Investigation of the Motion of Bubbles in a Centrifugal Pump Impeller

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Henrique Stel ◽  
Edgar M. Ofuchi ◽  
Renzo H. G. Sabino ◽  
Felipe C. Ancajima ◽  
Dalton Bertoldi ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Operating Conditions ◽  
Impeller Speed ◽  
Pump Impeller ◽  
Pump Performance ◽  
Liquid Flows ◽  
Centrifugal Pump Impeller

Centrifugal pumps operate below their nominal capacity when handling gas–liquid flows. This problem is sensitive to many variables, such as the impeller speed and the liquid flow rate. Several works evaluate the effect of operating conditions in the pump performance, but few bring information about the associated gas–liquid flow dynamics. Studying the gas phase behavior, however, can help understanding why the pump performance is degraded depending on the operating condition. In this context, this paper presents a numerical and experimental study of the motion of bubbles in a centrifugal pump impeller. The casing and the impeller of a commercial pump were replaced by transparent components to allow evaluating the bubbles' trajectories through high-speed photography. The bubble motion was also evaluated with a numerical particle-tracking method. A good agreement between both approaches was found. The numerical model is explored to evaluate how the bubble trajectories are affected by variables such as the bubble diameter and the liquid flow rate. Results show that the displacement of bubbles in the impeller is hindered by an increase of their diameter and impeller speed but facilitated by an increase of the liquid flow rate. A force analysis to support understanding the pattern of the bubble trajectories was provided. This analysis should enlighten the readers about the dynamics leading to bubble coalescence inside an impeller channel, which is the main reason behind the performance degradation that pumps experience when operating with gas–liquid flows.

scholarly journals Analisis Kinerja Pompa Sentrifugal pada Variasi Trim Diameter Menggunakan Simulasi Numerik

2021 ◽  
Vol 12 (2) ◽  
pp. 467-474
Author(s):  
Joko Waluyo ◽  
◽  
Kevin Mahardhika ◽  
Rahmat Waluyo
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Performance Prediction ◽  
Blade Angle ◽  
Pump Impeller ◽  
Pump Performance ◽  
Blade Passage ◽  
Dimension Ratio ◽  
Centrifugal Pump Impeller

Diameter trimming is one of the most common modification on centrifugal pump impeller aimed to keep conformity between pump performance and required head and flow rate. In its application, centrifugal pump performance with trimmed diameter could be predicted by using affinity equations which based on geometrical similarity between pre- and post-trimming impeller. However, diameter trimming also alter the dimension ratio in blade passage which prompt further investigation on performance prediction of pump with trimmed impeller diameter. This research is carried out by using numerical simulation to analyze performance of pump with trimmed impeller diameter. The simulation is conducted on radial-type centrifugal pump with impeller diameter 105 mm, inlet blade angle 200, outlet blade angle 280, and operating on mass flow rate 1.5 kg/s at rotational speed 2800 rpm. RNG k-e model is used to model turbulence while trimmed diameter values are 100 mm and 95 mm. Results indicate that there is significant differences on head and consumed power between predicted value by simulation and predicted value obtained by employing affinity equations.

scholarly journals Large Eddy Simulation of Periodic Transient Pressure Fluctuation in a Centrifugal Pump Impeller at Low Flow Rate

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 311
Author(s):  
Renfei Kuang ◽  
Xiaoping Chen ◽  
Zhiming Zhang ◽  
Zuchao Zhu ◽  
Yu Li
Keyword(s):  
Large Eddy Simulation ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Low Frequency ◽  
Pump Impeller ◽  
Eddy Simulation ◽  
Inlet Flow Rate ◽  
Large Eddy ◽  
Centrifugal Pump Impeller

This paper presents a large eddy simulation of a centrifugal pump impeller during a transient condition. The flow rate is sinusoidal and oscillates between 0.25Qd (Qd indicates design load) and 0.75Qd when the rotating speed is maintained. Research shows that in one period, the inlet flow rate will twice reach 0.5Qd, and among the impeller of one moment is a stall state, but the other is a non-stall state. In the process of flow development, the evolution of low-frequency pressure fluctuation shows an obviously sinusoidal form, whose frequency is insensitive to the monitoring position and equals to that of the flow rate. However, inside the impeller, the phase and amplitude in the stall passages lag behind more and are stronger than that in the non-stall passages. Meanwhile, the strongest region of the high-frequency pressure fluctuation appears in the stall passages at the transient rising stage. The second dominant frequency in stall passages is 2.5 times to that in non-stall passages. In addition, similar to the pressure fluctuation, the evolution of the low-frequency head shows a sinusoidal form, whose phase is lagging behind that by one-third of a period in the inlet flow rate.

