Date of Award
Doctor of Philosophy (PhD)
Dynamic wake models have been used in real-time flight simulations for over thirty years. The models have evolved from the earliest, three-degree-of-freedom models (derived from momentum theory) to full finite-state models derived from potential flow theory by a formal Galerkin method. These models are widely used in industry, but still have some drawbacks that need to be remedied. These drawbacks include: 1.) lack of good convergence both on the disk and off the disk (one can use one or the other but not both), 2.) poor results downstream in the limit of shallow skew angles, 3.) poor convergence inside of the rotor wake, 4.) lack of the effects of wake curvature and wake contraction, and 5.) lack of other important nonlinearities. This thesis uses applications of adjoint theorem, a special change of variable and effective introduction of solution blending to overcome these obstacles. The resultant model is well-behaved in all regimes and is applicable to use in realistic problems of flight simulation, even when only a few states are allowed.
Kenneth Jerina, Swami Karunamoorthy, Mark Meacham, Shankar Sastry, Heinz Schaettler