CFD Numerical Simulation of the Submarine Pipeline With Spoiler

2008 ◽  
Author(s):  
Jianping Zhao ◽  
Xuechao Wang
Keyword(s):  
Shear Stress ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Hangzhou Bay ◽  
Submarine Pipeline ◽  
Long Distance ◽  
Oil Transportation ◽  
Pipeline Failure ◽  
The Stability ◽  
Coating Weight

Submarine pipeline is one of the most important oil transportation components, pipeline failure due to over-span is the most serious failure mechanism. There are four reasons of pipeline span formation, including erosion of seabed, bumpy seabed, submarine pipeline climbing slope, and pipeline ascending to offshore platform. The Hangzhou Bay submarine pipeline is the most important subproject of the Yong-Hu-Ning network, and it is also the biggest long-distance pipeline for crude oil in China. Due to the dynamic nature of Hangzhou Bay, including high tides and high current amplified by the shallow waters, a self-burial method was selected as the best solution. By increasing the velocity of the stream between the pipeline and the seabed, shear stress on the seabed was enhanced. This localized increase in shear stress causes the seabed under the pipe to erode more quickly and facilitates self-burial of the pipe. To facilitate self-burial, a non-metallic vertical fin is fastened to the top of the pipeline. In this paper flow around a pipeline with and without a spoiler near a smooth wall is simulated with FLUENT version 6.1. The influences of the spoiler on pressure coefficient, lift coefficient, shear stress on the wall, as well as velocity profile are investigated. It is indicated that the coefficients for Drag and Inertia are increased with the application of the spoiler. The lift coefficient is reversed with the application of the spoiler increases the stability of the pipeline resulting in the reduction of the required coating weight.

CFD Numerical Simulation of the Submarine Pipeline With a Spoiler

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Jianping Zhao ◽  
Xuechao Wang
Keyword(s):  
Shear Stress ◽  
Hangzhou Bay ◽  
Shallow Waters ◽  
High Current ◽  
Submarine Pipeline ◽  
Dynamic Nature ◽  
Long Distance ◽  
Obvious Effect ◽  
Oil Transportation ◽  
Pipeline Failure

Submarine pipeline is one of the most important oil transportation components; pipeline failure due to overspan is the most serious failure mechanism. There are four reasons of pipeline span formation, including erosion of seabed, bumpy seabed, submarine pipeline climbing slope, and pipeline ascending to offshore platform. The Hangzhou Bay submarine pipeline is the most important subproject of the Yong-Hu-Ning network, and it is also the biggest long-distance pipeline for crude oil in China. Due to the dynamic nature of Hangzhou Bay, including high tides and high current amplified by the shallow waters, a self-burial method was selected as the best solution. By increasing the velocity of the stream between the pipeline and the seabed, shear stress on the seabed was enhanced. This localized increase in shear stress causes the seabed under the pipe to erode more quickly and facilitates self-burial of the pipe. To facilitate self-burial, a nonmetallic vertical fin is fastened to the top of the pipeline. In this paper flow around a pipeline with and without a spoiler near a smooth wall is simulated with FLUENT version 6.1. It is found that the velocity affected the shear stress, and the height of the spoiler does not have an obvious effect on the shear stress.

scholarly journals Effect of deflector curvature on hydrodynamic performances of a double-slotted cambered otter-board

2018 ◽  
Vol 38 ◽  
pp. 03049
Author(s):  
Lei WANG ◽  
Lu Min Wang ◽  
Jian Gao Shi ◽  
Wen Wen Yu ◽  
Guang Rui Qi ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Wind Speed ◽  
Reference Data ◽  
Center Of Pressure ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Moment Coefficient ◽  
Pitch Moment ◽  
Engineering Models ◽  
The Stability

