Pump Shaft Research Articles

Hydrodynamic Analysis of the Flow Field Induced by a Symmetrical Suction Elbow at the Pump Inlet

The paper investigates the hydrodynamic field generated by the symmetrical suction elbow at the pump impeller inlet. The full three-dimensional turbulent numerical investigation of the flow in the symmetrical suction elbow is performed using FLUENT then the flow non-uniformity generated by it is numerically computed. The numerical results on the annular cross section are qualitatively and quantitatively validated against LDV data. A good agreement between numerical results and experimental data is obtained on this cross section located downstream to the suction elbow and upstream to the pump impeller. The hydrodynamic flow structure with four vortices is identified plotting the vorticity field. The largest values of the vorticity magnitude are identified in the center of both vortices located behind the shaft. The vortex core location is plotted on four annular cross sections located along to the cylindrical part between the suction elbow and the pump inlet. Also, the three-dimensional distribution of the vortex core filaments is visualized and extracted. The shapes of vortex core filaments located behind the pump shaft agree well with its visualization performed on the test rig. As a result, the three-dimensional complex geometry of the suction elbow and the pump shaft are identified as the main sources of the flow non-uniformity at the pump inlet.

Resonance of torsional vibrations of centrifugal pump shafts due to cavitation erosion of pump impellers

Abstract Selected results were gathered during investigation of centrifugal pumps used in a sea water cooling system of one of Diesel power stations are presented in the paper. The main goal of research was to explain the reason of occurring fractures in pump shafts. The investigation has shown that the fractures were caused mainly by the resonance between pump shaft torsional natural vibrations and those following from the pressure fluctuations related to the frequency of the shaft rotational speed and the number of impeller blades. The resonance occurred as a result of intense erosion of pump impellers derived mainly from cavitation phenomenon that caused about 20% of the impeller mass decrease. The scope of the investigation has covered among others: erosion damage recognition, tests of the investigated pumps operating conditions, spectral analysis of pressure fluctuation generated by the pump blade system as well as strength analysis of the pump shaft and the frequencies of its natural bending and torsional vibrations.

Determination of Imbalance Problem in Electric Motor and Centrifugal Pump by Vibration Analysis

Solution of vibration problems in the electric motors and centrifugal pumps is important for proper operation and performance. Excessive vibrations seen in the electric motors and centrifugal pumps shorten the life of the machine and lead to the mechanical fatigue and even to damage of the machine. The causes of these vibrations in the electric motors and centrifugal pumps may be mechanical, fluid-borne or electromechanical [1]. Many of the mechanical and electromechanical-borne vibrations are directly related to the machine speed and can be determined by vibration analysis [2]. It is necessary to carry out the measurements in order to determine the source of vibrations. The source of the vibration can be determined by examining the relationships among data obtained from these measurements in the time and frequency domains. Imbalance is one of the vibration sources in the electric motors and centrifugal pumps. The main causes of this problem in the electric motors and the pumps are: defects during manufacturing, corrosion in the pump fan, partial permanent pollution of the pump fan blade, the unbalanced mounting of one of the pump bearings carrying the whole loads of pump fan, improper mass distribution in the rotor arms and blades of the electric motor, the bending of the pump and electric motor shaft. The imbalance problem encountered in electric motor and centrifugal pumps causes negative eects on pump

Numerical simulation on geometrical parameters for closed sump

The closed sump is a typical inlet passage of middle and small pumping station. It has the characteristics of low channel height, small foundation excavation depth, simple structure, a single cross sectional shape changes, ease of construction and other features, so more and more attention and application has been paying on this closed sump in pumping station project. However the flowing pattern within the closed sump is complex, the design is not perfect in some respects, the structure size does not be optimized. Based on the background for renewal and transformation of a pumping station, according to the three-dimensional incompressible fluid Reynolds-averaged N-S equations, the RNG k-e model, the CFD technology. The study on the draught in closed sump might reduce the length of pump shaft to enhance the stability of the pump unit operation. The results reveal the effect of the change of the height of plate. The turbulence in back wall might cause vortex when the height is high. The height of plate had be recommended control in 0.65D-0.85D.The better parameter combination of geometry of closed sump had be given through comparing the results of the orthogonal test and the comprehensive test. The floor clearance should be control in 1.0D. (D is the diameter of flared pipe)

