scholarly journals Internal Structure of a Jet Nozzle for Coalbed Methane Mining Based on Airfoil Curves

2018 ◽  
Vol 2018 ◽  
pp. 1-17
Author(s):  
Jian Chen ◽  
Liwen Guo ◽  
Yanwei Hu ◽  
Yong Chen
Keyword(s):  
Water Column ◽  
Coalbed Methane ◽  
Pressure Fluctuations ◽  
Axial Direction ◽  
Shock Pressure ◽  
Conical Nozzle ◽  
Small Pressure ◽  
Jet Nozzle ◽  
Column Pressure ◽  
Variation Rule

Based on airfoil curves that can effectively balance the rectification and drag reduction effects in flight hydrodynamics, we designed an internal streamline structure of jet nozzle for coalbed methane (CBM) mining. The three types of nozzles originating from three typical airfoil curves are compared with the conical nozzle. Results showed that the thin-type streamlined nozzle had the largest effective shock range and least radial divergence and was thus selected as the best nozzle. Moreover, the pressure distribution at the outlet of the nozzle was found to be related to the range and number of small-pressure fluctuations near the wall. A larger number of small-pressure fluctuations and a larger range caused faster pressure of the jet water column to decay along the axial direction. Rectification with a concentrated effect also slowed down the attenuation velocity of the jet-water-column pressure between the concentration point and the nozzle. The variation rule of shock pressure with range was further determined experimentally. We found that the shock pressure of jet water column initially increased within a short distance and then decreased rapidly. The effective shock range of the thin-type streamlined nozzle in air was 1.417 times that of the conical nozzle, and the effective reaming area was 1.104 times greater. Thus, the effect of reaming was effectively improved. The length of the water column at high pressure was larger than that of the conical nozzle, and the shock efficiency was relatively high.

Study on the atomization zones of the nozzle in the processes of material primary processing

2021 ◽  
pp. 1-8
Author(s):  
Nan Pan ◽  
Junbin Qian ◽  
Chengjun Zhao
Keyword(s):  
Axial Direction ◽  
Liquid Distribution ◽  
Primary Processing ◽  
Nozzle Injection ◽  
Injection Zone ◽  
Liquid Atomization ◽  
Whole Space ◽  
Simulation And Experiment ◽  
Jet Nozzle ◽  
Atomization Zone

It can divide the atomization effect in the direction of the nozzle axial injection into the jet area and the non-jet area by using the second crushing theory. On this basis, according to the feed liquid atomization particles discrete degree index of characteristics particle size of feed liquid atomization, it divides the injection zone into the atomization area and the diffusion area, so as to realize the axial direction of jet nozzle injection zone, atomization zone and the diffusion zone accurately. Simulation and experiment are used to verify the three zones of atomization nozzle. The division of three zones drives the study from the whole space of liquid distribution in the roller to atomization zone, clears the key zone of the roller in tobacco primary processing, and provides a basis for further work.

Flow-Induced Vibration of a Large-Diameter Elbow Piping Based on Random Force Measurement Caused by Conveying Fluid: Visualization Test Results

2005 ◽  
Author(s):  
Tomomichi Nakamura ◽  
Tadashi Shiraishi ◽  
Yoshihide Ishitani ◽  
Hisato Watakabe ◽  
Hiromi Sago ◽  
...  
Keyword(s):  
Force Measurement ◽  
Large Diameter ◽  
Pressure Fluctuations ◽  
Pressure Sensors ◽  
Maximum Flow ◽  
Axial Direction ◽  
Random Force ◽  
Test Facility ◽  
Flow Induced Vibration ◽  
Correlation Lengths

A 1/3 scale flow-induced vibration test facility that simulates the hot-leg piping of the JNC sodium-cooled fast reactor (JSFR) is used to investigate the pressure fluctuations of the pipe, where the high velocity fluid flows inside the piping. By the measurement of the pressure drop in the elbow piping while changing the Reynolds number, the similarity law of this model is confirmed. To evaluate the flow-induced vibrations for the hot-leg and cold-leg pipes, the random force distributions along the pipe and their correlations are measured with pressure sensors in a water loop. It is found that a flow velocity-dependent periodic phenomenon in the rear region of the elbow, and the maximum flow-induced random vibration force in the pipe are observed in the region of flow separation downstream the elbow. Finally, a design method is proposed with power spectral densities of the pressure fluctuations classified into four sections, correlation lengths in the axial direction divided into three sections, and with correlation lengths in the tangential direction into four sections.

