Keyword: CFD, Design, Impeller, Pump, Radial Flow, Vane. The impeller is a double-width, double-inlet (DWDI) centrifugal type with two nonstaggered blade rows. There are some advantages to sweeping the blade: (i) a blade starting at a lower radius near the shroud can prevent boundary-layer separation by accelerating the flow before it actually turns, and (ii) it changes in incidence at the leading edge attributed to the sweep can lower losses and increase efficiency. Design and simulation were conducted using ANSYS CFX, using the Navier-Stokes equation. Adapted from the grid topology used for the impeller design CFD, the impeller grid ended at a fixed radius for all coupling calculations except for the NEW impeller, which ended at a slightly smaller radius. From here on out, when this 3D version of the steer blade is integrated with the impeller, it is referred to as the NEW design impeller. In contrast, the shroud gap flow improves both the impeller and the fan efficiencies for the B#1 impeller. The double-discharge volute casing is a structural constraint and is maintained for its shape. The dramatic reduction in the volute loss for the NEW impeller suggests that the exit flow from the new impeller matches better with the downstream volute flow than those for the existing impellers. Fig. 3640-3643 (2017). In this paper, a systematic numerical study was carried out of the aerodynamic characteristics of the existing impellers. The performance-related parameters, that is, shaft power, output power, and total-to-total efficiency, for the impeller flow field are as follows:ShaftPWR=imp⋅,(4)ImpPWRout=Δimp⋅,(5)imp=ImpPWRout,ShaftPWR(6) The lift-side static and total pressures, along with their efficiencies are also tabulated. Although a drop of 2.14% in total head for the latter impeller occurred, the efficiency was maintained. 10, pp. The objective of the present study is to optimise the blade geometry, viz. References [9–12] provide additional details. For CFD simulation, it is needed to have a closed watertight model (sometimes called waterproof, or model negative, or wet surface) of … for determining performance of a centrifugal … (ii) The shroud gap between the bellmouth and the shroud carries less than 1% of the inflow back from the volute to the impeller for the current fans. Figure 16 shows the effects of the total pressure generated and the efficiency when changing the impeller width for the 11-bladed B#2 (B#2-11) impeller and the NEW impeller. Performance of the impellers was compared based on inlet and outlet power, impeller efficiency, pressure distribution, and static head pressure produced. Velocity and pressure distribution were analyzed for the modified impellers. Meanwhile, the prediction accuracies of three surrogate models, namely, Response surface model (RSM), Kriging model, and Radial basis neural network (RBNN), were compared. In summary, the NEW impeller improves fan efficiency by 1.2 percentage points and reduces power by 5.8%. Balancing holes in single-suction centrifugal pumps are generally applied to attenuate the axial thrust caused by a pressure difference between the front side of a shroud and the rear side of a hub of an impeller. The simulation on vane profile was solved by Navier-Stokes equations with modified K-turbulence model in the impeller. This suggests that conventional design methods such as a streamline curvature or an inviscid calculation method would be inadequate in addressing any aerodynamic improvements to the existing impellers. The NEW impeller has achieved twice the amount of power reduction from the baseline B#1 impeller and agrees well with the CFD predictions shown in the last section. Pumps are the heart of any flow system. The pressure increases gradually from impeller inlet to impeller outlet. For the incompressible flow calculation, a uniform inflow condition was imposed at the bellmouth inlet to maintain the required flow rate and a mass-averaged back pressure was applied at the impeller exit. Impeller design is the most significant factor for determining performance of a centrifugal pump. The optimization improves the impeller efficiency from 92.6% to 93.7%. The CFD predictions suggest that a Reynolds number effect exists between the model- and full-scale fans. [Online]. (9) In addition to the baseline impeller, there is an existing reference impeller (named the B#2 impeller) which provides further performance comparisons in reference to the baseline. The developed redesign procedures established based on the findings from the