The effect of deflector curvature on hydrodynamic performances of a double-slotted cambered otter-board was investigated using engineering models in a wind tunnel. Four different curvature (0.06,0.09, 0.12 and 0.15) were evaluated at a wind speed of 28 m/s. Parameters measured included: drag coefficient Cx, lift coefficient Cy, pitch moment coefficient Cm, center of pressure coefficient Cp , over a range of angle of attack (0° to 70°). These coefficients were used in analyzing the differences in the performance among the four otter-board models. Results showed that the maximum lift coefficient Cy of the otter-board model with the curvature (0.06) of two deflectors was highest (2.020 at °=55°). The maximum Cy/Cx of the otter-board with the curvature (0.12) of two deflectors was highest (3.655 at °=22.5°). A comparative analysis of Cm and Cp showed that the stability of otter-board model with the curvature (0.12) of two deflectors is better in pitch, and the stability of otter-board model with the curvature (0.06) of two deflectors is better in roll. The findings of this study can offer useful reference data for the structural optimization of otter-boards for trawling.

scholarly journals Effect of panel shape on hydrodynamic performances of vertical v-shaped double- slotted cambered otter-board

2018 ◽  
Vol 38 ◽  
pp. 03050 ◽  
Author(s):  
Lei Wang ◽  
Xun Zhang ◽  
Lu Min Wang ◽  
Hong Liang Huang ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Reference Data ◽  
Center Of Pressure ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Moment Coefficient ◽  
Isosceles Trapezoid ◽  
Pitch Moment ◽  
Engineering Models ◽  
The Stability

The effect of panel shape on hydrodynamic performances of a vertical v-shaped double-slotted cambered otter-board was investigated using engineering models in a wind tunnel. Three different shape panels (rhomboid, left trapezoid and isosceles trapezoid) were evaluated at a wind speed of 28 m/s. Parameters measured included: drag coefficient Cx, lift coefficient Cy, pitch moment coefficient Cm, center of pressure coefficient Cp , over a range of angle of attack (0° to 70°). These coefficients were used in analyzing the differences in the performance among the three otter-board models. Results showed that the maximum lift coefficient Cy of the otter-board model with the isosceles trapezoid shape panels was highest (2.103 at α=45°). The maximum Cy/Cx of the otter-board with the rhomboid shape panels was highest (3.976 at α=15°). A comparative analysis of Cm and Cp showed that the stability of otter-board model with the isosceles trapezoid shape panels is better in pitch, and the stability of otter-board model with the left trapezoid shape panels is better in roll. The findings of this study can offer useful reference data for the structural optimization of otter-boards for trawling.

scholarly journals Analisis Airfoil Double-Slot Flap LS(01)-0417 MOD Dengan Airfoil Tanpa Flap Nasa SC(2) 0610

2018 ◽  
Vol 11 (2) ◽  
pp. 49
Author(s):  
Gaguk Jatisukamto ◽  
Mirna Sari
Keyword(s):  
Computational Fluid Dynamic ◽  
Static Pressure ◽  
Fluid Dynamic ◽  
Dynamic Pressure ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Angle Of Attack ◽  
Airflow Velocity ◽  
The Difference ◽  
The Stability

