scholarly journals Characteristics of Centrifugal Pumps Working in Direct or Reverse Mode: Focus on the Unsteady Radial Thrust

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Anthony Couzinet ◽  
Laurent Gros ◽  
Daniel Pierrat
Keyword(s):  
Numerical Data ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Specific Test ◽  
Pump Operation ◽  
Reverse Mode ◽  
Ansys Cfx ◽  
Test Loop ◽  
Radial Forces ◽  
Radial Thrust

Experimental and numerical investigations have been carried out to study the behaviour of a centrifugal pump operating in direct mode or turbine mode. First of all, the complete characteristics (head, power, and efficiency) were measured experimentally using a specific test loop. The numerical data obtained from a CFD study performed with the ANSYS CFX software and based on steady state and unsteady approaches were compared to the experimental results. The representation in the 4 operating quadrants shows the various operating zones where the head is always positive. Then, the unsteady radial forces were analysed from transient computations. The results obtained for the pump operation are consistent with the literature and extended to the nonnormal operating conditions, namely, for very high flowrate values. The evolution of the radial load during turbine operation is presented for various partial flow operating points.

Numerical Analysis of Centrifugal Pumps Running in Turbine Mode Under Dynamic Operating Conditions

2017 ◽  
Author(s):  
Vincenzo De Rose ◽  
Francesca Martelli ◽  
Massimo Milani ◽  
Luca Montorsi
Keyword(s):  
Cfd Simulation ◽  
Energy Conversion Efficiency ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Pump Operation ◽  
Electric Generator ◽  
Reverse Mode ◽  
Hydropower Plants ◽  
Dynamic Operating ◽  
Turbine Mode

The use of pumps as turbines (PAT) has gained importance in the recent years as a possible alternative to specifically developed turbine for mini/micro hydropower plants. The use of production pump for hydropower generation reduces the capital cost of the plant but the energy conversion efficiency can be remarkably lower. The paper analyses the performance of a production centrifugal pump running both in direct and reverse mode. The analysis calculates theoretically the behavior of the PAT under the best efficiency point and extends the investigation to other operating points using both a combined theoretical approach and CFD simulation under dynamic conditions. The effects of possible modifications to the initial design of the pump are investigated when running in turbine mode and their influence on the standard pump operation is also determined. Numerical simulation demonstrates that the impeller trimming leads to improvement in the PAT efficiency in some operating conditions. Conversely, the rotational speeds close to the values typical for the electric generator reduce the PAT performance. Finally, the modification of the impeller geometry at the turbine inlet increases the PAT efficiency but lowers the performance of the machine when running in pump mode.

Aerodynamically Induced Radial Forces in a Centrifugal Gas Compressor: Part 1—Experimental Measurement

1998 ◽  
Vol 120 (2) ◽  
pp. 383-390 ◽  
Author(s):  
J. J. Moore ◽  
M. B. Flathers
Keyword(s):  
Experimental Measurement ◽  
Operating Conditions ◽  
Design Flow ◽  
Centrifugal Pumps ◽  
Pressure Distributions ◽  
Pressure Fields ◽  
Radial Forces ◽  
Overall Efficiency ◽  
Improved Performance ◽  
Radial Loading

Net radial loading arising from asymmetric pressure fields in the volutes of centrifugal pumps during off-design operation is well known and has been studied extensively. In order to achieve a marked improvement in overall efficiency in centrifugal gas compressors, vaneless volute diffusers are matched to specific impellers to yield improved performance over a wide application envelope. As observed in centrifugal pumps, nonuniform pressure distributions that develop during operation above and below the design flow create static radial loads on the rotor. In order to characterize these radial forces, a novel experimental measurement and post-processing techniquesis employed that yields both the magnitude and direction of the load by measuring the shaft centerline locus in the tilt-pad bearings. The method is applicable to any turbomachinery operating on fluid film radial bearings equipped with proximity probes. The forces are found to be a maximum near surge and increase with higher pressures and speeds. The results are nondimensionalized, allowing the radial loading for different operating conditions to be predicted.

An Experimental Investigation of Radial Thrust in Centrifugal Pumps

1960 ◽  
Vol 82 (2) ◽  
pp. 120-125 ◽  
Author(s):  
A. Agostinelli ◽  
D. Nobles ◽  
C. R. Mockridge
Keyword(s):  
Experimental Investigation ◽  
Centrifugal Pump ◽  
Graphical Form ◽  
Strain Gages ◽  
Centrifugal Pumps ◽  
Speed Range ◽  
Radial Forces ◽  
Specific Speed ◽  
Radial Thrust

An experimental investigation has been conducted to determine the magnitudes and directions of the unbalanced radial forces on centrifugal pump impellers. The work covers single volutes for a wide specific speed range, double volutes, concentric casings, and modifications of the concentric casing. The results are presented in graphical form and are discussed. A method, making use of strain gages, was devised for determining the magnitudes and directions of the resultant radial forces and is described.