assessment of the existing impellers are herewith provided below. A blade leading-edge extension and sweep into the shroud turning area prevents the air from separating from the shroud surface and improves the impeller’s efficiency. Subsequently, a piecemeal approach was taken in the redesign effort and the hub, shroud, and bellmouth as well as the impeller blades were redesigned to improve the performance of the fan system. Since flow separations at the shroud in front of the blade leading edges were predicted for the two existing impellers, further improvement in impeller performance would require reducing this shroud flow separation. Derived from the B#2 blading, a nearly linear performance was identified for the predicted shaft power (shown in [13]) and total head. the speed of rotation was set at 1150 rpm. L. Bachus and A. Custodio, "Know and understand centrifugal pumps", The interaction between the impeller and its associated volute can significantly alter the performance of the impeller. This allows the 14-bladed baseline B#1 impeller to be redesigned as the 11-bladed NEW impeller. Sign up here as a reviewer to help fast-track new submissions. International Journal of Rotating Machinery, Distance parameter used in defining the optimization objective function shown in  (, Fan tip speed (141.77 m/s@design condition), K. A. Kaupert and T. Staubli, “The unsteady pressure field in a high specific speed centrifugal pump impeller—part I: influence of the volute,”, K. Hillewaert and R. A. All rights reserved. (iv) The comparisons between the CFD predictions and measurements confirm that the existing fan was overpowered at design, which enabled a new impeller design with a lower power requirement. The continuity and Navier-Stokes equations with the k-e turbulence model and the standard wall functions were, Join ResearchGate to discover and stay up-to-date with the latest research from leading experts in, Access scientific knowledge from anywhere. The baseline volute shown in Figure 3 is connected to the impeller with a sudden expansion in the flow path area. Design optimization of a centrifugal pump impeller and volute using computational fluid dynamics J H Kim1,2, K T Oh1, K B Pyun1, C K Kim1, Y S Choi2 and J Y Yoon3 1Department of Mechanical Engineering, Hanyang University, 17 Haengdang-dong The efficiency predicted under the design flow rate was selected as the objective function. The obtainable overall efficiency correlates to specific speed and to the size and the type of the impeller as well as to special design features like bypass installations and auxiliary aggregates. and tear, or the pump is damaged from the fl. Similar reductions were predicted for the B#1 and B#2 impellers, that is, from 93% to 88%. Park, “A study of impeller-diffuser-volute interaction in centrifugal fan,”, A. Atif, S. Benmansour, and G. Bois, “Numerical investigation of velocity flow field inside an impeller air model of a centrifugal pump with vaned diffuser interactions and comparison with PIV measurements,”, K. V. Karanth and N. Y. Sharma, “CFD analysis on the effect of radial gap on impeller-diffuser flow interaction as well as on the flow characteristics of a centrifugal fan,”, M. E. Slipper, P. J. McGinnis, G. Choi et al., “Design and evaluation of high performance lift fan models for the landing craft, air cushion (LCAC),”, A. Hosangadi, R. A. Lee, B. J. York, N. Sinha, and S. M. Dash, “Upwind unstructured scheme for three-dimensiona combusting flows,”, A. Hosangadi, R. A. Lee, P. A. Cavallo, N. Sinha, and B. J. York, “Hybrid, viscous, unstructured mesh solver for propulsive applications,” in. pump efficiency increased by 2.23%. The GA uses the traditional selection, crossover, and mutation operators, whose implementation details are provided in [14]. Graph of Pressure vs Impeller Rotation Speed, Impeller Power and Efficiency Calculation, Table 4 below shows the power at the inlet and outlet of the impellers, and the, with 24.67m of static head. Although the calculated static pressures are all higher than the required lift-side discharge pressure (/ref>1), the air static pressures at the lift side for both NEW and B#2 impellers are lower than that of the B#1 impeller. The grid topology used for the impeller design calculation shown in Figure 5 was maintained. Impeller B#2 was used to investigate the grid density requirement. Computational Fluid Dynamics is most commonly used tool for simulation and analysis. The profile labelled with 0.0263 (local radius of curvature/D) corresponds to the B#2 