Effect Of Turbulence Intensity On Vortex Formation Threshold In A Jet Engine Test Cell

Vortical structures can develop in the intakes of aircraft engines during operation in the proximity of solid surfaces. Take-off and testing in a ground facility are clear examples of such scenarios. When such a vortex is formed and ingested into the engine, potentially catastrophic damage can occur. The vortex can cause the compressor to stall, resulting in severe damage to the engine. Procedures have been put in place to prevent such damage from occurring on the runway. However to prevent such vortices from forming, especially in the test cells, it is necessary to be able to predict the onset of the vortex or at least to understand the factors affecting the formation of such vortices. This paper extends the scope of previous investigations by investigating the effects that increasing upstream turbulence intensity has on the vortex formation threshold. The results show that an increase in upstream turbulence intensity increases the range of conditions over which a vortex forms. All three regimes show signs of shifting the threshold of vortex formation to lower ratio of inlet velocity over upstream average velocity (Vi/Vo) for a given ratio of inlet height over inlet diameter (H/Di).