INITIAL PRESSURE DISTRIBUTION DUE TO JET IMPACT ON A RIGID BODY

2001 ◽  
Vol 15 (2) ◽  
pp. 365-370 ◽  
Author(s):  
G.X. WU
Keyword(s):  
Rigid Body ◽  
Pressure Distribution ◽  
Initial Pressure ◽  
Jet Impact

Pressure distribution of bottom rollers below the aerator device

2019 ◽  
Vol 79 (4) ◽  
pp. 668-675 ◽  
Author(s):  
Yu Wang ◽  
Jianhua Wu ◽  
Fei Ma ◽  
Shangtuo Qian
Keyword(s):  
Pressure Distribution ◽  
High Water ◽  
Geometrical Parameters ◽  
Cavitation Damage ◽  
Novel Approach ◽  
Water Head ◽  
Jet Impact ◽  
Hydraulic Conditions ◽  
Relative Errors ◽  
Large Flow

Abstract With regard to high water head and large flow velocity in the spillway tunnels of hydraulic projects in China, the aerator device has been introduced and is widely used to prevent cavitation damage. The bottom rollers in the nappe cavity below the aerator device are a serious concern in designing suitable cavity regimes; however, observation of roller size may be inaccurate due to high flow turbulence and de-aeration in the jet impact region. In this study, a novel approach is proposed to predict roller sizes using pressure distribution of the bottom rollers. Pressure distribution characteristics are experimentally investigated under different geometrical parameters of aerator device and hydraulic conditions. The results specify the influence of the relative step height and working gate opening on pressure distribution. The simplified estimating formula of pressure distribution is derived within relative errors of 15%. The evaluation of the applicability of the proposed equation shows test data are in good agreement with the calculated value. Research results provide a reference for estimating bottom rollers of similar engineering.

Thermoplastic Instability for the Transient Contact Problem of Two Sliding Half-Planes

1986 ◽  
Vol 53 (3) ◽  
pp. 565-572 ◽  
Author(s):  
A. Azarkhin ◽  
J. R. Barber
Keyword(s):  
Steady State ◽  
Pressure Distribution ◽  
Half Plane ◽  
Initial Pressure ◽  
Approximate Solutions ◽  
Steady State Solution ◽  
Fourier Integral ◽  
Numerical Results ◽  
Initial Size ◽  
Transient Contact

We study the time dependent problem of a nonconducting half-plane sliding on the surface of a conductor with heat generation at the interface due to friction. The conducting half-plane is slightly rounded to give a Hertzian initial pressure distribution. Relationships are established for temperature and thermoelastic displacements due to a heat input of cosine type through the surface, and then these are used to obtain the solution in the form of a double Fourier integral. Numerical results show that, if the ratio of the initial size of the area of contact to that in the steady state is less than some critical value, the area of contact and the pressure distribution change smoothly toward the steady state solution. Otherwise the area of contact goes through bifurcation. The bifurcation accelerates the process. Numerical results are compared with previous approximate solutions.

Comparison of Formulations for the Hydrostatic Stiffness of Flexible Structures

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
H. R. Riggs
Keyword(s):  
Hydrostatic Pressure ◽  
Stress Distribution ◽  
Rigid Body ◽  
Pressure Distribution ◽  
Internal Stress ◽  
Flexible Structures ◽  
Restoring Force ◽  
The Relationship ◽  
Selection Of

The formulation for the hydrostatic stiffness (restoring force) for linear rigid body hydrodynamics is well known, whereas there are several formulations in literature for the corresponding stiffness of flexible structures. Which of these formulations to use is not immediately obvious. This paper clarifies the relationship and the differences between the formulations and the selection of the appropriate one. In addition, it will be shown that a general formulation of the hydrostatic stiffness for flexible structures involves the internal stress distribution under gravity loads, just as it does the corresponding hydrostatic pressure distribution.

