Accession Number : ADA307903
Title : Validation and Application of a Transient Aeroelastic Analysis for Shipboard Engage/Disengage Operations.
Corporate Author : NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
Personal Author(s) : Geyer, William P., Jr. ; Smith, Edward C. ; Keller, Jonathan
PDF Url : ADA307903
Report Date : 15 APR 1996
Pagination or Media Count : 21
Abstract : A previously developed transient aeroelastic rotor response analysis for shipboard engage/disengage sequences is utilized in the present research. The blade has elastic flap and torsion degrees of freedom and the equations of motion are discretized using the finite element method. The discretized equations of motion are integrated for a specified rotor speed run-up or run-down profile. Blade element theory is used to calculate quasi-steady or unsteady aerodynamic loads in linear and nonlinear regimes. Three deterministic wind gust distributions can be used to model the ship air wake environment. This analysis is modified to include a flap stop which restrains upper flap motion and a flap damper which damps flap hinge motion. In addition, an arbitrary gust model is incorporated into the analysis to enable more realistic airwake models. Validation studies are conducted using experimental data collected from a ship/helicopter model placed in a wind tunnel. Theoretical prediction show good agreement with experimental data for windward hub locations on the deck. A study of the effectiveness and feasibility of a flap damper placed at the flap hinge is conducted. It indicates that a flap damper is an effective and feasible method to reduce downward tip deflections for an H-46 if the flap stop angle is raised. One study of the effects of pilot controllable parameters shows that the H-46 throttle advancement rate reduces the maximum downward tip deflections for spatially varying gusts.
Descriptors : *AEROELASTICITY, *HELICOPTERS, *ROTOR BLADES, EQUATIONS OF MOTION, FINITE ELEMENT ANALYSIS, ELASTIC PROPERTIES, DAMPING, DEGREES OF FREEDOM, AERODYNAMIC LOADING, AERODYNAMIC FORCES, GUSTS, WAKE, WIND DIRECTION, SHIPBOARD, FLAPS(CONTROL SURFACES), UNSTEADY FLOW, WIND TUNNELS.
Subject Categories : Aerodynamics
Distribution Statement : APPROVED FOR PUBLIC RELEASE