Ionospheric Storms and Small Pressure Fluctuations at Ground Level

Nature ◽  
1966 ◽  
Vol 210 (5040) ◽  
pp. 1032-1034 ◽  
Author(s):  
G. G. BOWMAN ◽  
K. L. SHRESTHA
Keyword(s):  
Pressure Fluctuations ◽  
Ground Level ◽  
Small Pressure

scholarly journals Dynamic behavior of coalbed methane flow along the annulus of single-phase production

2019 ◽  
Vol 6 (4) ◽  
pp. 547-555 ◽  
Author(s):  
Xinfu Liu ◽  
Chunhua Liu ◽  
Guoqiang Liu
Keyword(s):  
Water Column ◽  
Dynamic Behavior ◽  
Coalbed Methane ◽  
Single Phase ◽  
Compressibility Factor ◽  
Production Performance ◽  
Flow Rates ◽  
Pressure Drops ◽  
Bottom Hole ◽  
Gravitational Gradients

Abstract Dynamic behavior of coalbed methane (CBM) flow will provide the theoretical basis to optimize production performance for a given well. A mathematical model is developed to simulate flowing pressures and pressure drops of CBM column from well head to bottom hole. The measured parameters and independent variables of flow rates, flowing pressures and temperatures are involved in CBM producing process along the annulus. The developed relationships are validated against full-scale measured data in single-phase CBM wellbores. The proposed methodology can analyze the dynamic behavior in CBM reservoir and process of CBM flow with an overall accuracy of 2%. The calculating process of flowing pressures involves friction factor with variable Reynolds number and CBM temperature and compressibility factor with gravitational gradients. The results showed that the effect of flowing pressure on CBM column was more obvious than that on CBM and water column accompanied by an increase of dynamic water level. The ratios of flowing pressure on increment of CBM column to the whole column increased with the declined flow rates of water column. Bottom-hole pressure declined with the decreased flowing pressure of CBM column along the annulus. It will lead to the results of the increased pressure drop of CBM column and CBM flow rate in single-phase CBM wellbores.

Analysis and Simulation of the Fluid Field in Thermal Water-Jet Nozzle Based on ANSYS FLUENT & ICEM CFD

2013 ◽  
Vol 423-426 ◽  
pp. 1677-1684 ◽  
Author(s):  
Jian Zhao Zhou ◽  
Xiao Pan Xu ◽  
Wei Jun Chu ◽  
Zi Cheng Zhu ◽  
Yun He Chen ◽  
...  
Keyword(s):  
Thermal Water ◽  
Initial Conditions ◽  
Water Jet ◽  
Conical Nozzle ◽  
Ansys Fluent ◽  
The Public ◽  
Fluid Field ◽  
Fluent Software ◽  
Jet Nozzle ◽  
Icem Cfd

Thermal water jet is an important part of the synthetically de-icing equipment designed to cut the frozen ice and snow on the public facilities. The inner structures of the jet nozzle, such as the conical and straight conical nozzles, have a crucial influence on the final efficiency of the cutting. In order to figure out the effect of these two kinds of nozzle structures to the jet fluid, and provide some strong references for the structure optimization, this paper synthetically uses ICEM CFD and ANSYS FLUENT software to analyze the fluid of the conical and straight conical jet nozzles. The results show that: as the initial conditions are determined, the conical nozzle has a higher speed and longer isokinetic core zone of the flux than that of the straight conical nozzle, and the speed changes more dramatically. However, the straight conical nozzle has a more stable speed, and lower operating vibrations. Through repeated indoor experiments, the simulation results are demonstrated.

scholarly journals A Modern Approach to Analyzing the Flowing Pressures of a Two-Phase CBM and Water Column in Producing Wellbores