Kestabilan pesawat terbang ditentukan oleh desain airfoil sayap dan ekor. Perbedaan kecepatan aliran udara antara permukaan atas dan bawah airfoil menghasilkan perbedaan tekanan sehingga akan memberikan gaya angkat (lift) pada sayap. Perbedaan tekanan udara pada permukaan sayap dinyatakan dengan pressure coefficient (Cp), yaitu perbedaan tekanan statik lokal dengan tekanan statik aliran bebas. Koefisien lift (Cl) adalah rasio antara gaya angkat (lift) dengan tekanan dinamis. Peningkatan angka CL sebesar 20,4% pada riset sebelumnya diperoleh berdasarkan simulasi penambahan flap. Tujuan penelitian ini adalah membandingkan hasil simulasi airfoil double slot flap LS(01)-0417 MOD  dengan airfoil NASA SC(2) 0610 yang tanpa flap dan mencari korelasi antara sudut serang (?) dengan koefisien lift (Cl ).Metodologi penelitian dilakukan dengan simulasi Computational Fluid Dynamic (CFD). Hasil penelitian dapat disimpulkan bahwa koefisien lift CL untuk airfoil double slot flap LS(01)-0417 MOD menghasilkan CL = 1,498 sedangkan dengan sudut serang ? = 16o sedangkan airfoil NASA SC(2) 0610 tanpa flap memiliki nilai CL = 1,095 dengan sudut serang 13o. The stability of the aircraft is ordered by the airfoil design of the wings and the tail. The difference in flow velocity between the surface and the bottom of the airfoil will produce styles that will present lift  on the wings. The difference in airflow velocity between the top and bottom surfaces of the airfoil produces a pressure difference so it will provide lift (lift) on the wing. The lift coefficient (CL) is the ratio between lift with dynamic pressure. The difference of air pressure on the wing surface is expressed by pressure coefficient (Cp), the difference of local static pressure with free flow static pressure. The lift coefficient (Cl) is the ratio of lift to dynamic pressure. An increase in CL value of 20.4% in previous research was obtained based on the simulation of flap addition. The purpose of this research is comparison between airfoil double slot flap LS (01)-0417 MOD with airfoil NASA SC (2) 0610 without flap and search between angle of attack (?) with coefficient of lift (Cl). Method research is done by Computational Fluid Dynamic (CFD). The result of this research can be concluded that lift coefficient CL for double slot airfoil flap LS (01)-0417 MOD yield CL = 1,498 while with angle of attack ? = 16o while airfoil NASA SC (2) 0610 without flap have value CL = 1,095 with angle of attack 13o

scholarly journals Unsteady Simulation of Transonic Buffet of a Supercritical Airfoil with Shock Control Bump

Aerospace ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 203
Author(s):  
Yufei Zhang ◽  
Pu Yang ◽  
Runze Li ◽  
Haixin Chen
Keyword(s):  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Flow Characteristics ◽  
Control Effect ◽  
Shock Control Bump ◽  
Shock Control ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Unsteady Simulation ◽  
Drag Ratio

The unsteady flow characteristics of a supercritical OAT15A airfoil with a shock control bump were numerically studied by a wall-modeled large eddy simulation. The numerical method was first validated by the buffet and nonbuffet cases of the baseline OAT15A airfoil. Both the pressure coefficient and velocity fluctuation coincided well with the experimental data. Then, four different shock control bumps were numerically tested. A bump of height h/c = 0.008 and location xB/c = 0.55 demonstrated a good buffet control effect. The lift-to-drag ratio of the buffet case was increased by 5.9%, and the root mean square of the lift coefficient fluctuation was decreased by 67.6%. Detailed time-averaged flow quantities and instantaneous flow fields were analyzed to demonstrate the flow phenomenon of the shock control bumps. The results demonstrate that an appropriate “λ” shockwave pattern caused by the bump is important for the flow control effect.

scholarly journals Simulation of the Load Evolution of an Anchoring System under a Blasting Impulse Load Using FLAC3D

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Xigui Zheng ◽  
Jinbo Hua ◽  
Nong Zhang ◽  
Xiaowei Feng ◽  
Lei Zhang
Keyword(s):  
Shear Stress ◽  
Dynamic Response ◽  
Axial Force ◽  
Mechanical Characteristics ◽  
Oscillation Amplitude ◽  
Anchoring System ◽  
Impulse Load ◽  
The Stability ◽  
Calculation Software ◽  
Dynamic Perturbation

A limitation in research on bolt anchoring is the unknown relationship between dynamic perturbation and mechanical characteristics. This paper divides dynamic impulse loads into engineering loads and blasting loads and then employs numerical calculation software FLAC3Dto analyze the stability of an anchoring system perturbed by an impulse load. The evolution of the dynamic response of the axial force/shear stress in the anchoring system is thus obtained. It is revealed that the corners and middle of the anchoring system are strongly affected by the dynamic load, and the dynamic response of shear stress is distinctly stronger than that of the axial force in the anchoring system. Additionally, the perturbation of the impulse load reduces stress in the anchored rock mass and induces repeated tension and loosening of the rods in the anchoring system, thus reducing the stability of the anchoring system. The oscillation amplitude of the axial force in the anchored segment is mitigated far more than that in the free segment, demonstrating that extended/full-length anchoring is extremely stable and surpasses simple anchors with free ends.

