Experimental setups, workstations, and accessories
Aeroacoustic Setup
This simple setup exhibits the rich dynamics of the fluid mechanical system. The setup has a plenum chamber followed by an acoustic duct. The acoustic duct bolsters the orifices at different locations of the duct. The bulk velocity of the flow is varied as a control parameter of the system. The nonlinear interaction between the hydrodynamics and acoustic fluctuations gives rise to the high amplitude self-sustained acoustic fluctuations referred to as aeroacoustic instability. We have discovered the intermittency route to aeroacoustic instability from the stable operation. Recently, we found that during the shifting in whistling frequency, the transition is either abrupt or occurs through an intermittency state. Further, we discovered that the acoustic and the hydrodynamic fields are phase synchronised during the periodic oscillations and are desynchronised during the aperiodic oscillations.
Annular combustor
Swirl-stabilised turbulent annular combustor setup mimics the turbulent flow and flame dynamics of real-world combustors in helicopters, aircraft, and powerplants. We have discovered the abrupt transition to thermoacoustic instability via secondary bifurcation, which could be a disastrous scenario if it occurs in the real world combustors. We also discovered the transition to azimuthal inatbility via the the state of intermittency. The overall objective of the setup is to study the mechanisms for the various transition to instability and design control strategies.
Cloud Setup
The rapid growth of cloud droplets to rain in warm clouds is still poorly understood. Turbulence in clouds is thought to be crucial in this transition. To understand the role of turbulence we create a lab-controlled cloud-like environment in our turbulence chamber. Here, we generate homogeneous isotropic turbulence of different intensities and seed the chamber with droplets similar to those seen in clouds. We investigate the droplet-turbulence interactions, using various optical diagnostic techniques such as PDPA, PIV, and ILIDS. The knowledge gained from this study can provide a deeper insight onto the rain formation process and help us better understand extreme events like cloud bursts
HPC Cluster
The computational server has the latest Intel Xeon processors, which perform nearly 1.4 TFLOPS. Nvidia Quadro Series Professional Graphics card accelerates image processing, visualization, and machine learning workflows. The server has scientific and mathematical libraries for running and developing parallel programs.
Rijke Tube
The Rijke tube serves as a widely adopted model within the combustion research community, offering insights into the problematic occurrence of thermoacoustic instability. In our exploration of the Rijke tube, we've employed diverse methodologies rooted in dynamical systems theory. These approaches have enhanced our comprehension of thermoacoustic oscillations, enabling us to develop insights into their prediction, prevention, and mitigation, both through experimental and theoretical means. The outcomes derived from our investigations within this system represent a foundational contribution to our understanding of intricate turbulent combustors.
Slotted burner
The slotted burner is dedicated to studying axial-mode thermoacoustic instability in both laminar and turbulent conditions. This compact burner exhibits rich spatiotemporal dynamics, as exhibited by the large-scale turbulent combustors. This burner can operate for an extended period of time, which is required for the statistical analysis of the turbulent flow. We conduct a variety of spatiotemporal measurements in this burner under both laminar and turbulent conditions and then develop phenological models.
Thermo-Acoustic Rig for Axial Instabilities (TARA)
The turbulent axial combustor is dedicated for studying the axial mode thermoacoustic instabilities, also known as combustion instability. Our experiments focus on understanding how the interplay of hydrodynamic, combustion, and acoustic subsystems leads to dangerous, high-amplitude pressure fluctuations. To achieve this, we employ laser-based combustion diagnostics and high-speed chemiluminescence imaging techniques. These tools enable us to capture flow and combustion dynamics, facilitating the development of phenomenological models.
Turbulent combustor with preheater
The presence of preheated reactants considerably alters the flame dynamics compared to when the incoming reactant is not preheated. The combustor operating under preheating conditions leads to a fundamentally different mechanism for the occurrence of thermoacoustic instability. To study the effect of reactant temperature on the flame dynamics inside a turbulent combustor, we perform experiments in a turbulent combustor having a preheater and operating at high Reynolds numbers.
