Experimental Visualization of Gas-Liquid Flow Patterns in a Centrifugal Rotor

2019 ◽  
Author(s):  
Henrique Stel ◽  
Edgar Minoru Ofuchi ◽  
Rafael Fabrício Alves ◽  
Sergio Chiva ◽  
Rigoberto E. M. Morales
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Volume Fraction ◽  
Flow Patterns ◽  
Centrifugal Pumps ◽  
Gas Volume Fraction ◽  
Gas Liquid Flow ◽  
Liquid Flows ◽  
Complex Phenomena ◽  
Gas Volume

Abstract Centrifugal pumps operating with gas-liquid flows can undergo severe performance degradation. This can be attributed to an effect of the gas phase on the liquid flow orientation in the pump impeller channels, which induces additional hydraulic losses that negatively affect the delivered head and flow rate. Effort to investigate the effect of many operating parameters on the pump performance under multiphase flows can be found on numerous experimental investigations. Few studies, however, bring together flow visualization to understand the physics behind the behavior of centrifugal pumps with gas-liquid flows. One issue is that pumps involve rotating parts, metallic casing and limited visual access, sometimes making it hard to interpret flow patterns and to understand complex phenomena, such as bubble breakup and coalescence. Such issues usually lead to unsatisfactory image quality, which in turn makes it difficult to extract quantitative data from the obtained images, such as gas volume fraction and bubble size distribution. In an attempt to overcome many difficulties of previous investigations, this work presents an experimental study aimed to visualize gas-liquid flow patterns in a centrifugal rotor prototype using a novel approach. The experimental apparatus uses a plane and transparent rotor, assembled with an intake pipe and a discharge chamber by means of a dynamic seal system that dismisses the use of an enclosing pump casing. This makes possible to use back illumination of the impeller for visualization, which in turn is done by using a camera attached to the impeller axis for filming in a rotating frame of reference. This setup, which is new in the open literature, provides high image contrast and sharpness for clear interpretation of the flow patterns found inside the rotor channels for a wide range of operating conditions. This advantage, in turn, allows using image processing for quantitative assessment of gas volume fraction distributions. Pressure rise versus flow rate curves are measured together to investigate the rotor performance degradation associated with the gas-liquid flow patterns for a range of liquid and gas flow rates. Information obtained with the designed experimental setup at controlled conditions help not just to bring further understanding to the complex phenomena involved with multiphase flows in rotating devices, but also in the direction of validating a numerical model for reliable simulations of gas-liquid flows in centrifugal pumps, which is lacking in the current literature.

Investigation of Gas-Liquid Flow Using Electrical Resistance Tomography and Wavelet Analysis Techniques for Early Kick Detection

2021 ◽  
Author(s):  
Abinash Barooah ◽  
Muhammad Saad Khan ◽  
Mohammad Azizur Rahman ◽  
Abu Rashid Hasan ◽  
Kaushik Manikonda ◽  
...  
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Electrical Resistance ◽  
Liquid Flow Rate ◽  
Volume Fraction ◽  
Gas Kick ◽  
Input Pressure ◽  
Gas Volume Fraction ◽  
Gas Liquid Flow ◽  
Gas Volume

Abstract Gas kick is a well control problem and is defined as the sudden influx of formation gas into the wellbore. This sudden influx, if not controlled, may lead to a blowout problem. An accidental spark during a blowout can lead to a catastrophic oil or gas fire. This makes early gas kick detection crucial to minimize the possibility of a blowout. The conventional kick detection methods such as the pit gain and flow rate method have very low sensitivity and are time-consuming. Therefore, it is required to identify an alternative kick detection method that could provide real-time readings with higher sensitivity. In this study, Electrical Resistance Tomography (ERT) and dynamic pressure techniques have been used to investigate the impact of various operating parameters on gas volume fraction and pressure fluctuation for early kick detection. The experiments were conducted on a horizontal flow loop of 6.16 m with an annular diameter ratio of 1.8 for Newtonian fluid (Water) with varying pipe inclination angle (0–10°) and annulus eccentricity (0–30%), liquid flow rate (165–265 kg/min), and air input pressure (1–2 bar). The results showed that ERT is a promising tool for the measurement of in-situ gas volume fraction. It was observed that the liquid flow rate, air input pressure and inclination has a much bigger impact on gas volume fraction whereas eccentricity does not have a significant influence. An increase in the liquid flow rate and eccentricity by 60% and 30% decreased the gas volume fraction by an average of 32.8% and 5.9% respectively, whereas an increase in the inclination by 8° increased the gas volume fraction by an average 42%. Moreover, it was observed that the wavelet analysis of the pressure fluctuations has good efficacy for real-time kick detection. Therefore, this study will help provide a better understanding of the gas-liquid flow and potentially provide an alternative method for early kick detection.

