Impeller Diameter Research Articles

Enhancing Efficiency of Industrial Centrifugal Fans Using Blade Adjustment Mechanism

The paper presents research on increasing the efficiency of industrial centrifugal fans, which are the third highest energy-consuming group of devices. This problem is related to the frequent incompatibility of the fan characteristics with the flow conditions of the installation in which they are operated, which lowers efficiency and increases energy consumption. By ensuring high efficiency of these devices, it is possible to significantly reduce the operating costs of such industrial equipment. For this purpose, a unique concept of regulating the flow parameters of centrifugal fans was developed. The scientific basis of this idea is that a relatively small change in the impeller diameter of the fan significantly affects the flow rate and the pressure rise of the fan. Therefore, the idea uses variable length of the impeller blades by dividing them into a fixed and a movable part. It enables adjustment of the length of the blades, which allows extension of the range of effective and efficient operating parameters. On this basis, several technical solutions of the regulation system were developed, which were then tested using simulation and analytical methods. Two material options for the moving part of the blade have also been developed, one made of metallic materials (high-strength steel and aluminum) and the other made of composite materials. The research showed a significant influence of the mass of the movable part of the blade on the load of the control system. Therefore, ultra-light material variants were used for the impeller blades. The flow simulation tests of the new method of adjusting the fan flow parameters confirmed the effectiveness of this solution. As a result, a wider range of highly efficient centrifugal fans equipped with such a control system was obtained.

Effect of outlet impeller diameter on performance prediction of centrifugal pump under single-phase and cavitation flow conditions

Abstract In this current study, the transient numerical calculations using CFD code are carried out under different outlet impeller diameters for the flow field within a centrifugal pump under single-phase and cavitation conditions. Both qualitative and quantitative analyses are carried out on all of these results in order to better understand the flow structure within a centrifugal pump. Also, the investigations using different outlet impeller diameters configurations relating to the static pressure, velocity magnitude, vapour volume fraction variations, as well as pressure fluctuations in both time and frequency domain at the impeller and volute of the pump are analysed. Velocity and static pressure variations of the pump under different outlet impeller diameters range (200, 210 and 220 mm) are investigated. Reliable model is developed and validated, at various pump operating conditions, to analyse the characteristics of pressure fluctuations in both time and frequency domain. Cavitation occurrence, under different outlet impeller diameters and flow rates, are detected and correlated, using a CFD model (volume fraction distributions). Based on the developed model’s findings, at the set operating conditions ranges, the distribution and impact (cavitation and head-wises) of both the pressure and velocity are analysed. The average pressure fluctuation in the volute for do = 210 mm is higher than for do = 200 mm by about 6.74%, also the maximum pressure fluctuation for do = 220 mm is higher than for do = 210 mm by around 7.4%. Furthermore, the maximum pressure fluctuation in the impeller for do = 210 mm is higher than for do = 200 mm by 12.48%, also for do = 220 mm is higher than for do = 210 mm by 10.8%. The developed CFD models are proved valuable tools in identifying and optimizing the pump performance and characterization. The head for when do = 220 mm is higher than for when do = 200 mm under both single-phase and cavitation conditions by around 14.13% and 14.69%. The maximum pressure fluctuation for do = 200 mm is lower than for do = 210 mm by 41.58%. Furthermore, the maximum pressure fluctuation at the impeller for do = 220 mm is higher than the two models. There is a small clearance between the impeller and the volute for this model, leading to the pressure fluctuation amplitudes being higher than the other above models.

Performance Prediction and Geometry Optimization for Application of Pump as Turbine: A Review

Pump as Turbine (PAT) is a technically and economically effective technology to utilize small/mini/micro/pico hydropower, especially in rural areas. There are two main subjects that influence the selection and application of PAT. On the one hand, manufacturers of pumps will not provide their characteristics under the turbine mode, which requires performance prediction methods. On the other hand, PAT efficiency is always slightly lower than that of pump, which requires further geometry optimization. This literature review summarized published research studies related to performance prediction and geometry optimization, aimed at guiding for selection and optimization of PAT. Currently, there exist four categories of performance prediction methods, namely, using BEP (Best Efficiency Point), using specific speed, loss modeling, and polynomial fitting. The using BEP and loss modeling methods are based on theoretical analysis, while using specific speed and polynomial fitting methods require statistical fitting. The prediction errors of published methods are within ±10% mostly. For geometry optimization, investigations mainly focus on impeller diameter and blade geometry. The influence of impeller trimming, blade rounding, blade wrap angle, blade profile, blade number, blade trailing edge position, and guide vane number has been studied. Among published methods, the blade rounding and forward-curved impellers are the most effective and feasible techniques.

