In turbofan engines, the bypass ratio (BPR, the ratio between the fan and core flows) directly influences the fuel burn efficiency of an engine with higher values leading to improved efficiency. The bypass is formed by an inner surface dictated by the outer mold line (OML) of the inner fixed structure (IFS) of the nacelle and the OML of the inner portion of the translating sleeve (XLS). The BPR can be increased by placing the OML of the IDS closer to the engine core. 

The Engine Build-Up (EBU) refers to the set of hydraulic and pneumatic ducts, wiring harnesses and equipment surrounding the engine core. 

To increase the efficiency of the engine, the ducts must be flattened for it to be placed in tighter areas in the EBU while maintaining the same pressure drop standards as the original duct. 

Our final design consisted of an elliptical duct that fits within a boundary condition envelope and matched the original air duct's characteristics. It consisted of a semi-major axis value (A) of 1.75 in and a semi-minor axis value of 0.41 in and gave us most optimal results. 

The final product was 3D printed via polylactic acid (PLA) plastic material. 

To ensure that the newly designed duct is able to capture similar characteristics as the original duct, we ran simulations and tests for both the original and oval ducts.

We analyzed the behavior of the original duct (Fig. 1) and the oval duct (Fig. 2) between Ansys Computation Fluid Dynamics (CFD) simulations and data that was collected from physically testing the ducts with our test setup as shown above.

• This was done to ensure that the expected characteristics of the duct are seen within the real world and vice versa as they both should mimic one another.

Once that is achieved, we can then compare experimental results between the original and oval duct (Fig. 3) with confidence that the data is reliable.

As a result of CFD simulations and physical testing, the oval duct resulted in having the most similar behavior in relation to the original duct.