Parametric Analysis of Variable Nacelle Nozzle Throat Area Using Warped Chevrons

Simulations of the NASA Rotor 67, Stator 67A stage integrated into a bespoke nacelle were performed using ANSYS CFX. The throat area of the nacelle nozzle was varied by use of warped chevrons. 8, 12 and 16 chevron nozzles were simulated to evaluate the impact of the variation in geometry upon the nacelle wake and local forces. The force produced from the nozzle and fan, is compared to the baseline case where the throat area is optimised for cruise conditions. The variation in gross thrust between cases is also analysed. The turbulence kinetic energy and total temperature variation through the wake is compared. A reduction in peak wake mixing massflow-averaged turbulent kinetic energy of 11.9% was attained. Surface force measurements of the rotor, stator and nozzle duct indicate a rising thrust loss with increasing nozzle throat area. However, measurement of the nozzle exit velocities and massflow rates enable subsequent estimation of the gross thrust which indicate a rise of 2.4% relative to the baseline is achievable.