Effect of Impeller Size on the Performance of a Single Blade Pump

Changing the impeller diameter is a frequently used method for adjusting pump performance parameters. In the case of conventional multi-blade impellers, this is done by reducing the diameter on the machine tool to the prescribed shape. The other dimensions of the pump (diffuser, inlet) remain unchanged. This method is called trimming. The article deals with the diameter reduction and subsequent modification of the performance parameters of a single blade pump. These pumps are characterized by certain specific features. First of all, it is an unsymmetrical impeller that must be both statically and dynamically balanced. This plays an essential role in the whole modification process. Research results obtained on a pump with an impeller diameter of 138 mm are presented. The change in diameter was monitored on a total of 3 impellers. Experiments were carried out in the laboratory of hydraulic machinery. The results were verified by CFD calculations. Research background: The article concerns the modification of impellers of single blade pumps. The effects of diameter modifications on multi-blade pumps are currently known. However, these have symmetrical impellers and can therefore be changed without restriction. For asymmetric (single blade) impellers, the problem is more complex as additional mass must be added to provide static and dynamic balance. Purpose of the article: The aim is to determine the nature of the change in performance parameters when the output diameter is changed. The results of the research can be applied in the prediction of the change in the operating point and the creation of tombstone charts. Methods: Two kinds of methods were used in the research: experiment and CFD calculation. A total of 4 impeller sizes were investigated. Findings & Value added: The results of the paper can be divided into two areas. In the experimental area, a device was designed to measure the characteristics of single blade pumps. Four impellers were manufactured and tested. In the area of CFD calculations, simulations of the hydraulic parameters around the best efficiency point (BEP) were performed. The calculation results were verified by experiment. The nature of the change of the BEP when the diameter of the impeller changes up to 87.9 % was found.

PIV Measurement of Flow Conditions near Casing Tongue of Mini Centrifugal Pump

Flow conditions near the casing tongue have a significant impact on the performance and stable operation of the centrifugal pump, so the internal flow conditions have been measured by the experiment and PIV measurement. The internal flow conditions of mini centrifugal pumps especially smaller than 100mm are less measured by PIV measurement and its flow conditions near the casing tongue are not clarified yet. Therefore, PIV measurement was conducted near the casing tongue for the mini centrifugal pump having 55mm impeller diameter. The two-dimensional open impeller with the large blade outlet angle β2=60° was selected as the test impeller. FlowMaster Stereo-PIV by LaVision was used for the PIV measurement and the whole test section was made of the acrylic resin including the test impeller. Two CCD cameras with its resolution 2048×2048 pixels were used and velocity vector and contour were calculated by the PIV measurement software DaVis(Lavision). The internal flow conditions near the casing tongue were focused in this research. The PIV measurement results at different flow rates were shown and the tongue flow angle was defined to clarify the flow condition near the casing tongue with the impeller rotation. With the increase of the flow rate, the tongue flow angle increases which means the flow near the casing tongue is discharged to the casing throat. In the present paper, the internal flow near the casing tongue is clarified by PIV measurement results and the flow conditions with the impeller rotation are discussed.

PENGGANDAAN SKALA PRODUKSI INSEKTISIDA HAMA WERENG COKELAT KAPASITAS 25 DAN 1000 LITER SERTA PELUANGNYA DI DUNIA INDUSTRI

