scholarly journals Hydraulic structure design and downhole flow field optimization of geophysical drill bits in a limestone stratum

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042093125
Author(s):  
Jing Zhu ◽  
Zhiqiang Huang ◽  
Yachao Ma ◽  
Dou Xie ◽  
Xueying Yang ◽  
...  
Keyword(s):  
Flow Field ◽  
Hydraulic Structure ◽  
Field Tests ◽  
Simulation Method ◽  
Flow Path ◽  
Structure Design ◽  
Drill Bit ◽  
Drilling Performance ◽  
Flow Field Characteristics ◽  
Shaft Lining

The hydraulic structure of conventional geophysical drill bit is designed for the general stratum. When conventional geophysical drill bit pierces into a limestone stratum, the shape of cuttings is large because of the high brittleness of limestone. The cuttings are ground repeatedly; this phenomenon can reduce drilling efficiency and increase drilling costs. According to the characteristics of limestone cuttings, the numerical simulation method is used to research downhole flow field characteristics of conventional geophysical drill bit. First, the influence of key hydraulic structure parameters on cuttings removal performance is found. Then, the hydraulic structure is optimized. The flow field characteristics of the hydraulic structure of the geophysical drill bit before and after optimization in the flow path is analyzed, at the bottom of the bit and the annulus area of the shaft lining. The optimized downhole crossflow area increased from 50% to 98%. No vortex was observed at the exit of the flow path and cuttings groove. The downhole pressure gradient increased from 0.12 Mpa to 0.15 Mpa. The cutting removal space in the annulus area of the shaft lining is fully utilized. Field tests show that the cutting removal and drilling performance of optimized geophysical drill bit has improved and the drilling speed increases by 20.6%.

scholarly journals SPH Simulation of Interior and Exterior Flow Field Characteristics of Porous Media

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 918 ◽  
Author(s):  
Shijie Wu ◽  
Matteo Rubinato ◽  
Qinqin Gui
Keyword(s):  
Numerical Simulation ◽  
Porous Media ◽  
Flow Field ◽  
Boundary Conditions ◽  
Water Waves ◽  
Flow Behavior ◽  
Simulation Method ◽  
Interface Problem ◽  
Ocean Engineering ◽  
Flow Field Characteristics

At the present time, one of the most relevant challenges in marine and ocean engineering and practice is the development of a mathematical modeling that can accurately replicate the interaction of water waves with porous coastal structures. Over the last 60 years, multiple techniques and solutions have been identified, from linearized solutions based on wave theories and constant friction coefficients to very sophisticated Eulerian or Lagrangian solvers of the Navier-Stokes (NS) equations. In order to explore the flow field interior and exterior of the porous media under different working conditions, the Smooth Particle Hydrodynamics (SPH) numerical simulation method was used to simulate the flow distribution inside and outside a porous media applied to interact with the wave propagation. The flow behavior is described avoiding Euler’s description of the interface problem between the Euler mesh and the material selected. Considering the velocity boundary conditions and the cyclical circulation boundary conditions at the junction of the porous media and the water flow, the SPH numerical simulation is used to analyze the flow field characteristics, as well as the longitudinal and vertical velocity distribution of the back vortex flow field and the law of eddy current motion. This study provides innovative insights on the mathematical modelling of the interaction between porous structures and flow propagation. Furthermore, there is a good agreement (within 10%) between the numerical results and the experimental ones collected for scenarios with porosity of 0.349 and 0.475, demonstrating that SPH can simulate the flow patterns of the porous media, the flow through the inner and outer areas of the porous media, and the flow field of the back vortex region. Results obtained and the new mathematical approach used can help to effectively simulate with high-precision the changes along the water depth, for a better design of marine and ocean engineering solutions adopted to protect coastal areas.

Analysis of a Control Valve's Inner Flow Field Characteristics Based on CFD

2013 ◽  
Vol 756-759 ◽  
pp. 4652-4655
Author(s):  
Liang Wang
Keyword(s):  
Flow Field ◽  
Energy Loss ◽  
Three Dimensional ◽  
Control Valve ◽  
Flow Path ◽  
Dynamics Simulation ◽  
Flow Field Characteristics ◽  
Simulation Results

In this paper, the inner flow field characteristics of a control valve were analysed through dynamics simulation and showed by using the three-dimensional visualization. Through the analysis of simulation results, reasons were found for the energy loss, which was, then, reduced by the optimized flow path. Calculations about the optimized positions were carried out, the results of which showed an improvement of flow and a significant decrease in energy loss.

scholarly journals Large Eddy Simulation and Flow Field Analysis of Car on the Bridge under Turbulent Crosswind

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Juyue Ding ◽  
Weitan Yin ◽  
Yongqi Ma
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Large Eddy Simulation ◽  
Wind Tunnel Test ◽  
Simulation Method ◽  
Field Analysis ◽  
Long Span Bridges ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Flow Field Characteristics

