scholarly journals Dynamic Analysis of Bottom Hole Assembly With External Vibrating Force Excitation

2013 ◽  
Author(s):  
Lei Wang ◽  
Stephen Butt ◽  
Jianming Yang
Keyword(s):  
Cfd Simulation ◽  
Model Simulation ◽  
Fluid Pressure ◽  
Rock Interaction ◽  
Bottom Hole ◽  
Bottom Hole Assembly ◽  
Computational Fluid Dynamics Cfd ◽  
Simulation Results ◽  
Force Excitation ◽  
Valve Part

Based on the Downhole Oscillating Device (DOD) newly developed for purpose of improving drilling efficiency, Computational Fluid Dynamics (CFD) simulation is conducted. The axial vibration force created by the DOD is thoroughly investigated. The simulation is focused on the valve part which generates the fluid pressure pulsations. Fluid flow rate and/or back pressure is applied to the model as boundary conditions. The DOD’s application will also induce the inertia phenomenon of the fluid column above the tool. This phenomenon is also studied based on parametric analysis. Within the simulation results, a dynamic model is developed to further investigate the effect of the oscillating force generated by the DOD on drilling efficiency. Nonlinearities in the bit-rock interaction are taken into account in the model. Simulation results show that application of the DOD in drilling may improve the ROP at least by 5%.

Investigation on Effect of Downhole Vibration Force on Drilling Performance With a Dynamic BHA Model

2015 ◽  
Author(s):  
Lei Wang ◽  
Jianming Yang ◽  
Stephen Butt ◽  
Hongyuan Qiu
Keyword(s):  
Finite Element Method ◽  
Angular Frequency ◽  
Mean Value ◽  
Rock Interaction ◽  
Drilling Performance ◽  
Bottom Hole ◽  
Bottom Hole Assembly ◽  
The Mean ◽  
Simulation Results ◽  
Force Excitation

A dynamic bottom hole assembly (BHA) model is built with finite element method (FEM) in this paper. This model is used for evaluation the influence of externally added vibration to the BHA system. With this dynamic model along with a general bit-rock interaction formula, the BHA’s motion in axial and torsional directions are examined. Parametric study is carried out by varying the parameters of the applied vibration force, including the mean value, amplitude, angular frequency, and the location of this force excitation. The simulation results indicate that externally applied vibration force is indeed able to improve drilling performance. In particular, the mean value and amplitude of the applied force have a almost linear relation with ROP and WOB. The stresses distributions along BHA are investigated as well.

Alpha Radioactivity Monitor Using Ionized Air Transport Technology for Large Size Uranium Waste: Part 2—Simulation Model Reinforcement for Practical Apparatus Design

2010 ◽  
Author(s):  
Takatoshi Asada ◽  
Yosuke Hirata ◽  
Susumu Naito ◽  
Mikio Izumi ◽  
Yukio Yoshimura
Keyword(s):  
Ion Transport ◽  
Simulation Model ◽  
Cfd Simulation ◽  
Transport Model ◽  
Model Simulation ◽  
Ion Density ◽  
Transport Simulation ◽  
Simulation Results ◽  
Alpha Radioactivity ◽  
Ionized Air

In alpha radioactivity measurement using ionized air transportation (AMAT), conversion from ion currents to radioactivity accurate is required. An ion transport simulation provides ways of complementarily determining conversion factors. We have developed an ion transport simulation model. Simulation results were compared with experiments with air speeds, faster than 1 m/s, achieving good agreement. In a practical AMAT apparatus, the air-flow at the alpha source may be slower than 1 m/s, and ion loss is likely to be large. Reinforcement of the ion transport model to cover the lower air speed region is effective. Ions are generated by an alpha particle in a very thin column. Since the ion density at this temporal stage is high, the recombination loss, proportional to the square of ion density, is dominant within a few milli-seconds. The spatial and temporal scales of this columnar recombination are too small for CFD simulation. We solve an ion transport equation during the period of columnar recombination with diffusion and recombination terms and incorporated the relation between ion loss and turbulent parameters into CFD. Using this model, simulations have been done for various air speeds and targets. Those for simulation results agree with experiments, showing improvement of simulation accuracy.

