Papers by Author: Bo Qin Gu

Abstract: In this paper, Taguchi experimental design method is applied, and injection molding CAE simulation analysis is conducted. Influence factors of warpage of products are analyzed. According to the results of ranking, influence factors of warpag are the packing pressure, packing time, melt temperature and mold temperature. The packing pressure is the most important influence factor. To get the best level combination of various factors, mixed level orthogonal experimental design is applied to the optimization. Optimal levels of combination process parameters are obtained and the quality of injection products is greatly improved.

Abstract: The BP ANN was established based on MATLAB to simulate the supercritical CO₂ extraction process for extracting peanut oil. The supercritical CO₂ extraction experiment for peanut oil was carried out and the experimental results were used to train the BP ANN. The operating pressure, temperature and time were regarded as the inputs of the BP ANN and the percentage extraction as the output. By testing the BP ANN with other groups of experimental data, the precision of the BP ANN was verified. This BP ANN can predict the percentage extraction when the processing parameters of supercritical CO₂ extraction are given, and the optimization of the processing parameters can also be realized.

Abstract: The flat end face mechanical seals are widely used in shaft sealing at moderate rotational speed. The thermal deformation of the rotating and stationary rings initiated by friction heat of fluid film should be primarily considered in the design of mechanical seal. In consideration of the coupling effect among the thermal deformation of sealing rings, the fluid flow in the gap composed by end faces of sealing rings and the heat transfer from fluid film to sealing rings, the optimum design method for flat end face mechanical seal is established. The end faces are fabricated to form a divergent gap at the inner side of the sealing rings, and a convergent gap will occur at the outer side and a parallel gap will be obtained at where the original divergent gap is due to the thermal deformation. After optimization, the leakage rate can be reduced while the bearing force of fluid film is still large enough to keep the fluid lubrication of the end faces.

Abstract: Volute casing is one of the important components in centrifugal pumps. The strength and stiffness of the volute casing made of PMMA used for PIV measurement were investigated by fluid-structure interaction (FSI) simulation in consideration of the impeller-volute interaction. The distribution of pressure and shear stress on the inner surface of the volute casing was obtained by FLUENT. Pressure, gravity and shear stress were imposed on the volute casing, and its stress and displacement distributions under different working conditions were obtained using ABAQUS. The results indicate that in comparison with pressure, gravity and shear stress have negligible influence on volute casing deformation. The volute casing is structurally safe under design condition, and its maximum rotational speed can reach to 1690r/min. At this rotational speed, the maximum displacement of the volute casing is 4.6mm, and measurement error caused by refraction is about 0.11%. Furthermore, two methods for improving the volute casing structure were put forward in consideration of light decay as well as the strength and stiffness of the volute casing.

Abstract: The heat transfer in solid-fluid coupling system relates to not only the heat transfer process in solid and fluid bodies but also the physical quantity exchange through the boundary. Because some boundary conditions, such as heat flux and coefficient of heat transfer, are uncertain, neither solid body nor fluid body can be separated from the coupling system when the thermal coupling analysis is carried out. A coupling analysis method based on numerical simulation codes ABAQUS and FLUENT was put forward to solve the boundary problem. The two simulation codes were controlled by the interface software which was developed to exchange the boundary conditions between solid and fluid models at each iteration step. A copper finned radiator model and its corresponding air model were built by ABAQUS and FLUENT respectively, and the heat elimination process of the radiator under forced convection conditions was investigated. The heat elimination characteristic of an aluminium radiator was also researched. By comparing with the copper radiator, it can be found that the larger the coefficient of heat conductivity is, the higher the heat elimination efficiency is.

Abstract: Using Reynolds average N-S equations closed by standard k- turbulence model, the steady and unsteady turbulent flow in centrifugal pump was simulated by using MRF model and SM model respectively. A method for predicting the performances of centrifugal pump was built on the basis of computational fluid dynamics. By the presented performance prediction method, not only the flow characteristics of centrifugal pump can be obtained, but also can its performances be evaluated quantitatively and qualitatively. The advantages and disadvantages of some traditional design methods for centrifugal pump were analyzed. On the basis of performance prediction and flow analysis, a new design method was put forward in consideration of the steady and unsteady performances of centrifugal pump. The proposed method can be used to design the centrifugal pump with high running stability, efficiency and cavitation resistance, and it is available for shortening development period and improving design quality of pump.

Abstract: In consideration of the similarities of supercritical fluid extraction (SFE) kettles, the parameterized finite element analysis system was developed based on ANSYS and Visual Basic. The parameterized model building, stress analysis and fatigue analysis for shell, nozzle and quick-opening sealing structure were realized by second development of ANSYS using APDL language. The program which can deal with design parameters was developed based on Visual Basic, and the command stream files, which can be recognized by ANSYS, were modified according to design parameters and sent to ANSYS solver by the program. With the system, the stress and fatigue analysis process for SFE kettle is simplified and the analysis efficiency of SFE kettle is improved.

Abstract: Four kinds of coating materials and two kinds of brush plating materials were screened and sprayed on the surface of valve ball by plasma spraying technology and brush plated on the surface of valve seat by electrical brush technology, respectively. The wear resistance of the sealing pairs and the properties of the plasma sprayed coatings were tested. The results indicate that the sealing pair composed of the valve ball with the plasma sprayed coating of Al2O3-TiO2 and the valve seat with the brush plating layer of nickel tungsten has best combination property. The gap of the sealing pair at room temperature and the leakage rate at elevated temperature of the high temperature ball valve were obtained by FEM method and analysis method, respectively. Therefore, the open and close torque of the high temperature ball valve was determined. According to the results of the research, the failed ball valve was remanufactured, and the performance inspection was also conducted. The remanufactured ball valve has much longer service life than the original one and its sealing behavior was also improved significantly.

Abstract: The time-correlated leakage characteristic of nonmetallic gaskets was analyzed. Considering the effect of the gasket material deterioration on the sealing performance, a time-correlated leakage predication model of nonmetallic gasket sealing connections based on the porous medium theory was proposed. Some tests were performed on compressed non-asbestos fiber gaskets, the leakage behavior was investigated and the coefficients in the leakage model were obtained by regression analysis of experimental data. The predicted leakage rates according to the model were compared with the data reported in some literatures, and the prediction accuracy was also validated. The presented time-correlated leakage model provides an effective way to predict the leakage rate and evaluating the life of gasket sealing connections.

Abstract: A new kind of sealing composite material reinforced mainly with carbon and glass hybrid fibers was developed with calendar preparation method. In consideration of the difference of surface behavior, carbon fiber and glass fiber were pretreated by various surface treatment methods, and the effect of these methods on the material properties and interface bonding between fibers and matrix was studied through the transverse tensile test and SEM analysis. The optimum prescription of the sealing composite material was obtained by regression design method, adopting stress relaxation at 300°C as evaluating indicator. The performances of the developed sealing composite material were tested, and the results indicated that the main performances of the material coincided with the requirements prescribed in Chinese national standard and some performances were even better than that of the products of some famous corporations.