scholarly journals Flow Field Analysis and Feasibility Study of a Multistage Centrifugal Pump Designed for Low-Viscous Fluids

2021 ◽  
Vol 11 (3) ◽  
pp. 1314
Author(s):  
Mohamed Murshid Shamsuddeen ◽  
Sang-Bum Ma ◽  
Sung Kim ◽  
Ji-Hoon Yoon ◽  
Kwang-Hee Lee ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Flow Behavior ◽  
Field Analysis ◽  
Low Flow ◽  
Design Stage ◽  
Pump Design ◽  
Second Stage ◽  
Low Viscosity ◽  
Multistage Centrifugal Pump ◽  
Return Channel

A multistage centrifugal pump is designed for pumping low-viscosity, highly volatile and flammable chemicals, including hydrocarbons, for high head requirements. The five-stage centrifugal pump consists of a double-suction impeller at the first stage followed by a twin volute. The impellers for stages two through five are single-suction impellers followed by diffuser vanes and return channel vanes. The analytical performance is calculated initially in the design stage by applying similarity laws to an existing scaled-down pump model designed for low flow rate applications. The proposed pump design is investigated using computational fluid dynamics tools to study its performance in design and off-design conditions for water as the base fluid. The design feasibility of the centrifugal pump is tested for other fluids, such as water at a high temperature and pressure, diesel and debutanized diesel. The pump design is found to be suitable for a variety of fluids and operating ranges. The losses in the pump are analyzed in each stage at the best efficiency point. The losses in efficiency and head are observed to be higher in the second stage than in other stages. The detailed flow behavior at the second stage is studied to identify the root cause of the losses. Design modifications are recommended to diminish the losses and improve the overall performance of the pump.

scholarly journals Analytical and experimental assessment of screw centrifugal pump at improving its design

2021 ◽  
pp. 63-68
Author(s):  
H Nazarenko
Keyword(s):  
Positive Result ◽  
Centrifugal Pump ◽  
High Precision ◽  
High Speed ◽  
Operating Mode ◽  
Low Flow ◽  
Design Stage ◽  
Pump Efficiency ◽  
Experimental Assessment ◽  
Pump Design

Purpose. Development of analytical and experimental assessment of screw centrifugal type pump at a design stage, which permits defining more precisely its power and cavitation characteristics. Methodology. To achieve the above-mentioned purpose, the technique that includes the following possibilities was developed: make the list of changes which increase the efficiency of the existing pump; quickly and with high precision to estimate influence of certain constructive and/or regime changes on efficiency of the existing pump without difficult flow calculations; determine the need to develop a new pump, if all the changes of the existing pump did not give a positive result; determine changes influence on cavitation properties of the existing pump; calculate the efficiency dispersion during hydraulic tests of the modified pump. Findings. During the research, an analytical and experimental technique which permits determining increase in the pump efficiency quickly and with high precision at the change in pump design and/or operating mode was developed. The developed technique determines how all changes in the existing pump influence its anti-cavitation properties. The above mentioned technique also allows calculating the efficiency dispersion during hydraulic tests of the modified pump. The technique determines the need to develop a new pump, if all the changes in the existing pump did not give a positive result. The use of the presented calculation technique, at a design stage, allows estimating the efficiency of the developed pump more precisely. The developed technique allows increasing the efficiency assessment accuracy and cavitation characteristics of low-flow high-speed screw centrifugal pump. Originality. During the research, new empirical dependences were obtained that permit defining more precisely power and cavitation characteristics of low-flow high-speed screw centrifugal pump. Practical value. The presented technique at a design stage allows estimating the developed pump efficiency more precisely. Due to this, it is possible to reduce the time for pump development and its development tests.

scholarly journals Investigations on the influence of tandem blades on inner flow and performance characteristics of centrifugal pump

2019 ◽  
Vol 234 (1) ◽  
pp. 46-55
Author(s):  
Xiaobing Shi ◽  
Jinling Lu ◽  
Lianming Zhao
Keyword(s):  
Centrifugal Pump ◽  
High Reliability ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Performance Characteristics ◽  
Low Flow ◽  
Hydraulic Loss ◽  
Centrifugal Pumps ◽  
Pressure Distributions ◽  
And Performance

