Research on structure design and flow field characteristics of the novel jet bit for radial horizontal drilling

According to the principle of fluid dynamics, the Fluent software is used for the numerical simulation analysis of three-dimensional single-hole nozzle submerged jet flow field of radial drilling inclined shaft. The results show that when the bottom is tilted, there are two sizes of spiral along the center axis, and the vortices along tilt direction of the wall are stronger. When the jet source closes the bottom, the kinetic energy of jet is converted into the impact for the bottom of well, making the pressure of bottom hole on the wall have a tendency to rise.

Download Full-text

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

Science Progress ◽

10.1177/0036850420931257 ◽

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%.

Download Full-text

Flow-field characteristics and normal-force correlations for delta wings from Mach 2.4 to 4.6

10.2514/6.1989-26 ◽

1989 ◽

Cited By ~ 1

Author(s):

PETER COVELL ◽

GARY WESSELMANN

Keyword(s):

Flow Field ◽

Normal Force ◽

Delta Wings ◽

Flow Field Characteristics

Download Full-text

Design and manufacture of the novel drum worm pair

Science Progress ◽

10.1177/0036850420981220 ◽

2020 ◽

Vol 103 (4) ◽

pp. 003685042098122

Author(s):

Jingzi Zhang ◽

Jin’ge Wang ◽

Kai Wang

Keyword(s):

Contact Stresses ◽

Primary Objective ◽

Structure Design ◽

Worm Gear ◽

The Novel ◽

Bending Stress ◽

Manufacturing Method ◽

Design And Manufacture ◽

Maximum Contact ◽

Worm Drive

Although a significant amount of research on robot joint reducer was conducted, there are few systematic investigations on a novel joint reducer adopting inner worm-gear plane enveloping drum worm drive. To satisfy the development of modular robot joint, the primary objective of this paper was to systematically investigate the drum worm drive adopted in the novel joint reducer with integrated structure of drive, transmission, and support in the following aspects: meshing theory, design, analysis, and manufacture. According to the gear meshing theory, mechanical design method, classical mechanics, finite element method, and machining principle of virtual center distance, the systematic investigations around the drum worm pair applied in the novel joint reducer were conducted including the macro and micro meshing theory, structure design, mechanical and contact properties analyses, and manufacturing method. The novel joint reducer’s integrated structure was designed, and the drum worm pair’s mechanical and contact properties analyses were conducted, which showed: (1) the worm’s bending stress and deflection, worm-gear teeth’s shear stress and bending stress as well as the maximum contact stresses were all below their corresponding allowable values; (2) the maximum contact stresses appeared at the engage-in position of the worm pair opposing to the engaging-out position where the largest contact areas appeared. Then the manufacturing of drum worm’s spiral tooth was conducted via the modified 4-axis linkage CNC grinder according to the conjugate motion. Finally the novel joint reducer’s industrial prototype was assembled. The novel joint reducer with integrated structure of drive, transmission and support was designed and manufactured for the first time. The flowchart of design and manufacture of the reducer’s drum worm pair in this process was formulated, which provides a new insight on the research of joint reducers as well as other fields.

Download Full-text

Coupled Fluid–Solid Numerical Simulation for Flow Field Characteristics and Supporting Performance of Flexible Support Cylindrical Gas Film Seal

Aerospace ◽

10.3390/aerospace8040097 ◽

2021 ◽

Vol 8 (4) ◽

pp. 97

Author(s):

Junfeng Sun ◽

Meihong Liu ◽

Zhen Xu ◽

Taohong Liao ◽

Xiangping Hu ◽

...

Keyword(s):

Flow Field ◽

Film Thickness ◽

Fluid Dynamic ◽

Structural Characteristics ◽

Structural Parameters ◽

Equivalent Stress ◽

Three Dimensional ◽

High Rotational Speed ◽

Flexible Support ◽

Flow Field Characteristics

A new type of cylindrical gas film seal (CGFS) with a flexible support is proposed according to the working characteristics of the fluid dynamic seal in high-rotational-speed fluid machinery, such as aero-engines and centrifuges. Compared with the CGFS without a flexible support, the CGFS with flexible support presents stronger radial floating characteristics since it absorbs vibration and reduces thermal deformation of the rotor system. Combined with the structural characteristics of a film seal, an analytical model of CGFS with a flexible wave foil is established. Based on the fluid-structure coupling analysis method, the three-dimensional flow field of a straight-groove CGFS model is simulated to study the effects of operating and structural parameters on the steady-state characteristics and the effects of gas film thickness, eccentricity, and the number of wave foils on the equivalent stress of the flexible support. Simulation results show that the film stiffness increases significantly when the depth of groove increases. When the gas film thickness increases, the average equivalent stress of the flexible support first decreases and then stabilizes. Furthermore, the number of wave foils affects the average foils thickness. Therefore, when selecting the number of wave foils, the support stiffness and buffer capacity should be considered simultaneously.

Download Full-text

Influence of Vortex Finder Structure on Separation Performance of Double-Overflow Three-Product Hydrocyclones

Separations ◽

10.3390/separations8060079 ◽

2021 ◽

Vol 8 (6) ◽

pp. 79

Author(s):

Yuekan Zhang ◽

Jiangbo Ge ◽

Lanyue Jiang ◽

Hui Wang ◽

Junru Yang ◽

...

