Numerical simulation of inlet vortex near the inlet air duct of an aircraft engine in headwind condition

Jet engines working near the ground, with low speed and high thrust can experience flow separation between ground and inlet which would lead to vortices, called Ground Vortex that have harmful effects on engine performance and can disrupt integrity of inlet flow. Deep understanding of the physics of this phenomenon could omit the injuries of foreign objects damages, engine surge, compressor stall, and fan vibration. In this study, the ground vortex formation near the inlet air duct of an aircraft engine is investigated using computational fluid dynamics. Simulations are performed for a 1:30 scale. The fluid flow is assumed to be compressible, three-dimensional and steady.The k-ω SST model is employed for incorporating turbulent characteristics. After mesh study, the boundary of Vortex or No-Vortex for results of this study compared with a theoretical and an empirical correlation by Murphy which showed good agreement. Moreover, despite free stream existence, decreasing non-dimensional velocity ratio causes the movement of vortex core and by approaching to the critical non-dimensional velocity ratio; the ground vortex would gradually disappear. For U^*= 33,44,66,132 ground vortex is formed, but for U^*=26.4 ground vortex disappears. The computational method has subsequently been applied to configurations that are difficult to test experimentally including headwind flows. According to this study, the formation of the vortical flow field permanently affects the total pressure distortion on the engine fan face. In this paper, DC60 is calculated under headwind condition. These coefficients are 0.39, 0.391, 0.447 and 0.3957 at U^*=33,44,66,132 respectively.