A Basic Study of the VTOL Ground Effect Problem for Planar Flow

Abstract

The force interaction between airframe undersurfaces and the ground in the presence of lift jets is an important consideration for VTOL aircraft design. As a first step toward prediction of this phenomenon, a combined theoretical and experimental investigation of planar turbulent jet impingement flowfields has been undertaken. Unvectored jets in close ground effect have been modeled using the incompressible Reynolds equations with a one-equation turbulence model. Distributions of the flow properties are computed as functions of undersurface shape, length scales, and jet exit height above ground. Computed flowfield properties are presented and comparisons are made with experimental measurements.