Temperature field study of hot water circulation pump shaft system

In the process of engineering application under the condition of hot water circulation pump, problems of stress concentration caused by the temperature rise may happen. In order to study the temperature field in bearing and electric motor chamber of the hot water circulation pump and optimize the structure, in present paper, the model of the shaft system is created through CREO. The model is analyzed by ANSYS workbench, in which the thermal boundary conditions are applied to calculate, which include the calorific values from the bearings, the thermal loss from electric motor and the temperature from the transporting medium. From the result, the finite element model can reflect the distribution of thermal field in hot water circulation pump. Further, the results show that the maximum temperature locates in the bearing chamber.The theoretical guidance for the electric motor heat dissipation design of the hot water circulation pump can be achieved.

High-Temperature Drive Shaft Failure with a Twist

An unusual high-temperature failure is presented involving the bearings and drive shaft of a centrifugal slurry pump. The unique characteristics of the failure are explored including localized heating and interactions between the ductile iron bearing collar and the shaft material. Maximum surface temperature of the shaft at the time of failure is estimated to be 2100–2300 °F. Partial melting of the ductile iron bearing collar and softening of the shaft appears to have resulted in both the inclusion of ductile iron in the shaft material in the molten state and a form of friction stir welding which joined the two components. Hardness values in excess of 900 Vickers were recorded around the material interface. It is theorized that rapid diffusion of carbon into the shaft material occurred during failure facilitated by mechanical mixing due to severe high-temperature deformation. Graphite nodularity and phase analysis of the ductile iron collar and an embedded ductile iron fragment were conducted by means of microscopy and image analysis.

Development of a virtual pump water flow meter with a flow rate function of motor power and pump head

Water flow rates are key operating variables in chilled and hot water systems. The water flow rate through a pump can be virtually measured using available motor power and pump head with projected motor and pump efficiencies. In general, motor efficiency is implicitly determined by motor power while pump efficiency is given as a function of water flow rate. As a result, the water flow rate has to be calculated through a numerical method, which is difficult to apply in building automation systems (BAS). The objective of this paper is to develop a virtual pump water flow meter, which can be implemented in BAS with an explicit expression of motor power and pump head. First, motor efficiency is regressed as a function of motor power by consolidating multiple dependent factors, then pump efficiency function is reconstructed with pump shaft power and head, and finally experiments are conducted to develop and validate a virtual pump water flow meter on a chilled water pump. The experimental results show that the virtual flow measurements agree well with the flow measurement by a physical meter. The measurement standard deviation is 0.5L/s for a pump with the design flow rate of 37.9L/s.

Assessment of using hollow fibre microfiltration in treating lake water

The main objective of this study was to determine the reliability of using microfiltration system which is composed of a coagulant such as ferric chloride (pretreatment substance) and hollow fibre membrane as filtering medium for improving water quality. In this study, raw water samples were collected from a lake located at the Faculty of Engineering, Universiti Putra Malaysia. The experiments were carried out in three stages: the first stage used distilled water, the second stage used lake water stored in a tank and the third stage used lake water stored in the tank and mixed with ferric chloride as coagulant. A storage tank and a separation tank were used; the storage tank is used to store water pumped from the lake (used in the second stage) while in the third stage, the stored water in tank was used for pretreatment or coagulation with optimum dosage of ferric chloride (determined from jar test). The experimental results show that the flux obtained from second and third stages was low. For lake water stage, the best flux was found to be 4.97 l/m2/h. The distilled water stage shows that shaft rotational speed of peristaltic pump was one of the factors affecting the flux. Therefore, a pump shaft rotational speed of 7 rpm was chosen based on flux and suction pressure. The experimental results show the ability of microfiltration using hollow fibre membrane together with ferric chloride as coagulant to produce treated water with 97% turbidity removal and 85% removal of total suspended solids (TSS). For treated raw water, it is found that the removals of TSS were ranged from 71.7 to 91.6% when alum was used as a coagulant while the TSS removals were ranged from 74.4 to 89.20% when ferric chloride was used as a coagulant. In this study, it is found that the optimum dosages of ferric chloride and alum were 4 and 20 mg/l, respectively. Although the percentage removal of TSS is slightly higher when alum is used as a coagulant compared with using ferric chloride, it is recommended to use ferric chloride as a coagulant due to its economical and health advantages. Furthermore, ferric chloride can be used in wide range of pH values while alum can only be effective when pH value around 7.

