Based on HLLEW (Harten-Lax-Van Leer-Einfeldt-Wada) scheme, low speed preconditioning technology is introduced to develop a three-dimensional Navier-Stokes solver for flows at all Mach numbers. Low speed preconditioning techniques is introduced to reconstruct dissipative term in HLLEW scheme and preconditioning HLLEW scheme is proposed. Implicit time-marching method is constructed based on preconditioning Jacobian Matrix. Results of NACA 4412 incompressible flow and RAE 2822 transonic flow with preconditioning HLLEW scheme are compared with results by original method and experimental data. It shows that preconditioning HLLEW method improves accuracy and convergence rate for low speed flow. It can be applied for flows at all Mach numbers.

A steady RANS approach is adopted to investigate ground effect of high speed trains. Variation of aerodynamic forces due to ground effect is studied. Comparisons of aerodynamic forces on high speed train at different yaw angles and with different ground boundary conditions are performed. It reveals that aerodynamic forces at a yaw angle of 0° are severely affected by the ground effect. As the yaw angle increases, however, influence on aerodynamic forces due to ground effect gets weaker. Influence of height between bottom of the train and the ground is carefully studied. It shows that lift reversal phenomenon exists at different heights and pressure wave on bottom surface of the train takes a linear relation with heights.

Menter SST based detached eddy simulations (DES) is performed for transonic flow over an open cavity to study unsteady flow and acoustic fields.Sound pressure level (SPL) spectra and overall sound pressure level(OASPL) on surface of the cavity floor and the cavity back wall are computed.It shows that the second mode is dominant with the largest magnitude in SPL.

Droplets in liquid-liquid two-phese flow are simulated by a perturbation finite volume (PFV) method and Level Set technique. Numerical results show that the PFV scheme has advantages in fewer nodes, high accuracy and efficiency, h facilitates programming. PFV scheme successfully simulates liquid-liquid two-phase flows.

A weakly-compressible two-dimensional axisymmetric isentropic vortex model is employed to stimulate interactions between single vortex and single optical wavefront. For near-field aero-optics at low beam energies geometrical optics is adopted. Optical-path-difference of propagated distorted wavefront is computed. It is confirmed that transform of beam wavefront is accelerated as beam passing through the vortex with low density. Single vortex defocuses the beam. Computation on COIL indicates that strength of vortex has strong effect on Strehl rate.

The explicit and implicit methods are employed in the numerical simulation of unsteady transonic NACA10012 airfoil flow,and comparison analyses have been made in the respects of computational results,efficiency,and sensitivity to grid quality.

In the previnus paper, the field calculatin for focus deflection system of a cam-era tube with electrostatic deflection yokes were deseribed. Now that the potential field is known we can treat the trajectories described by the electrons in this field. The electron trajectory calcula-tion in the focus-deflection system with the electrostatic deflection differs from usual trial solution determined by the discrete methods in the rotationally system field. Because poteotial fuoction of the focus-deflection field determined by the analytic method are analytic fuoctions of the variations r, θ, z, in the tracing process of the electron trajectories the potential and it's deriva-tives at an arbitrary point may be given by the aoalytic fuoctions.The purpose of the paper is to give the method of solving geoeral equation of motion for an electron in mixed field which produces a combined electromagnetic focus field and the electrostatic deflection field.

An electrostatic deflection-type camera tube has the following advantages: The small electron beam spots over the entire the scanned area provide uniform and high resolution picture, normal beam landing performance and deflection linearity are also excellent. The purpose of the paper is to .give the field calculation for focus deflection system of a camera tube with electrostatic deflection yokes.

The paper makes use of computer to simulate the law of variation fractal dimension D. in measurement of actul fractal, under differen conditions by N(ε)∞ε^-D. The meaning of the law and conditions are discussed on reatistic application.

Based on the finite difference method and the statistical theory of thermal electron emission, a set of computing and plotting programs using to computer aided design of electron beam device for electron guns and image tubes has been written in FARTRAN77 running on MV/8000 digital computer, and a good agreement between calculated result and that measured or given in ref has been obtained, This paper presents some numerical methods, such as optimization of Lagrange's interpolation function, determination of the optimum image plane using the statistical radius of the Airy disk, the tracing methods of equipotential lines and ion trajectories and so on. and some examples of the practical application, such as calculation and design for guns and image tubes, and analysis of the ion feedback in image tubes has been given.