Research Projects
GPU-accelerated solver for low-Mach-number combustion
I developed a high-order scalable GPU-accelerated CFD solver for low-Mach-number combustion. The code, based on the open-source spectral element code nekRS, uses detailed chemistry and mixture-averaged diffusion to solve the chemically-reactive Navier-Stokes equations. The solver provides a means for high-fidelity simulations (DNS/WRLES) of constant-pressure flames such as those encountered in gas turbines. The temporal integration employs a splitting method that decouples the stiff chemistry from the hydrodynamics, accelerating solutions while maintaining a high level of accuracy.
Temperature color contour for hydrogen-air swirling flame
A discontinuous-Galerkin method for high-speed combustion
Rotating detonation engines (RDEs) have received considerable attention recently as a means to provide more efficient forms of pressure gain combustion in stationary gas turbines and rocket engines. In particular, recent focus has been given to engines operating with low-carbon fuels such as hydrogen. During my time with Argonne, I developed a high-order discontinuous-Galerkin spectral element method (DGSEM) to solve the compressible chemically-reactive Navier-Stokes equations. The code uses both kinetic energy and entropy conservative fluxes for the interface and volume terms, and is supplemented by artificial viscosity and a positivity-preserving limiter to suppress non-physical oscillations. The code was successfully validated with solutions to 1D (steady ZND) and 2D detonations.
2D Detonation temperature contour
2D Detonation numerical soot foil
Concentric jet swirling flames
As part of my PhD research at UCSD, I investigated the effects of swirl-number and Damkohler number on laminar concentric jet swirling flames, a flow commonly encountered in gas turbines. The analysis of the laminar flow provided insight into the canonical swirl/chemistry interaction, which serves as a useful tool for the design of practical gas turbines operating at large Reynolds numbers. The analysis began with a description of the isothermal non-reactive flow in axisymmetric geometry, followed by an analysis of diluted and undiluted methane-air flames. 3D simulations were used to verify the axisymmetric assumption and also provide insight into the azimuthal instabilities present in swirling jets.
Temperature and reaction rate contours for concentric jet swirling fame
Swirling jets and flames
In combustion applications such as gas turbines, swirling jets are used to generate a vortex breakdown recirculation region that serves as a non-invasive flame stabilizer. In this work at UCSD, I conducted direct numerical simulations (DNS) of low-Mach-number gaseous swirling jets and diffusion flames. Initially, I focused on variable-density swirling jets to get a better understanding of the effects of non-uniform temperature on vortex breakdown. These 2D axisymmetric and 3D simulations revealed two breakdown modes, the bubble and the cone. Subsequently, I conducted simulations of the same flow in the presence of a Burke-Schumann diffusion flame. The results provide insight into the basic effects of heat release on vortex breakdown, which is critical for flame stabilization and blow-off in practical non-premixed gas turbine flames.