Experimental Approach to Predict the Residual Axial Thrust in Centrifugal Pumps

2019 ◽  
Author(s):  
Giulio Elicio ◽  
Francesco Annese
Keyword(s):  
Pressure Distribution ◽  
Rotational Speed ◽  
Experimental Approach ◽  
Thrust Bearing ◽  
High Energy ◽  
Operating Conditions ◽  
Back Side ◽  
Centrifugal Pumps ◽  
Axial Thrust ◽  
Pump Operation

Abstract The residual axial thrust of a centrifugal pump is the vector resultant of the hydraulic components of impellers and sleeves, the momentum force and other imbalance forces and is bear by the thrust bearing. Among all the components, the hydraulic is by far the most important because it is typically one order of magnitude bigger than the others and the final residual axial thrust itself; but it is also the most difficult to calculate or estimate. This is mainly due a lot of uncertainties in the definition of the pressure distribution in the sidewall gap, dependent on the rotational speed, the leakages through the annular seals, the inlet swirl to the sidewall, the axial alignment of the impeller with the stator, the geometric tolerances and the pump operation. In this paper an experimental approach to validate and calibrate the formulation to predict the hydraulic component of the impellers is presented. The typical formulation to evaluate the parabolic behavior of the pressure distribution is based on a series of coefficients, coming from literature, to consider all the above-mentioned influences. This formulation can be considered satisfying when dealing with pumps with back-to-back arrangement of the impellers on the rotor, since the hydraulic components are almost balanced. But with in-line configuration, all the hydraulic components of the impellers act against one direction and most of their force can be balanced by means of a balance drum, much more reliable than a balance disk. An experimental test campaign on a high energy diffuser pump was performed. The pump was equipped with load cells and temperature probes on the thrust bearing, and a special balancing line with a regulating bleed-off valve whose aim was to partialize the flowrate routed from the back side of the balancing drum to the suction. By throttling the bleed-off valve, it was possible to measure the hydraulic components of the impellers in very different operating conditions of the balancing drum, at different rotational speed and at different flowrates included zero residual axial thrust capability. As results of this campaign, once calibrated the coefficients on the full-scale pump, it is possible to calculate the residual axial thrust based on specific pressure measurements of the model test of a stage hydraulic; this also allows a thorough optimization of the thrust bearing selection.

scholarly journals Aerodynamically Induced Radial Forces in a Centrifugal Gas Compressor: Part 1 — Experimental Measurement

1996 ◽  
Author(s):  
J. Jeffrey Moore ◽  
Michael B. Flathers
Keyword(s):  
Experimental Measurement ◽  
Processing Technique ◽  
Operating Conditions ◽  
Design Flow ◽  
Centrifugal Pumps ◽  
Pressure Distributions ◽  
Pressure Fields ◽  
Radial Forces ◽  
Improved Performance ◽  
Radial Loading

Net radial loading arising from asymmetric pressure fields in the volutes of centrifugal pumps during off-design operation is well known and has been studied extensively. In order to achieve a marked improvement in overall efficiency in centrifugal gas compressors, vaneless volute diffusers are matched to specific impellers to yield improved performance over a wide application envelope. As observed in centrifugal pumps, nonuniform pressure distributions that develop during operation above and below the design flow create static radial loads on the rotor. In order to characterize these radial forces, a novel experimental measurement and post-processing technique is employed that yields both the magnitude and direction of the load by measuring the shaft centerline locus in the tilt-pad bearings. The method is applicable to any turbomachinery operating on fluid film radial bearings equipped with proximity probes. The forces are found to be a maximum near surge and increases with higher pressures and speeds. The results are nondimensionalized allowing the radial loading for different operating conditions to be predicted.

Preliminarily Design of Supercritical CO2 Compression Test System

2021 ◽  
Author(s):  
Geng Teng ◽  
Laijie Chen ◽  
Xin Shen ◽  
Hua Ouyang ◽  
Yubo Zhu ◽  
...  
Keyword(s):  
Simulation Model ◽  
Compression Test ◽  
Thermodynamic Model ◽  
Supercritical Co2 ◽  
Operating Performance ◽  
Test System ◽  
Operating Conditions ◽  
Working Fluid ◽  
Stable Operation ◽  
Test Loop

Abstract The centrifugal compressor is the core component of the supercritical carbon dioxide (SCO2) power cycle. It is essential to carry out component-level experimental research on it and test the working characteristics of the compressor and its auxiliary equipment. Building an accurate closed-loop simulation model of closed SCO2 compression loop is a necessary preparation for selecting loop key parameters and establishing system control strategy, which is also an important prerequisite for the stable operation of compressor under test parameters. In this paper, the thermodynamic model of compressor, pre-cooler, orifice plate and other components in supercritical CO2 compression test system is studied, and the simulation model of compression test system is established. Moreover, based on the system enthalpy equations and physical property model of real gas, the compressor, pre-cooler and other components in the test loop are preliminarily designed by using the thermodynamic model of components. Since the operating conditions are in the vicinity of the critical point, when the operating conditions change slightly, the physical properties of the working fluid will change significantly, which might have a greater impact on the operating performance of the system. So the operating performance and the parameter changes of key nodes in the test loop under different operating conditions are calculated, which will provide theoretical guidance for the construction of subsequent experimental loops.