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Xinfu Liu ◽  
Chunhua Liu ◽  
Jianjun Wu
Keyword(s):  
Water Level ◽  
Water Column ◽  
Water Flow ◽  
Flow Rate ◽  
Two Phase ◽  
Modern Approach ◽  
Flow Rates ◽  
Bottom Hole ◽  
Column Pressure ◽  
Phase Column

A modern methodology is presented for the system analysis of flowing pressures in order to forecast the dynamic behavior and solve the forthcoming problems that emerge in two-phase coalbed methane (CBM) wellbores. The proposed methodology involves a numerical integration technique to calculate flowing pressures and pressure drops of CBM and water flow from the bottom hole to the well head. The methodology is validated against full-scale measured data in coalfields. The relationships developed match CBM reservoir behavior and wellbore conditions along the annulus with an overall accuracy of 1.13%. The computation of flowing pressures involves a liquid holdup and kinetic energy term with flow rate increments, a compressibility factor with depth increments, and a friction factor with Reynolds number. The flowing pressures of a two-phase column fully reflect the dynamic flowing performance due to the combined action of the water level, CBM, and water flow rates. The effect of CBM and water column pressures is more obvious than that of CBM column pressures. The pressure ratios of CBM and the water column to the bottom hole decline rapidly with the increase of the dynamic water level. CBM and water flow rates can be improved with increases in CBM and water column pressure for two-phase producing wellbores. The decrease of flowing pressures and increased increment of the pressure drop for the two-phase column are beneficial to CBM desorption and result in the increased CBM and water production. It will control the falling speed of the dynamic water level above CBM and the water column and enhance CBM reservoir productivity. The increases of CBM and water column pressure from 34.6 kPa to 922 kPa and the decreases of pressure in the bottom hole from 2.252 MPa to 1.328 MPa lead to the increases of the CBM flow rate from 3327 m3/d to 6721 m3/d.

Prediction of Environmentally Assisted Cracking on Gas and Liquid Pipelines

2006 ◽  
Author(s):  
J. Been ◽  
R. Eadie ◽  
R. Sutherby
Keyword(s):  
Crack Growth ◽  
Growth Rates ◽  
Pressure Fluctuations ◽  
Low Frequencies ◽  
Small Pressure ◽  
Environmentally Assisted Cracking ◽  
Pressure Time ◽  
Growing Crack ◽  
Small Cracks ◽  
Crack Growth Rates

A model has been developed to predict crack growth on pipelines from environmentally assisted cracking in near-neutral pH environments (often-termed low-pH stress corrosion cracking (SCC)). The model is based on the results of cyclic loading experiments and is used in conjunction with pressure time variations in the pipeline determined from the operating SCADA records to predict the growth of an assumed existing crack in the pipe. The crack grows through different crack growth regimes, which are determined by the size of the pressure variations and the instantaneous crack dimensions. For a growing crack that experiences relatively high pressure fluctuations, as often encountered on liquid lines, reasonable crack growth predictions were made based on corrosion fatigue. An approach based on crack tip strain rate appears more suitable for the prediction of crack growth of small cracks and for cracks on gas lines with small pressure fluctuations. The model is designed so that the effect of stress intensifiers (like the long seam weld crown) that are often associated with these failures can be included. The model can be used in its present format for prioritizing inspections on both gas and liquid pipelines. Whereas predicted crack growth rates compare favorably with rates measured in the field, further work is required to incorporate additional mechanical and environmental effects, in particular to improve the prediction of small crack growth rates. Low crack velocities may be possible in the presence of small pressure fluctuations and low frequencies, but they may be less probable.

