scholarly journals Numerical simulation of gas–liquid flow behavior in the nozzle exit region of an effervescent atomizer

2019 ◽  
Vol 11 ◽  
pp. 175682771882159 ◽  
Author(s):  
Chunhua Sun ◽  
Zhi Ning ◽  
Xinqi Qiao ◽  
Ming Lv ◽  
Juan Fu ◽  
...  
Keyword(s):  
Void Fraction ◽  
Nozzle Exit ◽  
Flow Behavior ◽  
Exit Section ◽  
Exit Region ◽  
Flow Parameters ◽  
Effervescent Atomizer ◽  
Gas Liquid Flow ◽  
Churn Flow ◽  
Gas Void Fraction

The pressure drop and particular geometric structure of the nozzle exit region of an effervescent atomizer cause complex changes in the flow pattern, which could affect the spray performance. In this study, the gas–liquid two-phase flow behavior in the nozzle exit region of the effervescent atomizer was investigated numerically. The results show that the flow behaviors in the nozzle exit region have disparate characteristics with different upstream flow regimes. For upstream churn flow, the liquid film morphology is closely related to fluctuation in the gas–liquid velocity, and the flow parameters (fluids’ velocities and gas void fraction) at the exit section vary regularly with time. For upstream bubbly flow, the instantaneous gas void fraction is determined by the bubble distribution inside the mixing chamber. The bubble will form a tadpole-like shape as a result of the complex flow field and the surface tension. The flow parameters at the exit section are in an oscillatory decay, and the fluctuation amplitude is larger than for churn flow. For upstream slug flow, the gas void fraction varies significantly with time. The discrete characteristic of the gas–liquid flow parameters at exit section is very obvious.

Numerical Simulation of the Gas-Liquid Flow in a Rotary Gas Separator

1998 ◽  
Vol 120 (1) ◽  
pp. 41-48 ◽  
Author(s):  
G. Lackner ◽  
F. J. S. Alhanati ◽  
S. A. Shirazi ◽  
D. R. Doty ◽  
Z. Schmidt
Keyword(s):  
Void Fraction ◽  
Liquid Flow ◽  
Two Phase Flow ◽  
Numerical Procedure ◽  
Phase Flow ◽  
Two Phase ◽  
Free Gas ◽  
Gas Separator ◽  
Gas Liquid Flow ◽  
Gas Void Fraction

The presence of free gas at the pump intake adversely affects the performance of an electrical submersible pump (ESP) system, often resulting in low efficiency and causing operational problems. One method of reducing the amount of free gas that the pump has to process is to install a rotary gas separator. The gas-liquid flow associated with the down hole installation of a rotary separator has been investigated to address its overall phase segregation performance. A mathematical model was developed to investigate factors contributing to gas-liquid separation and to determine the efficiency of the separator. The drift-flux approach was used to formulate this complex two-phase flow problem. The turbulent diffusivity was modeled by a two-layer mixing-length model and the relative velocity between phases was formulated based on published correlations for flows with similar characteristics. The well-known numerical procedure of Patankar-Spalding for single-phase flow computations was extended to this two-phase flow situation. Special discretization techniques were developed to obtain consistent results. Special under relaxation procedures were also developed to keep the gas void fraction in the interval [0, 1]. Predicted mixture velocity vectors and gas void fraction distribution for the two-phase flow inside the centrifuge are presented. The model’s predictions are compared to data gathered on a field scale experimental facility to support its invaluable capabilities as a design tool for ESP installations.

Experimental Study on Two Different Gas-Liquid Separators Under Different Flow Patterns

2020 ◽  
Author(s):  
Xiaobo Zeng ◽  
Changqi Yan ◽  
Guangming Fan ◽  
Jie Cheng ◽  
Junxiu Xu ◽  
...  
Keyword(s):  
Void Fraction ◽  
Slug Flow ◽  
High Efficiency ◽  
Separation Efficiency ◽  
Experimental System ◽  
Flow Patterns ◽  
Separation Performance ◽  
Wide Range ◽  
Churn Flow ◽  
Gas Void Fraction

Abstract Gas-liquid separation is widely used in many fields, such as nuclear energy and petroleum resources. And the gas-liquid mixture separated gradually shows the characteristic of wide range of gas void fraction and variable flow patterns. However, the current separators only suit for narrow range of gas void fraction or single flow patterns. In this research, two different new type separators using centrifugal technology were designed and an experimental system was constructed to test the two separators using dry air and water under different flow patterns, including bubble, slug and churn flow. One was called inline separator consisting of three swirls and another was called double-layer cylinder separator composed of a central tube, a swirl and an outer tube. The results show that the separation performance of the inline separator was sensitive to flow patterns and the two-layer cylinder separator keeps high efficiency in different flow patterns. In bubble flow and slug flow patterns, the two separators kept high efficiency, while the oscillation of the gas core in the inline separator aggravated under slug flow condition. When increasing the gas void fraction, the turbulence of the churn flow led to the diameter of the gas core change drastically and reduce separation efficiency significantly.

