THEORETICAL PREDICTION OF THE FLOW IN THE WAKE OF A HELICOPTER ROTOR. PART 1. DEVELOPMENT OF THEORY AND RESULTS OF COMPUTATIONS
Abstract
A study was performed with the objective of predicting the time- varying flow in the vicinity of a helicopter in hovering or forward flight. An analytical model was formulated which represents the rotor, its wake and the fuselage of the aircraft. The model for the wake has been simplified in a manner consistent with flow visualization studies by representing the wake as tip vortices emanating from each blade. The wake vortices are assumed to be free to convect under the influence of the blades, the fuselage and the wake itself. The fuselage has been replaced by a surface distribution of sources, the strength per unit area being determined by assuming that the fuselage is subjected to a uniform, steady free stream. A digital computer program was written which implements the model developed. Flow calculations were performed which agree well with measurements of the time average of the flow in the wake of a two-bladed rotor. Extensive calculations were then carried out which define the flow in the vicinity of a UH-1B helicopter for a range of flight conditions from hover to high-speed cruise. Upon analysis of the results, it was concluded that the model developed provides a valid representation of the unsteady flow in the vicinity of a helicopter. It was pointed out that the formulation is somewhat restrictive, in that the flow in the rotor plane and immediately adjacent to the fuselage cannot be accurately predicted. However, the suitable refinements incorporated, these regions could be investigated as well.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1965
- Accession Number
- AD0629782
Entities
People
- Peter Crimi
Organizations
- Calspan