Optimal Hardware Placement in a Minitower Computer Enclosure System

2011 ◽  
Author(s):  
M. Alfaro Cano ◽  
A. Hernandez-Guerrero ◽  
C. Rubio Arana ◽  
Aristotel Popescu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Operating Temperature ◽  
Optimal Placement ◽  
Cfd Analysis ◽  
Computational Fluid Dynamics Cfd ◽  
Simulation Results ◽  
The Relationship ◽  
Key Questions

One of the requirements for existing personal computers, PCs, is that the hardware inside must maintain an operating temperature as low as possible. One way to achieve that is to place the hardware components at locations with enough airflow around it. However, the relationship between the airflow and temperature of the components is unknown before they are placed at specific locations inside a PC. In this work a Computational Fluid Dynamics (CFD) analysis is coupled to a Design of Experiment (DOE) methodology to answer typical minitower key questions: a) how do the possible positions of hardware components affect their temperature?, and b) is it possible to get an optimal placement for these hardware components using the data collected by the CFD simulation results? The DOE methodology is used to optimize the analysis for a very large number of possible configurations. The results help in identifying where the efforts need to be placed in order to optimize the positioning of the hardware components for similar configurations at the designing stage. Somehow the results show that general conclusions could be drawn, but that there are not specific rules that could be applied to every configuration.

Simulation on Flow Field and Temperature Field in Water Cooling Tuyere of Blast Furnace

2013 ◽  
Vol 753-755 ◽  
pp. 2709-2712 ◽  
Author(s):  
Ya Na Qie ◽  
Shu Hui Zhang ◽  
Qing Lv ◽  
Li Hong Zhang
Keyword(s):  
Temperature Field ◽  
Economic Benefit ◽  
Cfd Simulation ◽  
Water Pressure ◽  
High Yield ◽  
Maximum Temperature ◽  
Water Cooling ◽  
Direct Motion ◽  
Computational Fluid Dynamics Cfd ◽  
Simulation Results

Life span of water cooling tuyere is one of important factors of blast furnace’s direct motion and high yield. In order to improve the life of tuyere, the flow fleld and temperature field of tuyere were simulated by using computational fluid dynamics (CFD). Simulation results show that the maximum temperature appears at the front margin of tuyere outlet side. The highest temperature of tuyere reduces significantly with the increase of water pressure below 0.4MPa. When the water pressure exceeds 0.4Pa, the highest temperature reduces slowly. In consideration of economic benefit and cooling effect, the best point of inlet pressure is 0.4MPa or so.

Model Development of Torsional Drillstring and Investigating Parametrically the Stick-Slips Influencing Factors

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Parimal Arjun Patil ◽  
Catalin Teodoriu
Keyword(s):  
Nonlinear Differential Equations ◽  
Torsional Oscillation ◽  
Stick Slip ◽  
Friction Forces ◽  
Rock Interaction ◽  
Torsional Oscillations ◽  
Drilling Performance ◽  
Bottom Hole ◽  
Drilling Parameters ◽  
Bottom Hole Assembly

