Effect of Vibrations on the Performance of a Centrifugal Pump-Impeller When Using a Variable Frequency Drive

2016 ◽  
Author(s):  
G. Lara-Rodriguez ◽  
O. Begovich ◽  
J. L. Naredo
Keyword(s):  
Centrifugal Pump ◽  
Incidence Angle ◽  
Operating Conditions ◽  
Rapid Decline ◽  
Variable Frequency ◽  
Liquefied Petroleum Gas ◽  
Or Efficiency ◽  
Pump Impeller ◽  
Variable Frequency Drive ◽  
Partial Load

This paper deals with turbomachinery, such as pumps or turbines, which are very sensitive to changes in fluid speed over the contours of the blades when the volumetric flow is varied. These changes modify the fluid incidence angle, causing a rapid decline in pump performance. Our research focuses on an analysis of the performance or efficiency of a centrifugal pump with a variable frequency drive, where losses in efficiency are caused by turbulence generating harmful vibrations in the installation. The methodology consists of measuring the magnitude of the vibrations. The data obtained are compared to the performance reached when the change in velocity has been produced with the regulation of the volumetric flow to a partial load of the pump. This suggests an analysis to attempt to resolve the issue of density variation that occurs when pumping liquefied petroleum gas (LPG) under regular operating conditions.

scholarly journals Study on custom centrifugal pump performance in supplying food based high viscos liquid

2021 ◽  
Vol 5 (1) ◽  
pp. 80-88
Author(s):  
Nur Hanna Khairul Anuar ◽  
Mohd Nizar Mhd Razali ◽  
Mohamad Rusydi Mohamad Yasin ◽  
Musfirah Abdul Hadi ◽  
Abdul Nasir Abd. Ghaffar
Keyword(s):  
Centrifugal Pump ◽  
Variable Frequency ◽  
Pump Efficiency ◽  
Shaft Speed ◽  
Variable Frequency Drive ◽  
Viscous Liquids ◽  
Pump Performance ◽  
Dynamic Head ◽  
Shaft Power ◽  
Pump Shaft

Viscosity is one of the factors affecting the performance of the centrifugal pump. A centrifugal pump is a device that used driven motor called impeller to move fluid by rotational energy. This thesis is about the analysis of the performance of the centrifugal pump when transferring viscous liquids. For this project, the objective is to design and fabricate a device that can pump liquid with various viscosity using centrifugal pump. The liquids used in the experiment are comprised of a mixture of detergent and water with different ratio to alter the viscosity. The viscosity is being identified by the usage of Zahn Cup Method with the temperature kept constant at 26 °C throughout the experiment. The performance of the centrifugal pump is being investigated by four parameters which is the flowrate, Total Dynamic Head (TDH), power and efficiency. The performance of the centrifugal pump can be accessed by altering the pump shaft speed in order to get various reading for the flow rate. In order to alter the pump shaft speed, the usage of motor with Variable Frequency Drive (VFD) is implemented. The values for the flowrate and pump shaft power are measured by flowmeter and Variable Frequency Drive (VFD). The Total Dynamic Head (TDH), hydraulic power and pump efficiency is calculated based on the reading of the flowmeter and pump shaft power displayed at Variable Frequency Drive (VFD). At the end of this project, the pump performance while pumping different viscous liquids at different flowrates is being identified.

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.

Numerical Simulation of Hysteresis on Head/Discharge Characteristics of a Centrifugal Pump

2003 ◽  
Author(s):  
Masamichi Iino ◽  
Kazuhiro Tanaka ◽  
Kazuyoshi Miyagawa ◽  
Takeshi Okubo
Keyword(s):  
Numerical Simulation ◽  
Hysteresis Loop ◽  
Centrifugal Pump ◽  
Characteristic Curve ◽  
Swirl Flow ◽  
Centrifugal Pumps ◽  
Pump Impeller ◽  
Discharge Characteristics ◽  
Discharge Characteristic ◽  
Partial Load