scholarly journals Performance analysis of the working surface of the rails from test batches on the Test Loop of JSC “VNIIZhT”

2018 ◽  
Vol 77 (3) ◽  
pp. 141-148
Author(s):  
M. Yu. Khvostik ◽  
I. V. Khromov ◽  
O. A. Bykova ◽  
G. A. Beresten’
Keyword(s):  
Wear Resistance ◽  
Operating Time ◽  
Operating Conditions ◽  
Continuous Change ◽  
Wear Area ◽  
Railway Network ◽  
Operational Conditions ◽  
Rolling Surface ◽  
Test Loop ◽  
The Impact

The monitoring of railway rails damage on the railway network of the JSC “Russian Railways” as well as operational and polygon tests are conducted with the purpose of assessing the impact of operating conditions on the intensity of rails damage, obtaining initial data for forecasting rails failures. The increased intensity of rails wear on sites with a complex plan and profile leads to the fact that with a continuous change from the track, rails which have an underutilized service life of more than 20 % are retrieved. Polygon tests on the Test Loop of the JSC “VNIIZhT” near the Scherbinka station can provide the repeatability and reliability of the results, comparative tests are carried out under identical conditions and their duration is several times less than when tested at experimental sites under operational conditions. The results of the polygon tests of new differentially heat-strengthened rails did not reveal any advantages in the wear resistance of special purposed rails (laid in the recommended radius of the curve for its application) when comparing the rails of domestic manufacturers. Metal shelling out on the rolling surface of rails is the main reason for the removal of rails from test batches. The origin and development of defects of this kind is due to both violations of the technology of manufacturing rails, and because of violations of the current maintenance of the track. The metal stock in the area of the rail head of R65 type due to the increase in its dimensions positively affects the extension of the lifetime of the rails, reducing the cost of the life cycle and the rail itself, and the design of the track as a whole. When carrying out a separate study in order to obtain results characterizing the stability of high-quality rails to contact fatigue damage, it is advisable to optimize the conditions of the polygon tests, bringing them closer to operational ones. When forming the test results, it is necessary to expand the list of criteria for assessing the wear resistance of rails, supplementing it with the size of the wear area at the time of a certain operating time of the tonnage, with the introduction of this criterion into the appropriate methods for the polygon (operational) tests.

The Design and Operation of Pumps Furnished for Marine Cargo Service: Part II

1988 ◽  
Vol 25 (02) ◽  
pp. 75-104
Author(s):  
William J. Sembler
Keyword(s):  
System Design ◽  
Operating Conditions ◽  
Vapor Pressures ◽  
Pump Operation ◽  
Pump Performance ◽  
Wide Range ◽  
Different Types ◽  
Material Requirements

To a pump manufacturer, marine cargo service represents one of the most demanding applications for which he can design and furnish equipment. In addition to being subjected to the stresses encountered in a shipboard environment, cargo pumps must often perform over a wide range of operating conditions and handle multiple fluids with different viscosities, vapor pressures, specific gravities, temperatures, and material requirements. In this paper the author reviews characteristics of the different types of pumps used for marine cargo service, with an emphasis on the special features that should be incorporated into their design for this rigorous duty. Different types of automatic self-priming/stripping systems available for use with these cargo pumps are also examined. Pump operation is discussed, including the significant impact that system design has on proper pump performance.

scholarly journals A Review of the Flow-Induced Noise Study for Centrifugal Pumps

2020 ◽  
Vol 10 (3) ◽  
pp. 1022 ◽  
Author(s):  
Chang Guo ◽  
Ming Gao ◽  
Suoying He
Keyword(s):  
Optimization Design ◽  
Sound Field ◽  
Operating Conditions ◽  
Response Analysis ◽  
Centrifugal Pumps ◽  
Noise Optimization ◽  
Operating Stability ◽  
Study Results ◽  
Flow Induced Noise ◽  
Negative Impacts

Flow-induced noise is a significant concern for the design and operation of centrifugal pumps. The negative impacts of flow-induced noise on operating stability, human health and the environment have been shown in many cases. This paper presents a comprehensive review of the flow-induced noise study for centrifugal pumps to synthesize the current study status. First, the generation mechanism and propagation route of flow-induced noise are discussed. Then, three kinds of study methodologies, including the theoretical study of hydrodynamic noise, numerical simulation and experimental measurement study, are summarized. Subsequently, the application of the three study methodologies to the analysis of the distribution characteristics of flow-induced noise is analyzed from aspects of the noise source identification and comparison, the frequency response analysis, the directivity characteristics of sound field and the noise changing characteristics under various operating conditions. After that, the analysis of the noise optimization design of centrifugal pumps is summarized. Finally, based on previous study results, this paper puts forward the unsolved problems and implications for future study. In conclusion, the information collected in this review paper could guide further study of the flow-induced noise of centrifugal pumps.

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.

Sign in / Sign up

Export Citation Format

Share Document