Papers by Author: Lin Yang

Abstract: Traction devices are power transmission components of railbound vehicle. This article discusses the gearbox mechanical properties numerical calculation and strength analysis. It established calculation model based on field test parameters. And it finished analysis about elastic deformation of large displacement and contact problem of nonlinear finite element method during numerical calculation. With comparison of energy strength theory and ASME VIII-2 standard, it chooses the suitable strength method for gearbox. With definition of key parameters, the mechanical properties numerical calculation results were given in different load conditions. According to displacement, strain and stress analysis, the gearbox strength is analyzed based on ASME VIII-2 standard. The results show: under field test loads, the gearbox satisfies strength requirement. But there is stress concentration phenomenon. During independent analysis process of gearbox, hanging and assembly, the results of displacement, strain and stress assume certain regularity.

Abstract: With calculation results comparison of different throttle nozzle diameter value, This article analyses the flow field with throttle nozzle diameter variety of 1.0mm, 2.0mm, 2.4mm, 2.6mm, 2.8mm, 4.0mm, while the other parameters take same value (such as the inlet pressure is 20mpa, the outlet pressure is 10MPa, the temperature is 333k, and the well depth is about 2000m). the results present the influence upon downhole choke flow field including pressure, velocity, temperature distribution. The pressure field composed by minimum on the axis shows the pressure dropping change at the throttle nozzle outlet. Velocity field gives the maximum value of velocity and Mach number, which determines the flow field is subsonic or supersonic flow. With hydrate formation conditions, temperature field formed by minimum on the axis gives the existing judgment of hydrate formation under a certain condition. With the throttle nozzle diameter increasing, the outlet flow maximum velocity increases, and the differential pressure before and after nozzle becomes larger, which means the pressure drop effect is better. The downhole choke design of throttle nozzle needs to consider the combination effects of pressure drop and temperature drop. These parameters provide reference for downhole choke structure design and operating performance improvement.

Abstract: Natural gas downhole choke process inlet is high temperature and high pressure. Usually it can achieves 10~30MPa, while it will be higher in high pressure drilling well. It is installing thousands of meters underground. It is difficult carrying on field test during working process. These special situations make the choke outlet flow being complex, which includes expansion wave, compression wave, and energy transformation. The physical experiment is difficult. To be more accurately analyzing the compressible viscous turbulent motion of downhole choke internal flow field, this article uses RNG − model for three dimensional numerical simulation. It analyzes the result of flow field streamlines, velocity, Mach number, pressure, and temperature distribution. It analyzes the influence on hydrate formation of choke working process. Numerical calculation can provide useful reference for the prevention of natural gas hydrate formation and optimization design of downhole choke.