Drillstring vibration is one of the limiting factors maximizing drilling performance. Torsional vibrations/oscillations while drilling is one of the sever types of drillstring vibration which deteriorates the overall drilling performance, causing damaged bit, failure of bottom-hole assembly, overtorqued tool joints, torsional fatigue of drillstring, etc. It has been identified that the wellbore-drillstring interaction and well face-drill bit interaction are the sources of excitation of torsional oscillations. Predrilling analysis and real time analysis of drillstring dynamics is becoming a necessity for drilling oil/gas or geothermal wells in order to optimize surface drilling parameters and to reduce vibration related problems. It is very challenging to derive the drillstring model considering all modes of vibrations together due to the complexity of the phenomenon. This paper presents the mathematical model of a torsional drillstring based on nonlinear differential equations which are formulated considering drillpipes and bottom-hole assembly separately. The bit–rock interaction is represented by a nonlinear friction forces. Parametric study has been carried out analyzing the influence of drilling parameters such as surface rotations per minute (RPM) and weight-on-bit (WOB) on torsional oscillations. Influences of properties of drillstring like stiffness and inertia, which are most of the times either unknown or insufficiently studied during modeling, on torsional oscillation/stick-slip is also studied. The influences of different rock strength on rate of penetration (ROP) considering the drilling parameters have also been studied. The results show the same trend as observed in fields.

scholarly journals Performance Assessment of Bladeless Micro-Expanders Using 3D Numerical Simulation

2019 ◽  
Vol 113 ◽  
pp. 03016 ◽  
Author(s):  
Avinash Renuke ◽  
Alberto Traverso ◽  
Matteo Pascenti
Keyword(s):  
Shear Stress ◽  
Cfd Simulation ◽  
Numerical Data ◽  
Flow Density ◽  
Cfd Analysis ◽  
Mixing Zone ◽  
Sst Turbulence Model ◽  
Computational Fluid Dynamics Cfd ◽  
Simulation Results ◽  
First Time

This paper summarizes the development of fully 3D Computational Fluid Dynamics (CFD) analysis for bladeless air micro expander for 200 W and 3 kW rated power. Modelling of nozzle along with rotor is done using structured mesh. This analysis, for the first time, demonstrates the interaction between nozzle and rotor using compressible flow density-based solver. The Shear Stress Transport (SST) turbulence model is employed to resolve wall effects on the rotor and to determine the shear stress accurately. The results illustrate the flow field inside stator and rotor along with complicated mixing zone between stator and rotor. The comparison of rotor-stator CFD simulation results is done with experiments to preliminary validate the model. The losses in the turbine are discussed with the help of experimental and numerical data.

The Effect of Stick Slip Vibration on the Backward Whirl of Bottom Hole Assembly in Drillstring

2016 ◽  
Author(s):  
Dapeng Zhao ◽  
Sigve Hovda ◽  
Sigbjørn Sangesland
Keyword(s):  
Torsional Vibration ◽  
Borehole Wall ◽  
Stick Slip ◽  
Rock Interaction ◽  
Bottom Hole ◽  
Nonlinear Contact ◽  
Backward Whirl ◽  
Bottom Hole Assembly ◽  
Rotary Speed ◽  
Drill Collar

The whirl phenomena in the bottom hole assembly (BHA) is believed to be formed by the imbalance of the rotational drill collar. Backward whirl is caused by the nonlinear contact between the BHA and the borehole, and can be extremely damaging to the down hole tools and borehole. In the previous studies, a two-degrees-of-freedom lumped parameter model is developed for representing the drill collar in lateral motions (whirl). Due to the bit-rock interaction, the stick slip torsional vibration is very common. In the current work, therefore, the torsional vibration causing fluctuation of rotary speed is taken into account. The simulation results indicate that the drill collar whirls forward at lower constant rotary speed. With increasing rotary speed, the backward whirl is activated by the contact between the drill collar and the borehole wall. The nonlinear contact forces obey the Hertzian contact law, which led to lateral bounce of the drill collar and impact borehole wall chaotically. The modified Karnopp friction model is adopted to simulate the stick slip rotary vibration of the BHA. The different characters of lateral vibrations are identified by a power spectrum density diagram with and without consideration of the stick slip vibration.