The objectives of the present study were to investigate influences of fins, set in a suction part, on the positive slope and hysteresis loop in head/discharge characteristic curves of centrifugal pumps in the experiment as well as in the numerical prediction. The fins were located in upstream side of a pump impeller to suppress swirl flow occurring before the impeller inlet at partial load operation. We had two kinds of centrifugal pump with/without the fins, the number of which is 16. These two centrifugal pumps had a shrouded impeller with 7 blades and a diffuser with 20 guide vanes with the same configuration. In the experiment, the pump with them had a large hysteresis loop at partial load operation in the head/discharge characteristic curve, although the pump without them had no hysteresis loop. In the numerical simulation based on periodic flow, the incompressible turbulent flow field was calculated for partial blade-passages with periodic boundary conditions. As a result, the simulated characteristics had the same tendencies as the experimental results. Furthermore, the causes of the discontinuous head/discharge characteristics depending on the direction of partial load operation were clarified through calculating and comparing the internal flow fields in the cases with/without the fins. The pumps had the large backflow and recirculation areas in two places, one of which was near the shroud at the impeller inlet including the fins area and another near the central part of the diffuser. The difference in the hysteresis loop between with and without the fins was caused by the existence of the fins, which suppressed or promoted the backflow at the impeller.

Flow Field Instability and Rotordynamic Impedances for an Open Impeller Centrifugal Pump in Transient Four-Quadrant Regimes

2020 ◽  
Author(s):  
Md Shujan Ali ◽  
Farzam Mortazavi ◽  
Alan Palazzolo
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Turbulence Model ◽  
Flow Direction ◽  
High Energy ◽  
Operating Conditions ◽  
Mesh Deformation ◽  
Pump Impeller ◽  
Transient Regimes ◽  
Dynamic Forces

Abstract The American Petroleum Institute (API) level 2 rotordynamic stability analysis requires determination of possible destabilization forces on a compressor or pump impeller. Dynamic forces in transient regimes are often excluded although a turbomachine impeller may experience transient operation intentionally or accidentally. The centrifugal pump head, flow direction, rotation and torque can be both positive and negative in transient regimes. For example, in a renewable energy application, pump flow direction and rotation are reversed to generate power from the imposed fluid head. The complete characteristics of a centrifugal pump correspond to all four quadrants (4Q) of operation, to encompass all possible operating conditions. It is required to understand centrifugal pump impeller dynamic forces and rotordynamic responses for all 4Q for design, fault diagnostic, instability analysis, upset conditions (such as water hammer, surge etc.) and for reliable operation of high energy density machines. In the open literature, whirling impeller rotordynamic analyses appears only for normal pump operation. Centrifugal pump dynamic forces, rotordynamic impedances and flow instabilities of an open impeller are reported for 4Q operating regimes in this paper. A transient Computational Fluid Dynamics (CFD)-based model is implemented which is applicable to nonaxisymmetric turbomachinery components, such as with a volute and/or vaned diffuser. Whirling motion of the impeller is modeled by imposing mesh deformation at the impeller walls. A phase modulated multi-frequency mesh deformation method is imposed for better numerical efficiency. Reynolds Averaged Navier-Stokes (RANS) equations with the Shear Stress Transport (SST) turbulence model along with a transitional bypass turbulence model are employed for the CFD solution. The results show the underlying flow field instability and stall cells responsible for the impedance shapes. Furthermore, the model is employed for determining the dependence of the outputs on specific speed to extract rotordynamic forces more efficiently. Impeller dynamic forces are found to scale with the size of the impeller for the same eccentricity ratio and the same flow coefficient. Strength of impeller rotating stalls has dependence on whirl frequency ratio.