Investigation of Parameters Affecting the Limiting Shear Stress-Pressure Coefficient: A New Model Incorporating Temperature

1994 ◽  
Vol 116 (3) ◽  
pp. 612-620 ◽  
Author(s):  
Victoria Wikstro¨m ◽  
Erik Ho¨glund
Keyword(s):  
Shear Stress ◽  
Film Thickness ◽  
Contact Pressure ◽  
Pressure Coefficient ◽  
Oil Viscosity ◽  
New Model ◽  
Lubricated Contacts ◽  
Limiting Shear Stress ◽  
Essential Parameter ◽  
Maximum Contact

When calculating film thickness and friction in elastohydrodynamically lubricated contacts, assuming a non-Newtonian fluid, the lubricant limiting shear stress is an essential parameter. It influences minimum film thickness and determines traction in the contact. The limiting shear stress is pressure dependent according to the Johnson and Tevaarwerk equation: τL=τ0+γp The limiting shear stress-pressure coefficient γ has in a previous screening investigation been shown to depend on several parameters: oil type, oil viscosity at + 40°C, maximum contact pressure and temperature. In the present investigation, the preliminary data is used together with response surface methodology. With these results in mind, further experiments are made and an empirical model is built. This paper presents a new model for γ which is valid for two types of oil (a polyalphaolefine with diester and a naphthenic oil) with different viscosities at +40°C. The model incorporates the influence of maximum contact pressure and oil temperature on γ. The measurements on which the model is based were carried out at temperatures ranging from −20 to + 110°C. The pressure range was 5.8–7 GPa and the shear rate was about 106 s−1.

Flow Properties of Utah Shale Oils

1981 ◽  
Vol 21 (06) ◽  
pp. 679-686 ◽  
Author(s):  
W.H. Seitzer
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Pour Point ◽  
Water Solution ◽  
Shale Oil ◽  
Concentric Cylinder ◽  
Long Distance ◽  
Time Calibration ◽  
The Difference ◽  
Cylinder Viscometer

Abstract In a concentric cylinder viscometer. Utah shale oils have different characteristics, both at equilibrium flow and during start-up from rest, depending on whether the wax has crystallized as needles or spherulites. Compared with waxy crude oils, which are thixotropic, shale oil had the added rheological property of being antithixotropic. Introduction The most likely liquid synthetic fuel to be produced initially in the U.S. will be raw shale oil from western oil shale. This abundant resource is located principally in the western Rocky Mountain states of Colorado. Utah. and Wyoming (Fig. 1). Ultimate commercial production probably will be transported to marketing, distribution, and refining centers by pipeline. It has been reported that Utah shale oils produced by the Union "B" and Paraho DH retorting processes gave similar physical and chemical properties. Some properties of the two Utah shale oils are given in Table 1. The only major difference is that the Union shale oil has a pour point of - 1 degree C compared with a pour point of 25 degrees C for the Paraho oil. Wax Crystallization The difference in the pour points of the oils from the Utah shale retorted by Union Oil Co of California and Paraho is caused mainly by the difference in how the wax in the respective oils crystallizes. In the high- pour-point (25 degrees C) Paraho DK oil, the wax, under a microscope, appears as fine (1 to 10 m) needles, as expected for normal paraffins. However, the wax in the low-pour-point (−1 degrees C) Union oil forms small spherulites.Wax spherulites have not been reported before: however, this type of crystal is seen commonly in polymer. Spherulites show up as round areas containing a maltese cross when observed between crossed polars under a microscope.Photomicrographs of these crystals are shown in Figs. 2 and 3. The former, showing spherulites, is of the Union oil. In contrast, they are very different from the customary needles as typified by the Paraho oil in the latter micrograph. Presumably, these highly ordered spheres are made up of wax needles grown out radially from the center as described by Hartshorne and Stuart. The polarized light is scattered only by those needles not parallel nor perpendicular to the plane of polarization. Viscometer Measurements To understand the effect of these spherulites on the flow characteristics of raw shale oil at flow conditions expected in a long-distance pipeline, typical stress-rate measurements were made in a rotating cylinder viscometer, the Haake Rotovisco RV3 with MK500 measuring head and MVI coaxial cylinder sensor having an 82-mm cup and radii ratio of 0.95. This equipment has provisions for varying shear rate continuously at selected values down to 23.4 sec(−1)/min and can produce and record shear stress as a function of either shear rate or time. Calibration of the sensor was verified with a sucrose/water solution at several temperatures.Changes in temperature always were made from lower to higher to keep the sensor full of oil. Also, the shear-stress/ shear-rate curves were obtained by starting at high shear, down to zero, and then back up. SPEJ P. 679^