impeller. The purpose of this paper is to identify /observe and determine the pattern of pressure distribution by using CFD simulation, Blade thickness and blade height are the most influencing parameters on the performance of pump. Table 1and Figure 3show the main specifications and forms of the two optimized design impellers (OPT1 and OPT2), and a baseeline impeller, respectively. K. Schoenheit, "Detecting Pump Cavitation", Modern Pumping Today® The MS CFD predictions agree well with the model test data for both B#1 and NEW impellers, particularly the rise and fall for the NEW impeller. Side View of Pressure Distribution at 2500, Fig. Figure 4 shows the assembly of the bellmouth and impeller for one half of the fan. Both existing impeller's blades were primarily 2D blades, that is, the leading and trailing edges at hub and shroud started at the same radii. This paper presents the use of state-of-the-art reliability techniques to develop efficient structural design guidelines for civil engineering structures in a manner that includes overall structural system effects. Tabular data provided in Table 3 for the B#2 and NEW impellers also indicate the shaft powers are reduced by 6.0% and 8.7%, respectively, as compared to the B#1 impeller. In other words, the B#2 and NEW impellers reduce the shaft power by 2.2% and 8.8%, respectively, in comparison with the B#1 impeller. Fan Parts-Impeller Design The centrifugal fans impeller have five basic blade shapes, and a number of impeller configurations (i.e) DWDI (Double width double inlet) or SWSI (Single width single inlet). The 2D blade cross-section design described in the previous section was performed in a relatively conservative manner due to an “unknown” coupling effect from the downstream volute. The grids were then passed to CRUNCH CFD and the performance of the altered designs was evaluated. After the final 3D modification, the fitness and efficiency are further improved from those obtained for the 2D blade design by GA. Therefore, the design can be. As a consequence, the pressure rise was determined from the difference between the inlet and exit pressures and is a function of the impeller design. Impeller design is the most significant factor for determining performance of a centrifugal pump. fluid dynamics (CFD) has been used. Centrifugal pump usage has increased over the past year due to its importance and efficiency. This rise in pressure does not occur for the other two impellers. (ii)The flow turning area from the axial to the radial direction in front of the blade leading edge is required to be adequately designed to avoid the shroud flow separation. It is very difficult and complex to analyze the hydraulic performance and characteristics of a centrifugal pump. The impeller-only calculations for the baseline B#1 impeller and the reference B#2 impeller indicate that the total efficiencies of both existing impellers are high (above 92%). This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ANSYS CFX (ver.14.0). Comparisons shown in Figure 21 include the original design required pressure rise, model test data, and CFD predictions for the full-scale (FS) and model-scale (MS) fans. The volute losses (column “Loss”) at the lift side were estimated by subtracting the lift-side total pressure from the impeller head (del_Pt). The deformation was performed on a 2D airfoil shape and maintained along the spanwise direction. However, the limited compression ratio of the pumps limits the achievable ultimate pressure, Design and Analysis of Centrifugal Pump Impeller using ANSYS FLUENT. The steer blade-1 was considered too aggressive in meeting the requirement; therefore, the more conservative steer blade was chosen for further investigation. The process is accomplished by convergence of key quantities such as the total pressures and mass flow rates at the impeller inlet, interface, and volute outlets. Van Den Braembussche, “Numerical simulation of impeller-volute interaction in centrifugal compressors,”, Y. T. Lee and T. W. Bein, “Performance evaluation of an air-conditioning compressor—part II: volute flow predictions,”, T. Meakhail and S. O. (v)The width of the impeller is almost linearly related to the impeller total head generated. A schematic of the design optimization framework is shown in Figure 10. program after the 3D design and modeling of the pump is made using CATIAV5 basically , this paper revolves around the idea of investigating the effect and distribution of pressure in pump. It computes the entire (all blades