Experimental Analysis of Gas–Liquid Flows in a Centrifugal Rotor

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Henrique Stel ◽  
Edgar M. Ofuchi ◽  
Rafael F. Alves ◽  
Sergio Chiva ◽  
Rigoberto E. M. Morales
Keyword(s):  
Liquid Flow ◽  
Experimental Analysis ◽  
Volume Fraction ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Phase Dynamics ◽  
Wide Range ◽  
Experimental Apparatus ◽  
Gas Liquid Flow ◽  
Liquid Flows

Abstract This work presents an experimental analysis of gas–liquid flows in a centrifugal rotor prototype. Pressure rise curves are evaluated considering a wide range of liquid and gas flowrates and different rotating speeds. An innovative apparatus including a dynamic sealing system, back illumination, and filming in a rotating frame of reference is employed to visualize gas–liquid flow patterns at different operating conditions. Volume fraction measurement and bubble-size evaluation are also taken into account. The experimental apparatus allowed analyzing details of the gas-phase dynamics inside the rotor channels. That includes preferential bubble paths and zones of agglomeration, gas pocket formation, coalescence and breakup, and the effect of flow pattern transition on different degrees of performance degradation that centrifugal rotors are subject to when working with gas–liquid flows. Also, important information about the effect of the gas flowrate and the rotating speed on the performance of the assumed rotor prototype could be gathered. Discussions in this work should contribute to comprehend the behavior of gas–liquid flow in centrifugal pumps, a topic that is still far from being well understood. Qualitative and quantitative data here presented could also be valuable to guide the development of numerical models to solve this problem.

scholarly journals Effect of the Gas Volume Fraction on the Pressure Load of the Multiphase Pump Blade

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 650
Author(s):  
Guangtai Shi ◽  
Dandan Yan ◽  
Xiaobing Liu ◽  
Yexiang Xiao ◽  
Zekui Shu
Keyword(s):  
Flow Rate ◽  
Static Pressure ◽  
Volume Fraction ◽  
Pump Impeller ◽  
Impeller Blade ◽  
Multiphase Pump ◽  
Pressure Load ◽  
Gas Volume Fraction ◽  
Power Capability ◽  
Gas Volume

The gas volume fraction (GVF) often changes from time to time in a multiphase pump, causing the power capability of the pump to be increasingly affected. In the purpose of revealing the pressure load characteristics of the multiphase pump impeller blade with the gas-liquid two-phase case, firstly, a numerical simulation which uses the SST k-ω turbulence model is verified with an experiment. Then, the computational fluid dynamics (CFD) software is employed to investigate the variation characteristics of static pressure and pressure load of the multiphase pump impeller blade under the diverse inlet gas volume fractions (IGVFs) and flow rates. The results show that the effect of IGVF on the head and hydraulic efficiency at a small flow rate is obviously less than that at design and large flow rates. The static pressure on the blade pressure side (PS) is scarcely affected by the IGVF. However, the IGVF has an evident effect on the static pressure on the impeller blade suction side (SS). Moreover, the pump power capability is descended by degrees as the IGVF increases, and it is also descended with the increase of the flow rate at the impeller inlet. Simultaneously, under the same IGVF, with the increase of the flow rate, the peak value of the pressure load begins to gradually move toward the outlet and its value from hub to shroud is increased. The research results have important theoretical significance for improving the power capability of the multiphase pump impeller.

Experimental Study of Gas-Liquid Pressurization Performance and Critical Gas Volume Fractions of a Multiphase Pump

2021 ◽  
Author(s):  
Liang Chang ◽  
Qiang Xu ◽  
Chenyu Yang ◽  
Xiaobin Su ◽  
Xuemei Zhang ◽  
...  
Keyword(s):  
Liquid Flow ◽  
Volume Fraction ◽  
Extreme Points ◽  
Transition Flow ◽  
Two Phase ◽  
Flow Rates ◽  
Multiphase Pump ◽  
Gas Liquid Flow ◽  
Relative Errors ◽  
Gas Volume

Abstract Gas entrainment may cause pressurization deterioration and even failure of pumps under conditions of high inlet gas volume fraction (GVF). When the inlet GVF increases to a critical value, an obvious deterioration performance of pump occurs. Air-water pressurization performance and inlet critical GVFs of a centrifugal multiphase pump are investigated experimentally under different inlet pressures and gas-liquid flow rates. To determine the first and second critical GVFs, a new method is proposed by computing the local extreme points of the second derivative of performance curves. New prediction correlations for two critical GVFs are established with relative errors lower than ±10% and ±8%. Boundaries of three different flow patterns and the transition flow rates are determined and presented by critical GVFs on the flow pattern diagram. Moreover, boundaries of maximum pressurization are determined by performance curve clusters and a power function correlation of gas-liquid flow rates when reaching the maximum pressurization is established. With the increase of inlet pressure from 1MPa to 5MPa, two-phase pressurization performance is significantly increased; occurrences of pressurization deterioration are obviously delayed with the first and second critical GVFs increasing by maximums of 8.2% and 7.1%.