Gas Void Fraction Prediction for Air-Water and Air-Oil Two-Phase Flows via Artificial Neural Network

2019 ◽  
Author(s):  
Tiago Ferreira Souza ◽  
Caio Araujo ◽  
Maurício Figueiredo ◽  
FLAVIO SILVA ◽  
Ana Maria Frattini Fileti
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Void Fraction ◽  
Two Phase Flows ◽  
Two Phase ◽  
Artificial Neural ◽  
Gas Void Fraction

Interaction Between Impeller and Volute of Pumps at Off-Design Conditions

1986 ◽  
Vol 108 (1) ◽  
pp. 12-18 ◽  
Author(s):  
J. A. Lorett ◽  
S. Gopalakrishnan
Keyword(s):  
Analytical Solution ◽  
Flow Behavior ◽  
Cyclic Variation ◽  
Test Results ◽  
Flow Parameters ◽  
Pump Output ◽  
Simplifying Assumptions ◽  
Radial Thrust ◽  
Relative Flow ◽  
Good Agreement

In a centrifugal pump of volute type, the respective characteristics of the impeller and the volute are such that at only one operating point can the flow parameters be constant along the length of the volute. At off-design conditions the mismatching of characteristics causes variations of velocity and pressure along the periphery of the impeller. This in turn forces cyclic variation of the flow in the impeller channels, introduces variations of the inlet incidence and contributes significantly to the direction and the magnitude of the radial thrust. Furthermore, below a certain pump output, a complete flow reversal occurs over a part of the impeller periphery, thus explaining the onset of recirculation. The paper describes the calculation approach used to derive this aspect of the flow behavior. Because of difficulties in obtaining a closed analytical solution, a step by step computation is employed. Beginning with arbitrarily chosen conditions at the volute tongue, the program computes the flow parameters for following segments, using the continuity and the momentum equations, until the exit from the last segment is reached. The inherent unsteadiness of the relative flow in the impeller is explicitly accounted for. Since the inflow and the velocity in the first segment depend upon the exit conditions of the last, the initial input must be modified, and the computation repeated, until the values are compatible with the exit conditions. In spite of several simplifying assumptions, the results of the calculations show very good agreement with published test results.

scholarly journals On the MHD Casson Axisymmetric Marangoni Forced Convective Flow of Nanofluids

Mathematics ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 1087 ◽  
Author(s):  
Anum Shafiq ◽  
Islam Zari ◽  
Ghulam Rasool ◽  
Iskander Tlili ◽  
Tahir Saeed Khan
Keyword(s):  
Differential Equations ◽  
Convective Flow ◽  
Flow Behavior ◽  
Marangoni Effect ◽  
Casson Fluid ◽  
Linear Ordinary Differential Equations ◽  
Metallic Particles ◽  
Flow Parameters ◽  
Forced Convective Flow ◽  
The Impact

The proposed investigation concerns the impact of inclined magnetohydrodynamics (MHD) in a Casson axisymmetric Marangoni forced convective flow of nanofluids. Axisymmetric Marangoni convective flow has been driven by concentration and temperature gradients due to an infinite disk. Brownian motion appears due to concentration of the nanosize metallic particles in a typical base fluid. Thermophoretic attribute and heat source are considered. The analysis of flow pattern is perceived in the presence of certain distinct fluid parameters. Using appropriate transformations, the system of Partial Differential Equations (PDEs) is reduced into non-linear Ordinary Differential Equations (ODEs). Numerical solution of this problem is achieved invoking Runge–Kutta fourth-order algorithm. To observe the effect of inclined MHD in axisymmetric Marangoni convective flow, some suitable boundary conditions are incorporated. To figure out the impact of heat/mass phenomena on flow behavior, different physical and flow parameters are addressed for velocity, concentration and temperature profiles with the aid of tables and graphs. The results indicate that Casson fluid parameter and angle of inclination of MHD are reducing factors for fluid movement; however, stronger Marangoni effect is sufficient to improve the velocity profile.

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