scholarly journals Design and numerical analysis of a large‐diameter air reverse circulation drill bit for reverse circulation down‐the‐hole air hammer drilling

2019 ◽  
Vol 7 (3) ◽  
pp. 921-929
Author(s):  
Xinxin Zhang ◽  
Yongjiang Luo ◽  
Xin Gan ◽  
Kun Yin
Keyword(s):  
Numerical Analysis ◽  
Large Diameter ◽  
Drill Bit ◽  
Air Hammer ◽  
Reverse Circulation

The Modal Analysis of Large Diameter Percussive Reverse Circulation Drill Bit

2017 ◽  
Author(s):  
Xiao-Qin Shen ◽  
Huan-Huan Li ◽  
Bo Wang ◽  
Qi-Liang Cheng
Keyword(s):  
Modal Analysis ◽  
Large Diameter ◽  
Drill Bit ◽  
Reverse Circulation

Structure Design of and Numerical Simulation on an Annular Reverse Circulation Drill Bit

2015 ◽  
Vol 733 ◽  
pp. 558-561 ◽  
Author(s):  
Jin Song Wang ◽  
Pin Lu Cao ◽  
Kun Yin
Keyword(s):  
Numerical Simulation ◽  
Mineral Resources ◽  
Structure Design ◽  
Drilling Fluids ◽  
Drill Bit ◽  
Well Drilling ◽  
Air Hammer ◽  
Reverse Circulation ◽  
New Type ◽  
Drilling Bit

The reverse circulation drilling technology of hollow through DTH air hammer is a set of efficient coring with DTH air hammer, full-hole reverse circulation with drilling fluids, and continuous coring without power lack. It been successfully applied in mineral resources exploration, water well drilling, infrastructure construction and other fields. We designed a new type of annular reverse circulation drilling bit in order to prevent drilling accident when drilling in complex strata, such as breakage and leakage. In this paper, the computational fluid dynamics (CFD) code, FLUENT, is employed to simulate the flow phenomena of reverse circulation drill bit. Numerical simulation results show that the values of negative pressure of new type annular reverse circulation drill bit which formed in the center channel and the bottom of hole were larger than those of the normal bit. Under the same conditions, the suction quantity from annulus of annular drilling bit is 1.4 times to the normal one.

The numerical analysis of a large diameter spherical valve

2018 ◽  
Vol 18 (5) ◽  
pp. 300
Author(s):  
Shidong Li ◽  
Zhiyong Wu
Keyword(s):  
Numerical Analysis ◽  
Large Diameter

Study on Structure Parameters of Reverse Circulation Drill Bit Secondary Injector Device Based on Injector Coefficient

2016 ◽  
Author(s):  
Huang Yong ◽  
Zhu Lihong ◽  
Zou Deyong ◽  
Liao Hualin ◽  
Wang Jinying ◽  
...  
Keyword(s):  
Drill Bit ◽  
Structure Parameters ◽  
Reverse Circulation

Axial performance of micropile groups in cohesionless soil from full-scale tests

2020 ◽  
Vol 57 (7) ◽  
pp. 1006-1024
Author(s):  
Maged A. Abdlrahem ◽  
M. Hesham El Naggar
Keyword(s):  
Group Performance ◽  
Large Diameter ◽  
Small Diameter ◽  
Element Model ◽  
Cohesionless Soil ◽  
Drill Bit ◽  
Load Testing ◽  
Dense Sand ◽  
Full Scale Tests ◽  
Square Configuration

Hollow bar micropile (HBMP) groups are used for supporting large loads as an alternative foundation option to large diameter drilled shafts. In such cases, it may be necessary to increase the micropile’s diameter by increasing the drill bit diameter (Db). This paper investigates experimentally and numerically the effect of increasing Db and micropile spacing on the group performance. A field load testing program was conducted on four groups of HBMPs installed in sand; each group comprised four micropiles arranged in a square configuration. All micropiles were constructed with the same size hollow bar, Dh = 51 mm; two groups comprised micropiles constructed with drill bit, Db = 115 mm, and two groups comprised micropiles constructed with drill bit, Db = 152 mm. One group of each set was installed with spacing to micropile diameter ratio, S/Db = 3 and the other group with S/Db = 5. In addition, full 3D finite element model (FEM) was developed and calibrated to simulate the behaviour of micropile groups and to evaluate the failure load for groups that were not loaded to failure. The results demonstrated that micropile groups constructed with the large diameter drill bits displayed higher stiffness and load carrying capacity than the groups constructed with small diameter bits, which confirms the effectiveness of using a larger drill bit. In addition, the group efficiency ratio values at both working load and ultimate capacity were found to be close to unity for all groups. The ultimate skin friction values of grouted micropiles obtained from this study were higher than the values suggested by the US Federal Highway Administration for medium to very dense sand. It was also found that the settlement of the 4-HBMP group increased by 25% to 33% over that of a single HBMP due to group effect.

scholarly journals Orthogonal experimental research on the structural parameters of a novel drill bit used for ice core drilling with air reverse circulation