Comparative modeling and analysis of the flow asymmetricity in a centrifugal pump impeller at partial load

2019 ◽  
Vol 234 (2) ◽  
pp. 237-247 ◽  
Author(s):  
Ran Tao ◽  
Zhengwei Wang
Keyword(s):  
Flow Regime ◽  
Centrifugal Pump ◽  
Channel Flow ◽  
Pressure Pulsation ◽  
Rotating Stall ◽  
Pressure Pulsations ◽  
Pump Impeller ◽  
Partial Load ◽  
Load Conditions ◽  
Centrifugal Pump Impeller

Undesirable flow regime occurs at partial-load conditions of the centrifugal pump. Flow separates at the leading edge and pulses in the blade channel with complex stall cell transfer law. The passing capability of the blade channel becomes important when rotating stall happens. In this study, the blade channel number influence on the flow stability in a centrifugal pump impeller was studied by unsteady flow simulations after numerical-experimental verification. The 5-, 6-, and 7-blade impellers were discussed under the same partial-load flow rate condition and the same rotating speed. Results show that the internal flow pattern was strongly influenced by the blade channel number. Periodic half-blockage was observed in the 5-blade impeller. Alternating stall with three stalled and three well-behaved channels existed in the 6-blade impeller. Complex aperiodic flow pattern occurred in the 7-blade impeller with the well-behaved, half-blocked, and fully stalled passages were all observed with stall cell transfer. The different flow regime caused different pressure pulsations. In the 5-blade impeller, the inter-channel flow frequencies, which were induced by the fluid extruded from blocked channels flowed into other channels, dominated. In the 6-blade impeller, the pressure pulsations performed low-in-amplitude and high-in-frequency. The flow regime was stable even under the rotating stall. In the 7-blade impeller, the rotating stall frequency dominated. The inter-channel flow frequencies were also obvious. The stable rotating stall pattern does not strongly influence the pressure pulsation and impeller axial and radial forces. The transferring stall cell induces extra mild pressure pulsation and impeller forces. The inter-channel flow adds strong pressure pulsation and impeller forces. When centrifugal pumps are operating at partial-load conditions, the flow characters especially the inter-channel flow caused by half-channel-blockage should be checked to avoid operation instability and security.

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.

Experimental Investigation on Pressure Fluctuation Reduction in a Double Suction Centrifugal Pump: Influence of Impeller Stagger and Blade Geometry

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Yongshun Zeng ◽  
Zhifeng Yao ◽  
Fujun Wang ◽  
Ruofu Xiao ◽  
Chenglian He
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
High Amplitude ◽  
Operating Conditions ◽  
Center Frequency ◽  
Centrifugal Pumps ◽  
Pump Impeller ◽  
Axial Forces ◽  
Large Peak ◽  
Blade Geometry

Abstract The reduction in pressure fluctuation can suppress noise, balance the radial and axial forces, and restrain the vibration level of a centrifugal pump. Impeller stagger and blade geometry influence the pressure fluctuation characteristics of double suction centrifugal pumps. In the present investigation, the pressure fluctuation characteristics of the baseline impeller, the staggered impeller, and the blade geometry modified impeller were investigated experimentally under design and off-design operating conditions. The frequency spectrum was analyzed by fast Fourier transform (FFT) and continuous wavelet transform (CWT) methods. The broadband frequencies are defined quantitatively and analyzed emphatically. The significant linear relationship between the center frequency of the broadband frequencies and the flowrate is discovered for the first time. The center frequency decreases as the flowrate increases. The linearity varies below and above the design flowrate. When the discrete frequencies are in range of the broadband frequencies, a high amplitude of pressure fluctuation occurs. This could explain the large peak-to-peak value of the pressure fluctuation at 1.24Qn, which may be due to the coincidence between broadband frequencies and the components at the frequencies fr and 2fr. Both the staggered impeller and the blade geometry modified impeller can reduce the level of pressure fluctuation; in particular, it is reduced to 35% and 13% compared to that of baseline impeller near the volute tongue region under the design flowrate, respectively. The staggered impeller and the blade geometry can obviously affect the decreasing slopes between the center frequencies and the flowrate.

scholarly journals Improving power efficiency of underloaded pipelines with variable frequency drives

2020 ◽  
Vol 4 (1) ◽  
pp. 4-9
Author(s):  
Pavel A. Revel-Muroz ◽  
◽  
Georgy N. Matveev ◽  
Leonid M. Bekker ◽  
Konstantin Y. Shtukaturov ◽  
...  
Keyword(s):  
Power Consumption ◽  
Energy Saving ◽  
Power Efficiency ◽  
Electric Energy ◽  
Operating Conditions ◽  
Main Line ◽  
Variable Frequency ◽  
Variable Frequency Drive ◽  
Trunk Pipeline ◽  
Variable Frequency Drives

