Double Suction Research Articles

Investigation of unsteady pressure fluctuations and methods for its suppression for a double suction centrifugal pump

Double suction centrifugal pumps find their usage in a variety of applications because of their ability to deliver good performance at higher flowrates and heads. The main issue with these devices is the occurrence of large pressure pulsations which cause noise, vibration, and unstable operation. The present work makes an effort using steady and unsteady computational fluid dynamics (CFD) approach to minimize these pulsations and also to improve the hydraulic performance of the considered pump. The CFD methodology and obtained results were validated by the experimental data to ensure reliability of the study. Fast Fourier Transform (FFT) analysis was performed to calculate the amplitude of these pressure pulsations. A parametric study was undertaken to find the effect of impeller stagger angles in reducing these pulsations and finding the most desirable stagger angle. Then, the performance of reference non-staggered impeller design was evaluated with the use of split volute arrangement and its comparison was done with the staggered impeller design. Finally, a combination of staggered impeller design with the split volute arrangement was tested to find its utility in suppressing pressure pulsations. It was observed that the best hydraulic performance could be obtained by the staggered 30° design with reduced pulsations; however, the least pressure pulsations were delivered by the combination of staggered 30° design with the split volute. The use of CFD helped in better visualization of the inherent flow physics associated with these designs.

Performance and Unsteady Pressure Pulsation Analysis for a Double Suction Centrifugal Pump at Off-Design Operating Conditions

Performance and Unsteady Pressure Pulsation Analysis for a Double Suction Centrifugal Pump at Off-Design Operating Conditions

Investigation of Unsteady Pressure Fluctuations and Methods for Its Suppression for a Double Suction Centrifugal Pump

Double suction centrifugal pumps find their usage in a variety of applications because of their ability to deliver good performance at higher flowrates and heads. The main issue with these devices is the occurrence of large pressure pulsations which cause noise, vibration and unstable operation. The present work makes an effort using steady and unsteady computational fluid dynamics (CFD) approach to minimize these pulsations and also to improve the hydraulic performance of the considered pump. Fast Fourier Transform (FFT) analysis was performed to calculate the amplitude of these pressure pulsations. A parametric study was undertaken to find the effect of impeller stagger angles in reducing these pulsations and finding the most desirable stagger angle. Then, the performance of reference non-staggered impeller design was evaluated with the use of split volute arrangement and its comparison was done with the staggered impeller design. Finally, a combination of staggered impeller design with the split volute arrangement was tested to find its utility in suppressing pressure pulsations. It was observed that the best hydraulic performance could be obtained by the staggered 30° design with reduced pulsations; however, the least pressure pulsations were delivered by the combination of staggered 30° design with the split volute.

Microconvection of MHD Solarized Nanofluid in the Presence of Double Slip and Surface Suction

In recent years, some researchers have analyzed nanofluids and tried to identify potential active ingredients that give nanofluids enormous thermal conductivity (nanoparticle suspensions). In such suspensions, the Brownian motion of the nanoparticles is the only technique expected to enhance the thermal conductivity of the nanofluids, and the sections that can contribute to this are the subject of rules and discussion. When studying the flow, the influence of Brownian motion through the implantation of nanoparticles into the base fluid was investigated and came to the conclusion that Brownian motion of nanoparticles is the only means associated with the enormously improved thermal conductivity of nanofluids. Suction is the only viable way to control cooling rate in multiple product formation processes. The quality and mechanical properties of the final product can be improved by controlling the cooling rate during the melting of raw material and the subsequent condensation process. Slip conditions of the first and second order are also included in the current development. An interesting feature of this model is that the Brownian motion of nanoparticles can be accelerated by solar energy, thereby increasing the temperature of the base fluid. These interesting features increase the demand for this model in many industrial applications.

Operation Strategy of Supercritical Reheat Double Suction Back Pressure Steam Turbine

Operation Strategy of Supercritical Reheat Double Suction Back Pressure Steam Turbine

The Influence of Different Blade Outlet Angle and Wedge Groove on the Performance of the Double Suction Pump

This study aims to significantly improve the performance of the centrifugal pump by designing a wedge grooves on the outside of the impeller cover, and investigating the method for determining the blade outlet angle that plays important roles in the energy conversion. The solidliquid two-phase flow fields with the designed pump and an original pump were numerically simulated in the ANSYS-FLUENT. Compared with the original pump, reducing the blade outlet angle can effectively improve the sand-water wear on the blade surface and opening wedge grooves can slow down impeller ring wear. The head of the improved model pump decreases by about 1.5% and the efficiency increases by about 1.5%.