Although significant advances have been made in tandem-blade technology for axial and centrifugal compressors, little attention has been paid to its application in centrifugal pumps. In this study, we propose a new tandem-blade design method for improving inner flow characteristics and overall performance of a centrifugal pump. With the SST k − ω turbulence model, three-dimensional turbulent flow fields in the centrifugal pump with tandem blades are simulated and analyzed. The effects of tandem blades on the inner flow and performance characteristics of the centrifugal pump are investigated. The predicted velocity and pressure distributions and flow behavior of the tandem-blade impeller are compared with those of a conventional single row blade impeller. It is indicated that the centrifugal tandem-blade impeller exhibits a significant advantage in terms of the uniformity of the impeller discharge flow. The tandem blades improve the jet-wake structure and uniformity of velocity and pressure distributions at the impeller outlet, and thus reduce the pressure fluctuation and hydraulic loss. Moreover, the hump phenomenon is eliminated or alleviated under low flow rate conditions, and the tandem-blade impeller has better hydraulic performance within a wider operating range as well as high reliability. This study provides a basis for the further development of the centrifugal pump with tandem blades.

scholarly journals Effect of an Inducer-Type Guide Vane on Hydraulic Losses at the Inter-Stage Flow Passage of a Multistage Centrifugal Pump

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 526
Author(s):  
Mohamed Murshid Shamsuddeen ◽  
Sang-Bum Ma ◽  
Sung Kim ◽  
Ji-Hoon Yoon ◽  
Kwang-Hee Lee ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Guide Vane ◽  
Three Dimensional ◽  
Design Flow ◽  
Hydraulic Losses ◽  
Second Stage ◽  
Multistage Centrifugal Pump ◽  
Overall Performance ◽  
High Head

A multistage centrifugal pump was developed for high head and high flow rate applications. A double-suction impeller and a twin-volute were installed at the first stage followed by an impeller, diffuser and return vanes for the next four stages. An initial design feasibility study was conducted using three-dimensional computational fluid dynamics tools to study the performance and the hydraulic losses associated with the design. Substantial losses in head and efficiency were observed at the interface between the first stage volute and the second stage impeller. An inducer-type guide vane (ITGV) was installed at this location to mitigate the losses by reducing the circumferential velocity of the fluid exiting the volute. The ITGV regulated the pre-swirl of the fluid entering the second stage impeller. The pump with and without ITGV is compared at the design flow rate. The pump with ITGV increased the stage head by 63.28% and stage efficiency by 47.17% at the second stage. As a result, the overall performance of the pump increased by 5.78% and 3.94% in head and efficiency, respectively, at the design point. The ITGV has a significant impact on decreasing losses at both design and off-design conditions. An in-depth flow dynamic analysis at the inducer-impeller interface is also presented.

scholarly journals Analysis of High Vibration Causing 211-P-25A Centrifugal Pump Damage in Hydrocraker Process

2021 ◽  
Vol 80 (2) ◽  
pp. 13-21
Author(s):  
Eflita Yohana ◽  
Bachtiar Yusuf ◽  
Muhammad Arrafi Lazuardi ◽  
Mohamad Endy Julianto ◽  
Vita Paramita
Keyword(s):  
Power Plant ◽  
Centrifugal Pump ◽  
Analytical Method ◽  
High Speed ◽  
Visual Observation ◽  
Low Flow ◽  
Internal Circulation ◽  
Pump Design ◽  
The Right ◽  
Plant Components

