Large-Eddy Simulation of Single-Element Gas-Centered Swirl-Coaxial Injectors for Combustion Stability Prediction

Umphrey, Clancy; Harvazinski, Matthew E.; Schumaker, Stephen A.; Sankaran, Venkateswaran

doi:10.2514/6.2017-4689

Cited by 4 publications

(1 citation statement)

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“…Computational Fluid Dynamics (CFD) method is regarded as an effective way to investigate combustion instability, which can provide insight into more detailed physical processes. Large Eddy Simulation (LES) is a good candidate, and it has been used to predict combustion instability successfully [16][17][18][19][20][21]. Detached Eddy Simulation (DES) featuring little demands on computational resources has been developed to investigate combustion instability [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Self-Excited Combustion Instabilities in a Small MMH/NTO Liquid Rocket Engine

Qin

Zhang

2020

International Journal of Aerospace Engineering

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Combustion instabilities in a small MMH/NTO liquid rocket engine used for satellite attitude and course control are numerically investigated. A three-dimensional Navier-Stokes code is developed to simulate two-phase spray combustion for cases with five different droplet Sauter Mean Diameters. As the droplet size increases from 30 microns to 80 microns, pressure oscillations are stronger with larger amplitudes. But an increase of the droplet size in the range of 80 microns to 140 microns indicates a reduction in the amplitudes of pressure oscillations. This trend is the same as the Hewitt criterion. The first tangential (1T) mode and the first longitudinal (1L) mode self-excited combustion instabilities are captured in the 60-micron and 80-micron cases. Abrupt spikes occur in the mass fraction of MMH and coincide with abrupt spikes in the mass fraction of NTO at the downstream regions just adjacent to the impinging points. Thus, local combustible high-dense mixtures are formed, which result in quasiconstant volume combustion and abrupt pressure spikes. The propagation and reflection of pressure waves in the chamber stimulate the combustion instability. When the droplet size is too small or too large, it is difficult to form local high-dense premixtures and combustion is stable in the chamber.

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