The downstream of DEA surfactant products has great potential in the industrial world, one of which is agricultural product in the form of insecticides. The purpose of this study is to examine the scale multiplication of insecticide products for the brown planthopper on a pilot scale of 25 l and an industrial scale of 1000 l and calculating the selling price of insecticide products with different profit variations based on the cost of production. The scale multiplication was based on the unit of power per unit volume (Pg /V) which had a fixed value. The optimal agitation speed in product formation was obtained from a small-scale experiment, and the results were used to obtain the agitation speed on a large scale, which required the same power per unit volume. A simple step to calculate multiplication of the scale was by using the basic geometric shape of the tools used in the process performed. The determination of the tools used was based on the effectiveness of the two types of tools, namely mixer and homogenizer. Furthermore, the multiplication of the scale into geometric shapes on the scale of 25 l was carried out and continued on the scale of 1000 l. The required parameters in determining the geometry of the reactor were impeller diameter (Di), tank diameter (Dt), sample of liquid height (HL), impeller rotation (Ni). The results obtained showed that the effectiveness of insecticide production was higher in the use of this type of homogenizer tool. In this study, the power per unit volume (Pg /V) was fixed. Calculation data obtained from the laboratory scale include Ht; HL; Di and Dt. On the scale of 25 L were 28.2; 19.5; 12.2 and 33.6 cm, meanwhile on the scale of 1000 L were 95.7; 66.9; 41.7 and 115.4 cm. The result of the calculation of the impeller rotation speed at a scale multiplication of 1000 L was 396 rpm. The calculation of the selling price of the brown planthopper insecticide per bottle (200 ml) for the 50% profit margin was IDR 13,043, the 100% profit margin was IDR 17,390 and the 200% profit margin was IDR 26,086.

Effect of Impeller Trimming on Centrifugal Pump

Pumps, especially centrifugal pumps, play an important role in engineering application, such as petroleum and petro-chemical industries, agricultural industries, portland cement industries etc. To obtain the best performance of the pumps, one has to operate the pumps at their design conditions. In some circumstances, however, the pumps must operate lower than their design conditions and result in the decrease in their performances. In such cases, it is possible to replace the pump impeller with the smaller impeller diameter or to cut its original impeller to smaller size as necessary. The cut of the impeller, or it is frequently referred to as impeller trimming, in some extence is preferable than replacing with new impeller or even by replacing with new pump with smaller head and capacity. In this study, we examine the effect of the pump impeller trimming to the pump performaces. The study was performed in the Fluid Mechanics Laboratory, Mechanical Engineering Department of ITS, Surabaya. The pump impellers were cut up to approximately 19 percent of its original pump impeller diameter, where the original pump impeller diameter is 129 mm. The pump has the maximum capacity of 100 liters/min and the total head of 31.5 m. The pump is powered by a 300 Watt electrical motor. Parameters to be studied in this research include pump capacity, pump head, pump power, and pump efficiency. The results of this study show that all data are in good agreement with the pump affinity laws. Pump capacity, pump head, and pump power decresase as the pump impeller diameter decreases. The pump efficiency is, however, in some extent, increases as the pump impeller diameter decreases. The maximum increase in pump efficiency is obtained when the ratio between the trimmed impeller to its original pump impeller diameter is approximately 89 percent (i.e. D2/D1 = 0.89), with the increase in pump efficiency of approximately 20 percent.

Giluyskaya Hydropower – new approach to project development

Multivariate water-power calculations were carried out and the main parameters of the reservoired Gilyuyskaya HPP were justified. The Gilyuy river is located in the Amur Region of the Far Eastern Federal District and is a right tributary of the Zeya River. The mouth of the Gilyuy river is located above the power site of Zeyskaya HPP. Based on the water-power calculations, it was found that the most efficient way is to use live storage capacity of 3.13 km3 and the turbine flow rate of HPP equal to 268 m3/s. The installed power capacity of Giluyskaya HPP is justified on the basis of maximizing the net present value and is assumed to be 213 MW. Hydropower has three hydraulic units with radial-axial turbine RO115with impeller diameter of 3.35 m and synchronous speed of 214.3rpm.The high-head water power development includes as follows: a concrete gravity dam, a concrete spillway dam with nappe-shaped profile, a concrete power dam with three water inlets and three steel pipelines with a diameter of 4 m, as well as HPP building. The HPP building is 48.68 m long and consists of three hydropower units with a width of 16.23 m. The length of the tent of HPP building along the flowstream is 18.5 m. The assembly area is 24.34 m long.