Numerical Simulation to Investigate the Occurrence of Vortices at Double Vertical Pumps Intakes

The pumping station is widely used in our modern life. The occurrence of the vortex at pumpsump, which is causing air entering pipe intake, is a common problem in the design of pumps. Thisphenomenon, including surface and sub-surface vortex, may lead to damage to the pumping structure, highpower consumption, and loss in pump performance. In some requirements, the multiple suction pipes areusing to get the required flow. Due to this arrangement, the performance of the suction pipes will influence.This paper is aimed to investigate the occurrence of vortices around the flow pattern of two pumps by usingComputational Fluid Dynamic (CFD) code Fluent. This CFD model is based on solving Navier-Stockequations by finite volume method. The model of double suction pipes was investigated under five differentsubmergence depth (S) and five different suction velocities (v). The SST k-ω turbulence model was selectedfor the turbulence. The results showed that the air entering vortex does not appear when the submergencedepth (S) is equal or greater than 1.5 times from the diameter of the bellmouth for intake pipe (D). Thesurface vortex appeared obviously when the submergence depth (S) equals to 1.25D and the Froude numberat the bell is equal to or greater than 1.028, and appeared clearly when the (S/D=1) and Froude number isequal to or more than 0.77. The nearer attached wall vortex does not appear when the space from the centerof the suction pipe to the sidewall (C) equals 2 times of bell diameter.

Cause analysis and Countermeasures for shaft fracture of closed pump

Two 350MW supercritical wet cooling units in a power plant, the closed water pump adopts horizontal single-stage double suction split centrifugal pump. In recent two years, the shaft of the closed pump B of 1 unit has been fractured twice. In this paper, the fracture causes of the closed pump shaft are analyzed from the aspects of closed pump operation, material analysis and micro organization, and treatment measures are taken to solve the problem.

Structural optimization of the low-pressure Venturi injector with double suction ports based on computational fluid dynamics and orthogonal test

Structural optimization of the low-pressure Venturi injector with double suction ports based on computational fluid dynamics and orthogonal test

PERHITUNGAN NILAI OVERALL EQUIPMENT EFFECTIVENESS PADA POMPA DISTRIBUSI KUBOTA DOUBLE SUCTION VOLUTE PUMP MODEL DV-L DI PT. ABC

Evaluation of machine performance is certainly very necessary to improve company production performance, one of which can be done by knowing the value of performance effectiveness using the Overall Equipment Effectiveness (OEE) calculation. This research was conducted on the Kubota Double Suction Volute Pump Model DV-L centrifugal pump at PT. ABC. The purpose of this study is to determine the Overall Equipment Effectiveness (OEE) value based on availability, performance and rate of quality factors. To compare the company OEE values obtained with the Overall Equipment Effectiveness World Class standard and proceed with identifying six big losses and knowing the root causes of OEE values using a causal diagram. Calculations obtained an Availability value of 99,07%, Performance of 91,53% and Quality of 100% and an average OEE of 90,68%. It is known that the OEE value is at the OEE standard >85%, but the performance value of the pump is still below the JIPM performance standard of >95% so that corrective action can be taken to increase the performance value of the effectiveness of the clean water distribution process using the Kubota Double Secton Volute centrifugal pump Pump Model DV-L.

Effects of gap between impeller and volute tongue on a pressure fluctuation in double-suction pump

The pump is a machine that receives power through a rotating shaft and converts the mechanical energy into pressure and kinetic energy of fluid. Therefore, it is widely used in various industrial fields, and many studies have been conducted to improve the performance of pumps. In this paper, the effect of the gap between the impeller and the volute tongue on the performance and pressure fluctuation of the double suction pump was investigated. Numerical analysis was conducted using the commercial code ANSYS CFX ver. 18.1. Three different values of gap between the impeller and the volute tongue, 0.067%, 0.145% and 0.224% of the impeller diameter were considered.

COVID-19 and Paediatric Dentistry after the lockdown.

