scholarly journals An in-depth numerical analysis of transient flow field in a Francis turbine during shutdown

Author(s):  
Saeed Salehi ◽  
Håkan Nilsson ◽  
Eric Lillberg ◽  
Nicolas Edh
Author(s):  
Dadi Ram Dahal ◽  
Hari Prasad Neopane ◽  
Biraj Singh Thapa ◽  
Nikshan Paudel ◽  
Sailesh Chitrakar ◽  
...  

Author(s):  
Angela O. Nieckele ◽  
Luis Fernando Figueira da Silva ◽  
Joa˜o Carlos R. Pla´cido

Thermal spallation is a possible drilling technique which consists of using hot supersonic jets as heat source to perforate hard rocks at high rates. This work presents a numerical analysis of a typical spallation drilling configuration, by the finite volume method. The time-averaged conservation equations of mass, momentum and energy are solved to determine the turbulent compressible gas phase flow field. Turbulence is predicted by the classical high Reynolds number κ-ε model, as well as with a low Reynolds number κ-ε model. The influence of the jet Reynolds number is investigated. Special attention is given to the rock surface temperature, since its accurate determination is required to predict spallation rates under field-drilling conditions.


Author(s):  
Mengxuan Li ◽  
Chaohua Gu ◽  
Xiaohong Pan ◽  
Shuiying Zheng ◽  
Qiang Li

A new dynamic mesh algorithm is developed in this paper to realize the three-dimensional (3D) computational fluid dynamics (CFD) method for studying the small clearance transient flow field of tilting pad journal bearings (TPJBs). It is based on a structured grid, ensuring that the total number and the topology relationship of the grid nodes remain unchanged during the dynamic mesh updating process. The displacements of the grid nodes can be precisely recalculated at every time step. The updated mesh maintains high quality and is suitable for transient calculation of large journal displacement in FLUENT. The calculation results, such as the static equilibrium position and the dynamic characteristic coefficients, are consistent with the two-dimensional (2D) solution of the Reynolds equation. Furthermore, in the process of transient analysis, under conditions in which the journal is away from the static equilibrium position, evident differences appear between linearized and transient oil film forces, indicating that the nonlinear transient calculation is more suitable for studying the rotor-bearing system.


1988 ◽  
Author(s):  
D. M. Swain ◽  
M. T. Jacoby ◽  
J. D. Tomassian

Author(s):  
Cosimo Bianchini ◽  
Antonio Andreini ◽  
Bruno Facchini ◽  
Ignazio Vitale ◽  
Fabio Turrini

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