Experimental Research and Numerical Analysis of Pressure Fluctuation Characteristics of Rim Driven Propulsion Pump Outlet

The pressure fluctuation characteristics of a rim driven propulsion pump are studied by an experimental method firstly, and then its unsteady inner flow is studied by numerical simulation to reveal the generating mechanism of the pressure fluctuation. In the experiment, a monitoring point was set in a downstream region with a distance of 1D (D, Diameter of impeller) to the impeller. The monitoring point’s dominant frequencies within a low frequency band are 1APF (APF, Axial Passing Frequency) and 2APF. In the numerical simulation, the main fluctuation near the impeller region appears at 1BPF (BPF, Blade Passing Frequency) and as the monitoring point moves downstream, the amplitude becomes smaller. The 1BPF fluctuation nearly disappears when the distance exceeds 1D, and the main frequency moves to 1APF and 2APF, which is in good agreement with the experimental results in the low frequency band. The transient velocity, pressure and vorticity distribution were studied to reveal the causes of 1BPF, 1APF and 2APF fluctuation. The main cause of 1BPF is the jet from the tail of the blade and the main cause of 2APF is the movement of a large-scale double vortex structure on both sides of the low-pressure zone. The movement of the vortex group near the wall may be the main cause that induces the 1APF fluctuation.

Multi-condition design optimization of groove flow control technique in an axial-flow pump

Abstract To address the limitations of conventional groove designs in groove flow control technique, this paper optimizes the groove flow control technique for an axial-flow pump combining the design of experiment (DOE), response surface methodology (RSM), and particle swarm optimization (PSO). The sample space is designed using a combination method (OD-LHS) of orthogonal design (OD) and Latin hypercube sampling (LHS). Performance prediction models for the axial-flow pump are established using RSM. Taking the multi-condition comprehensive evaluation function as the final optimization objective, PSO is used to find the optimum groove parameters. The results show that the proposed method is effective in solving multi-condition optimization problems for grooves in axial-flow pumps. The optimal groove length, depth, and distance from the center of the impeller are 0.8, 0.05, and 0.2 times the impeller diameter, respectively, and the number is three times the number of blades. In addition, the optimal grooves effectively improve the hydraulic performance of the axial-flow pump under stall conditions. This study sheds light on the design optimization of the groove flow control technique for axial-flow pumps and other types of hydraulic machinery.

PERFORMANCE EVALUATION OF LOCALLY FABRICATED MECHANICAL SURFACE AERATOR

Experimental analysis for a fabricated Low-Speed surface aerator that can be used in wastewater and water treatment is presented in this research. The designed impeller configuration was tested to determine its power consumption, standard oxygen transfer rate (SOTR), and standard aeration efficiency (SAE). Impeller oxygen transfer and power consumption in a scaled laboratory tank were measured during aeration phase. The impeller was consisting of 8 inclines flat blades with an angle of 45° from center of the disc, was operated at 3 different immersion depths and 5 different rotational speeds for examining the impact of such factors on impeller efficiency. The results recorded that the best standard aeration efficiency for this configuration is (0.206 Kg. O2/KW.hr) at 120rpm and 7cm depth of the submersion, i.e. submersion depth to impeller diameter (h/D) ratio equals 0.175. Submergence depth increase beyond this limit would result in SAE decrease and definitely result into more power consumption.

CFD research on the influence of geometry characteristic on flow pattern and the transition mechanism in Rushton turbine stirred vessels

Abstract In this paper, the transient MRF approach coupled with the standard k-ε and SST k-ω turbulence models was employed to study the effect of bottom shape, impeller diameter (D J) and bottom height (H 2) on critical impeller off-bottom clearance (C). It was found the bottom shape and bottom height (H 2) have obvious influence on the flow pattern transition from double-loop to single-loop of RT impeller. The flow pattern transition mechanism was inferred to relate to the relationship between the space required by the lower circulation zone and the actual space. The boundary conditions of critical C were further concluded to help distinguish the flow pattern and receive the expected one in the stirred vessel design.

Analisis Kinerja Pompa Sentrifugal pada Variasi Trim Diameter Menggunakan Simulasi Numerik

Diameter trimming is one of the most common modification on centrifugal pump impeller aimed to keep conformity between pump performance and required head and flow rate. In its application, centrifugal pump performance with trimmed diameter could be predicted by using affinity equations which based on geometrical similarity between pre- and post-trimming impeller. However, diameter trimming also alter the dimension ratio in blade passage which prompt further investigation on performance prediction of pump with trimmed impeller diameter. This research is carried out by using numerical simulation to analyze performance of pump with trimmed impeller diameter. The simulation is conducted on radial-type centrifugal pump with impeller diameter 105 mm, inlet blade angle 200, outlet blade angle 280, and operating on mass flow rate 1.5 kg/s at rotational speed 2800 rpm. RNG k-e model is used to model turbulence while trimmed diameter values are 100 mm and 95 mm. Results indicate that there is significant differences on head and consumed power between predicted value by simulation and predicted value obtained by employing affinity equations.

