T⁃shaped multi⁃branch pipeline is a kind of T⁃shaped pipeline with complex multi⁃branch structure, which is now widely used in the research of two⁃phase and multi⁃phase flow.In this article,the fluid simulation tool Fluent was used to simulate the oil and gas two⁃phase flow in the T⁃shaped pipeline at different times with obtained the oil and gas separation characteristics of each branch and the mass flow data of the inlet and outlet.The results indicate that, when the oil and gas two⁃phase mixed infusion flows through the T⁃shaped pipeline, the phase distribution of the oil and gas two⁃phase in the pipeline is uneven due to the effect of gravity.With the increase of time, the gas⁃outlet at the top is mostly gas, while the oil⁃outlet at the bottom is mostly liquid, thus achieving a initial separation of oil and gas. T⁃shaped pipeline with different branch pipe heights are selected for simulation, and the characteristics of oil⁃gas separation phenomena are analyzed. Then select different inlet velocity of T⁃shaped main pipe to observe the effect of inlet velocity on oil⁃gas separation.Finally, by analyzing the turbulent vortex structure and flow field characteristics in the pipeline, the turbulence coherent structure shows the characteristics of regularity and repeatability under the same structural parameters, and the influence of branch pipeline on flow pattern and turbulence vortex.

The spindle is the core part of the high speed milling machine, its dynamic characteristics directly affect the machining accuracy of the milling machine.Taking a German GMN high⁃speed milling machine electric spindle as an example, the finite element method was used to establish a finite element model of the spindle⁃bearing system, the natural vibration characteristics of the spindle were studied, and the influence of bearing stiffness on the natural vibration mode and critical speed of the spindle was analyzed.On this basis, the unbalanced response characteristics of the high⁃speed spindle were studied, and the influence of the unbalance amount and position on the vibration sensitivity of the spindle was analyzed. It was found that the unbalanced response at both ends of the spindle was sensitive, especially at the end where the tool was connected. The results could provide a certain reference for the dynamic design of the high⁃speed machine tool spindle system.

Steam turbines are widely used in electric power, petroleum, petrochemical and aviation industries. The rotor system is a key component of the steam turbine. Because the turbine rotor structure is more complex, high working speed and complex temperature environment of the rotor system easily lead to excessive vibration, rubbing, crack, fracture, other serious accidents and even units damage, resulting in loss of personal and economic property. Through the establishment of a dynamic finite element model for the steady⁃state vibration response of the bending moment excitation of the turbine rotor⁃bearing system, calculation of steam turbine rotor bending moment for steady⁃state vibration displacement and stress response curve, analyses the size and location of bending moment on the influence of steam turbine rotor steady⁃state vibration response, providing theoretical basis for design of steam turbine rotor system dynamics.

The dynamic response characteristics of the internal rotor⁃bearing system are directly related to the pros and cons performance of the turbine.In this paper, the finite element method is used to model the rotor⁃bearing system, considering the effect of bearing stiffness on the critical speed of the system, the unbalanced response characteristics at the same speed and different speeds,the unbalanced response characteristics are discussed in detail, the sensitive position of the system is determined, which provides the basis for the optimization design of the steam turbine.

Taking the rotor-bearing system of a steam turbine as the research object, considering the influence of the shaft gyro moment and moment of inertia, the finite element model of rotor-bearing system dynamics is established . The dynamic response characteristics of the rotor-bearing system under earthquake excitation are studied by inputting different ground motion peak acceleration and changing phase angle in X direction and X-Y direction. The equivalent stress and displacement trends of key nodes in rotor-bearing system are analyzed, and the safety of turbine rotor-bearing operation under seismic load is discussed. The aim is to provide a theoretical reference for the seismic design of rotor-bearing system.

The finite element method was used to compare and analyze fluid flow and mixing characteristics between three kinds of rotor mixer, 4WS,4WH and 6WI.The UG software was used to build 3D geometry models. The Gambit software was used to be grid division. And model was used to simulate the flow field of three kinds of internal mixer by BirdCarreau constitutive model and Polyflow software. By comparing the average velocity, the axial velocity and the shear rate, the flow patterns of the three flow fields were obtained. At the same time, the distribution of the mixture of the three parameters was described by using the parameters of the particle index, the average logarithmic stretch index, the probability of the particle index, the average mixing efficiency and the residence time distribution. The simulation results showed that, because of the special variable clearance rotor structure of 6WI rotor mixer, the flow field was more easily changed, and its mixing performance was higher than that of the other two kinds of rotor mixer.

The flow fields in four kinds of combined screws of the tri-screw extruders were analyzed by using finite element method. The velocity, pressure, maximum shear rate, maximum stretching rate and residence time distribution in four extruders were specially analyzed. The results showed the combined screws of the triscrew extruders could weaken the axial velocity to a certain extent and increased the residence time distribution. Those were beneficial to the full mixing of the material. Moreover, the effects of screw deformation on fluid-structure coupling were further analyzed by ANSYS workbench. By comparison, the design of combined screws four was more reasonable due to the high mixing performance and the small deformation of screws.

The model and numerical simulation of three-dimensional non-isothermal for sol-gel reaction process of preparing PP/TiO₂ nanocomposites between mixing and reaction process in twin screw extruder were established by POLYFLOW software with the finite element method. The effects of screw speed, screw pitch and precursor concentration on the preparation of PP/TiO₂ nanocomposites reaction process about mixing efficiency and reaction rate were analyzed. The results showed that the increasing pitch which enhanced the temperature of polymer and improved mixing efficiency in twin screw extruder contributes to the reaction process. The increasing screw speed and precursor concentration were not conducive to the reaction, because of the drop of the fractional conversion.

Hydrogenation reactor is an important equipment of petroleum refining industry, which usually was operated in the environment of high temperature and pressure. The stress distribution of the hydrogenation reactor was very complicated. Especially, the manhole area of the hydrogenation reactor was the high stress area and its security was related to the safe operation of entire equipment. The thermal-structure coupling finite element model of hydrogenation reactor manhole area was established by using ANSYS software. Moreover, the stress analysis and strength evaluation of the manhole area were employed by combining with JB 4732—1995" steel pressure vessel-analysis and design standard ". The results showed that the maximum stress occured in the connecting region of manhole flange and the semicircle head, the maximum stress value was 154.681 0 MPa. The evaluation results illustrated that the manhole area were qualified in the stress strength.

The 2.25Cr1Mo steel that was frequently used in petrochemical equipment was welded by hot welding process at 750 ℃ and 850 ℃. The welding residual stress of every welded specimen was measured by the small blindhole method. The electrochemical workstation was used to measure the stress corrosion property of every welded specimen in alkaline, acidic and neutral medium. The microstructure of welded joint was analyzed by metallographic technique. The results showed the hot welding process could obviously reduce the welding residual stress of 2.25Cr1Mo steel welded plate and raise the stress corrosion property of it in every medium. In addition, the higher the process temperature was, the bigger the reduced degree of welding residual stress was, the more the stress corrosion property was improved. At 850 ℃, the welding residual stress was reduced by the degree of above 60% and the stress anticorrosion property was raised by the degree of above 30%. The microstructure of welded joint was improved after high temperature welding. The mechanical property was maintained.

The geometric models and finite element models of triscrew extruder with different rotors have been established, and the models have been simulated by Polyflow. The mixing index, shear rate, logarithm of stretching, instantaneous efficiency, the average time efficiency and other evaluation parameters have been calculated using particle tracking method. The results show that, the number of shear and stretching in triscrew extruder in the same period increase with the increase of screw head numbers. Accordingly, the mixing effect is also increased gradually.