes of oscillations were observed. For intermediate flow rates, vortex shedding becomes the dominant mode. As flow rate is further increased, the frequency of the vortex shedding mode increases and merges with the first acoustic mode of the system. At this point, there is a sharp increase in the amplitude of the oscillation. Beyond this flow rate, only the frequency of the acoustic mode is present. The frequency of vortex shedding locks on to the frequency of the acoustic mode. This behaviour is identified as vortex-acoustic lock-on.

Microvec PIV system with 5M camera, MicroPulse 725 synchronizer and 200mJ double pulse laser was used to capture air flow.

Flow visualization for the case with a) circular disc and without c) circular disc. b) Velocity vectors obtained from PIV in the presence of circular disc. b) Spatial x and y coordinates are nondimensionalized with the radius of the circular disc (d).