Investigation of dense slurry suspensions with coaxial mixers: Influences of design variables through tomography and mathematical modelling

The coaxial mixers enhance the suspension of concentrated slurries in an agitated reactor. In this research work, the complex slurry suspension and dissemination behavior in a coaxial slurry mixing system (comprised of a close clearance anchor rotating with a low speed and an inner axial impeller rotating with a high speed) was analyzed employing ERT (electrical resistance tomography, a non-intrusive flow visualization technique), and computational fluid dynamics (CFD). The numerical models were validated by comparing the axial solid concentration profiles generated using the ERT data and the CFD simulation results. The influences of various important parameters such as the diameter of the inner axial impeller, the inner impeller type, and the inner impeller spacing on the hydrodynamic characteristics of the slurry suspensions in a coaxial mixing vessel were thoroughly analyzed. The radial and axial velocity profiles of solid particles were generated using the validated mathematical models. The assessment of energy loss due to the solid–solid collisions, the particle–fluid frictions, and the particle–vessel wall collisions was conducted. The evaluation of optimum inner impeller clearance and inner impeller diameter is essential to attain a high degree of solids suspension and dissemination in a coaxial slurry mixing system.

Multi-Physical Simulation of Stirring Effect on Heating Uniformity in a Microwave Reactor With an Interlayer

Abstract Due to the exhaustion of fossil fuels and environmental degradation, biodiesel has attracted much attention as a new energy source. Currently, microwave reactors are used extensively for producing biodiesel. However, nonuniform heating of producing biodiesel in microwave reactors is a major problem. In order to solve the problem, a microwave reactor with an interlayer which can obviously improve the uniformity of microwave heating was designed. In this work, the heating efficiency and heating uniformity of the reactor were discussed from two aspects of waveguide position and interlayer thickness by means of multi-physical coupling calculation. According to the calculation results, the optimization model of a microwave reactor with an interlayer was obtained. Then, based on the above optimization model of a microwave reactor with an interlayer, a stirrer that can improve the heat transfer of the fluid material was introduced. The Maxwell equation, heat transfer equation, and flow equation were coupled by the multi-physical field simulation method to explore the influence of different factors of the stirrer on power consumption and heating uniformity. Through response surface analysis, it was found that the primary and secondary order of stirring factors affecting microwave heating uniformity was stirring speed > impeller diameter > bottom clearance, and there was an interaction between different factors. From the two aspects of stirring power consumption and heating uniformity, the best stirring effect was obtained.

Effects of Impeller Geometry on the 11α-Hydroxylation of Canrenone in Rushton Turbine-Stirred Tanks.

The 11α-hydroxylation of canrenone can be catalyzed by Aspergillus ochraceus in bioreactors, where the geometry of the impeller greatly influences the biotransformation. In this study, the effects of the blade number and impeller diameter of a Rushton turbine on the 11α-hydroxylation of canrenone were considered. The results of fermentation experiments using a 50 mm four-blade impeller showed that 3.40% and 11.43% increases in the conversion ratio were achieved by increasing the blade number and impeller diameter, respectively. However, with an impeller diameter of 60 mm, the conversion ratio with a six-blade impeller was 14.42% lower than that with a four-blade impeller. Data from cold model experiments with a large-diameter six-blade impeller indicated that the serious leakage of inclusions and a 22.08% enzyme activity retention led to a low conversion ratio. Numerical simulations suggested that there was good gas distribution and high fluid flow velocity when the fluid was stirred by large-diameter impellers, resulting in a high dissolved oxygen content and good bulk circulation, which positively affected hyphal growth and metabolism. However, a large-diameter six-blade impeller created overly high shear compared to a large-diameter four-blade impeller, thereby decreasing the conversion ratio. The average shear rates of the former and latter cases were 43.25 s-1 and 35.31 s-1, respectively. We therefore concluded that appropriate shear should be applied in the 11α-hydroxylation of canrenone. Overall, this study provides basic data for the scaled-up production of 11α-hydroxycanrenone.