included) impeller steady flow field in the rotational frame and converts the flow field information to a stationary frame at an interface near the impeller exit to the downstream volute. Impeller is designed for the head (H) 24 m; discharge (Q) 1.583 L/sec; and speed (N) 2880 rpm. For very high flow coefficients, an axial flow blade design is utilized. In order to analyze the flow, Computation The outlet boundary condition defines, Fig. We are committed to sharing findings related to COVID-19 as quickly as possible. The B#2 and NEW impellers suffer about 0.5% reduction in fan efficiency due to the gap-affected impeller exit flow [17] into the volute which induces impeller blade trailing-edge flow recirculation, as shown in Figure 19. A detailed study was also carried out of the coupled impeller-volute system. However, the majority of the prior related investigations in the literature dealt with centrifugal impellers and single discharge volutes. Impeller width is defined in Figure 9 as the distance between the backplate and the shroud. The steering process and 3D blade construction is discussed in the following sections. This allows the 14-bladed baseline B#1 impeller to be redesigned as the 11-bladed NEW impeller. For the B#1 impeller, a sudden pressure rise exists near the design condition. The numerical simulation can be used to detect the cavitation in centrifugal pump and to get safe range of operating at different flow rate and rotating speed. In this study, Computational Fluid Dynamics (CFD) approach was suggested to investigate the flow in the centrifugal pump impeller using the SolidWorks Flow Simulation (SWFS). Fan performance data obtained from impeller/volute coupling CFD. Refined CFD calculations coupling the impeller, the volute, and the shroud gap that were used to assess the design and quantify the volute feedback to the impeller performance are discussed after the design procedure. Experiential steering was used to alter the optimized two-dimensional blade profile into a three-dimensional swept blade that further enhanced the performance of the impeller. Y. T. Lee, L. Mulvihill, R. Coleman et al., “LCAC lift fan redesign and CFD evaluation,”, Y. T. Lee, V. Ahuja, A. Hosangadi, and M. Ebert, “Shape optimization of a multi-element foil using an evolutionary algorithm,”, S. Kim, J. By integrating all of the above findings, which include the effects from the hub and bellmouth/shroud design, the 2D blade profile optimization, the steering of blade shape, the 3D swept blade design, and the impeller width control, an assembled impeller is shown in Figure 17 with eleven 3D blades. CFD prediction results were also made for the 11-bladed B#2 impeller, which was constructed based on the 12-bladed impeller to maintain a constant throat area, that is, at the location with the maximum blade thickness. For the impeller-flow calculation, all boundary conditions used for the CFD design calculations were maintained except for eliminating the periodic boundary condition and controlling the exit back pressure through the interface information exchange. It is interesting to note that the B#2 impeller now requires less shaft power (0.8%) than the B#1 impeller. As a result, the performance of the impeller increases as the efficiency increases. AIAA-91-1548, 1991. In Figure 12, the impeller total head generated and efficiency associated with each blade design during the 6 generation calculations are plotted in black diamond symbols versus the shaft power. 1st ed. rate (Q) 5000 LPH, Head (H) 28-26 m, speed 6000 rpm. The impeller torque was calculated by integrating the forces from the blade, hub, shroud, and backplate. In addition, the period of the design phase was limited. Figure 8 shows similar flow traces for impeller B#2’s surfaces. This reduction in power agrees with the 8.7% reduction obtained from the CFD predictions. T. J. Barth and S. W. Linton, “An unstructured mesh newton solution for compressible fluid flow and its parallel implementation,” Paper No. The objective of the GA was to measure the distance from a target ShaftPWR and output power, that is,obj=(ShaftPWR−581)2+ImpPWRout−5522PWRref. CFD predictions were validated with the measurements. Probabilistic design is done by explicitly accounting for the uncertainties in the different variables and their influence on structural performance. It can also be observed that the efficiency of the impeller increases as the rotation speed increases. Isometric View of Fixed Boundary Condition. points were set at the impeller-volute coupling