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Centrifugal pumps performance is highly affected by working fluid viscosity. So, optimization of such pumps for pumping of viscose fluids is very important. In the present paper, multi-objective optimization of the centrifugal pumps is performed to obtain optimum impellers for pumping fluids with various viscosities at different volumetric flow rates. In this way, theoretical head and impeller hydraulic losses are considered as objective functions. Design variables defined in this optimization problem are passage width of impeller and outlet angle of blade. Diagrams of Pareto fronts and Pareto sets are extracted for different viscosities and different volumetric flow rates. Some trade-off optimum design points are selected from all non-dominated points using three different methods namely break point, TOPSIS and near to ideal point. Such methods are defined completely and employed to achieve compromising point successfully. Obtained optimum points contain interesting results which cannot be achieve without using proposed multi-objective optimization approach.

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As pumps are used frequently in industrial plants, their performance improvement is important. In this study, performance improvement of centrifugal pumps by application of splitter blades have been investigated both numerically and experimentally. Radial impellers with different length of splitter blades have been manufactured and tested to obtain performance charts. On the other hand, the flow in impeller and volute has been investigated numerically by ANSYS-CFX commercial code. Numerical study has been done using Finite volume method and k-ωSST turbulence model. Rotating and stationary frames have been used to analyze flow in impeller and volute respectively and the results have been coupled by Frozen Rotor. Three impellers with the lengths of splitter blades equal to 0, 33% and 66% of original blades were tested. Results show head increase when the splitter blades added while the amount of increase depends on the splitter blades length. At BEP (Best Efficiency Point) the maximum head increase was reported for impeller type three (the length of splitters equal to 66% of original blades) about 10.5 percent. It should be noted that as the capacity tends to BEP, the effect of splitter blades is more significant.

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slip factor is one of the most important parameters used in centrifugal pumps performance prediction. Knowing this parameter as a function of flow rate seems essential for off-design performance prediction. In this paper, it is intended to establish the slip factor dependence upon flow rate for a centrifugal pump using computational fluid dynamics. For this purpose, the full 3D-RANS equations in coupled with RNG k-ε turbulence model were solved for several flow rates ranging from 45% to 120% of rated condition by means of a commercial code, CFX. In the steady state, this simulation is defined by means of the multi-reference frame technique, in which the impeller is situated in the rotating reference frame, and the volute is in the fixed reference frame. The validity of the numerical model was confirmed by matching the calculated characteristic curves with the associated experimental data. It was found that there is a good coincidence between the numerical results and available experimental data of global performance, local velocity distribution and slip factors. A comparison was performed among the well-known slip models which reveals, that the slip factor variations can be predicted very well using CFD analysis.

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This article presents a numerical investigation of fluid flow in one of the centrifugal pumps of pump-Iran Corporation. A computational fluid dynamics (CFD) analysis is performed by using the CFX software for a wide range of volumetric flow rates for two different rotor speeds of 1450 rpm and 2900 rpm and the numerical results of water are validated against measured values of head and total efficiency with an overall acceptable agreement. The obtained results have been obtained for crude oil as diagrams of head and total efficiency as the function of volumetric flow rate and other variables and compared with results of water. Numerical results show that the absolute pressure on blade surfaces for crude oil is 705 kpa less than when using water. The absolute pressure difference between inlet and outlet of impeller and spiral volute for crude oil is comparatively less than those amounts in comparison with water. Also by increasing the angular velocity of rotor, it was observed that high levels of turbulence intensity are transmitted from outlet pipe bending to the impeller outlet at volumetric flow rate of 30 m3/h that causes the efficiency reduction and high levels of turbulence intensity for crude oil are less than those amounts in comparison with water within impeller area. Finally, to represent an impeller pump head curve for crude oil over the overall operation range of the pump, a second order polynomial equation was fit to numerical data.

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Pumps consume about 20% of whole electricity power in the world. Centrifugal pump is one of the most common pumps that works by the transfer of angular momentum to the fluid. The behavior of such a fluid flow in the side chamber, may affect the pump performance. The side chamber is defined the free space between the fixed (pump casing) and the rotating (pump impeller) parts. Steady, fully 3D computations of the Reynolds-averaged Navier-Stokes equations using a commercial CFD code are conducted in order to study the flow field in the whole pump including both side chambers. Numerical results are validated by comparison with the existing experiments. The impact of fluid flow in hub and shroud side chambers with the volute is investigated qualitatively by using 2D stream lines. Evaluation of the empirical equations shows that the frictional torque may be decreased more than 10%, by using the proper gap size. Considering this situation, the changes in the flow pattern and the value of power loss resulting from friction in hub and shroud side chamber is studied. It reveals that the variation in friction depends on the initial flow pattern in cavity. Finally, in order to obtain the relationship between the power loss and the flow rate, nondimensional coefficients are derived. These coefficients show that the change in the power loss due to the volumetric flow rate, is the same as its change with the gap changing, but their slopes are not equal.

