scholarly journals Construction of Pressure Tunnels

2019 ◽  
Vol 66 (3-4) ◽  
pp. 77-100
Author(s):  
Lesław Zabuski
Keyword(s):  
Rock Mass ◽  
Numerical Analysis ◽  
Finite Difference Method ◽  
Water Reservoir ◽  
The Other ◽  
Clay Shales ◽  
Carpathian Flysch ◽  
Internal Forces ◽  
The Finite Difference Method ◽  
Preliminary Support

AbstractThe paper focuses on two pressure tunnels in the design of “Kąty-Myscowa” water reservoir. One of them serves as a discharge conduit, whereas the other plays an energetic role. Their depths range between 0 and 75 metres and their diameters equal 5 m. Tunnels are located in the rock mass of Carpathian flysch which is anisotropic and heterogeneous, composed of layers of sandstone and clay shales and intersected with interbedding fissures and numerous joints. The paper is divided in two parts. The first part focuses on methods of excavating and supporting, as well as injecting and sealing (i.e. waterproofing) the tunnel. In the second part, a numerical analysis using the FLAC2D code based on the finite difference method was carried for calculating displacements and internal forces in the preliminary support and in permanent lining. Results of the analysis allow for the assessment of conditions in the tunnel during its excavation and exploitation stages.

Boundary-layer flow between nodal and saddle points of attachment

1970 ◽  
Vol 41 (4) ◽  
pp. 823-835 ◽  
Author(s):  
J. C. Cooke ◽  
A. J. Robins
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Saddle Point ◽  
Difference Method ◽  
Series Solution ◽  
Nodal Point ◽  
Saddle Points ◽  
The Other ◽  
The Finite Difference Method ◽  
Layer Flow

A simplified example of this type of flow was examined in detail by developing two series, eventually matched, one about the nodal point and the other about the saddle point, and also by finite differences, marching from the nodal point to the saddle point. It was found that the results of marching the two series were in agreement with the finite difference method. The series solution near the saddle point is not unique, but numerical evidence indicates that the correct solution is that which has ‘exponential decay’ at infinity, and that this type of solution, if such exists, automatically emerges when the finite difference method is used.

Nonlinear Analysis of Rotating Stall

1972 ◽  
Vol 94 (4) ◽  
pp. 279-293 ◽  
Author(s):  
H. Takata ◽  
S. Nagano
Keyword(s):  
Numerical Analysis ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Axial Flow ◽  
Rotating Stall ◽  
Wave Shape ◽  
Flow Fluctuations ◽  
Velocity Wave ◽  
Blade Row ◽  
The Finite Difference Method

A new stall model to describe rotating stall in axial-flow compressors is established, where blade rows are replaced by semiactuator disks, flow fluctuations are permitted to be finite and nonsteady, and blade row characteristics are taken into consideration in nonlinear and nonsteady forms. Through numerical analysis using the finite difference method, it is attempted to make clear the aspects of rotating stall—such as number of stall cells, stall propagation velocity, wave shape and magnitude of disturbance and their variations with flow rate through the compressor, and the mechanisms which control them. Most of the aims are achieved by taking into consideration the effects of blade row interference and the nonlinearities of blade row characteristics.

The Numerical Analysis of the Velocity and Pressure Distribution of the Oil Film in Heavy Hydrostatic Thrust Bearing

2014 ◽  
Vol 541-542 ◽  
pp. 658-662
Author(s):  
Jian Li ◽  
Yuan Chen ◽  
Yang Chun Yu ◽  
Zhu Xin Tian ◽  
Yu Huang
Keyword(s):  
Mathematical Model ◽  
Numerical Analysis ◽  
Pressure Distribution ◽  
Working Conditions ◽  
Thrust Bearing ◽  
Rotation Speed ◽  
The Other ◽  
Surface Load ◽  
Oil Film ◽  
Volume Method

To study the velocity and pressure distribution of the oil film in a heavy hydrostatic thrust bearing, a mathematical model of the velocity is proposed and the finite volume method (FVM) has been used to simulate the flow field under different working conditions. Some pressure experiments were carried out and the results verified the correctness of the simulation. It is concluded that the pressure distribution varies small under different rotation speed when the surface load on the workbench is constant. But the velocity of the oil film is influenced greatly by the rotation speed. When the rotation speed of the workbench is as quick as enough, the velocity of the oil film on one radial side of the pad will be zero, that is to say the lubrication oil will be drained from the other three sides of the recess.

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