Three-Dimensional Numerical Simulation of Steam Turbine Exhaust Channel Considering Pipeline and Four Wall Reinforcement
A three-dimensional numerical simulation of the internal structure of the exhaust channel was carried out by using Fluent software. A three-dimensional model was established by step-by-step simulation of the internal structure of the exhaust pipe performance impact. The results show that the support pipe and the four-wall stiffeners increase the complexity of the flow field. By blocking the effect of the vortex, the static pressure recovery capacity of the exhaust cylinder is improved and the uniformity of the flow rate of the throat outlet section is reduced, but the total pressure loss was increased. Introduction The steam turbine exhaust channel is composed of the exhaust cylinder and the condenser throat, which is the channel connecting the final stage of the steam turbine and the condenser, introducing the steam turbine exhaust into the condenser and converting the steam kinetic energy of the final stage steam into pressure as much as possible Can [1] improve the exhaust gas channel performance, can effectively reduce the steam turbine exhaust pressure, improve the unit economy. For high-power turbo-generator units, the exhaust cylinder energy is equivalent to more than 2% of the total available energy, accounting for about 0.15% of the total unit loss [2] . In addition, according to the theory of field synergy, to improve the exhaust steam channel outlet steam flow uniformity, can strengthen the condenser tube bundle convection heat transfer effect [overweight, etc.], reduce the condenser heat transfer side difference, to reduce the steam turbine exhaust The results show that when the steam flow rate is below 50m/s, the local convective heat transfer coefficient of the condenser tube bundle increases with the inlet steam velocity, but when the steam flow rate is higher than 50m/s, the steam velocity is higher The effect of heat transfer coefficient is no longer obvious [3] . Therefore, it is very important to study the steam flow field and its influencing factors in the exhaust gas outlet, which is very important to reduce the steam exhaust pressure and improve the unit economy. The horizontal axial exhaust of the turbine is bent or flipped in the exhaust channel to eventually form a vertical downward main flow, which enters the condenser and scans the cooling tube and is cooled into water. In addition to low-pressure heaters, low-pressure pumping pipe, but also includes many to prevent the deformation of the condenser truss, stiffeners, etc., in addition to low-pressure bypass temperature and pressure relief device, drive Feed water pump small steam turbine exhaust and so on are collected to the condenser throat. These internal components are bound to interfere with the steam flow, the throat outlet cross section of the uniformity of the steam flow field and the condenser tube bundle heat transfer effect. The influence of the internal components of the exhaust gas channel as a whole on the flow field of the outlet cross section has been paid attention to in recent years. Cao Lihua, Zhou Lanxin [4 ~ 5] and others in considering the throat low pressure heater on the basis of three-dimensional numerical simulation, that small steam turbine exhaust access, leading to the condenser throat outlet flow field in the access position The lower part of the local low-speed area, and the scope of the growing, the throat outlet flow uniformity have a certain negative impact. Cui Guoming, Guo Yuguang [6 ~ 7] and