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Abstract:
An analysis has been developed to predict transient aeroelastic response of gimballed tiltrotors during shipboard engage/disengage operations. The blades are modeled as slender elastic beams attached to a gimballed rotor hub undergoing flap and lag bending, elastic twist, and axial deflection. The gimbal restraint is stimulated using a conditional rotational spring. The rotor equations of motion are formulated using Hamilton's principle and spatially discretized using the finite clement method. The discretized equations of motion are integrated in time for a specified rotor speed profile. Blade element theory is used to calculate quasi-steady loads in linear and nonlinear regimes. Studies for a 1/5th-slze aeroelastically scaled tiltrotor are conducted to validate the analysis and investigate transient response and loads. Good correlation existed between the experimental data and the prediction of blade flap and lag moments in a hover condition. Blade bending moment and hub moment predictions indicated that gimbal restraint impacts could induce high transient loads on tee rotor blades and hub. A new method for simulating ship airwake flow fields is presented. Ship airwake flow fields are inherently unsteady and very difficult to predict with numerical tools. The method presented in this paper is called tee Nonlinear Disturbance Equations (NLDE) and is fourth order accurate in both space and time. ...
| Limitations: |
 APPROVED FOR PUBLIC RELEASE |
| Description: |
Final rept. 1 Apr 1997-30 Sep 1998 |
| Pages: |
28 |
| Report Date: |
15 FEB 2001 |
| Contract Number: |
N00014-97-1-0530 |
| Report Number: |
A584783 |
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