To investigate influence mechanism of the second viscosity on internal flow of a normal shock wave, one-dimensional Navier-Stokes equations are numerically solved. It indicates that the second viscosity has a smoothing effect on density, heat flow and energy distribution in the shock wave, which results in a decrease of peak value of heat and entropy flows, and an increase of shock thickness. Due to the production of normal viscous dissipation, some lost mechanical energy is converted into internal energy. As considering the second viscosity, density distribution and shock thickness are greatly improved. They are in good agreement with experimental data. In addition, Knudsen number is obtained 0.12≤Kn≤0.4 within Mach number range from 1.2 to 10. It indicates that Navier-Stokes equations with the second viscosity simulate normal shock structure more accurately.

With kinetic and continuum theories of bulk viscosity coefficient, bulk-viscosity effect on two-dimensional toroidal shock-wave focus (Mach number Ma=2.0) is studied numerically. It shows that bulk-viscosity effect on toroidal shock-wave focusing is not negligible for perfect gases. Due to bulk viscous effect in compressible flows, pressure, temperature and density at the central focus perform 20% reduction, 10% increase and 30% reduction, respectively. Compared with rotational mode, shock wave focusing present obvious bulk-viscosity effect in vibrational mode, since bulk viscous stress has same order of magnitude with thermodynamic pressure.

According to advection upstream splitting method,a flux splitting method called K-CUSP is proposed.The greatest difference between K-CUSP and two traditional CUSP schemes,namely H-CUSP and E-CUSP,is splitting of total energy:All kinematic quantities and thermodynamic quantities should be separately split into convective term and pressure term by K-CUSP scheme.Numerical tests indicate that:① K-CUSP scheme inherits the simplicity and robustness of FVS scheme.It is less prone to pressure overshoot after shock and no oscillations in expansion area,which is better than AUSM and WPS schemes.② K-CUSP scheme also inherits resolution of FDS scheme.Shock resolution is almost the same with H-CUSP and E-CUSP schemes.Contact discontinuity resolution is better than FVS schemes,a little worse than Roe,AUSM and WPS schemes.However,velocity of contact discontinuity in AUSM and WPS schemes exist large oscillation,while our scheme does not.

Two phase detonations of aluminum dust are simulated in a multi-fluid model to study particle energy calculation methods. In previous studies heat capacities of solid particles are constants, while realistic heat capacities change with temperature. In this simulation, effects of realistic heat capacities are studied. Numerical results show that detonation parameters are influenced significantly. The results with realistic capacities are close to experiments, while the results with fixed capacities overestimate pressure and detonation velocity. In detonation initiation, run-up distance is mainly decide by ignition energy, while realistic effect makes the distance shorter than that in the fixed heat capacity case.

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.

Three-dimensional CFD technology is applied in a RADICL model by solving laminar Navier-Stokes equations and transportation equations to study iodine molecule dissociation rate,iodine atom pumping rate,singlet oxygen yield rate and small signal gain at different flow rate ratio of primary and secondary flow.It is found that an appropriate flow rate ratio plays an important role in spatial distribution of the small signal gain.Rich or poor oxygen conditions go against with a proper gain.

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.

Three-dimensional CFD technology is applied in an RADICL model by solving laminar Navier-Stokes equations and transportation equations. Mixing and reaction of flows, gas-dynamics fields and gains are studied at different jet intensity. It is found that the penetration depth plays an important role for special distribution of small signal gain macroscopically. Strong impinges between jets and unsteady structures are induced by over-penetration in mixing flow field.

One-dimensional overdriven detonation initiation is investigated numerically within a finite rate detailed chemical reaction model. Numerical results exhibit that due to upstream inflow at high temperature, pressure and velocity, a leading shock followed by induction and heat-release zones appears. Because of inflow disturbances, the interface between induction and heat-release zones becomes unstable and overdriven detonation waves are generated. With simulation of unstable interfaces with different gas species, temperatures, inflow pressures and velocities, overdriven detonation initiation process is analyzed and illustrated.

Numerical simulation of spherically imploding detonation waves in hydrogen-oxygen is carried out in an elementary chemical reaction model.Compared with numerical results of imploding shock waves in nitrogen,the discrepancies of gas dynamic characteristics between shock and detonation waves are investigated during implosion.The effect of chemical reactions,combustion and dissociation on detonation waves is revealed.As the wave fronts converge toward the center of symmetry,the front pressures at different radii are almost the same in the two cases.However the front temperatures are different.The temperature increases more rapidly in nitrogen than in hydrogen-oxygen mixture.Higher temperature is reached near the focal point in nitrogen due to its higher dissociation temperature.The energy released at the wave front is negligible in predicting pressure,while it needs to be considered in predicting temperature.

In this paper, an implicit and upwind incremental Block-Line-Gauss-Seidel Method is developed for solving compressible Navier Stokes equations in the Body-Fitted coordinate system. The computational solutions of the internal compressible turbulence flow have been obtained by the method with a two-layer eddy viscosity model employing a Baldwin-Lomax algebraic turbulece model. Numerical experiments show that the computational procedure is of good stability and convergence. Numerical results of the Poissuil flow and Couette flow are good agreement with its analytic solution and computational results of flows in S-Shaped channel with different wall curvature are satisfactorily.