Rotor Induced-Inflow-Ratio Measurements and CAMRAD (Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics) Calculations
Abstract
Comparison of the inflow calculations between an analytical rotor- wake method and rotor-inflow measurements using a laser velocimeter has been presented. The inflow measurements were made above a four-bladed rotor system using rectangular planform blades operating in forward flight at a thrust coefficient of 0.0064 and at rotor advance ratios of 0.15, 0.23, and 0.30. The experimental measurements showed that as the advance ratio u increased, the induced-upflow region moved progressively from the forward 20 percent of the rotor disc at u=0.15 to a point where it covered most of the forward half of the rotor disc at u=0.30. The induced-inflow characteristics at all advance ratios were unsymmetrical about the longitudinal centerline. The comparisons with the analytical method CAMRAD (Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics) show that the region of induced upflow over the rotor disc was effectively modeled only at u=0.15. The importance of the choice of rotor-trim option is examined, and results of two trim selections are detailed. Keywords: Helicopter wake; Helicopter inflow; CAMRAD; Blade-tip vortices; Laser velocimeter.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1990
- Accession Number
- ADA219296
Entities
People
- Danny R. Hoad
Organizations
- Langley Research Center