The more developing technology enhances the need for energy; this requires the maximization of the performance of power plant components and energy. Refinery Unit (RU) is currently one of the real applications. Reliable equipment is required in running a massive industry. In running the oil production process at Refinery Unit (RU), the thing that needs to be put into consideration is pumps. A pump is a device for distributing fluids from one place to another. In Refinery Unit (RU), the pump is not only for oil but also for other fluids. In this research at Refinery Unit, the pump that is to be discussed is a centrifugal pump 211-P-25A. The objective of this research is to analyze the damage of pump 211-P-25A, which indicated high vibration. This causes the pump not to work optimally, so it requires the right maintenance. The research is done by using an analytical method, visual observation towards impeller and shaft, and comparing the results in accordance to API 610. Afterwards, the right maintenance will be known for centrifugal pump 211-P-25A to reduce the high vibration that occurred in the pump. High vibration may be caused by cavitation and internal recirculation. The damage in pump 211-P-25A is caused by repeated internal circulation, which causes damage to the impeller and high-speed shaft. Pump 211-P-25A experiences high vibration due to low flow. The flow produced is 2.67 m3/h, with a pump design minimum flow of 8.6 m3/h. This causes damage to pump components. Due to this damage, the performance of the pump will not be optimal, and its efficiency will be reduced.

Unsteady Flow Patterns for a Double Suction Centrifugal Pump

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
José González ◽  
Jesús Manuel Fernández Oro ◽  
Katia M. Argüelles Díaz ◽  
Eduardo Blanco
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Numerical Procedure ◽  
Numerical Results ◽  
Field Analysis ◽  
Navier Stokes ◽  
Inlet Flow ◽  
Pump Design

The flow in a double suction centrifugal pump is presented in this paper. The static performance of the machine has been obtained in a proper test rig, and the results have been compared with equivalent numerical results from an Unsteady Reynolds Averaged Navier–Stokes Equations (URANS) calculation. In a second step, the numerical results have been exploited to get detailed information about the flow inside the turbomachine. The main goal of the study is, on one hand, the validation of the numerical procedure proposed and, on the other hand, the detailed flow-field analysis for the machine, which points out the possibilities and drawbacks of the pump design. For a double suction machine, the inlet flow is characterized by the existence of a particular geometry that tries to force a uniform flow, at least for the nominal flow rate. On the contrary, at off-design conditions the lack of uniformity produces an unsteady incidence that gives rise to strong hydraulic loading variations. Instantaneous and average pressure fields have been analyzed in this paper to study the evolution of such inlet flow unsteadiness throughout the impeller and the volute. The analysis of both static and dynamic effects on the pump shaft has been carried out from the numerical calculation of the radial forces. The results have shown that the performance of the double suction centrifugal pump is suitable for typical design conditions. The best operation point or nominal flow rate is found to be at φ=0.274, which turns out to produce a specific speed ωS=1.25, well in the range for centrifugal impellers. This operating point is also found to be the one with better efficiency and with better flow characteristics, regarding the axisymmetry of the flow pattern and the fluid forces obtained. However, some particular features produce also interesting results for off-design operating points.

Numerical Investigation of the Transient Flow in a Centrifugal Pump Stage

2005 ◽  
Author(s):  
F.-K. Benra ◽  
H. J. Dohmen
Keyword(s):  
Numerical Investigation ◽  
Centrifugal Pump ◽  
Transient Flow ◽  
Flow Behavior ◽  
Centrifugal Pumps ◽  
Flow Parameters ◽  
Pump Stage ◽  
Dependent Flow ◽  
Return Channel ◽  
Grid Nodes

The knowledge of the flow behavior in pump stages which consist of an impeller, a bladed diffuser and a bladed return channel is of great importance for the design of multistage centrifugal pumps. Especially the Interaction of the impeller flow with the stationary diffuser blades and the behavior of the return channel blades affect the efficiency of a pump stage in a considerable way. In this contribution the transient flow in an industrial centrifugal pump stage, which has an impeller with seven blades, a radial diffuser with ten blades and a return channel with also ten separate blades, has been simulated numerical by using the commercial software code CFX-5.7. Because of the unfavorable ratio of blade numbers a complete meshing of all flow channels was necessary. In consequence the cumulative amount of grid nodes reached a number of nearly 6 million nodes. As a result of the numerical investigation of the time dependent flow accomplished for this contribution, the influence of the rotating impeller on the flow in the stationary parts of the pump is presented in detail. All flow parameters are shown as a function of time and are discussed with respect to the position of the impeller relative to the stator blades.

scholarly journals Backflow effects on mass flow gain factor in a centrifugal pump

