This research aims to study the trajectory of an object inside a serpentine duct of a gas turbine engine using computational fluid dynamics. The coupled implicit solver with 6-degree of freedom (6-DOF) and chimera mesh (Overset mesh) is used to track the object’s trajectory. Various object orientation and aircraft angle of attack (AoA) at a speed of Mach 0.3 is studied. This provides an understanding of the bird’s movement inside the duct that might cause damage to the engine components during takeoff and landing. It was observed that the combination of AoA and object orientation decide the length of the trajectory before impact. The object is found to travel the farther when the AoA is at -20o with object oriented at 0o and 45o.The object tends pitch and yield to the flow irrespective of its initial orientation and hence the aircraft angle of attack is a more predominant factor. The effect of pressure recovery due to AoA and object orientation is also presented. The recovery is found to be at its best for AoA of 0o irrespective of object orientation. This approach could be utilised for designing an intake duct that can limit the damage to engine components due to bird ingestion and simultaneously maintain good pressure recovery.

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Increasing interest in improving the efficiency of the turbo-fan engine results in a large low pressure compressor and small high pressure core. The consequence of the increment in radial offset is that the importance of the transition duct is growing. Shortening this transition duct length can effectively reduce the weight of the engine. However, it conflicts with the need to avoid flow separation within the duct. Further, radial struts are also present in duct passage for support. In present work, numerical investigations were performed on an annular S-duct with bypass suitable for connecting the compressor spools of a small turbofan engine. The length of S-duct was reduced by 6%, 12%, and 18% from the original S-duct length. The wall contour was selected based on the optimum value of the total pressure loss coefficient for the particular length. It was found that the loss coefficient is a weak function of duct length as long as the flow is attached. Further, the effect of the radial strut on the selected contour for two different lengths was studied. The increase in loss for 100% and 88% length in the presence of all struts was 17% and 27%.