Keyword(s):

Numerical Simulation ◽

Flow Field ◽

Experimental Research ◽

Separation Efficiency ◽

Structural Parameters ◽

Separation Performance ◽

Insertion Depth ◽

Flow Field Characteristics ◽

Vortex Finder ◽

Fine Classification

In view of the difficulty of traditional hydrocyclones to meet the requirements of fine classification, a double-overflow three-product (internal overflow, external overflow and underflow) hydrocyclone was designed in this study. Numerical simulation and experimental research methods were used to investigate the effects of double-overflow flow field characteristics and structural parameters (i.e., internal vortex finder diameter and insertion depth) on separation performance. The research results showed that the larger the diameter of the internal vortex finder, the greater the overflow yield and the larger the cut size. The finest internal overflow product can be obtained when the internal vortex finder is 30 mm longer than the external vortex finder. The separation efficiency is highest when the internal vortex finder is 30 mm shorter than the external vortex finder.

Download Full-text

Design of a Double-Nozzle Air Spray Gun and Numerical Research in the Interference Spray Flow Field

Coatings ◽

10.3390/coatings10050475 ◽

2020 ◽

Vol 10 (5) ◽

pp. 475

Author(s):

Yin-An Wang ◽

Xiao-Peng Xie ◽

Xiao-Hui Lu

Keyword(s):

Flow Field ◽

Central Region ◽

Interference Effect ◽

Thickness Distribution ◽

Computational Domain ◽

Coating Film ◽

Discrete Phase Model ◽

Spray Painting ◽

Flow Field Characteristics ◽

Spray Gun

Spray painting robots equipped with air spray guns have been widely used in the painting industry. In view of the low efficiency of single-nozzle air spray guns when spraying large targets, a new double-nozzle air spray gun structure was designed in this paper based on the Coanda effect of double jets. Firstly, a 3-D physical model of the double-nozzle air spray gun was built in Solidworks, in which unstructured grids were generated for the computational domain by ICEM. Secondly, the spray painting process was numerically modeled with the help of the computational fluid dynamics (CFD) software ANSYS-Fluent 16.0. The two-phase spray flow was calculated by coupling a discrete phase model (DPM) and the Taylor analogy breakup (TAB) method. The TAB model was applied to predict the secondary break-up. The DPM model was applied to predict the droplet trajectories. The geometry of an air spray gun has a significant influence on the spray flow field characteristics. The influence of the air spray gun geometry on the interference spray flow field characteristics and coating film thickness distribution were investigated by changing the values of the distance between the centers of the two paint holes (L) and the angle between the axes of the two paint holes (θ). Numerical results show that the smaller L and θ are, the stronger the interference effect between the two jets, while the more concentrated the paint is in the central region of the target surface, the easier it is for overspray to occur. With increasing L and θ, the interference effect gradually decreased and the extension distance of the coating film along the x-axis gradually increased. However, if L and θ are too large, the interference effect will become too weak and the shape of the coating film will become a concave, with more paint on both side regions and less paint in the central region, which will cause an uneven coating film. From the simulation results, it can be concluded that a more uniform coating film can be obtained when L = 30 mm and θ = 10°. The effective coating width of the double-nozzle air spray gun was increased by 85.7% compared with the single-nozzle air spray gun, which improved the spraying efficiency.

Download Full-text

Effects of Flue Gas Inlet Structure on the Flow Field Characteristics of Multi-Stage Liquid Column Scrubber

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.773.749 ◽

2013 ◽

Vol 773 ◽

pp. 749-754

Author(s):

Zhen Ya Duan ◽

Fu Lin Zheng ◽

Hui Ling Shi ◽

Jun Mei Zhang

Keyword(s):

Flow Field ◽

Flue Gas ◽

Static Pressure ◽

Liquid Column ◽

Liquid Distribution ◽

Multi Stage ◽

Flow Field Characteristics ◽

Wall Flow ◽

Two Peaks ◽

Saddle Shape

In this paper, the numerical model of multi-stage liquid column scrubber was established. The flow field of liquid column scrubber with different inlet structure was respectively simulated by a commercial CFD code, Fluent. Considering the distribution characteristics of static pressure and velocity in the scrubber, this inlet type, single horizontal gas inlet with a notch at the bottom, is regarded as the most reasonable structure. On one hand, that structure has uniform distribution of static pressure. On the other hand, the velocity profile of its field presents saddle shape, i.e. the low central velocity exists between two peaks, which could contribute to weakening wall-flow phenomenon and obtaining uniform gas-liquid distribution.

Download Full-text

Research on Flow Field Characteristics Affected by Obstacles of Pull-Push Ventilation System of Plating Tanks through Numerical Simulation

MATEC Web of Conferences ◽

10.1051/matecconf/20166808001 ◽

2016 ◽

Vol 68 ◽

pp. 08001

Author(s):

Hong Hu ◽

Can-nan Yi

Keyword(s):

Numerical Simulation ◽

Flow Field ◽

Ventilation System ◽

Flow Field Characteristics

Download Full-text

A Study of Two-Dimensional Supersonic Air Ejector Systems

Proceedings of the Institution of Mechanical Engineers ◽

10.1243/pime_proc_1973_187_064_02 ◽

1973 ◽

Vol 187 (1) ◽

pp. 733-743

Author(s):

R. S. Benson ◽

V. A. Eustace

Keyword(s):

Flow Field ◽

Secondary Flow ◽

Ambient Pressure ◽

Performance Characteristics ◽

Constant Density ◽

Two Dimensional ◽

Theoretical Predictions ◽

Flow Field Characteristics ◽

Air Ejector

The performance and flow field characteristics for two-dimensional ejector systems are determined theoretically for the condition when operation is independent of ambient pressure. The method considers the detailed inviscid interaction between the primary and secondary streams within the mixing tube and an estimate is made of the secondary flow entrained by the two-stream viscous mixing region. The validity of the theory is tested by comparing the performance characteristics of an experimental ejector facility with theoretical predictions and by comparing the theoretical flow field, in terms of constant density contours, with infinite fringe interferograms.

Download Full-text