A hybrid lattice Boltzmann flux solver for integrated hypersonic fluid-thermal-structural analysis

In this paper,a hybrid Lattice Boltzmann Flux Solver(LBFS)with an improved switch function is proposed for simulation of integrated hypersonic fluid-thermal-structural problems.In the solver,the macroscopic Navier–Stokes equations and structural heat transfer equation are discretized by the finite volume method,and the numerical fluxes at the cell interface are reconstructed by the local solution of the Boltzmann equation.To compute the numerical fluxes,two equilibrium distribution functions are introduced.One is the D1Q4 discrete velocity model for calculating the inviscid flux across the cell interface of Navier–Stokes equations,and the other is the D2Q4 model for evaluating the flux of structural energy equation.In this work,a new dual thermal resistance model is proposed to calculate the thermal properties at the fluid–solid interface.The accuracy and stability of the present hybrid solver are validated by simulating several numerical examples,including the fluid-thermal-structural problem of cylindrical leading edge.Numerical results show that the present solver can accurately predict the thermal properties of hypersonic fluid-thermalstructural problems and has the great potential for solving fluid-thermal-structural problems of long-endurance high-speed vehicles.

Pressure-induced instability and its coupled aeroelasticity of inflated pillow

A floating air weapon system(such as airborne floating mines)plays an important role in modern air defense operations.This paper focuses on aeroelastic characteristics of airborne floating mine named inflated pillow.Firstly,the dynamic deployable process of the pillow and characteristics of the local instability of the edge are studied,and the evolution mechanism of wrinkles and kinks is analyzed.Secondly,in the cruising stage,the fluid-structural-thermal coupling analysis is performed on the pillow,and the aeroelastic characteristics are studied.Thirdly,the shapepreserving effect of the inflated pillow during the“negative pressure”slow landing stage is evaluated.It is found that when the wind velocity is higher,the pillow has a collapsed instability(surface extrusion and contact),and when the wind velocity is lower,snap-through instability occurs.Finally,for the collapsed instability,a carbon fiber skeleton is added to discrete the large global collapsed fold into small local folds,thus achieving shape-preserving effect of pillow.For snapthrough instability,the critical internal pressure and different shape evolution under different wind velocity are evaluated.Through the analysis of the mechanical mechanism and control of the structural morphological evolution,it provides theoretical guidance for the application of the curved shell structure in floating air weapon system.