A Multi-Diagnostic Approach to Testing V/STOL Craft.

Susan M. Foley, Robert B. Funk, Phillip .A. Fawcett, Narayanan M. Komerath.

AIAA Paper 92-4008, Presented at the AIAA Ground Test Conference, Nashville, TN, July 1992.

Abstract: The interactive aerodynamics of new V/STOL designs require a new approach to ground testing, where multiple properties are measured both on and away from surfaces during continuous changes in test parameters. Using a set of experiments of increasing complexity, a new capability is demonstrated for capturing surface pressure, velocity fields and vortex flow features over a range of test parameters. Two-dimensional velocity fields are captured over a full-scale UH-1 helicopter stabilator, a wing/canard configuration, and under the hub of a rotor in forward flight. Surface pressures and vortex flow features are captured over a wing/rotor configuration. Short tunnel run-times are achieved at the expense of large computational post-processing resources. It is shown that such experiments can be performed while the configuration geometry and flow conditions are continuously varied through a wide range of parameters. This experiment led to the discovery and capture of massive flow separation caused by vortex interaction on wings at moderate angles of attack, large-scale deflection of vortex wake trajectories by wake/wing interaction, unsteady flows over wings generated by canard interaction, and quasi-steady separation phenomena caused by the difference in time scales between separation and reattachment.

Complete paper in pdf format