CW Pump Fluid Induced Vibration Troubleshooting Methodology

Fluid-machines experience a variety of forces during their operation result in different type of dynamic vibration behavior. Fluid induced instability phenomena are one such issue that typically manifests itself as a large amplitude sub-synchronous vibration of the pump shaft and pump structure due to whirl or vortex. When a pump is not operated at its Best Efficiency Point the part of mechanical energy is transferred to the fluid that develops Vortices. It occur in shear layers between the main flow and the re-circulating fluid. This rotating fluid (Vortex) having very low pressure in its centre and forms vapor bubbles at very high rate this vapor bubbles formation and collapse (cavitation) produce hammering effect that begins to participate in the system dynamics and can lead to fluid induced vibration and sound under certain machine state & operating regime favorable to the same. It should be avoided as it can lead to machine failures due to stress-cycle fatigue

Turbulent Flow Characteristics in an Axial-flow Pump at Direct and Reverse Modes

ABSTRACT A reversible axial-flow pump equipped with S-shaped blades is investigated. Numerical simulation is employed as the major instrument to virtually visualize complex turbulent flows in the pump at direct and reverse operation modes. Cavitation is taken into account as well. Pressure fluctuations near the inlet and outlet of the impeller are obtained with unsteady simulation. At nominal flow rate, a relative difference of pump head of 15% is manifested between direct and reverse operation modes. At direct mode merely, cavitation zones are aggregated near the leading edge of the blade and assume a small volume fraction. The contribution of pump shaft is remarkable in terms of affecting pressure fluctuation characteristics upstream of the impeller. Characteristic frequencies immediately downstream of the impeller are analogous for the two operation modes and pressure fluctuation magnitudes are large relative to their counterparts upstream of the impeller.

Design and experimental studies of a novel double-row radial piston pump

This paper proposed a novel double-row radial piston pump. In this pump, the transformation from the rotation of the shaft to the reciprocation of the piston is realized by a pentagon mechanism, and the oil is distributed by check valves, which are integrally designed on the pump body. Theoretical calculation demonstrated that this improved design can substantially reduce the force on the main shaft of pump. The formulas of instantaneous flow rate and fluctuation coefficient of the pump are deduced. For studying the working characteristics of the pump further, a prototype was manufactured and tested. Results show that when the rotation speed is over 125 r/min, the performances of pump prototype are qualified, the fluctuation rate is limited to 20% and the volumetric efficiency can reach 90%. Moreover, the pump was disassembled after 100 h of service and the wear condition was checked. Except for the pentagon which has indentation on the surface, the components of the pump are all kept intact.

Experimental research on water-lubricated marine stern tube bearings in conditions of improper lubrication and cooling causing rapid bush wear

Water-lubricated polymer bushes are increasingly popular in sliding bearings of marine propellers, water turbines, and pump shafts. This environmentally friendly solution is relatively simple and usually proves to be durable.However, in practical experience one may also observe cases of rapid wear or even malfunctions of this type of bearing, some of which may be caused by insufficient flow of lubricant. The main purpose of the conducted research was to identify how different bearing types operate under conditions of no lubricant flow.The conducted research determined that certain bearings continue to work properly despite a lack of lubricant flow and cooling. This is due to low frictional resistance levels, resulting in sufficiently low heat being generated in the friction zone of such bearings and dispersed into the surroundings once the bearing׳s temperature has risen and stabilized at a safe level.