Investigation on Complex Pressure Fluctuations in a Gas-Solids Circulating Fluidized Bed Rieser

2012 ◽  
Vol 538-541 ◽  
pp. 610-615
Author(s):  
Jun Xu ◽  
Xing Xing Chen ◽  
Gui Lei Wang ◽  
Yao Dong Wei
Keyword(s):  
Fluidized Bed ◽  
Pressure Fluctuation ◽  
Circulating Fluidized Bed ◽  
Pressure Fluctuations ◽  
Low Frequency ◽  
Axial Direction ◽  
High Amplitude ◽  
Solid Mass ◽  
Two Phase ◽  
Mass Fluxes

The experiment is carried out in a 13-meter-high circulating fluidized bed(CFB) to investigate gas-solid two-phase flow by pressure sensor. The axial pressure and pressure fluctuation are measured in different solid mass fluxes. With the solid mass flux increasing, pressure gradually increases, and pressure gradually decreases along the riser upwards. The characteristic of pressure fluctuation in the riser is analyzed, which indicates that pressure fluctuation in the riser originates from the inlet. The intensity of the pressure fluctuation decreases along the riser upwards. This pressure fluctuation is composed of two types: one is of low frequency and high amplitude, which is resulted from unstable feeding to the riser and keeps coherent along the axial direction. And the other is of high frequency and low amplitude, which is the result of a variety of factors, such as cluster movement, gas-solid interaction and gas velocity fluctuation.

Investigation on the influence of aerostatic pressure upon surface generation in flycutting

2018 ◽  
Vol 233 (4) ◽  
pp. 1136-1143 ◽  
Author(s):  
Congying Deng ◽  
Chenhui An ◽  
Bo Wei ◽  
Jianguo Miao
Keyword(s):  
Single Point ◽  
Complex Structure ◽  
Pressure Fluctuations ◽  
Potassium Dihydrogen Phosphate ◽  
Axial Direction ◽  
Surface Generation ◽  
Dihydrogen Phosphate ◽  
Machined Surface ◽  
Potassium Dihydrogen ◽  
The Relationship

Single-point diamond flycutting is an important technology for cutting flat KH2PO4 (potassium dihydrogen phosphate) crystals of large size. However, there always exist some undesirable waviness errors on the machined surface, which can directly reduce the optical performance of the potassium dihydrogen phosphate crystals. This article presents a kind of low-frequency waviness errors with wavelength about 26 mm along the feeding direction in single-point diamond flycutting, which has not been described yet. In order to find the main source of the mentioned waviness errors, the relationship between the displacement of the cutting tool and the aerostatic pressure was quantitatively studied for the first time. And then, surface simulation considering the aerostatic pressure fluctuations was carried out based on the relationship. Besides, a novel method that can achieve online submicron feeding along axial direction in single-point diamond flycutting without complex structure was proposed considering the spindle motion errors, the spindle dynamic characteristics and the aerostatic pressure. The experimental results validate that the mentioned waviness errors are mainly generated by the bolt stretched phenomenon and deformation of the big disk flycutting head due to the aerostatic pressure fluctuations. And the proposed method can achieve a cutting depth of about 120 nm when the aerostatic pressure increases from 0.52 to 0.56 MPa, which can reduce the cutting force and is beneficial for the performance of single-point diamond flycutting.

Wall Pressure in Developing Turbulent Pipe Flows

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Kamal Selvam ◽  
Emir Öngüner ◽  
Jorge Peixinho ◽  
El-Sayed Zanoun ◽  
Christoph Egbers
Keyword(s):  
Turbulent Flows ◽  
Exponential Growth ◽  
Pressure Fluctuations ◽  
Axial Direction ◽  
Wall Pressure ◽  
Mean Velocity ◽  
Critical Position ◽  
Velocity Fluctuations ◽  
Developed Turbulence ◽  
Layer Flow

Velocity fluctuations are widely used to identify the behavior of developing turbulent flows. The pressure on the other hand, which is strongly coupled with the gradient of the mean velocity and fluctuations, is less explored. In this study, we report the results of wall pressure measurements for the development of pipe flow at high Reynolds numbers along the axial direction. It is found that the pressure fluctuations increase exponentially along the pipe with a self-similarity scaling. The exponential growth of the pressure fluctuations along the pipe saturates after reaching a critical position around 50 diameters from the inlet. It qualitatively agrees with the critical position usually adopted for fully developed turbulence, which was obtained from earlier velocity fluctuations at various locations along the pipe centerline. Results also show that the exponential growth of the pressure fluctuations is weakly affected by the presence of ring obstacles placed close to the pipe inlet. Finally, it is found that the pressure fluctuations decrease as a function of Reynolds number, contrary to the boundary layer flow.

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