Based on NACA airfoils,a new type of tandem buoyancy-lifting airships with both higher utility and economy efficiency was developed.With numerical simulations aerodynamic and configuration design for buoyancy-lifting airships was investigated and buoyancy-lifting characteristics were evaluated and analyzed synthetically.It shows that a tandem buoyancy-lifting airship has considerable volume efficiency.Its lift-drag ratio is increased 50% than single wing resulted from block of airflow by posterior flying-wing and speedup of airflow in overlay field.Its deadweight can be decreased and payload is increased as velocity is higher than 30 m·s^-1.At the same time,chord wise size of tandem airship is comparatively small so that surface tension of skin material can be reduced availably.It provides a wider scope for skin flexible material selection of high altitude aircrafts.

It focuses on an approach to generating 2D unstructured grids for the solution of Euler equations.Unlike the generation of unstructured grids before with background grids,the background information needed in Avancing Front Method is obtained directly with the distance to the airfoil surface.In solving the Euler equations,the cell centered finite volume method is used for space discretization,and four step Runge Kutta method is adopted for time marching.Two kinds of boundary condition are presented and three kinds of boundary conditions are applied and analyzed.The calculated results are given and discussed.

The aeroelastic behaviour of wings with different types of separated vortex at high incidences is investigated.The unsteady aerodynamic equations and the equations of motion are solved simultaneously in the time domain.The separated vortices shed-ding from the leading-edge and/or side-edge of wings are taken into account by an improved Nonlinear Vortex-Lattice Method.The equations of motion are integrated by Runge-Kutta Method.Wings with different planforms at different basic incidences are consid-ered.It is found that (1) the separated vortex shedding from the leading-or side-edges results in the critical flutter speed of the wing lower,and the higher the basic incidence,the lower the critical flutter speed.(2) the smaller the sweep of wing,the smaller the in-fluence of separated vortex on the aeroelastic characteristics.(3) at certain flight speeds and basic incidences,stable limit cycles ap-pear,and the amplitudes of limit cycles even keep constant when the initial distu rbances of response vary.