2019 ◽  
Vol 65 (254) ◽  
pp. 1011-1022 ◽  
Author(s):  
Pinlu Cao ◽  
Qi Zhao ◽  
Zhuo Chen ◽  
Hongyu Cao ◽  
Baoyi Chen
Keyword(s):  
Structural Parameters ◽  
Ice Core ◽  
Influential Factor ◽  
Dominant Factor ◽  
Orthogonal Experimental Design ◽  
Drill Bit ◽  
Entrainment Ratio ◽  
Core Drilling ◽  
Helical Angle ◽  
Reverse Circulation

AbstractA new type of ice core drill bit, designed with a vane swirler, was developed for ice core drilling with air reverse circulation. An orthogonal experimental design method was employed to investigate the effects of the swirler structure parameters on the reverse circulation performance of the drill bit including helical angle, number of blades, blade length and blade central angle, etc. The entrainment ratio was used to evaluate the reverse circulation effectiveness of the drill bit. The results show that the helical angle is the dominant factor regardless of whether or not the flushing nozzles are part of the design of the drill bit. The number of blades is the least important factor for the drill bit designed with the flushing nozzles (referred to as drill bit I), while the outlet area of the swirling slot is the least influential factor for the drill bit without flushing nozzles (referred to as drill bit П). In addition, the appearance of the ice core has a certain effect on the air reverse circulation for both drill bits. Within the ranges of this study, the optimal structure of the drill bit was determined based on the range analysis of the orthogonal design.

Numerical Analysis of a Single Large-diameter Cofferdam under Offshore Loadings

2019 ◽  
pp. 107-112
Author(s):  
Jeongsoo Kim ◽  
Yeon-Ju Jeong ◽  
Min-Su Park
Keyword(s):  
Numerical Analysis ◽  
Large Diameter

Numerical Analysis of Flow-Induced Vibration of Large Diameter Pipe With Short Elbow

2017 ◽  
Author(s):  
Shigeru Takaya ◽  
Tatsuya Fujisaki ◽  
Masaaki Tanaka
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Fast Reactor ◽  
Pressure Fluctuation ◽  
Cooling System ◽  
Large Diameter ◽  
Recirculation Region ◽  
Flow Induced Vibration ◽  
Scaled Model ◽  
Energy Agency

Japan Atomic Energy Agency is now conducting design study and R&D of an advanced loop-type sodium cooled fast reactor. The cooling system is planned to be simplified by employing a two-loop configuration and shortened piping with less elbows than a prototype fast reactor in Japan, Monju, in order to reduce construction costs and enhance economic performance. The design, however, increases flow velocity in the hot-leg piping and induces large flow turbulence around elbows. Therefore, flow-induced vibration (FIV) of a hot-leg piping is one of main concerns in the design. Numerical simulation is a useful method to deal with such a complex phenomenon. We have been developing numerical analysis models of the hot-leg piping using Unsteady Reynolds Averaged Navier-Stokes simulation with Reynolds stress model. In this study, numerical simulation of a 1/3 scaled-model of the hot-leg piping was conducted. The results such as velocity profiles and power spectral densities (PSD) of pressure fluctuations were compared with experiment ones. The simulated PSD of pressure fluctuation at the recirculation region agreed well with the experiment, but it was found some underestimation at other parts, especially in relatively high frequency range. Eigenvalue vibration analysis was also conducted using a finite element method. Then, stress induced by FIV was evaluated using pressure fluctuation data calculated by URANS simulation. The calculated stress generally agrees well the measurement values, which indicates the importance of precise evaluation of the PSD of pressure fluctuation at the recirculation region for evaluation of FIV of the hot-leg piping with a short elbow.

scholarly journals Experimental and Numerical Analysis of Flow Behavior for Reverse Circulation Drill Bit with Inserted Swirl Vanes

Geofluids ◽  
2022 ◽  
Vol 2022 ◽  
pp. 1-13
Author(s):  
Cheng Yang ◽  
Jianliang Jiang ◽  
Bo Qi ◽  
Guoqing Cui ◽  
Liyong Zhang ◽  
...  
Keyword(s):  
Cfd Simulation ◽  
Structural Parameters ◽  
Flow Behavior ◽  
Experimental Tests ◽  
Maximum Error ◽  
Influential Factors ◽  
Drill Bit ◽  
Entrainment Ratio ◽  
Helical Angle ◽  
Reverse Circulation

A swirling drill bit designed with an integrated vane swirler was developed to improve reverse circulation in down-the-hole hammer drilling. Its entrainment effect and influential factors were investigated by CFD simulation and experimental tests. The numerical results exhibit reasonable agreement with the experimental data, with a maximum error of 13.68%. In addition, the structural parameters of the swirler were shown to have an important effect on the reverse circulation performance of the drill bit, including the helical angle and number of spiral blades, swirler outlet area, and the flushing nozzles. The optimal parameters for the swirling drill bit without flushing nozzles include a helical angle of 60°, four spiral blades, and the area ratio of 2, while it is about 30°, 3, and 3 for the drill bit with flushing nozzles. Moreover, the entrainment ratio of the drill bit without flushing nozzles can be improved by nearly two times compared with one with flushing nozzles under the same conditions.

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