scholarly journals A Comparative Assessment of Spalart-Shur Rotation/Curvature Correction in RANS Simulations in a Centrifugal Pump Impeller

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Ran Tao ◽  
Ruofu Xiao ◽  
Wei Yang ◽  
Fujun Wang
Keyword(s):  
Kinetic Energy ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Comparative Assessment ◽  
Turbulence Kinetic Energy ◽  
Low Flow ◽  
Pump Impeller ◽  
Curvature Correction ◽  
Centrifugal Pump Impeller ◽  
Low Flow Rate

RANS simulation is widely used in the flow prediction of centrifugal pumps. Influenced by impeller rotation and streamline curvature, the eddy viscosity models with turbulence isotropy assumption are not accurate enough. In this study, Spalart-Shur rotation/curvature correction was applied on the SSTk-ωturbulence model. The comparative assessment of the correction was proceeded in the simulations of a centrifugal pump impeller. CFD results were compared with existing PIV and LDV data under the design and low flow rate off-design conditions. Results show the improvements of the simulation especially in the situation that turbulence strongly produced due to undesirable flow structures. Under the design condition, more reasonable turbulence kinetic energy contour was captured after correction. Under the low flow rate off-design condition, the prediction of turbulence kinetic energy and velocity distributions became much more accurate when using the corrected model. So, the rotation/curvature correction was proved effective in this study. And, it is also proved acceptable and recommended to use in the engineering simulations of centrifugal pump impellers.

scholarly journals Analyses of Hydrodynamic Radial Forces on Centrifugal Pump Impellers

1988 ◽  
Vol 110 (1) ◽  
pp. 20-28 ◽  
Author(s):  
D. R. Adkins ◽  
C. E. Brennen
Keyword(s):  
Theoretical Model ◽  
Centrifugal Pump ◽  
Substantial Effect ◽  
Operating Conditions ◽  
Pump Impeller ◽  
Pressure Distributions ◽  
Flow Disturbances ◽  
Radial Forces ◽  
Flow Through ◽  
Centrifugal Pump Impeller

Hydrodynamic interactions that occur between a centrifugal pump impeller and a volute are experimentally and theoretically investigated. The theoretical analysis considers the inability of the blades to perfectly guide the flow through the impeller, and also includes a quasi-one dimensional treatment of flow in the volute. Flow disturbances at the impeller discharge and the resulting forces are determined by the theoretical model. The model is then extended to obtain the hydrodynamic force perturbations that are caused by the impeller whirling eccentrically in the volute. Under many operating conditions, these force perturbations were found to be destabilizing. Comparisons are made between the theoretical model and the experimental measurements of pressure distributions and radial forces on the impeller. The theoretical model yields fairly accurate predictions of the radial forces caused by the flow through the impeller. However, it was found that the pressure acting on the front shroud of the impeller has a substantial effect on the destabilizing hydrodynamic forces.

Effects of Operating Parameters on the Efficacy of Engineered Water Nanostructures (EWNS) in Inactivating Escherichia coli on Stainless-Steel Surfaces

2021 ◽  
Vol 64 (6) ◽  
pp. 1913-1920
Author(s):  
Yuchen Si ◽  
Yingjie Yang ◽  
Myra Martel ◽  
Brooke Thompson ◽  
Bernardo Predicala ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Flow Rate ◽  
Liquid Flow ◽  
Applied Voltage ◽  
Counter Electrode ◽  
Liquid Flow Rate ◽  
Operating Conditions ◽  
Stainless Steel Surface ◽  
Bacterial Concentration ◽  
E Coli

HighlightsThe efficacy of EWNS to disinfect surfaces was assessed at a bacterial concentration similar to pig barns.Liquid pH, liquid conductivity, and applied voltage were found to directly affect the efficacy of EWNS.The efficacy increased as liquid flow rate and distance between needle tip and counter electrode decreased.An E. coli reduction of 3.0 log was achieved on a stainless-steel surface after 15 min exposure to EWNS.Abstract. Several studies have shown the potential of engineered water nanostructures (EWNS) generated using a capillary electrospray system to inactivate foodborne bacteria; however, there is a lack of data on EWNS performance in inactivating microbes in livestock facilities. Thus, this laboratory-scale study investigated the effects of operating conditions on the efficacy of EWNS in inactivating Escherichia coli (E. coli) on coupons made of stainless steel, a common surface material in pig barns, at a bacterial concentration similar to levels found on pig barn surfaces. The electrospray module was composed of a capillary needle that was connected to a high-voltage power supply. The efficacy of the technology in inactivating E. coli was assessed with various operating parameters (i.e., applied voltage, distance between needle tip and counter electrode, and liquid flow rate, pH, and conductivity). The efficacy of the EWNS was found to be directly related to the liquid pH, liquid conductivity, and applied voltage, but inversely related to the liquid flow rate and distance between the needle tip and counter electrode. An E. coli reduction of 3.0 log was obtained after 15 min exposure to EWNS under the following operating conditions: liquid flow rate of 1 µL min-1, pH of 12, liquid conductivity of 14.72 mS cm-1, 2 cm distance between the needle tip and counter electrode, and -7.6 kV applied voltage. The results of this study can serve as an initial basis for the application of EWNS on surfaces in a real barn environment, where the presence of other factors, such as gases, dust, and other organic matter and microbial species, must be taken into account. Keywords: Electrospray, Engineered water nanostructures, E. coli, Stainless-steel surface, Surface decontamination.