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042199886
Author(s):  
Wenzhe Kang ◽  
Lingjiu Zhou ◽  
Dianhai Liu ◽  
Zhengwei Wang
Keyword(s):  
Centrifugal Pump ◽  
Mass Flow ◽  
Flow Rate ◽  
Low Frequency ◽  
Gain Factor ◽  
Low Flow ◽  
Cavity Volume ◽  
Cavitating Flows ◽  
Inlet Tube ◽  
Low Flow Rate

Previous researches has shown that inlet backflow may occur in a centrifugal pump when running at low-flow-rate conditions and have nonnegligible effects on cavitation behaviors (e.g. mass flow gain factor) and cavitation stability (e.g. cavitation surge). To analyze the influences of backflow in impeller inlet, comparative studies of cavitating flows are carried out for two typical centrifugal pumps. A series of computational fluid dynamics (CFD) simulations were carried out for the cavitating flows in two pumps, based on the RANS (Reynolds-Averaged Naiver-Stokes) solver with the turbulence model of k- ω shear stress transport and homogeneous multiphase model. The cavity volume in Pump A (with less reversed flow in impeller inlet) decreases with the decreasing of flow rate, while the cavity volume in Pump B (with obvious inlet backflow) reach the minimum values at δ = 0.1285 and then increase as the flow rate decreases. For Pump A, the mass flow gain factors are negative and the absolute values increase with the decrease of cavitation number for all calculation conditions. For Pump B, the mass flow gain factors are negative for most conditions but positive for some conditions with low flow rate coefficients and low cavitation numbers, reaching the minimum value at condition of σ = 0.151 for most cases. The development of backflow in impeller inlet is found to be the essential reason for the great differences. For Pump B, the strong shearing between backflow and main flow lead to the cavitation in inlet tube. The cavity volume in the impeller decreases while that in the inlet tube increases with the decreasing of flow rate, which make the total cavity volume reaches the minimum value at δ = 0.1285 and then the mass flow gain factor become positive. Through the transient calculations for cavitating flows in two pumps, low-frequency fluctuations of pressure and flow rate are found in Pump B at some off-designed conditions (e.g. δ = 0.107, σ = 0.195). The relations among inlet pressure, inlet flow rate, cavity volume, and backflow are analyzed in detail to understand the periodic evolution of low-frequency fluctuations. Backflow is found to be the main reason which cause the positive value of mass flow gain factor at low-flow-rate conditions. Through the transient simulations of cavitating flow, backflow is considered as an important aspect closely related to the hydraulic stability of cavitating pumping system.

scholarly journals Synthesis of Bulk Zr48Cu36Al8Ag8 Metallic Glass by Hot Pressing of Amorphous Powders

2021 ◽  
Vol 5 (1) ◽  
pp. 23
Author(s):  
Tianbing He ◽  
Nevaf Ciftci ◽  
Volker Uhlenwinkel ◽  
Sergio Scudino
Keyword(s):  
Metallic Glass ◽  
Metallic Glasses ◽  
Flow Behavior ◽  
Matrix Composites ◽  
Powder Consolidation ◽  
Low Viscosity ◽  
Flash Annealing ◽  
Amorphous Powders ◽  
Temperature Window ◽  
Glass Matrix Composites

The critical cooling rate necessary for glass formation via melt solidification poses inherent constraints on sample size using conventional casting techniques. This drawback can be overcome by pressure-assisted sintering of metallic glass powders at temperatures above the glass transition, where the material shows viscous-flow behavior. Partial crystallization during sintering usually exacerbates the inherent brittleness of metallic glasses and thus needs to be avoided. In order to achieve high density of the bulk specimens while avoiding (or minimizing) crystallization, the optimal combination between low viscosity and long incubation time for crystallization must be identified. Here, by carefully selecting the time–temperature window for powder consolidation, we synthesized highly dense Zr48Cu36Ag8Al8 bulk metallic glass (BMG) with mechanical properties comparable with its cast counterpart. The larger ZrCu-based BMG specimens fabricated in this work could then be post-processed by flash-annealing, offering the possibility to fabricate monolithic metallic glasses and glass–matrix composites with enhanced room-temperature plastic deformation.

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