Three-dimensional Navier-Stokes equations in high temperature real gas model and perfect gas model are solved for hypersonic entry process. Good agreement is achieved between numerical results, reference values and flight data of Viking, which validates physical-chemical models and numerical methods. Aerodynamic prediction of Mars Pathfinder proves that results of real gas model are close to LAURA. Perfect gas model with effective specific heat ratio is capable of computing lift and drag coefficients. At 2° angle of attack, MPF exhibits static instability along trajectory, which perfect gas model failed to catch on. It is considered that main reasons of static instability are sonic line shifting around shoulder in windward, subsonic area varying and subsonic bubble occurring in leeward. They result in different pressure change in shock layer and in transportation process from expansion zone to upstream.

Test particle Monte Carlo (TPMC) method is presented. Return flux on four geometric surfaces due to ambient scatter of outgassing molecules is simulated. Return flux ratio (RFR) obtained for flow past a sphere is in good agreement with DSMC results. RFR on outgassing and freestream conditions for flows past three geometric bodies, including a circle flat plate, a convex and concave hemisphere, is investigated. RFR for flows past a circle flat plate and a concave hemisphere is much greater than that for flows past a convex hemisphere. Outgassing molecules collide on outgassing surfaces directly forming direct flux contamination for flows past concave surfaces, which is much greater than RFR. Thus, using convex outgassing surfaces in spacecraft design can decrease return flux contamination effectively.

Three-dimensional Navier-Stokes equations in real gas models are solved with a parallel code to analyze aerodynamic characteristics of Mars Science Laboratory in hypersonic entry in Martian atmosphere. Good agreement between numerical results and flight data of Viking validates physical-chemical models and numerical methods. It shows that impacted by real gas effect,shock layer thickness is reduced; drag coefficient rises,lift coefficient is almost unchanged. Difference of trim angle between real gas and perfect gas is about 2.2°; As keeping altitude,greater Mach number results in greater drag and pitching moment coefficient. Difference of trim angle varies from 1.6° to 2.6°. Increasing Mach number enhances real gas effect. As keeping Mach number,increasing altitude weakens chemical reactions behind the shock,but it has weak influence on aerodynamic coefficient.

Three-dimensional algorithms solving laminar Navier-Stokes equations coupled with chemical reaction and transportation equations are developed.Detailed flow field and distribution of yield,dissociation and pumping rates and small signal gain are obtained which cannot easily be got in experiments.The reason that experimental results are not as good as that in theories is analyzed.Furthermore,a better way to operate the system is suggested.It is shown that the mixing and chemical process in a nozzle of limited length is not complete due to the high speed in supersonic mixing zone and low mixing efficiency.Higher iodine concentration for speeding up chemical reaction causes insufficient of singlet oxygen,so as an unreasonable gain.A primary flow without buffer gas is claimed necessary and essential to reduce flow velocity and assure mixing process and chemical reaction accomplished before arriving the cavity.With an appropriate flow rate ratio,a small signal gain can reach 1.3% cm^-1.

A integrated method solving fluid and solid simultaneously is used to deal with complicated flow and solid temperature field coupling problems.A simple but effective approach is proposed to overcome stiffness in two-equation turbulence models.Related theory is provided.With this method,efficiency in multigrids and LUSGS implicit temporal stepping method is increased remarkably.

A Cartesian mesh algorithm is developed for numerical solution of supersonic flows with arbitrarily complex and moving solid boundaries.The method defines and tracks fluid-solid interfaces with a level set function. Fluid-solid boundary condition is dealed with a ghost cell technique and is calculated separately in normal and tangential directions.The method proposed is simple,robust,and can work with high-order finite difference schemes.To validate the scheme,one-and two-dimensional numerical examples involving static or moving boundaries are included.

Shock/turbulent boundary layer interaction(STBLI) in a M_∞=3.0 supersonic compression ramp flow are studied using a spatial large eddy simulation method. At upstream, flat plate transition and developed turbulent boundary layer are simulated in which Shock/turbulent boundary layer interaction shows at the ramp. Analysis on mechanism of turbulent boundary layer/shock interaction indicates that linear unstable disturbance leads transition rapidly. In the process of STBLI, average separation range of the ramp is smaller than that in the laminar flow. However, extent of the separation shows different characteristics in different span-wise positions due to high velocity strip and low velocity strip.