Dynamic Modelling of Horizontal Shafts With Annular Surface Contact and Friction: Application to Oilwell Drilling

2014 ◽  
Author(s):  
Md. Mejbahul Sarker ◽  
D. Geoff Rideout ◽  
Stephen D. Butt
Keyword(s):  
Three Dimensional ◽  
Dynamic Modelling ◽  
Lateral Vibration ◽  
Horizontal Section ◽  
Stick Slip ◽  
Rock Interaction ◽  
Bottom Hole ◽  
Proposed Model ◽  
Bottom Hole Assembly ◽  
Friction Dynamics

Lateral whirl vibrations in long sections of horizontal oilwell drillstrings, which are essentially enclosed shafts lying on the low side of the wellbore, are potentially destructive to the bit, pipes and downhole tools. Forward or backward whirl can lead to impact with the borehole, and stick slip and bit bounce can cause tool joint failure, twist-off, and bit damage. A complete deviated drillstring has been modelled by having decoupled axial and torsional segments for the vertical and curved portions, and nonlinear three-dimensional multibody segments with lateral vibration in the final horizontal section ending at the bit. The model can predict how axial and torsional bit-rock reactions are propagated to the surface, and the role that lateral vibration near the bit plays in exciting those vibrations and stressing components in the bottom-hole-assembly. The proposed model includes the mutual dependence of these vibrations, which arises due to bit-rock interaction and friction dynamics between the drillstring and wellbore wall.

scholarly journals CFD Simulation of the Airflow Distribution Inside Cube-Grow

CFD Letters ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 81-89
Author(s):  
Arina Mohd Noh ◽  
Hamdan Mohd Noor ◽  
Fauzan Ahmad
Keyword(s):  
Plant Growth ◽  
Urban Agriculture ◽  
Cfd Simulation ◽  
Measurement Data ◽  
Actual Measurement ◽  
Airflow Distribution ◽  
Computational Fluid Dynamics Cfd ◽  
Simulation Results ◽  
Urban People ◽  
Air Hole

Cube-Grow was developed by MARDI to promote urban agriculture to the urban population. The product enables urban people to grow their vegetables with limited space. The initial test run of the system shows that the plant growth inside the structure was below expectation. The problem arises due to a lack of airflow or improper ventilation inside the structure. Optimum ventilation or airflow is crucial for plant growth as it enhances evapotranspiration at the leaf area to promote optimum plant growth. Therefore, this study aims to increase the airflow inside the Cube-Grow and find the best location for the air hole. Computational fluid dynamics (CFD) simulation was used in this study the analyse the effect of adding an air hole to the airflow characteristic inside the Cube-Grow. CFD also was used to select the best location to place the air hole. 3 option of air hole location was analysed and the results were compared with the existing design. The initial CFD simulation results were compared with the actual measurement data before it was used for further analysis. The result shows that adding an air hole increases overall airflow inside the Cube-Grow. Option 3 was chosen as the best location for the air hole as it produces a uniform and higher airflow inside the Cube-Grow. The study proved that CFD was able to be used to optimize the design of Cube-Grow before the actual prototype was built.

Optimization of Quench Tank Structure Based on CFD Simulation

2006 ◽  
Vol 118 ◽  
pp. 363-368 ◽  
Author(s):  
Nai Lu Chen ◽  
Wei Min Zhang ◽  
Qiang Li ◽  
Chang Yin Gao ◽  
Bo Liao ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Draft Tube ◽  
Structure Design ◽  
Rate Distribution ◽  
Large Size ◽  
Solid Foundation ◽  
Computational Fluid Dynamics Cfd ◽  
Simulation Results

In order to investigate the flow rate distribution and improve the flow rate uniformity of the quenchant in a quench tank, the ultrasonic Doppler velocimeter (UDV) was used to measure the flow rate of quenchant with agitation, and then a computational fluid dynamics (CFD) simulation was carried out to simulate the flow rate distribution without / with flow baffles. According to the CFD simulation results, the structures and positions of flow baffles in the draft-tube were optimized to obtain the uniform flow rate distribution in the quench zone, which were verified by experiments as well. The simulation and experimental results show that the UDV is suitable for measuring the flow rate of a large-size quench tank. This research provided a solid foundation for optimizing the structure design of flow baffles in production quench tanks.

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