Unstructured Dynamic Mesh Under The Unsteady Aerodynamic Power Calculations And Buzz

In the dissertation, the unstructured dynamic mesh technique is investigated. Full implicit dual-time temporal derivatives and cell-center finite volume method spatial derivatives are adopted to simulate unsteady flow fields of 2-D airfoil, 3-D wing and wing-body configuration. Transonic single-freedom flutter of flap-buzz is studied with the unsteady flow field solver of the unstructured dynamic grid technique.An effective and well robust unstructured dynamic grid method is developed to solve the unsteady aerodynamic problem. On the basis of classic linear spring analogy, several modified methods for the linear spring stiffness coefficient is introduced. These methods take into account segments, facets and bodies of the cell, In the case of not much penalty in computing, the adaptation of the unstructured dynamic mesh is greater enhanced.In the paper, 2-D and 3-D unsteady flow fields are computed. The results of solving the unsteady flow fields that are in agreement with the experiments show that the unsteady flow field solver is correct and the unstructured dynamic mesh technique of the dissertation is well robust. So the unsteady flow field solver can be applied to various kinds of problems with moving and deforming bodies.In the thesis, an energy analysis method is applied to study the buzz. Through solving the unsteady flow fields of an airfoil-flap, the mechanism of buzz is intensively studied. On the basis of the unsteady flow fields of an airfoil-flap with an upper-wing spoiler, the mechanism of the upper-wing spoiler suppressing the buzz is researched. In additions, the comparisons of the unsteady flow fields of an airfoil-flap with and without a separator show that the separator reduce the speed of the buzz.