As more long-span bridges continue to be completed and opened to traffic, the safety of cars driving across the bridge has attracted more and more attention, especially when the car is suddenly affected by the crosswind, the car is likely to have direction deviation or even a rollover accident. In this paper, the large eddy simulation method is used to study the flow field characteristics and safety of the car on the bridge under the turbulent crosswind. The numerical simulation model is established by referring to the Donghai Bridge, and the correctness of the car model is validated by combining with the data of wind tunnel test. The influence of factors such as the porosity and height of the bridge guardrail and the Reynolds number of airflow on the flow field characteristics is analyzed. The study shows that, in order to ensure the safety of cars on the bridge, the bridge guardrail porosity should be small, 35.8% is more suitable, the guardrail height should be more suitable within the range of 1.5–1.625 meters, and the Reynolds number should not be 3.51e + 5. The research results of this paper will provide reference for the optimal design of bridge guardrail.

Study on Mechanical Characteristic of Two-Layer Steel Plate Concrete Shaft Lining under Non Uniform Pressure

2013 ◽  
Vol 351-352 ◽  
pp. 17-21
Author(s):  
Hai Bing Cai ◽  
Hua Cheng ◽  
Yi Chun Huang
Keyword(s):  
Mechanical Characteristic ◽  
Steel Plate ◽  
Concrete Strength ◽  
Simulation Method ◽  
Structure Design ◽  
Actual Condition ◽  
Uniform Pressure ◽  
Research Findings ◽  
Shaft Lining ◽  
Layer Steel

Aiming at the actual condition that non uniform pressure act on shaft linging, adopting finite element numerical simulation method, mechanical characteristic of two-layer steel plate concrete shaft lining is researched. Based on pertinent regulations of concrete strength improving coefficient in the state of triaxiality stress, designed twolayer steel plate concrete shaft lining meet strength need under non uniform pressure. The research findings can provide referrence for similar structure design.

scholarly journals Research on variation law of geophysical drill-bit downhole flow field under the interaction of multiple hydraulic factors

2021 ◽  
Vol 104 (3) ◽  
pp. 003685042110316
Author(s):  
Zhiqiang Huang ◽  
Wenlin Zhang ◽  
Jing Zhu ◽  
Dou Xie ◽  
Maolin Dai
Keyword(s):  
Flow Field ◽  
Removal Efficiency ◽  
Hydraulic Structure ◽  
Simulation Software ◽  
Flow Channel ◽  
Petroleum Exploration ◽  
Drill Bit ◽  
Geophysical Prospecting ◽  
Structure Factors ◽  
Chip Removal

Mountain geophysical prospecting operations play an important role in the entire petroleum exploration field. Geophysical drill-bit is the main tool for mountain geophysical prospecting operations. Its hydraulic structure directly affects the downhole flow field and then affects the chip removal efficiency and drilling efficiency of the bit. At present, most of the scholars’ research is focused on Poly Diamond Crystalline bit, roller bit, etc., and the research on geophysical drill-bit is less, and most of them study the downhole flow field based on the change of single hydraulic structure. The primary objective of this research is to study the variation law of the downhole flow field under the interaction of multiple hydraulic structure factors. The drilling time and cuttings size of two geophysical drill-bits with different hydraulic structures are compared, and the key hydraulic structure factors are selected for analysis. Using numerical simulation software, take different levels of key hydraulic structure parameters and carry out orthogonal experiments. Under the interaction of various factors, study the flow field distribution in the flow channel, the downhole, and the annulus area of the shaft lining. The hydraulic structure of the geophysical drill-bit is closely related to the drilling speed and chip removal efficiency. When multiple hydraulic factors are changed, the diameter of the flow channel is the best when it is 10–12.5 mm, the inclination of the flow channel should be set as close as possible to the center of the downhole, and the length of the chip groove increases, the movement of cuttings is more stable. Variation law of downhole flow field under the interaction of multiple hydraulic factors is studied. This study provides a basis for the hydraulic structure design and optimization of the geophysical drill-bit.

Study on the Technology of Stabilization of Sands Using Aeolian Sand Bag in the Desert Area

2014 ◽  
Vol 501-504 ◽  
pp. 2365-2369
Author(s):  
Guang Li Sun ◽  
Qiang Xin ◽  
Hong Zhang ◽  
Jun Bao Luo
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Flow Field ◽  
Field Tests ◽  
Desert Area ◽  
Aeolian Sand ◽  
Speed Reduction ◽  
Fixation Effect ◽  
Flow Field Characteristics ◽  
Desert Areas

Based on "controlling sand to fix sand, managing sand with sand", aiming to the problems of sand hazard in the northwest desert area during the highway construction, the new technique of sand fixation is formed by bags of using widely distributed desert aeolian sand. The flow field characteristics of aeolian sand barrier with fins & nofins are analyzed by wind tunnel tests, the influence of sand barrier forms and specifications to wind speed reduction ratio and roughness are researched by field tests as well as sand fixation effect, the results can provide the guidance and application value to sand fixation engineer of the desert areas

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