scholarly journals Sensitivity of Axial Velocity at the Air Gap Entrance to Flow Rate Distribution at Stator Radial Ventilation Ducts of Air-Cooled Turbo-Generator with Single-Channel Ventilation

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3442
Author(s):  
Yong Li ◽  
Weili Li ◽  
Ying Su
Keyword(s):  
Flow Velocity ◽  
Calculation Method ◽  
Air Gap ◽  
Test Method ◽  
Distribution Law ◽  
Stator Core ◽  
Flow Phenomenon ◽  
Turbo Generator ◽  
Ventilation Ducts ◽  
Ventilation Duct

In the design and calculation of a 330 MW water-water-air cooling turbo-generator, it was found that the flow direction of the fluid in the local stator radial ventilation duct is opposite to the design direction. In order to study what physical quantities are associated with the formation of this unusual fluid flow phenomenon, in this paper, a 100 MW air-cooled turbo-generator with the same ventilation structure as the abovementioned models is selected as the research object. The distribution law and pressure of the fluid in the stator radial ventilation duct and axial flow velocity at the air gap entrance are obtained by the test method. After the calculation method is proved correct by experimental results, this calculation method is used to calculate the flow velocity distribution of the outlets of multiple radial ventilation ducts at various flow velocities at air gap inlets. The relationship between the flow distribution law of the stator ventilation ducts and the inlet velocity of the air gap is studied. The phenomenon of backflow of fluid in the radial ventilation duct of the stator is found, and then the influence of backflow on the temperature distribution of stator core and winding is studied. It is found that the flow phenomenon can cause local overheating of the stator core.

scholarly journals A Comprehensive Analysis on Transient Electromagnetic Force Behavior of Stator Windings in Turbo-Generator

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Hong-Chun Jiang ◽  
Yu-Ling He ◽  
Gui-Ji Tang ◽  
Ming-Xing Xu
Keyword(s):  
Electromagnetic Force ◽  
Mechanical Response ◽  
Comprehensive Analysis ◽  
Simplified Model ◽  
Force Density ◽  
Stator Core ◽  
Stator Windings ◽  
Fea Model ◽  
Transient Electromagnetic ◽  
Turbo Generator

This paper presents a comprehensive analysis on the transient electromagnetic force behavior of the stator windings in a QFSN-600-2YHG type turbo-generator. Different from other studies, this paper investigates not only the distribution regularities of the resultant force and the force density, but also the force harmonic characteristics, and the mechanical responses which will cause sensitive impact on the insulation wearing. The whole work is generally based on a proposed simplified model and the 3D finite element coupling calculation. The simplified model contains two parts. The first part is the theoretical model that employs the approximate solution of the image current to obtain the analytic formula of the electromagnetic force on the end windings conveniently. The second part is the FEA model that employs only the end windings and one-tenth of the stator core to save the calculating memory and, meanwhile, obtain the qualified electromagnetic force as well as the mechanical response. It is shown that the nose-top, the connection point between the line part and the end part, and the middle of the involute are the three most dangerous positions of the end winding to sustain serious insulation wearing. Moreover, the winding, which endures the maximum mechanical response, is neither always consistent with the one that has the largest resultant electromagnetic force nor directly in accordance with the winding that affords the most intensive electromagnetic force density. The findings in this paper will be beneficial for the insulation monitoring and the manufacturing improvement on the stator windings.

scholarly journals Simple numerical calculation method of flow velocity on roof of train running in tunnel

2018 ◽  
Vol 5 (3) ◽  
pp. 17-00545-17-00545 ◽  
Author(s):  
Katsuhiro KIKUCHI ◽  
Yuhei NOGUCHI ◽  
Koji NAKADE ◽  
Shinya MASHIMO
Keyword(s):  
Numerical Calculation ◽  
Flow Velocity ◽  
Calculation Method ◽  
Numerical Calculation Method

Research of Flow Field and Temperature Field in 2D Annular Space of Air-Gap

2012 ◽  
Vol 214 ◽  
pp. 76-81
Author(s):  
Lu Tang ◽  
Yi Ping Lu ◽  
Hai Yan Deng ◽  
Zuo Min Wang
Keyword(s):  
Temperature Field ◽  
Boundary Conditions ◽  
Turbulent Flow ◽  
Flow Model ◽  
Radiation Heat Transfer ◽  
Air Gap ◽  
Rotating Flow ◽  
Annular Space ◽  
Concentric Cylinder ◽  
Turbo Generator

The flow in air-gap of turbo-generator was simplified to the rotating flow model in the 2D concentric cylinder annular space. According to the CFD principle, the rotating flow model equations of the laminar flow and the turbulent flow were solved with Finite Volume Method. After being compared with the analytical solution of the 2D concentric cylinder Couette shear flow, the 2D air-gap model, the boundary conditions and the calculation results were proved to be accurate. On the basis of the study of the velocity field, the energy equation and the radiation equation were added to study the temperature field in the annular space. The convection and the radiation heat transfer were considered under the first boundary conditions. The turbulent flow and temperature distribution of the annular space under the steady-state were analyzed

A simple calculation method for estimating the flow velocity on the roof of a train running through a tunnel using an unsteady incompressible flow model