Experimental study of an electromagnetic flow meter for liquid metals based on torque measurement during pumping process

This paper presents a detailed experimental study on an electromagnetic flow measurement technique to measure the flow rate of liquid metals. The experimental setup consists of a contactless electromagnetic pump with a torque sensor mounted on the pump shaft. The electromagnetic pump is composed of two rotating steel discs having embedded permanent magnets with alternating poles. The rotation of the discs creates a travelling sinusoidal magnetic field and eddy currents within the liquid metal. The metal is contained inside the duct located between the discs of the pump. The interaction of the magnetic field and the induced eddy currents generates an electromagnetic Lorentz force providing the pumping effect. The flow rate is proportional to this force. The torque sensor measures the moment of the discs due to the Lorentz force, which is converted to a flow rate value. We name the method Lorentz torque velocimetry (LTV). The full calibration procedure and experimental investigation of the LTV are described. The method can be used as a non-contact flow rate control technique for liquid metals.

Scaling and Numerical Analysis of Nonuniform Waterjet Pump Inflows

Numerical simulations of the velocity fields entering the pump of a waterjet propelled ship have been performed to evaluate the level of nonuniformity in axial velocity. Nonuniform axial velocity entering the pump causes unsteady loading of the rotor blades resulting in noise and vibrations, and can increase the risk of rotor cavitation. The hull form modeled in this study is the R/V Athena, fitted with a waterjet propulsion system. Ship speeds correspond to Froude numbers between 0.34 and 0.84 and Reynolds numbers between 3.6 $\,\times {\hbox {10}}^{8}$ and 9.0 $\,\times {\hbox {10}}^{8}$ . The pump flow rate and shaft speed are determined via calm water resistance data from experiments and the pump curves for the axial flow pump. The numerical simulations are for steady, single phase flow and do not include free surface effects. In all of the numerical simulations, the hull draft is constant and the trim angle is fixed at 0 $^{\circ}$ (even keel). The variation in axial velocity is quantified by total distortion coefficient, harmonic components, and rotor section inflow angles. Using harmonic analysis, it is shown that the nondimensional wake entering the pump exhibits a mean axial velocity component that varies proportionally to nozzle velocity ratio (NVR) and harmonics of constant amplitude and phase, for all ship speeds. Thus, the wake pattern at any ship speed can be approximated using the harmonic content of the wake at one ship speed, and scaling the mean component of axial velocity. It is found that this hull and pump configuration resulted in the pump operating at a fixed pump flow coefficient for all ship speeds simulated. Thus, the average rotor section inflow angles are also constant over the speed range examined, which would be ideal for a rotor with a fixed pitch distribution as the mean angle of attack on a given rotor section will be independent of ship speed.

Analysis and Simulation of an Oil Lubrication Pump for Internal Combustion Engines

This paper presents a simulation model of an oil-lubrication gerotor pump for internal combustion engines. The model was constructed by using a monodimensional commercial code that accounted for all phenomena that occur during the revolution of the pump shaft. Several geometric considerations and theoretical observations are presented. An experiment was also performed to validate the simulation model. In these experimental tests, particular attention was paid to the behavior of the pressure oscillations during the pump shaft revolutions. The final aim of this activity is to obtain an instrument that allows the in-depth analysis of the functioning of the pump and lubrication circuit. Additionally, this instrument can be coupled with other models (e.g., variable valve actuation (VVA) and variable valve timing (VVT)) to account for different problems experienced by the hydraulic components of engines.

