Use of a Navier‐Stokes Code in Understanding Tiltrotor Flowfields in Hover

Three‐dimensional Navier‐Stokes flow calculations applied to a tiltrotor in hover for a no wind condition are examined. The results of the computations focus on the quantification of the fountain flow region above the wing and fuselage center section (all cnmponents of velocity), radial and azimuthal variation of rotor loads. This paper presents 3‐D Navier‐Stokes computations of the fountain flowfield using, (i) a two rotor configuration, (ii) a single rotor configuration with a wing, image plane, and ground plane, and (iii) a completely isolated rotor. The image and ground plane is modeled as a viscous wall. The three‐dimensional code uses time‐averaged momentum source terms in the momentum equations and solves the steady, incompressible, laminar Navier‐Stokes equations, in a non‐body‐fitted three‐dimensional Cartesian coordinate system. This approach makes the code an ideal design tool for complex problems. The results compare how well a semi‐span model with a single rotor and image plane predicts the result of the full span configuration with dual rotors. The 3‐D Navier‐Stokes computations are compared with previous test data.