scholarly journals Design and Testing of a LUT Airfoil for Straight-Bladed Vertical Axis Wind Turbines

2018 ◽  
Vol 8 (11) ◽  
pp. 2266 ◽  
Author(s):  
Shoutu Li ◽  
Ye Li ◽  
Congxin Yang ◽  
Xuyao Zhang ◽  
Qing Wang ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Vertical Axis ◽  
Reynolds Numbers ◽  
Optimization Method ◽  
Geometrical Parameters ◽  
Vertical Axis Wind Turbines ◽  
University Of Technology ◽  
Horizontal Axis Wind Turbines

The airfoil plays an important role in improving the performance of wind turbines. However, there is less research dedicated to the airfoils for Vertical Axis Wind Turbines (VAWTs) compared to the research on Horizontal Axis Wind Turbines (HAWTs). With the objective of maximizing the aerodynamic performance of the airfoil by optimizing its geometrical parameters and by considering the law of motion of VAWTs, a new airfoil, designated the LUT airfoil (Lanzhou University of Technology), was designed for lift-driven VAWTs by employing the sequential quadratic programming optimization method. Afterwards, the pressure on the surface of the airfoil and the flow velocity were measured in steady conditions by employing wind tunnel experiments and particle image velocimetry technology. Then, the distribution of the pressure coefficient and aerodynamic loads were analyzed for the LUT airfoil under free transition. The results show that the LUT airfoil has a moderate thickness (20.77%) and moderate camber (1.11%). Moreover, compared to the airfoils commonly used for VAWTs, the LUT airfoil, with a wide drag bucket and gentle stall performance, achieves a higher maximum lift coefficient and lift–drag ratios at the Reynolds numbers 3 × 105 and 5 × 105.

scholarly journals Numerical Simulation on Large Deformation of Weak Rock Mass Tunnel Under High Geostress

2018 ◽  
Vol 175 ◽  
pp. 03025
Author(s):  
Feng Zhou ◽  
Hongjian Jiang ◽  
Xiaorui Wang
Keyword(s):  
Rock Mass ◽  
Large Deformation ◽  
Lateral Pressure ◽  
Simulation Analysis ◽  
Pressure Coefficient ◽  
Surrounding Rock ◽  
Analog Simulation ◽  
Lateral Pressure Coefficient ◽  
High Geostress ◽  
The Stability

The problem about the stability of tunnel surrounding rock is always an important research object of geotechnical engineering, and the right or wrong of the result from stability analysis on surrounding rock is related to success or failure of an underground project. In order to study the deformation rules of weak surrounding rock along with lateral pressure coefficient and burying depth varying under high geostress and discuss the dynamic variation trend of surrounding rock, the paper based on the application of finite difference software of FLAC3D, which can describe large deformation character of rock mass, analog simulation analysis of surrounding rock typical section of the class II was proceeded. Some conclusions were drawn as follows: (1) when burying depth is invariable, the displacements of tunnel surrounding rock have a trend of increasing first and then decreasing along with increasing of lateral pressure coefficient. The floor heave is the most sensitive to change of lateral pressure coefficient. The horizontal convergence takes second place. The vault subsidence is feeblish to change of lateral pressure coefficient. (2) The displacements of tunnel surrounding rock have some extend increase along with increasing of burying depth. The research conclusions are very effective in analyzing the stability of surrounding rock of Yunling tunnel. These are going to be a reference to tunnel supporting design and construction.

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