Experimental and analytical investigations of primary coolant pump coastdown phenomena for the Jordan Research and Training Reactor

Many low-power research reactors including the Jordan Research and Training Reactor (JRTR) are designed to have a downward core flow during a normal operation mode for many convenient operating features. This design feature requires maintaining the downward core flow for a short period of time right after a loss of off-site power (LOOP) accident to guarantee nuclear fuel integrity. In the JRTR, a big flywheel is installed on a primary cooling system (PCS) pump shaft to passively provide the inertial downward core flow at an initial stage of the LOOP accident. The inertial pumping capability during the coastdown period is experimentally investigated to confirm whether the coastdown half time requirement given by safety analyses is being satisfied. The validity and consistency of the experimental dataset are evaluated using a simulation software package, modular modeling system (MMS). In the MMS simulation model, all of the design data that affect the pump coastdown behavior are reflected. The experimental dataset is well predicted by the MMS model, and is confirmed to be valid and consistent. The designed coastdown half time is confirmed to be well above the value required by safety analysis results.wwwyoon@gmail.com

The calculation of optimal parameters of low emission centrifugal pump semi-open impeller

The paper provides methodology of calculation basic design parameters of low emission centrif- ugal pump. The main design parameters that should be calculated according the method are rotation frequency of the pump shaft, diameters of the inlet and the outlet of impeller, width of the inlet and the outlet of the impeller, angles of the blades at the inlet and the outlet of the impeller, number of impeller blades. The procedure gives approximate results and enables to calculate required num-bers. Its results could be used to make adjusted calculation of low emission centrifugal pump.

The Analysis of Finishing Tooling Influence on Friction Factor Examined by T-05 Tester

The article presents the research results referring to the analysis of the influence of finish treatment (finishing turning, grinding, burnishing) on the friction factor of steel applied to marine pump shafts. The research was performed on a roller 39 mm in diameter made of stainless steel 304L. The finish tooling of pump shaft pins was carried out on a universal centre lathe. The finish turning process was carried out by means of a WNMG WF 080408 Sandvik Coromant cutting tool with replaceable inserts. The grinding process was performed by grinding attachment for lathes. The 1 – 80×10×32 – 99C 80-N V grinding wheel was used for the process. The process of burnishing was done by SRMD burnishing tool by Yamato. The burnishing process could be carried out at the following technological parameters: burnishing force 1.1 kN, burnishing speed 35 m/min, feed 0.13 mm/rev [1, 2, 3]. The paper aimed at defining the influence of burnishing on service conditions by: testing electrochemical corrosion, friction wear and contact fatigue. The work presented the research results of friction factor tests of the samples after finish turning, grinding and burnishing. In addition, the influence of the burnisher passes number on the friction factor was determined. The experiment was performed on block – roll tester machine.

Significance determination on operating event of broken shaft of RCV pump for nuclear power plant

Significance determination on operating event of broken shaft of RCV pump for nuclear power plant

The Analysis of Finishing Tooling Influence on Corrosion Properties of Stainless Steel

Angular momentum pumps are very often applied on-board ships. These pumps are used in cooling circuits of medium and high power engines, power plant boilers and in bilge, ballast and fire installations. Very extensive use of angular momentum pumps on board is linked with their numerous advantages. During operation, the wear of the marine hull, the rotor and the shaft seals takes place. The research attempts to increase the service life of shafts. The article presents the research results referring to the analysis of the influence of finish treatment (turning, grinding and burnishing) on the corrosion properties of steel applied to marine pump shafts. The research was performed on a roller of 40 mm in diameter made of X5CrNi18-10 (AISI 304 L) stainless steel. The turning process was carried out by means of a WNMG WF 080408 Sandvik Coromant cutting tool with replaceable inserts. The grinding process was performed by grinding attachment for lathes. The 1 – 80×10×32 – 99C 80-N V grinding wheel was used for the process. The process of burnishing was done by SRMD burnisher from Yamato. In addition, the influence of the burnisher passes number on the corrosion properties was determined. The paper will present the results of electrochemical impedance spectroscopy and potentiodynamic research. To conduct the survey, the Atlas 0531 EU & IA potentiostat was used. Determination of the corrosion process parameters was performed by the computer programs: AtlasLab 2.0, EIS Spectrum Analyzer and Elfit2.