Research Projects

The increasing demand for cleaner and more efficient energy systems in India has emphasized the need for combustion technologies that are both fuel-flexible and environmentally sustainable. Natural gas (NG), owing to its lower carbon footprint, has emerged as a preferred alternative to conventional fossil fuels. However, its combustion under lean conditions poses stability challenges due to low flame speeds and high ignition energy. A promising near-term solution lies in blending NG with hydrogen (H₂), which improves flame stability, broadens flammability limits, and enhances combustion efficiency. To fully exploit this strategy, the development of an advanced burner capable of handling a range of hydrogen blending ratios is essential. The proposed research aims to develop a synthetic jet-based coaxial burner that utilizes active flow control to enhance fuel–air mixing and combustion stability for hydrogen–natural gas blends. The technology builds upon our recently patented synthetic jet actuators (Indian Patent Application Nos. 202131047214 & 201731035216), capable of introducing localized and bulk perturbations in the flow without additional mass input. This pulsation can be tuned in frequency, amplitude, and phase to modulate coherent vortex structures in the shear layers of a coaxial jet, thereby improving mixing quality. The proposed hypothesis is that actively modulating the vorticity dynamics in both inner and outer shear layers of a coaxial jet can lead to enhanced mixing, enabling lean, stable, and efficient combustion of NG and H₂-NG blends. This is especially critical for hydrogen, whose high diffusivity and low ignition energy require finely controlled mixing to ensure safety and minimize emissions. The objectives of the project are as follows: 1. Development of a proof-of-concept synthetic jet-based coaxial burner suitable for a wide range of H₂-NG mixtures. 2. Design and fabrication of active flow excitation mechanisms for both local (synthetic jet array) and bulk (acoustic speakers) disturbances. 3. Experimental evaluation of flow and combustion performance, including flame stability, mixing efficiency, and emission characteristics under varying hydrogen blending ratios. 4. Investigation of coherent structure dynamics in coaxial jets using advanced diagnostics such as hot-wire anemometry, particle image velocimetry (PIV), and planar laser-induced fluorescence (PLIF). Preliminary non-reacting flow studies at IIT Bhubaneswar have shown that bulk pulsation and synthetic jets can significantly enhance jet spreading and mixing. Flow measurements confirmed early breakdown of large vortices and interaction of frequency modes, supporting the hypothesis. Main experiments will include hot-wire measurements, high-speed imaging, PIV, and PLIF under cold flow and reacting conditions across a matrix of velocity ratios, hydrogen concentrations, and excitation parameters. A coaxial jet test rig integrated with synthetic jet arrays and pulsation modules will be fabricated to conduct these studies. The experiments will be designed to capture the coupling between shear layer instabilities and synthetic jet-induced disturbances, which influence the development and breakdown of Kelvin–Helmholtz vortices. If successful, the research will contribute significantly to both fundamental fluid–combustion interaction understanding and practical burner design. The outcomes include a modular, scalable burner system compatible with existing natural gas infrastructure. This provides a transitional path toward hydrogen usage in industrial and residential heating without overhauling legacy systems. Beyond scientific insight, the work is expected to deliver patents, high-impact publications, and a demonstrable prototype ready for pilot-scale testing. It will also train students in advanced diagnostics and support industrial technology transfer.