Experimental study of a centrifugal compressor with two successive and counter-rotating impellers

In many industries, reducing the size of the compression system represents a significant goal for designers. In fact, increasing the power density of the compressor actually means lowering production costs. The chief purpose of this study is to compare, in terms of aerodynamic performances, a centrifugal compressor consisting of an impeller and a volute, to an innovative concept based on the principle of two successive impellers and designed to work in counter-rotation. To simplify the experimental research in this study, the volute of the conventional compressor is maintained for the new design. The conventional impeller has been replaced by two successive impellers having the same meridian profile, and whose diameter of the rear impeller is identical to that of the conventional impeller. The impellers design of the counter-rotation stage was carried out granting to an approach proposed here. The numerical results underline the advantage of the innovative compressor, in terms of power density, compared to the conventional design. The numerical forecasts also agree significantly with the results of experimental tests got on a test bench exclusively designed for compressors. Experimental optimization of the rotational speed ratio of the two counter-rotating impellers has demonstrated the possibility of increasing the compression ratio and efficiency over a wide range of flow.

Mixing optimization with inward flow configuration contra-rotating impeller, baffle-free tank

In this study, pitched-blade, contra-rotating impeller, baffle-free tank with opposing inward flow is optimized using various designs of mixers derived from the Taguchi method. Mixing efficiency and torque are used to find the optimal design for the different specific gravities of solid particles employing in both experiments and CFD simulations. The analysis of signal-to-noise ratio shows that the impeller clearance and diameter are significant factors on the fluid flow and thus the mixing efficiency. In this study, 27 cases were studied to determine and report the optimal design parameters. A combination of CFD simulation with a strong design of experiment illustrates the ability to characterize and optimize the design parameters that affect mixing efficiency, showing promise as design guideline for the contra-rotating impeller. The best compromise between high mixing efficiency and low torque for pilot scale was found in the following configuration: a 300 mm diameter tank with liquid filled to a height of 300 mm; four pitched-blades rotating at 100 RPM with an impeller diameter of 150 mm; and a 125 mm impeller-impeller and impeller-bottom clearance.

Multistage pump axial force control and hydraulic performance optimization based on response surface methodology

In order to comprehensively optimize the axial force and hydraulic performance of the multistage pump, considering that there are relatively more secondary impeller stages and the blade profile has a greater impact on the axial force and hydraulic performance, Plackett–Burman test design method in this paper is adopted to conduct significance analysis and screening of the secondary impeller parameters. Based on the response surface methodology, a central composite test is designed for three control variables with strong sensitivity. The multiple regression model between the parameters of the secondary impeller and the hydraulic performance and axial force of the multistage pump is established. The optimal parameter combination which takes the performance and axial force into account is obtained. The accuracy of the optimization results is verified through tests. The results show that the blade exit angle, outlet diameter and blade wrap angle of the secondary impeller have the most significant influence on the axial force and hydraulic performance of the multistage pump. The results of variance analysis and coefficient test show that the regression model is highly significant and can reflect the objective relationship between the control parameters of the secondary impeller shape and the response objectives. A larger outlet diameter and blade wrap angle of the secondary impeller can improve the head of the multistage pump. A larger blade wrap angle and a smaller blade exit angle of the secondary impeller can reduce the axial force of the multistage pump. By solving the multiple regression equation, it is found that when the outlet diameter of the secondary impeller is 292 mm, the blade exit angle is 22°, and the blade wrap angle is 150°, the axial force of the multistage pump is the lowest and the hydraulic performance is slightly improved. It is verified by experiments that the head and efficiency of the optimized multistage pump increase by 0.95% and 1.71%, respectively, the temperature of the front and rear bearings decreases by 16.49% and 16.17%, respectively, and the vibration speed of the multistage pump along three directions is significantly reduced.

Effect of Impeller Diameter on Dynamic Response of a Centrifugal Pump Rotor

This paper investigates the effect of impeller diameter on the dynamic response of a centrifugal pump using an inverse dynamic method. For this purpose, the equations of motion of the shaft and the impeller are derived based on Timoshenko beam theory considering the impeller as a concentrated mass disk. For practical modeling, the model of Jones and Harris is added to the equation to include the effect of bearings. As a case study, the model is applied to a process pump used in an oil refinery. Computing the eigenvalues of the model and comparing them with the natural frequencies of the structure, the model updating of the problem is performed through an indirect method. Three impellers with different diameters are applied to the updated model. The results show that increasing the diameter of the pump impeller can increase the amplitude of vibration up to 52% at critical speeds of the rotor. It is found that in addition to the hydraulic condition and efficiency, the impeller diameter should be considered as an important factor in the selection of centrifugal pumps.