A model of the beam centroid motion in a linear induction accelerator(LIA) was developed. It calculates the track of the beam centroid under the condition of cell magnet misalignment. The 3D magnetic field distribution is calculated with a coordinate transform. The track of the beam centroid is given by a coupled solution of the beam centroid and envelope equations. Quantitative relation between the transverse displacement of beam centroid and the misalignment of magnets is useful in the installation of magnets and the adjustment of steering coils.

A reduced chemical kinetics model for typical combustion reaction systems is derived by means of the Computational Singular Perturbation (CSP) method.The combustion reaction governing equations are employed to construct ideal basis vectors,with them the coupling between the fast mode and the slow mode is decoupled properly.Several significant parameters are defined,such as the participation index,the radical pointer,and the importance index.Then the state equations of the fast modes and the reduced chemical kinetics model are obtained.A typical mixed combustion reaction system of CO-CH₄-Air is calculated,and the results show that the reduced combustion reaction system obtained by CSP method approximates the original system well.

A calculation model of accelerator beam envelope has been developed. It can predict beam envelope in linear induction accelerator from the injector to the final focus region. Its code can easily calculate the effect of various electric and magnetic element parameters on the beam. As calculating examples, the envelopes of 3 kA-beam current under the condition of 40 m long magnetic profiles are given.

The temporal spatial discrete Fourier transformation is employed to analyze the dissipation and dispersion errors of the numerical algorithm used here. Based on directly solving the two dimensional time dependent compressible Navier Stokes equations, the spatial evolution of primary vortex generated in forced compressible plane free shear layers is simulated numerically by using a new fifth order upwind compact difference scheme. The phenomena, including the primary vortex saturating, the first pairing, and the second pairing, are shown with the passively conserved scalar method and so on. The initial value effect related to subharmonic disturbances in incoming flows is studied. The results show that the spatial evolution type of large scale compressible vortices is associated with the disturbance modes.

The linear instabilities in compressible shear layers are investigated by solving the two and three dimensional time dependent compressible Navier Stokes equations.A high accuracy upwind/symmetric compact difference hybrid algorithm is used.A pseudo random number generation technique is employed to simulate the white noise disturbance.Based on numerically solving the three-dimensional viscous disturbance equations by using a new method named as SCD-MNR,some results related to linear stability analysis are first given.Both two-and three-dimensional waves are considered.Compressibility effect can increase the most unstable wave angles besides that damps the growth rates of unstable waves.Numerical results confirm the prediction of linear theory that during the initial evolution of the compressible shear layer unstable waves are linear,and that in this course the wave number and angle of the most unstable disturbance are selective.The algorithm used here appears to be effective.It is a reasonable means for the study on compressible shear layers that linear theory combines with numerical simulation.

Based on the Fourier analysis method, a fully-discretized dispersion relation is derived for a family of high accuracy upwind compact difference schemes by considering one dimensional linear convetion equation temporally discretized by the explicit multi-step Runge-Kutta algorithm. The effects of CFL numbers on the characteristics of these schemes, including dissipation and dispersion errors, phase velocity and group velocity, are analyzed. The two-dimensional anisotropy problem is discussed. Moreover, an eigenvalue analysis is performed. Two numerical examples are used to show the high accuracy and resolution of these schemes.

The stability of temporally evolving compressible plane mixing layers is investigated numerically by solving the three dimensional compressible linear disturbance equations.A high order finite difference method is used.The effects of key parameters such as convective Mach number and Reynolds number on the stability characteristics of compressible mixing layers are analyzed.The comparsions between two and three dimensional,viscous and inviscid disturbances are presented.Part of the numerical results obtained here are in agreement with those of relative literature.

Based on a static non-overlapped domain decomposition method,the problem is studied about the parallel implementation of a Harten-Yee implicit TVD difference algorithm on a MIMD multi-computers parallel system.The convergence and stability of the parallel processing techniques used here are manifested well through numerical simulation of the steady "super-supersonic" jet flow fields,and the parallel parameters obtained are promising.