Helicopter Blade-vortex Interaction Locations: Scale-model Acoustics and Free-wake Analysis Results

Helicopter Blade-vortex Interaction Locations: Scale-model Acoustics and Free-wake Analysis Results
Author: Danny R. Hoad
Publisher:
Total Pages: 112
Release: 1987
Genre:
ISBN:

The results of a model rotor acoustic test in the Langley 4- by 7-Meter Tunnel are used to evaluate a free-wake analytical technique. An acoustic triangulation technique is used to locate the position in the rotor disk where the blade-vortex interaction noise originates. These locations, along with results of the rotor free-wake analysis, are used to define the geometry of the blade-vortex interaction noise phenomena as well as to determine if the free-wake analysis is a capable diagnostic tool. Data from tests of two teetering rotor systems are used in these analyses. Keywords; Helicopter rotor disks; Free wake; Blade-vortex interactions; Acoustic properties.

Acoustic Measurements from a Rotor Blade-vortex Interaction Noise Experiment in the German-Dutch Wind Tunnel (DNW)

Acoustic Measurements from a Rotor Blade-vortex Interaction Noise Experiment in the German-Dutch Wind Tunnel (DNW)
Author: Ruth McVoy Martin
Publisher:
Total Pages: 188
Release: 1988
Genre: Rotors (Helicopters)
ISBN:

Acoustic data are presented from a 40-percent-scale model of the four-bladed BO-105 helicopter main rotor, tested in a large aeroacoustic wind tunnel. Rotor blade-vortex interaction (BVI) noise data in the low-speed flight range were acquired using a traversing in-flow microphone array. The experimental apparatus, testing procedures, calibration results, and experimental objectives are fully described. A large representative set of averaged acoustic signals are presented.

Full-Potential Modeling of Blade-Vortex Interactions

Full-Potential Modeling of Blade-Vortex Interactions
Author: Henry E. Jones
Publisher:
Total Pages: 96
Release: 1997
Genre: Unsteady flow (Aerodynamics)
ISBN:

A study of the full-potential modeling of a blade-vortex interaction was made. A primary goal of this study was to investigate the effectiveness of the various methods of modeling the vortex. The model problem restricts the interaction to that of an infinite wing with an infinite line vortex moving parallel to its leading edge. This problem provides a convenient testing ground for the various methods of modeling the vortex while retaining the essential physics of the full three-dimensional interaction. A full-potential algorithm specifically tailored to solve the blade-vortex interaction (BVI) was developed to solve this problem. The basic algorithm was modified to include the effect of a vortex passing near the airfoil. Four different methods of modeling the vortex were used: (1) the angle-of-attack methods, (2) the lifting-surface method, (3) the branch-cut method, and (4) the split-potential method. A side-by-side comparison of the four models was conducted. these comparisons included comparing generated velocity fields, a subcritical interaction, and a critical interaction. The subcritical and critical interactions are compared with experimentally generate results. The split-potential model was used to make a survey of some of the more critical parameters which affect the BVI.