Accession Number:

ADA099532

Title:

Rotor Dynamic Inflow Derivatives and Time Constants from Various Inflow Models.

Descriptive Note:

Doctoral thesis,

Corporate Author:

ARMY TROOP SUPPORT AND AVIATION MATERIEL READINESS COMMAND ST LOUIS MO

Personal Author(s):

• Pitt,Dale M.

Report Date:

1980-12-01

Pagination or Media Count:

235.0

Abstract:

A linear, unsteady theory is developed that related transient rotor loads thrust, roll moment, and pitch moment to the overall transient response of the rotor induced-inflow field. The relationships are derived from an unsteady, actuator-disc theory and some are obtained in closed form. The theory is used to determine the effects of lift distribution and shaft angle-of-attack on the said relationships. Also, two different assumptions are used in the unsteady calculations, finally, a prescribed wake analysis is used to validate the actuator-disc theory for normal flight conditions. The results reveal both the strengths and weaknesses of previous formulations and reveal areas in which further study is needed. The most significant result is an analytic, three-degree-of-freedom inflow model that is shown to be accurate for use in the dynamic analysis of rotors. Author

Descriptors:

• *MATHEMATICAL MODELS
• *TIME DEPENDENCE
• *CONSTANTS
• *GAS FLOW
• *DERIVATIVES(MATHEMATICS)
• *AXIAL FLOW FANS
• LINEAR SYSTEMS
• STEADY STATE
• TRANSIENTS
• PITCH(MOTION)
• THEORY
• ANGLE OF ATTACK
• HELICOPTER ROTORS
• RESPONSE
• SHAFTS(MACHINE ELEMENTS)
• DISKS

Subject Categories:

• Helicopters
• Numerical Mathematics
• Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE