Papers by Author: Xin Qi Yu

Abstract: In this paper, the entire structure and operating principles of the toss feeding typed stalk baler are introduced. The baler is mainly consisted of collecting, feeding, compression and knotting component. A Y-shaped straw chopper blade is used in the collecting. A combination component of auger and toss machine is adopted in the feeding system. The sliding block of compressor is driven by rod-crank mechanism. Structure analysis shows that the toss feeding typed straw baling machine has advantages of simple structure, high efficiency and low manufacturing cost. At the same time, the structural analysis provides an important theoretical basis for further optimal design of baling machine.

Abstract: By using finite element software ANSYS, stress analysis was conducted to the annular sector semicircular cross section vessel which was made up of an annular sector plate, two semicircular plates and a semi-cylindrical with thicknesses of 20mm. The analysis results show that the maximum equivalent stress of the annular sector plate appears in the middle of the plate, and the maximum equivalent stress of the semicircular plate and the semi-cylindrical appear in the inner surface of the connections. The equivalent stress distribution trend of the annular sector plate, semicircular plates and the semi-cylindrical was obtained. Through these researches, the distribution trend of equivalent stress provided a reference for the design of the annular sector semicircular cross section vessel.

Abstract: Models with main-branch channel, crossing channel and net type channel are established and nutrient liquid with a velocity of 0.01m/s is adopted in the study to investigate the fluid field in the channel by using FEA software FLUENT. The velocity and pressure distribution have been obtained in the investigation. By comparing the results in the three models, pressure and velocity distribution in the second and the third models are relatively uniform and are appropriate for the bionics principles. Studies in this paper will be of benefits for the development of tissue engineering.

Abstract: A small indoor cooling system through cold water circulation is introduced in this paper. The system mainly includes cooling pool, cold water circulation equipment, indoor heat exchanger, temperature measurement equipment and induction controlling equipment. The indoor cooling is achieved by heat transfer between the natural underground water of lower temperature and indoor air of higher temperature, and it is different from the traditional compression refrigeration system in which a great amount of electric energy is consumed while the refrigerant is compressed. Compared with the ordinary air conditioning system, this system has obvious advantages on economy, application potential and energy conservation in rural developing areas.

Abstract: An analytical model is developed to study the sealing performance of the mechanical seals with a laser-textured micro-pore face. The pressure distribution between the seal faces at various operation conditions and micro-pore geometry parameters can be obtained from a solution of the Reynolds equation by finite difference method, and then opening force and liquid film stiffness can be calculated. Seal face geometry parameters can be optimized by analyzing regulation of their effect on opening force and liquid film stiffness. Results of parametric study demonstrate that substantial hydrodynamic effect can be produced on the seal face with micro-pores.

Abstract: An analytical model is developed to study the effects of operation conditions and micro-pore geometry parameters on the friction performance of the mechanical seals with a laser-textured micro-pore face. Seal opening forces at various operation conditions and micro-pore geometry parameters are obtained from the solution of the Reynolds equation by the finite difference method. A derivative expression of the friction torque of the mechanical seals with a laser-textured micro-pore face is calculated and contributing factors of the friction torque are analyzed. It is shown that fiction torque increases with increase of the rotating speed. An optimum pore size that corresponds to minimum friction torque is found and is consistent with experimental results.

Abstract: In this article, factors that influence the reliability of non damage testing is studied, and a method was developed to calculate the reliability of non damage testing. More over, a method based on the reliability of non damage testing was developed to calculate the possible maximum size of defect. This study will offer original defect size data to the safety assessment.

Abstract: A theoretical model has been developed for the mechanical seals with a laser-textured porous seal face. By means of variable dimensionless steps, parametric analysis has been performed to obtain dimensionless liquid film pressure by the finite difference method. Liquid film pressure profiles over the pore column have be achieved by the computer program MATLAB. It is found from calculating results that average liquid film pressure increases with increase of the rotational speed, liquid viscosity and reduction of liquid film thickness. Hydrodynamic effect produced by micro-pores decreases with increase of fluid pressure. In addition, the effect of the pore area density and depth over diameter ratio on the liquid film pressure is very significant. Optimum values of these parameters can maximize the average liquid film pressure.

Abstract: A calculation model is developed for mechanical seals with a laser-textured micro-pore face. The dimensionless hydrodynamic pressure distribution on the seal face at various operating conditions and micro-pore geometry parameters is obtained from a solution of the Reynolds equation by the finite difference method. An optimum micro-pore geometry parameter is found and consistent with experimental results. Results of parametric study demonstrate that the substantial hydrodynamic effect can be produced on the seal face with micro-pores.

Abstract: Regular micro-surface structure in the form of micro-pores produced on the face of mechanical seals by laser technology can be used to improve the friction performance of the seal mating rings. A test rig with variable axial load was used to test laser-textured seal rings with micro-pores of various pore depth and pore ratio to study the effect of the laser-textured seal face structure parameters on the friction performance of mechanical seals. It is found that there are optimum texturing face parameters at which the friction torque and the face temperature rise of seal rings are minimum. Results of these tests show that the micro-pores on one of the seal mating faces can generate substantial hydrodynamic effect. Heat generation due to frictional contact on seal-ring surfaces is a major factor that causes deterioration of face seals and shortens their service life[1,2]. Excessive temperature rise can be avoided by improving structure of a seal surface. By means of laser technology return-flow structure, oblique line groove and spherical micro-pores are engraved on the seal face[3-5]. The research shows that substantial hydrodynamic effect can be generated between the seal faces with micro-pores[6-8]. In this study experiments are performed on laser-textured micro-pores seal faces at various axial loads to investigate the effect of the face structure and operating parameters on friction torque and face temperature rise.