Modeling & Simulation

Combustion Stability

The emergence of resonant acoustic waves in large combustors stands as arguably the single most debilitating obstacles reported in the developmental stages of new propulsive systems. Their appearance signals the presence of combustion instabilities, which commonly manifest as high-amplitude pressure oscillations. In some cases, acoustic pressure amplitudes exceeding 100% of the mean chamber pressure are measured. These may lead to severe structural vibrations, increased heat transfer, or outright catastrophic failures.

GTL is a recognized leader in modeling and analysis of combustion instabilities. Their Universal Combustion Device Stability (UCDS™) framework is an energy-based approach developed to quantify the physical processes leading to the emergence of combustion instabilities. This multi-faceted framework can be applied to provide rapid predictions of combustion systems instabilities as well as a method for providing maximum insight from computational and experimental data.

Combustion Stability

UCDS Compared Against Experimental Data

CFD Capabilities

GTL employs a variety of computational fluid dynamics software to accurately model fluid flow through a wide range of applications. GTL uses these solutions in a variety of ways. Foremost, accurate computational models provide the critical first step within the UCDS framework. The software includes open source software such as OpenFOAM, custom written software for both Eulerian and Lagrangian frameworks, and COMSOL’s commercially available Multiphysics software. These tools are used by our engineers to support and further the mission and design goals of GTL.

CFD Capabilities

Temperature surface plot for methane/air combustion

CFD Solution of Compressible Jet

SPH Modeling

GTL’s Smoothed Particle Hydrodynamics (SPH) algorithms offers unique modeling capabilities not feasible with traditional computational methods. Smoothed particle hydrodynamics (SPH) is a Lagrangian, mesh-less approach for solving multi-physics problems. It was originally devised to solve gas dynamics problems in astrophysics. Later it was adapted to other branches of computational physics including fluid dynamics and elastic structures.

Smoothed Particle Hydrodynamics provides unified framework to address multi-physics problems in computational fluid dynamics, combustion chemistry, computational solid mechanics, and aeroelastics. A primary benefit of moving from a traditional grid-based approach to a mesh-less solution is a significant reduction in the computational overhead needed to interface multi-physics domains. Paired with the linear nature of the Lagrangian fluid dynamics equations, and the ease at which SPH can be parallelized on CPUs and GPUs, the time-to-solution can be drastically reduced. SPH offers the modeling capabilities and accuracy of traditional computational physics models but at the lower computational cost of reduced order models.

Tank Discharge Modeling with SPH