2019 ◽  
Vol 234 (7) ◽  
pp. 734-748
Author(s):  
Katsuhiro Kikuchi ◽  
Satoru Ozawa ◽  
Yuhei Noguchi ◽  
Shinya Mashimo ◽  
Takanobu Igawa
Keyword(s):  
Boundary Layer ◽  
Flow Velocity ◽  
Calculation Method ◽  
Model Experiment ◽  
Flow Model ◽  
Simple Calculation ◽  
Dimensional Model ◽  
One Dimensional ◽  
Calculation Results ◽  
Tunnel System

Predicting the aerodynamic phenomena in a train-tunnel system is important for increasing the speed of railway trains. Among these phenomena, many studies have focused on the effects of pressure; however, only a few studies have examined the effects of flow velocity. When designing train roof equipment such as a pantograph and an aerodynamic braking unit, it is necessary to estimate the flow velocity while considering the influence of the boundary layer developed on the train roof. Until now, numerical simulations using a one-dimensional model have been utilized to predict the flow velocity around a train traveling through a tunnel; however, the influence of the boundary layer cannot be taken into consideration in these simulations. For this purpose, the authors have previously proposed a simple calculation method based on a steady incompressible tunnel flow model that can take into account the influence of the boundary layer, but this method could not incorporate the unsteadiness of the flow velocity. Therefore, in this study, the authors extend the previous simple calculation method such that it can be used for an unsteady incompressible tunnel flow. The authors compare the calculation results obtained from the extended method with the results of a model experiment and a field test to confirm its effectiveness.

scholarly journals The Rule of Carrying Cuttings in Horizontal Well Drilling of Marine Natural Gas Hydrate

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1129 ◽  
Author(s):  
Na Wei ◽  
Yang Liu ◽  
Zhenjun Cui ◽  
Lin Jiang ◽  
Wantong Sun ◽  
...  
Keyword(s):  
Particle Size ◽  
Flow Velocity ◽  
Gas Hydrate ◽  
Horizontal Well ◽  
Drilling Fluid ◽  
Test Method ◽  
Critical Flow ◽  
Fluid Density ◽  
Critical Flow Velocity ◽  
Orthogonal Test Method

Horizontal well drilling is a highly effective way to develop marine gas hydrate. During the drilling of horizontal wells in the marine gas hydrate layer, hydrate particles and cutting particles will migrate with the drilling fluid in the horizontal annulus. The gravity of cuttings is easy to deposit in the horizontal section, leading to the accumulation of cuttings. Then, a cuttings bed will be formed, which is not beneficial to bring up cuttings and results in the decrease of wellbore purification ability. Then the extended capability of the horizontal well will be restricted and the friction torque of the drilling tool will increase, which may cause blockage of the wellbore in severe cases. Therefore, this paper establishes geometric models of different hole enlargement ways: right-angle expansion, 45-degree angle expansion, and arc expanding. The critical velocity of carrying rock plates are obtained by EDEM and FLUENT coupling simulation in different hydrate abundance, different hydrate-cuttings particle sizes and different drilling fluid density. Then, the effects of hole enlargement way, particle size, hydrate abundance and drilling fluid density on rock carrying capacity are analyzed by utilizing an orthogonal test method. Simulation results show that: the critical flow velocity required for carrying cuttings increases with the increase of the particle size of the hydrate-cuttings particle when the hydrate abundance is constant. The critical flow velocity decreases with the increase of drilling fluid density, the critical flow velocity carrying cuttings decreases with the increase of hydrate abundance when the density of the drilling fluid is constant. Orthogonal test method was used to evaluate the influence of various factors on rock carrying capacity: hydrate-cuttings particle size > hole enlargement way > hydrate abundance > drilling fluid density. This study provides an early technical support for the construction parameter optimization and well safety control of horizontal well exploitation models in a marine natural gas hydrate reservoir.

Analysis of Unbalanced Magnetic Pull Calculation in Generators With Two Pole Pairs

2009 ◽  
Author(s):  
Lucia Frosini ◽  
Paolo Pennacchi ◽  
Carlo Maria Stoisser
Keyword(s):  
Time Instant ◽  
Harmonic Spectrum ◽  
Dynamical Behaviour ◽  
Air Gap ◽  
Dynamic Effects ◽  
Accurate Calculation ◽  
Unbalanced Magnetic Pull ◽  
Turbo Generator ◽  
Vibratory Analysis ◽  
Linear Effects

The modelling of the unbalanced magnetic pull (UMP) and the analysis of its effects on the dynamical behaviour of a large turbo-generator are presented in this paper. The UMP is the consequence of the electromagnetic forces acting upon rotor and stator generator surfaces and depends on the non-uniform air-gap distribution between rotor and stator. The flexibility and the dynamic effects on the generator behaviour are taken into account by an accurate calculation of the air-gap distribution depending on the position in a generic time instant of the rotor inside the stator. The method is then applied for the vibratory analysis of a two pole pair generator of a steam turbo-set: the harmonic spectrum of the UMP is evaluated and the presence of non-linear effects highlighted.

Sign in / Sign up

Export Citation Format

Share Document