Air-Pressure Characteristics of Aircushion Supported Large Floating Structures

2004 ◽  
Author(s):  
Tomoki Ikoma ◽  
Koichi Masuda ◽  
Chang-Kyu Rheem ◽  
Hisaaki Maeda ◽  
Ryo Iwasa
Keyword(s):  
Theoretical Prediction ◽  
Pressure Distribution ◽  
Prediction Method ◽  
Initial Pressure ◽  
Exciting Force ◽  
Adiabatic Compression ◽  
Air Pressure ◽  
Floating Structure ◽  
Floating Structures ◽  
Pressure Characteristics

Air-pressure characteristics of air supported fixed floating structures are described in this paper. The theoretical prediction method of responses of the aircushion type floating structure in waves has been proposed. The adiabatic compression is assumed to the prediction method. In this study, model experiments using two aircushion type models are carried out in the wave tank. Then, pressures in the aircushion and the wave exciting force of heave are measured. It is verified to assume spatially uniformly distribution to pressure distribution from explorations by using the experimental results of the pressure and the phase difference. In addition, effects of the initial pressure of the aircushion and the draft of the skirt bounding the aircushion and/or water are little.

scholarly journals A New Method and Application of Full 3D Numerical Simulation for Hydraulic Fracturing Horizontal Fracture

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 48 ◽  
Author(s):  
Bing Xu ◽  
Yikun Liu ◽  
Yumei Wang ◽  
Guang Yang ◽  
Qiannan Yu ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Pressure Distribution ◽  
Three Dimensional ◽  
Initial Pressure ◽  
Fluid Viscosity ◽  
Fracturing Fluid ◽  
Horizontal Fracture ◽  
Initial Fracture ◽  
Net Pressure ◽  
Fracture Height

The numerical simulation of hydraulic fracturing fracture propagation is the core content of hydraulic fracturing design and construction. Its simulation results directly affect the effect of fracturing, and can effectively guide the fracturing construction plan and reduce the construction risk. At present, two-dimensional or quasi-three-dimensional models are mainly used, but most of them are used to simulate the vertical fracture of hydraulic fracturing. There are errors in the application process. In this paper, a three-dimensional mathematical model, including an elastic rock mechanics equation and a material flow continuity equation, is established to simulate horizontal fracture propagation in shallow reservoirs. The emphasis of this paper is to propose a new method for solving equations. The basic idea of the iteration method has been proposed by previous scholars: Firstly, assuming that the initial pressure of each point in the fracture is uniform, the fracture height of each initial point can be obtained by using Equation (20). Using the initial height values, the pressure values at each point of continuous variation are calculated by Equation (16), and then the new fracture height values are obtained by Equation (20). Because of the equal initial pressure, this method leads to too many iterations in the later stages, which makes the calculation more complicated. In this paper, a new Picca iteration method is proposed. The iteration parameters are changed sequentially. Firstly, the distribution value of fracture height is assumed. Then, the pressure distribution value is calculated according to Equation (16). Then, the new distribution value of fracture height is obtained by bringing the obtained pressure distribution value into Equation (20). Then, the new distribution value of the fracture height is calculated according to Equation (16). The pressure distribution value completes an iteration process until the iteration satisfies the convergence condition. In addition, Sneddon’s model is introduced into the hypothesis of fracture height to obtain the maximum fracture height and assume that the initial fracture profile is a parabola. Finally, the proposed method can rapidly improve the convergence rate. Next, on the basis of investigating the solutions of previous equations, the Galerkin finite element method is used to solve the above equations. The new Picard iteration sequence method is applied to solve the height and pressure at different points in the fracture. By calculating the stress intensity factor, we can judge whether the fracture continues to extend or not, and then simulate the full three-dimensional horizontal fracture of the hydraulic fracturing expansion process. The infiltration process of three types of oil reservoirs in Daqing Changyuan oilfield is simulated. The results show that during the initial fracture stage, the radius and height of fractures increase rapidly, and the rate of increase slows down with the increase of construction time. The height and net pressure of each point in the fracture are unequal. The height and net pressure of the fracture in the wellbore reach the maximum, and gradually decrease to the front of the fracture. Compared with conventional fracturing, the fracturing-flooding percolation process has the characteristics of short fracture-making and large vertical percolation distance, which can greatly increase the swept volume of flooding fluid and thus enhance oil recovery. With the increase in the rock modulus of elasticity, the radius of fractures decreases and the height of fractures increases. With the increase in construction displacement, the radius of fractures hardly changes, the height of fractures increases, and the vertical infiltration distance of the fractures increases. It is suggested that the construction displacement should be 4.0 m3/min. In the range of fracturing fluid viscosity in the studied block, with the change of fracturing fluid viscosity, the change of fracture radius and height is not obvious. In order to further increase sweep volume, the fracturing fluid viscosity should be further reduced.

Influence of Nonuniform Initial Pressure Distribution in Well Test Data

2000 ◽  
Author(s):  
Antonio Sampayo-Trujillo ◽  
Rodolfo Camacho-Velazquez
Keyword(s):  
Pressure Distribution ◽  
Test Data ◽  
Initial Pressure ◽  
Well Test
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