Theoretical Analysis of Flow Through Two-Dimensional Centrifugal Pump Impeller by Method of Singularities

1971 ◽  
Vol 93 (1) ◽  
pp. 35-40 ◽  
Author(s):  
S. K. Ayyubi ◽  
Y. V. N. Rao
Keyword(s):  
Centrifugal Pump ◽  
Operating Conditions ◽  
Two Dimensional ◽  
Pump Impeller ◽  
Pump Operation ◽  
Wide Range ◽  
Hydrodynamic Method ◽  
Flow Through ◽  
Experimental Values ◽  
Centrifugal Pump Impeller

The hydrodynamic method of singularities is used to analyze the flow through two-dimensional centrifugal pump impellers with blades of an arbitrary geometry. Computed values of ideal head are compared with experimental values obtained for a commercial pump. The agreement between theory and experiment is very close over a wide range of pump operation. The discrepancies that occur at other operating conditions are attributed to the effects of inlet passage and volute casing.

Effects of Near-Wall Vortices on Wall Shear Stress in a Centrifugal Pump Impeller

2021 ◽  
Vol 16 ◽  
pp. 37-47
Author(s):  
Salman Shahid ◽  
Abdul Qader Hasan ◽  
Sharul Sham Dol ◽  
Mohamed S. Gadala ◽  
Mohd Shiraz Aris
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Head ◽  
Research Paper ◽  
Shear Stresses ◽  
Pump Impeller ◽  
Wall Shear ◽  
Pump Pressure ◽  
Centrifugal Pump Impeller ◽  
Near Wall

Boundary layer separation and vortex formation cause unappealing deterioration of pump pressure head. The purpose of this research paper is to correlate formation of vortices with near-wall shear stresses resulting in a loss of pump pressure head. This phenomenon is observed at the centrifugal pump impeller tip at various flow rates and impeller rotational velocities through CFD (Computational Fluid Dynamic) analysis. This research paper investigates internal flow in a shrouded centrifugal impeller that is modelled under design flow rate conditions using ANSYS Fluent as its simulation bases solving built-in Navier-Stokes equation, and 𝑘 − 𝜔 SST turbulence model under steady conditions. Numerical results revealed an increase in wall shear stresses with increasing flow rate ranging from 314.2 Pa to 595.60 Pa at increments that pulsate per flow rate. Flow characteristics, such as evolution of vortices and flow turbulence enhance wall shear stresses increasing the wall skin-friction remarkably leading towards a loss in pressure head. This paper analyzes the vortices and turbulence in flow structures with regards to their influence upon the impeller performance.

Absorption and Mass Transfer of CO2 in Monoethanolamine Solution

2016 ◽  
Vol 859 ◽  
pp. 153-157
Author(s):  
Pao Chi Chen ◽  
Sheng Zhong Lin
Keyword(s):  
Mass Transfer ◽  
Flow Rate ◽  
Liquid Flow ◽  
Gas Flow ◽  
Liquid Flow Rate ◽  
Bubble Column ◽  
Operating Conditions ◽  
Gas Flow Rate ◽  
Constant Ph ◽  
Gas Liquid Flow

This work uses a continuous bubble-column scrubber for the absorption of CO2 with a 5M MEA solution under a constant pH environment to explore the effect of the pH of the solution and gas-flow rate (Qg) on the removal efficiency (E), absorption rate (RA), overall mass-transfer coefficient (KGa), liquid flow rate (QL), gas-liquid flow ratio (γ), and scrubbing factors (φ). From the outlet CO2 concentration with a two-film model, E, RA, KGa, QL, γ, and φ can be simultaneously determined at the steady state. Depending on the operating conditions, the results show that E (80-97%), RA(2.91x10-4-10.0x10-4mol/s-L), KGa (0.09-0.48 1/s), QL(8.74-230.8mL/min), γ (0.19-5.39), and φ (0.031-0.74 mol/mol-L) are found to be comparable with other solvents. In addition, RA, KGa, E, and QL have been used to correlate with pH and Qg, respectively, with the results further explained.

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