CFD-Aided Structural Rigidity Analysis for the Ignition Assistance Device Applicable to Small Aircraft Engines

This study provides the dynamical behavior of thermomechanical stress acting on the ignition assistant device embedded in a combustion engine for small aircraft propulsion systems. Thermomechanical impacts become significant on the structural component of the ignition assistance system. They were mainly attributed to the fuel spray impingement and the subsequent combustion dynamics. While the previous studies can limitedly employ the thermodynamic impact from the ambient flow, the present analysis incorporates mechanical stress acting on the structure owing to the direct spray impingement. This impact becomes more significant when the ignition assistance device is installed with the short-impacting distance configuration. To address this aspect, the U.S. Army Spray-Induced Wall Stress (SIWS) model was proposed in the prior study by the authors. In this study, a trustworthy workflow is proposed to verify the model’s predictive accuracy in a single spray-jet-wall impingement configuration and conduct an engineering-level system rigidity analysis. To this end, the model was incorporated in the large-eddy simulation (LES) model setup and adequately validated against the experimentally measured momentum flux of a single spray- jet. The subsequent analysis provides the estimation of the mechanical wall stress possibly formed on the ignition-assistance (IA) device structure in the spray impingement and high- temperature combustion environment.