scholarly journals Transport Performance Improvement of a Multiphase Pump for Gas–Liquid Mixture Based on the Orthogonal Test Method

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1402
Author(s):  
Guangtai Shi ◽  
Helin Li ◽  
Xiaobing Liu ◽  
Zongku Liu ◽  
Binxin Wang
Keyword(s):  
Flow Rate ◽  
Volume Fraction ◽  
Liquid Mixture ◽  
Suction Side ◽  
Orthogonal Test ◽  
Test Method ◽  
Trailing Edge ◽  
Multiphase Pump ◽  
Gas Volume Fraction ◽  
Gas Volume

To improve the transport performance of a rotodynamic multiphase pump for a gas–liquid mixture, we took the head and efficiency index at rated flow rate with 15% inlet gas volume fraction as the indices, and used the orthogonal test design method and CFD technology to optimize. We selected the blade shroud angles at the leading edge and trailing edge, and axial length of the impeller, as well as the inlet incidence angle and blade number of the diffuser, and a total of five factors were used for the orthogonal test. The weight function was used to determine the final trial protocol. The results showed that the blade shroud angle at the trailing edge had the greatest influence on the head and efficiency indices. Under the rated flow rate with a 15% inlet gas volume fraction, the head and efficiency of the optimized pump were increased by 2.81 m and 5.6%, respectively, in comparison to the base pump. After the optimization, the partial fast-speed regions at the inlet of the impeller passage and the partial low-pressure regions on the blade suction side of the impeller disappeared, the accumulation of the gas phase on the blade suction side at the impeller outlet was suppressed, and the pumping performance of the impeller using the gas–liquid mixture was improved greatly. This study provides an important theoretical basis for the optimization and design of a multiphase pump.

CFD-Analyse zur Leistungssteigerung eines Orbit-Motors*/CFD investigation of the performance of an orbital motor - CFD investigation of the influence of the rotor teeth number and eccentricity on the performance of an orbital motor

2015 ◽  
Vol 105 (06) ◽  
pp. 433-439
Author(s):  
A. Mishev ◽  
T. Stehle
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Rate ◽  
Volume Fraction ◽  
Cfd Analysis ◽  
Rotor Design ◽  
Pressure Ripple ◽  
Computational Fluid Dynamics Cfd ◽  
Gas Volume Fraction ◽  
Gas Volume

Vorgestellt wird ein neuer Orbit-Motor mit innovativem Rotor-Design. Der Motor wurde grundlegend mit der Methode „Computational Fluid Dynamics (CFD) Analysis“ (numerische Strömungsmechanik) simulativ untersucht und entwickelt. Sechs volle dreidimensionale transiente CFD-Orbit-Motor-Modelle wurden entwickelt und mit dem CFD-Modell eines Standard-Orbit-Motors verglichen. Dabei weisen die CFD-Simulationsergebnisse für die neuen Orbit-Motoren-Modellvarianten einen deutlichen Anstieg des Motordrehmoments sowie wesentlich geringere Druck- und Gasvolumen-Anteil-Pulsationen gegenüber dem Standard-Orbit-Motor auf.   In this paper a new orbital motor with innovative rotor design is presented and fundamentally investigated by means of CFD analysis. Six full 3D transient CFD orbital motor models were designed and compared to a standard orbital motor. The results from the simulation showed a substantial increase of the motor torque and reduction of the pressure ripple and gas volume fraction ripple of all six models. Furthermore the flow rate and the volumetric efficiency of all orbital motor models were predicted.

scholarly journals Velocity bias in intrusive gas-liquid flow measurements

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
B. Hohermuth ◽  
M. Kramer ◽  
S. Felder ◽  
D. Valero
Keyword(s):  
Liquid Flow ◽  
Breaking Waves ◽  
Correction Method ◽  
Force Balance ◽  
Bubble Velocity ◽  
Natural Environments ◽  
Flow Measurements ◽  
Gas Liquid Flow ◽  
Liquid Flows ◽  
Velocity Bias

AbstractGas–liquid flows occur in many natural environments such as breaking waves, river rapids and human-made systems, including nuclear reactors and water treatment or conveyance infrastructure. Such two-phase flows are commonly investigated using phase-detection intrusive probes, yielding velocities that are considered to be directly representative of bubble velocities. Using different state-of-the-art instruments and analysis algorithms, we show that bubble–probe interactions lead to an underestimation of the real bubble velocity due to surface tension. To overcome this velocity bias, a correction method is formulated based on a force balance on the bubble. The proposed methodology allows to assess the bubble–probe interaction bias for various types of gas-liquid flows and to recover the undisturbed real bubble velocity. We show that the velocity bias is strong in laboratory scale investigations and therefore may affect the extrapolation of results to full scale. The correction method increases the accuracy of bubble velocity estimations, thereby enabling a deeper understanding of fundamental gas-liquid flow processes.

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