Analysis of installation aerodynamics and comparison of optimised configuration of an ultra-high bypass ratio turbofan nacelle

A Review of Novel and Non-Conventional Propulsion Integrations for Next-Generation Aircraft

“…A more advanced analysis is proposed in [73], in which CFD simulations with steady RANS solvers are used to thoroughly investigate the effects of UHBR turbofan installation. Starting from the results previously obtained by the same authors in [74], numerical simulations are used to assess and characterise the complex aerodynamic flow around the nacelle of a UHBR turbofan (with a value of BPR > 14) mounted underwing to the longrange NASA common research model [75] and to evaluate the impact of engine positioning on the mutual interaction with the wing in cruise condition (where the Mach number is 0.85 and the aircraft altitude is 10,667 m).…”

CFD-Based Analysis of Installed Fuel Consumption and Aerodynamics of Transonic Transport Aircraft during Cruise Flight

“…The scarfed and drooped non axisymmetric nacelle had a nominal mass flow capture ratio around 0.7 and a cowl length to highlight diameter of 1.6. The underwing installation position has a major effect on the interference drag and the thrust losses [16]. The nacelle trailing edge was set to have a wing chordnormalised offset from the wing leading edge of −0.05 in the horizontal direction and −0.11 in the vertical direction (with the minus sign indicating upstream and down from the wing leading edge, respectively) to mimic a close-coupled installation.…”

“…Grid resolution for the Wing Body Nacelle Pylon (WBNP) configuration of the NASA CRM was first specified in accordance with workshop guidelines [25,26] and assessed for the current geometry with a powered-on nacelle. A detailed description of the numerical model validation is reported in [16,27]. Here, a summary of the mesh sensitivity analysis at the ADP is reported for completeness in Table 1.…”

“…In steady-state CFD simulations, flight conditions are supposed to be constant, which would require a zero net force on the right-hand side for dynamic translational equilibrium to be achieved; otherwise, the calculation of the propulsive forces is biased by the presence of a thrust excess or defect, which in practice results in a deviation from the prescribed boundary conditions. In [29], a method of obtaining a dynamic equilibrium in a steady CFD simulation was presented, and was employed in [16] to compare the present reference nacelle with an optimised version. Here, the procedure is extended to the integration of the aircraft mission over the cruise segment for fuel consumption evaluation.…”

“…For large UHBPR turbofans, however, additional interference drag coming from engine/wing interaction is present and is typically not explicitly included. This is a relevant component, amounting to 10-15% of airframe drag, with the nacelle drag alone being around half that of the wings [16].…”