Coronaviruses are a large family of respiratory RNA viruses that can cause severe infections of the airways, as we have seen in the past, difficult months. We know that the route of transmission of the disease is through saliva droplets produced by speaking, coughing and sneezing. The virus is highly infectious, and each infected individual infects 2.5 people on average. The average incubation period is about 5 days, with an estimated range from 2 to 14 days; the incubation period in children is similar, however some have exhibited a longer incubation. The virus binds to the cellular receptor ACE2, which in children has a structural and functional immaturity thus offering lower affinity to the pathogen; this could explain the lower incidence of infection from SARS-CoV-2 in this segment of the population.The common clinical observation is that COVID-19 is less severe in children, and in this group the disease is often asymptomatic. Pending further clinical studies able to clarify the infection and transmission dynamics, it is therefore important to apply also in children all preventive and hygiene measures recommended by the health authorities during dental treatment. We should avoid procedures that generate aerosols as much as possible, minimising the use of the air syringe. When possible, it is recommended to employ minimally invasive procedures and ART (Atraumatic Restorative Treatment). The latter is a technique that can also be employed in very young and uncooperative patients with widespread carious lesions, in order to avoid more invasive and complex procedures. Ozone therapy could be of great help in the control of the progression of the asymptomatic carious lesions, especially during the Phase 2 of reopening, when we should to minimise the use of rotating instruments producing aerosols. The above introduces a new concept of "no aerosol" that will possibly guide our therapeutic choices not only in the immediate future but also in the long term, opening scenarios of prevention and cure that are more efficient, safe, and sustainable. During procedures that generate aerosols, the use of proper PPE is crucial to minimise the risk of transmission. It is also strongly recommended to work with an assistant, and to use double suction and a rubber dam. We will have to rethink and review the schedule of daily activities, in terms of timing and mode of delivery of care, on the basis of an agenda which can be divided into "no aerosol" and "aerosol" procedures, and "virtual visits" (including management of true emergencies), creating a virtuous optimisation of care for the safety of operators and office staff, as discussed in an article published on this very EJPD issue. In the coming months we will perhaps deliver more "patient-oriented" than "tooth-oriented" treatments, and this is true not only for young patients!

Investigation of the influence of wear in impeller seals on the axial force in double suction pumps

This article is devoted to the investigation of axial force on the rotor of the double suction centrifugal pump at unequal wear of impeller seals. The annular seal of the double suction centrifugal pump is considered as an object of the study. The distribution of the fields of velocities and pressure in the seals of the pump are obtained by numerical modeling. The leakage rate resulting from the simulation is compared to the existing formulas.

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

Design, Fabrication and Testing of Hydraulic Turbine Runner for a Double Suction Centrifugal Pump in Turbine Mode

Design, Fabrication and Testing of Hydraulic Turbine Runner for a Double Suction Centrifugal Pump in Turbine Mode

Experimental Investigation of Transient Characteristics of a Double Suction Centrifugal Pump System during Starting Period

The starting phase for pumps in water transportation pipelines is crucial and has significant transient characteristics which merit further study in order to evaluate the operational stability of the pumping system. This paper presents the results of a study in which the relative steady operating conditions and starting period of a large double-suction centrifugal pump were monitored in real time, including pressure fluctuations, shaft run-out and vibration at the bearing. The transient characteristics of a double-suction centrifugal pump under different operating conditions have been analyzed using fast Fourier transform (FFT) and continuous wavelet transform (CWT). Results indicate broadband frequency components within the spectrum of pressure fluctuations in the volute casing under all test conditions, and the central frequency of the broadband frequency gradually decreases as flow rate increases and approaches the blade frequency, which is the primary reason for an increase in blade-frequency amplitude. This may produce a vibration frequency that is similar to the natural frequency of a certain part of the double-suction centrifugal pump during the starting period, which causes the resonance phenomenon. The radial force is also large during the starting period, which causes eccentric wear of the seal ring at the impeller inlet.

