Abstract

In a continuation of ongoing Naval Postgraduate School efforts to study the performance characteristics of waverider configured vehicles, a computational fluid dynamic (CFD) analysis of the Mach 6 L/DI(sp)(max) optimized Price waverider was conducted. This analysis was performed to determine the theoretical force and moment data over a broad Mach number spectrum, and to compare theoretical and experimental results in the subsonic flight regime. The CFD determination of force and moment data represents a continuation of the ongoing analysis of the Price waverider configuration. Selected viscous and inviscid flow solutions for flight conditions in the range 0.3 " M(infinity) "6. 0, as well as a subsonic (M(infinity) = 03) angle of attack sweep, were conducted using NASA CFD software (OVERFLOW1.8b). Examination of the computed converged flow field solutions suggests that the surface pressure distributions and Mach number contours surrounding the holy are valid. Low speed force and moment coefficient data are shown to exhibit reasonable agreement with the available subsonic wind tunnel data. Additionally, supersonic CFD results show the development of the expected shock layer, exhibiting an attached shock bed at the design Mach number (M(infinity) = 6.0). Evaluation of the computed Mach number effects on lift and drag coefficients at subsonic, transonic and supersonic Mach numbers suggests that the Price waverider may exhibit some flight instabilities across the flight Mach number spectrum. http://www.archive.org/details/computationalana00coyn Lieutenant Commander, United States Navy Approved for public release; distribution is unlimited.

Abstract

Until recently, computer simulations of helicopter rotor dynamics have employed equations of motion that have been linearized or simplified. These modified equations of motion did not allow for the evaluation of nonlinear material properties in the rotor since higher order terms in the dynamics had been modified in the simplification process. With recent advances in both computer simulation hardware and symbolic mathematic manipulation software, the full nonlinear equations of motion may be utilized in helicopter rotor simulations. This dissertation reports on the use of the full nonlinear equations of motion in the analysis of rotor blade lead/lag motion and its effect on rotor hub and rigid body fulselage motion. Nonlinear modeling methods are implemented using Maple symbolic mathematic manipulation software and Matlab and Simulink computer simulation environments. Results are compared to the RAH- 66 Comanche Froude scale wind tunnel article and new methodologies evaluated in the search for a damperless rotor system that is free of ground and air resonance mechanical instabilities http://www.archive.org/details/nonlineardynamic00king Naval Postgraduate School author. Approved for public release; distribution is unlimited.