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In the present work, an inverse design algorithm called Ball-Spine (BSA) is developed as a quasi-3D method on the meridional plane of a centrifugal pump impeller with rotating frame and incompressible viscous flow within it, with the aim of improving its performance. In this method, numerical analysis of viscous flow on a thin plane of flow between two blades using a 3D viscous flow solver is combined with BSA, which modifies hub and shroud geometries. Namely, instead of solving inviscid quasi-3D flow equations in the meridional plane, full 3D Navier-Stokes equations is solved on the thin plane of flow. To show the validity of the present work, centrifugal pump is numerically evaluated and numerical results are compared with experimental results, and flow field in the meridional plane of pump impeller is obtained using quasi-3D method. By studying the algorithm in the rotating geometry and choosing static pressure and reduced pressure as target parameters the ability of performance of the algorithm is assessed. After that, the new impeller geometry is obtained in conformity with the modified pressure distribution, by defining target pressure distribution on the hub and shroud surfaces of the conduit and trying to eliminate excess pressure gradients. Obtained results indicate good rate of convergence and desirable stability of BSA in the design of rotating conduits with incompressible viscous fluids. By using the above-mentioned optimization method following results was observed: increase of static pressure along streamline, 1% of increase in the pump total head, delay in impeller cavitation inception.

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Despite significant improved survival rate in patient with heart failure by Ventricular Assist Devices (VADs), complications related to blood hemolysis and pump thrombosis have challenged the improvement of these devices. Hence, the first step of VADs improvement is studding the flow field and the effect of different parameters on blood hemolysis. Consequently, at the first step of the current study, the CFD analysis of hemolysis in laminar flow inside a pipe and turbulent flow inside a chamber with rotating disc were compared with Analytical solution and experimental results, respectively, and good agreements were achieved. Then, numerical simulation was used to calculate the hemodynamics in one axial and one centrifugal pump as a Left Ventricular Assist Device (LVAD), and a comparative analysis of operating conditions, efficiency and hemolysis index was performed among them. The results showed that the axial VAD had a higher hemolysis index, due to its longer residence time and higher shear stress. The higher shear stress in simulated axial VAD compared to centrifugal VAD arises from its higher operating speed and lower gap size. Furthermore, at the required conditions for blood flow in the human body, the centrifugal VAD has higher efficiency than axial VAD.

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Centrifugal pumps as a heart of the system which are used to move fluids are used widely in most of the industries and have considerable contribution in the amount of energy consumption, so improving of their performance has been attended for researchers .In this paper the aim of studying is the effect of double splitter blades on pump’s performance numerically and experimentally. Three type impellers have been made as experimental investigation. Pump with this impellers is tested and extracted the performance curve. Also, for investigation of the flow pump has been simulated numerically by ANSYS-CFX commercial code. Numerical method of finite volume with k-ω SST turbulence model for numerical analysis. Numerical and experimental results show reasonable agreement that increasing of head and variation of NPSHR due to adding of double splitter blades. The maximum head increased was obtained related to third type of Impeller about 6.33 percent. Furthermore, third type is selected as best impeller. Also, it is observed that around point of designing of pump the effect of double splitter blades on pump’s performance is more significant and deviation from this point will decrease the effect of it.

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Fault propagation analysis is a method based on graph theory used to study the propagation of the effects of faults and disturbances in the system parts. The inclusion of fault propagation and interference of fault and disturbance effects in the design of fault detection algorithms increases reliability and reduces false alarms in critical equipment. In this paper the failure mode and effects analysis (FMEA) method was used to prepare a list of the possible faults and disturbances of each part of a system including of an induction motor and a centrifugal pump. Then a logical model is obtained through the fault propagation analysis to explain the connection between different parts of this system and the propagation of the electrical, vibrational and process effects. This model can be used to consider the propagation of the effects of faults and disturbances in system parts, and the interference of these effects and to select the appropriate effects or sensor configurations required for robust fault detection. The concept of this method is illustrated in this paper by applying this technique to an experimental system.

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Inducers are important devices which are mounted upstream of the inlet to the main impeller of the centrifugal pump to achieve higher suction performance and rotate with the same speed as the impeller. Inducers improve the hydraulic performance and lifespan of the pump through increasing the inlet pressure, but the quantity of the improvement is dependent on the geometrical parameters of the inducer. Therefore, the optimization of these parameters is crucial. In the present study, the performance of an inducer is optimized by considering the inlet tip blade angle, the outlet tip blade angle and the ratio of the outlet hub radius to inlet hub radius as design variables and the head coefficient, the hydraulic efficiency and the required net positive suction head as objective functions. The inducer performance is simulated using 3-D computational fluid dynamics and compared with experimental data which shows the validity of the used method and assumptions. The artificial neural network is used to relate between design variables and objective functions. Then, the Pareto fronts are plotted using the modified non-dominated sorting genetic algorithm II and the proposed optimum points are presented using nearest point to the ideal point method. Using multi objective optimization, the head coefficient, the hydraulic efficiency and the net positive suction head are improved 14.3%, 0.3% and 30.2%, respectively. Recommended design points unveil important optimal design principles that would not have been obtained without the use of a multi objective optimization approach.