Efficiency Prediction of Centrifugal Pump Using the Modified Affinity Laws

Abstract This research is a continuation of efforts aimed at establishing the modified affinity laws for viscosity to predict the pump performance directly from a plot in terms of dimensionless numbers, i.e., flow coefficient, Reynolds number, head coefficient, and efficiency. The group has earlier proposed modified head coefficient affinity law. This work proposes and validates a similar efficiency plot that completes the set of modified affinity laws that include all the input and output parameters for a specific pump design and type. A wide range of viscosities and flow rates are considered for CFD analysis to have a comprehensive set of data that includes enough data points to comment on both the laminar and turbulent flow cases categorized based on the hydraulic Reynolds number (2300). Initial analysis shows some inconsistency based on laminar versus turbulent simulation model selection which is addressed in the latter part of this work. In general, two curves can be constructed for laminar and turbulent flow cases. These curves have different axes parameters (exponents of the dimensionless numbers) depending on the plot being for a laminar or a turbulent flow case. Validation with established experimental data shows good agreement in terms of the variation of axes parameters (their exponents) depending on the pump type for a single suction impeller and a double suction impeller pump. The distinction between laminar and turbulent flow cases is found to be applicable to established experimental data as well.

Artificial Neural Networks Approach for a Multi-Objective Cavitation Optimization Design in a Double-Suction Centrifugal Pump

Double-suction centrifugal pumps are widely used in industrial and agricultural applications since their flow rate is twice that of single-suction pumps with the same impeller diameter. They usually run for longer, which makes them susceptible to cavitation, putting the downstream components at risk. A fast approach to predicting the Net Positive Suction Head required was applied to perform a multi-objective optimization on the double-suction centrifugal pump. An L32 (84) orthogonal array was designed to evaluate 8 geometrical parameters at 4 levels each. A two-layer feedforward neural network and genetic algorithm was applied to solve the multi-objective problem into pareto solutions. The results were validated by numerical simulation and compared to the original design. The suction performance was improved by 7.26%, 3.9%, 4.5% and 3.8% at flow conditions 0.6Qd, 0.8Qd, 1.0Qd and 1.2Qd respectively. The efficiency increased by 1.53% 1.0Qd and 1.1% at 0.8Qd. The streamline on the blade surface was improved and the vapor volume fraction of the optimized impeller was much smaller than that of the original impeller. This study established a fast approach to cavitation optimization and a parametric database for both hub and shroud blade angles for double suction centrifugal pump optimization design.

Slip Factor Correction in 1-D Performance Prediction Model for PaTs

In recent years, pumps operated as turbines (PaTs) have been gaining the interest of industry and academia. For instance, PaTs can be effectively used in micro hydropower plants (MHP) and water distribution systems (WDS). Therefore, further efforts are necessary to investigate their fluid dynamic behavior. Compared to conventional turbines, a lower number of blades is employed in PaTs, lowering their capability to correctly guide the flow, hence reducing the Euler’s work; thus, the slip phenomenon cannot be neglected at the outlet section of the runner. In the first part of the paper, the slip phenomenon is numerically investigated on a simplified geometry, evidencing the dependency of the lack in guiding the flow on the number of blades. Then, a commercial double suction centrifugal pump, characterized by the same specific speed, is considered, evaluating the dependency of the slip on the flow rate. In the last part, a slip factor correlation is introduced based on those CFD simulations. It is shown how the inclusion of this parameter in a 1-D performance prediction model allows us to reduce the performance prediction errors with respect to experiments on a pump with a similar specific speed by 5.5% at design point, compared to no slip model, and by 8% at part-loads, rather than using Busemann and Stodola formulas.

Design and CFD performance analysis of a novel impeller for double suction centrifugal pumps

Abstract Double suction centrifugal pumps are the main devices involved in the feedwater system of nuclear power plants and they are responsible for a significant share of their energy consumption (by affecting the balance of both the gross and net electrical energy production), hence even an efficiency increase of only a few percentage points could be substantial in their economy. Herein a novel impeller designed for low-medium specific speed double suction centrifugal pumps ( n q 60 ) is proposed showing an efficiency improvement with respect to conventional designs in the order of 1–2% associated to a slip factor increase, secondary losses reduction and impeller outflow homogeneity improvement. The novel double suction impeller is characterized by a new arrangement of its flow channels, which come up alternately on the same circumferential exit even if they start from the two different sides. The flow field through the impeller is investigated via numerical simulations run by means of the open source CFD code OpenFOAM and its performance is compared against experimental results. The CFD model set-up, in terms of grid size and discretization schemes, has been previously assessed against results of consolidated CFX simulations on a conventional centrifugal pump.