Applied Mechanics and Materials Vols. 670-671

Abstract: In this paper, the glass was coated by silica film using sol-gel method. The influence of preparation conditions (such as the ratio of water to silica, aging time of the sol and the drying time of the film) on the film cracking was studied. Results show that when the ratio of water to silica is 1, aging time 72 h and drying time 6 h, the obtained film is crack-free. The film consists of nanoparticles distributed in silica gel. The thickness is about 45~60 nm. The visible light spectra measurements indicate that the coated film increase the transparency of the glass substrate. After the acid treatment and a scratching of 50 times, the spectra remain unchanged, suggesting a good acid and abrasion resistance of the prepared film.

Abstract: This paper studies the seepage flow mathematical model of three-area composite reservoir under three kinds of outer boundary conditions (infinite boundary, constant pressure boundary and closed boundary), in which influences of well-bore storage and skin factor are not taken into consideration. On the basic of theory of similar structure of solution of boundary value problem of differential equation, this paper obtain the solution of the seepage flow model of three-area composite reservoir. The study is not only conducive to further analyze the inherent law of the solution and solve corresponding application problems, but also easy to compile corresponding analysis software.

Abstract: The aerodynamics of the rotor/wing during conversion from rotary to fixed-wing flight was numerical investigated. It is shown that increasing forward speed can provide more thrust when rotation speed and collective angle maintain a constant, but also appear greater torque. Thrust of the rotor/wing can maintain aircraft to hover at some cases when forward speed changes with other variable. As long as major and minor rotor converse with reasonable variable change alternatively, the dual rotor/wing can converse smoothly. Moreover, the total drag of minor first conversion is smaller than that of major first conversion.

Abstract: The influence of boundary layer ingestion (BLI) on the aerodynamics of airfoil RAE2822 in subsonic is investigated by numerical method. Based on the calculation, it is found that the mass flow ratio (MFR), intake height, cowl length and intake position in the chord can affect on the lift, drag and pitching moment remarkable. Considering a maximum lift-over-drag, intake position in the chord should be rearward as possible with a certain high MFR at a small angle of attack and a considerable intake height. There is a proper MFR which makes drag lowest.

Abstract: This work presents a numerical study of the natural convection in a saturated porous medium bounded by two horizontal concentric cylinders. The governing equations (in the stream function and temperature formulation) were solved using the ADI (Alternating Direction Implicit) method and the Samarskii-Andreev scheme. A comparison between the two methods is conducted. In both cases, the results obtained for the heat transfer rate given by the Nusselt number are in a good agreement with the available published data.

Abstract: For a holonomic system with variable mass, the conformal invariance and the conserved quantity of Mei symmetry of Appell equations are investigated. First, by the infinitesimal one-parameter transformation group and the infinitesimal generator vector, the Mei symmetry and the conformal invariance of differential equations of motion for Appell equations in a holonomic system with variable mass are defined, and the determining equation of Mei symmetry and conformal invariance for Appell equations in a holonomic system with variable mass are given. Then, the Mei-conserved quantity corresponding to the system is derived by means of the structure equation to which the gauge function satisfies. Finally, an example is given to illustrate the application of the result.

Abstract: The new control problems for the stationary magnetohydrodynamics equations under inhomogeneous boundary conditions for the magnetic field are considered. In these problems we use velocity and magnetic field boundary controls to minimize functionals depended on velocity and pressure. We study uniqueness and stability of solutions to these control problems and discuss some computational results.

Abstract: This paper addresses elastic analysis based on 3D finite element model for hollow sphere structures. In finite element models, which were analyzed under pressure of 1MPa, volume fraction of hollow spheres is kept at 30%, and hollow spheres are randomly located in the matrix. Five types of hollow sphere are used to form the model. All the types of hollow spheres have 60μm particle sizes, but different wall thicknesses. A comparison in stress distribution between the hollow sphere and matrix is made, which shows that in composites containing thin-walled hollow particles the maximum stress is located in the inner surface of particle wall, whereas increasing the wall thickness of hollow spheres results in getting some part of matrix around hollow spheres involved in energy absorption. Moreover, the location of the maximum stress in matrix related closely to the spatial arrangement of the particles. The study provides an insight into the micro structural performance of syntactic foam under load.

Abstract: By using ANSYS software parameter of design language APDL the parametric design macro program of two types of equilateral triangle cylindrical lattice shell are given with the given parameters of the span S, the length L, the rise F, the number of lattice in the span direction the model of equilateral triangle cylindrical lattice shell would be obtain easily. Thus offer convenience for force analysis and optimization design about this structure. The force analysis of the two type equilateral triangle cylindrical lattice shell is done. By contrast with the five typical cylindrical shells, the two type equilateral triangle cylindrical lattice shell has good rigidity and strength, and has application value in practice engineering.

Abstract: In order to investigate the cause of the typical bush rupture and wear damages in the journal bearing of the steam turbine generator set, the lubrication turbulence and thermo-hydrodynamic effects were studied. The generalized Reynolds equation, energy equation and heat conduction equations were solved with the finite difference method, and the pressure, temperature, thickness distribution of the oil film were obtained. Analysis results can be well explains the bearing bush burst in bearings maximum pressure place because of heavy load running. The bearing bush burst made friction intensified that caused oil temperature increasing and the viscosity reduce, which led to the rotor eccentricity increase, the minimum film thickness smaller and bearing static working point down, thus causing the wear damages until shutdown.