The paper considers the option to reduce power consumption in the operation of the underloaded trunk pipeline by engaging additional pump units with lower rotor r.p.m. control using variable frequency drive. Under these conditions, the operating point of the pumps (delivery rate, head) approaches to the rated output, thus increasing the efficiency of the pumps and decreasing the electricity power consumption for pumping operations. The paper presents comparative calculations of operating conditions for a section of the trunk pipeline with a specified pumping capacity of 35 million t/year (60 % of the design load) when one, two and three main line pumps with variable frequency drives are engaged. The power consumption for pumping is calculated using the dependence of the variable frequency drive and motor efficiencies on the electric motor load and rotational speed. Based on the results of calculations, the electric energy saving is determined when additional pumping units are engaged. The experience has shown that when the second main line pump was engaged, the electric energy saving for pumping was 3.7% compared to the condition with one pump running. However, if the third pump is engaged, the saving is only 1.9 % – the decrease is due to lower motor and variable frequency drive efficiencies in the underloaded condition.

scholarly journals Advanced Control of a Compensator Motor Driving a Variable Speed Diesel Generator with Rotating Stator

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2224
Author(s):  
Mohammadjavad Mobarra ◽  
Bruno Tremblay ◽  
Miloud Rezkallah ◽  
Adrian Ilinca
Keyword(s):  
Diesel Engine ◽  
Asynchronous Motor ◽  
Operating Conditions ◽  
Variable Frequency ◽  
Variable Speed ◽  
Diesel Generator ◽  
Variable Frequency Drive ◽  
Advanced Control ◽  
Optimal Value ◽  
Processor Board

Variable speed generators can improve overall genset performance by allowing the diesel engine to reduce its speed at lower loads. In this project, a variable speed diesel generator (VSDG) uses a rotating stator driven by a compensator motor. At lower loads, the stator turns in the opposite direction of the rotor, a process that can be used for purposes like maintaining a fixed relative speed between the two components of a generator. This allows the diesel engine to turn at a lower speed (same as the rotor) and to increase its efficiency. The present research addresses the control of the compensator motor driving the generator’s stator using a variable-frequency drive that adapts the speed to its optimal value according to the load. The performance of the proposed control strategy was tested using a Freescale microcontroller card programmed in C-code to determine the appropriate voltage for the variable-frequency drive. The control algorithm uses a real-time application implemented on an FDRM-KL25Z signal processor board. The control performance of a 2 kW asynchronous motor (LabVolt EMS 8503-00/208 V/3 ϕ/60(50) Hz) was demonstrated experimentally at different operating conditions.

KARAKTERISTIK POMPA SENTRIFUGAL ALIRAN CAMPUR DENGAN VARIABLE FREQUENCY DRIVE

ROTASI ◽  
2013 ◽  
Vol 15 (3) ◽  
pp. 30
Author(s):  
Sri Utami Handayani
Keyword(s):  
Centrifugal Pump ◽  
Maximum Speed ◽  
Variable Frequency ◽  
Centrifugal Pumps ◽  
Variable Frequency Drive ◽  
Speed Reduction ◽  
Pump Speed ◽  
Dynamic Head ◽  
Reduce Energy Consumption ◽  
Static Head

In an industry that uses large centrifugal pumps continuously, pump speed setting can reduce energy consumption significantly. By changing the speed of a centrifugal pump,  capacity, head, and pump power required will change according to pump affinity laws. Speed of a centrifugal pump can be changed  by variable frequency drive . This study aimed to investigate the characteristics of mixed flow centrifugal pumps with variable frequency drive. The results showed that 10% of maximum speed reduction can decrease power consumtion until 50%, while the increase in the efficiency is maximum 7.2%. The power reduction is different for different speed reduction. In a dynamic head dominated system the efficiency will remain constant during speed reduction while in static head dominated system will change.

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