Accession Number : ADA193183

Title :   Analytical Modeling of Helicopter Static and Dynamic Induced Velocity in GRASP (General Rotorcraft Aeromechanical Stability Program).

Descriptive Note : Technical memo.,

Corporate Author : NATIONAL AERONUATICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER

Personal Author(s) : Kunz, Donald L ; Hodges, Dewey H

PDF Url : ADA193183

Report Date : Nov 1987

Pagination or Media Count : 10

Abstract : This paper describes the methodology used by the General Rotorcraft Aeromechanical Stability Program (GRASP) to model the characteristics of the flow through a helicopter rotor in hovering or axial flight. Since the induced flow plays a significant role in determining the aeroelastic properties of rotorcraft, the computation of the induced flow is an important aspect of the program. Because of the combined finite-element/multibody methodology used as the basis for GRASP, the implementation of induced velocity calculations presented an unusual challenge to the developers. To preserve the modeling flexibility and generality of the code, it was necessary to depart from the traditional methods of computing the induced velocity. This is accomplished by calculating the actuator disc contributions to the rotor loads in a separate element called the air mass element, and then performing the calculations of the aerodynamic forces on individual blade elements within the aeroelastic beam element. Keywords: Rotor flow fields; Rotary wings.

Descriptors :   *AEROELASTICITY, *ROTOR BLADES(ROTARY WINGS), *FLOW FIELDS, *HOVERING, ACTUATORS, AERODYNAMIC FORCES, AIR, BODIES, DISKS, DYNAMICS, FINITE ELEMENT ANALYSIS, FLIGHT, FLOW, HELICOPTER ROTORS, HELICOPTERS, LOADS(FORCES), MASS, MATHEMATICAL MODELS, METHODOLOGY, ROTARY WING AIRCRAFT, ROTARY WINGS, STATICS, VELOCITY, VERTICAL ORIENTATION

Subject Categories : Aerodynamics
      Helicopters

Distribution Statement : APPROVED FOR PUBLIC RELEASE