scholarly journals Particle Motion Characteristics in W-Shaped Hydrocyclones

Separations ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 121
Author(s):  
Lanyue Jiang ◽  
Peikun Liu ◽  
Yuekan Zhang ◽  
Xinghua Yang ◽  
Xiaoyu Li ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Particle Motion ◽  
Fine Particles ◽  
Separation Efficiency ◽  
Particle Density ◽  
Flow Characteristics ◽  
Simulation Method ◽  
Inertia Force ◽  
Gradient Force ◽  
Pressure Gradient Force

To investigate the multiphase flow characteristics and improve the classification mechanism of a W-shaped hydrocyclone, this paper adopts the numerical simulation method to evaluate the effects of the particle size and density on the separation characteristics and motion behavior of particles. Forces, such as the centrifugal inertia force, pressure gradient force and fluid drag force, which control particle motion, are analyzed, and the classification mechanism of W-shaped hydrocyclones is examined in terms of the particle distribution and separation efficiency. The results indicate that the radial centrifugal inertia and pressure gradient forces in W-shaped hydrocyclones are hundreds of times the gravity force, which is the main driver of radial motion. Particle density and size changes greatly impact the movement and distribution of coarse particles, but no notable change occurs in fine particles. With increasing particle density, the cut size decreases, and the fractionation accuracy increases.

Simulation on Incipient Particle Motion in Highly-Inclined Annulus

2020 ◽  
Vol 14 (1) ◽  
pp. 103-112
Author(s):  
Chen Ye ◽  
Wang Kelin ◽  
Sun Xiaofeng ◽  
Qu Jingyu ◽  
Cao lihu
Keyword(s):  
Particle Motion ◽  
Particle Density ◽  
Horizontal Wells ◽  
Adhesive Force ◽  
Gradient Force ◽  
Pressure Gradient Force ◽  
Mass Force ◽  
Incipient Motion ◽  
Motion Velocity ◽  
Cuttings Bed

Background: Highly-inclined and horizontal wells have been widely used for the development of mature oilfield, marine oilfield, and low permeable oilfield. During drilling operations, cutting particles will accumulate in the low side of wellbore and cuttings bed may be formed, which may lead to high drag and torque, stuck pipe, and other drilling problems. We reviewed the patents about cutting bed cleaning tool. Objective: The goal of this work is to determine the incipient motion velocity or rate to re-suspend and remove the cutting particles. Methods: In this study, the random distribution function of particles is introduced to determine the percentage of incipient particle motion, and the mechanical models for rolling and lifting method considering the net gravity, drag force, lift force, additional mass force, adhesive force and flow pressure gradient force are developed to predict the incipient motion velocity or rate. Also, the model has been verified by published experimental data. Results: The critical particle size of incipient motion rate is approximately 1 mm. The incipient motion rate decreases as the height of cuttings bed decreases, and the minimum flow rate that prevents the bed formation may be estimated when bed height is small enough. Also, increasing wellbore inclination or fluid density has a positive effect on incipient motion rate, but increasing particle density or percentage of incipient particle motion has an adverse effect. Conclusion: This study may provide a guideline for designing hydraulic parameters and sand washing in the highly-inclined and horizontal wells, thereby contributingin economic production.

scholarly journals On the fine vertical structure of the low troposphere over the coastal margins of East Antarctica

2019 ◽  
Author(s):  
Étienne Vignon ◽  
Olivier Traullé ◽  
Alexis Berne
Keyword(s):  
Pressure Gradient ◽  
Vertical Structure ◽  
East Antarctica ◽  
Radiosonde Data ◽  
Gradient Force ◽  
Pressure Gradient Force ◽  
Near Surface ◽  
Ice Shelves ◽  
Low Level ◽  
Humidity Profiles

Abstract. Eight years of high-resolution radiosonde data at nine Antarctic stations are analysed to provide the first large scale characterization of the fine scale vertical structure of the low troposphere up to 3 km of altitude over the coastal margins of East Antarctica. Radiosonde data show a large spatial variability of wind, temperature and humidity profiles, with different features between stations in katabatic regions (e.g., Dumont d'Urville and Mawson stations), stations over two ice shelves (Neumayer and Halley stations) and regions with complex orography (e.g., Mc Murdo). At Dumont d'Urville, Mawson and Davis stations, the yearly median wind speed profiles exhibit a clear low-level katabatic jet. During precipitation events, the low-level flow generally remains of continental origin and its speed is even reinforced due to the increase in the continent- ocean pressure gradient. Meanwhile, the relative humidity profiles show a dry low troposphere, suggesting the occurence of low-level sublimation of precipitation in katabatic regions but such a phenomenon does not appreciably occur over the ice-shelves near Halley and Neumayer. Although ERA-Interim and ERA5 reanalyses assimilate radiosoundings at most stations considered here, substantial – and sometimes large – low-level wind and humidity biases are revealed but ERA5 shows overall better performances. A free simulation with the regional model Polar WRF (at a 35-km resolution) over the entire continent shows too strong and too shallow near-surface jets in katabatic regions especially in winter. This may be a consequence of an understimated coastal cold air bump and associated sea-continent pressure gradient force due to the coarse 35 km resolution of the Polar WRF simulation. Beyond documenting the vertical structure of the low troposphere over coastal East-Antarctica, this study gives insights into the reliability and accuracy of two major reanalysis products in this region on the Earth and it raises the difficulty of modeling the low-level flow over the margins of the ice sheet with a state-of-the-art climate model.

scholarly journals Zonal Momentum Balance in the Tropical Atmospheric Circulation during the Global Monsoon Mature Months

2013 ◽  
Vol 70 (2) ◽  
pp. 583-599 ◽  
Author(s):  
Wenchang Yang ◽  
Richard Seager ◽  
Mark A. Cane
Keyword(s):  
Angular Momentum ◽  
Pressure Gradient ◽  
Atmospheric Circulation ◽  
Coriolis Force ◽  
Gradient Force ◽  
Pressure Gradient Force ◽  
Global Monsoon ◽  
Upper Troposphere ◽  
Nonlinear Advection ◽  
Zonal Momentum

Abstract In this paper, zonal momentum balances of the tropical atmospheric circulation during the global monsoon mature months (January and July) are analyzed in three dimensions based on the ECMWF Interim Re-Analysis (ERA-Interim). It is found that the dominant terms in the balance of the atmospheric boundary layer (ABL) in both months are the pressure gradient force, the Coriolis force, and friction. The nonlinear advection term plays a significant role only in the Asian summer monsoon regions within the ABL. In the upper troposphere, the pressure gradient force, the Coriolis force, and the nonlinear advection are the dominant terms. The transient eddy force and the residual force (which can be explained as convective momentum transfer over open oceans) are secondary, yet cannot be neglected near the equator. Zonal-mean equatorial upper-troposphere easterlies are maintained by the absolute angular momentum advection associated with the cross-equatorial Hadley circulation. Equatorial upper-troposphere easterlies over the Asian monsoon regions are also controlled by the absolute angular momentum advection but are mainly maintained by the pressure gradient force in January. The equivalent linear Rayleigh friction, which is widely applied in simple tropical models, is calculated and the corresponding spatial distribution of the local coefficient and damping time scale are estimated from the linear regression. It is found that the linear momentum model is in general capable of crudely describing the tropical atmospheric circulation dynamics, yet the caveat should be kept in mind that the friction coefficient is not uniformly distributed and is even negative in some regions.

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