interface, inlet and outlet faces of the pump. A total drop of five to six percentage points in the impeller efficiency with the volute feedback is considered. The measured power reduction for the new impeller is 8.8% lower than the baseline. CFD simulation makes it possible to visualize the flow condition inside centrifugal pump. The ONR Program Manager was Dr. Ki-Han Kim. The CFD calculations for evaluating the fan performance were performed using a frozen impeller approach to compute the steady flows throughout the impeller and the volute. The large curvature of the shroud as it approaches the blade may be partially responsible for the flow separation seen at the shroud due to the difficulty of the boundary layer to remain attached as the flow negotiates the turn near the shroud. This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. Side View of Pressure Distribution at 1750. the speed of rotation was set at 2500 rpm. This reduction in power agrees with the 8.7% reduction obtained from the CFD predictions. The CRUNCH CFD code employs a multielement, cell-vertex-based unstructured framework which allows for a combination of tetrahedral, prismatic, and hexahedral cells. The design of the lift fan system is subject to meet payload, machinery spacing, and ruggedness requirements [1]. International Journal of Research in Engineering and Technology, vol. Here, we outline some basics about the pump and follow that up with the simple steps used in the design process. The objective function was set to compare impeller B#1’s performance data of 603.3 and 558.5 kWs, which has an impeller efficiency of 92.6% as described previously. The performance of the pump was first determined using the existing number of the blades Surrogate model based shape optimization methodology to enhance performance of a centrifugal pump has been implemented in this work. 14. It is an extension of derivative and integral calculus, and uses very large matrix arrays and mesh diagrams to calculate stress points, movement of loads and forces, and other basic physical behaviors. 11. Lee and Bein [4] also applied steady CFD calculations to a centrifugal refrigerant compressor with an impeller, a vaneless diffuser, and a single discharge volute and obtained a good agreement in volute circumferential pressure with the measurements, particularly the pressure dip at the volute tongue. For the volute-flow calculation, the mass-averaged discharge pressures from the two exits are prescribed to keep (a) the required flow to the lift side, (b) the extended surface from the impeller backplate modelled as a symmetry plane, (c) the shroud as the rotating wall, and (d) all other casing surfaces as no-slip walls. This may have been caused by the unstable gap-flow solution using the current steady calculation procedure. finite element analysis, structural analysis, computational, calculation of the simulations faster, more accurate and more efficient [12. It also reduces fan efficiency by 0.5%. Both fans with the existing impellers and the fan system with the redesigned impeller were tested to verify improvement in performance. The present paper describes the head, power, efficiency and to evaluate the pump performance using the ANSYS CFX-14, a computational fluid dynamics simulation tool. For example, Kaupert and Staubli [2] recorded strong blade loading fluctuations as the blade passed the volute tongues on a double spiral volute, particularly at below design flow rates. Impeller using ANSYS FLUENT", International Journal of Science, A refined CFD assessment of the impeller/volute coupling and the gap between the stationary duct and the rotating shroud revealed a reduction in efficiency due to the volute and the gap. Figure 2 – Centrifugal Blower Design with Airfoil Impeller Arrangement in AxSTREAM Perhaps the most important centrifugal fan impeller orientation, the backward orientation, comes in three standard shapes: backward inclined, backward curved, and backward inclined aerofoil (or airfoil). The impeller blade passing frequency and impeller rotational frequency were the dominant frequency at different positions, where the dominant frequency of the impeller-volute coupling interface was nearly equal to the impeller rotational frequency, and that at the inlet and outlet face were nearly equal to the impeller blade passing frequency. The present effort utilized a numerical optimization with experiential steering techniques to redesign the fan blades, inlet duct, and shroud of the impeller. http://www.modernpumpingtoday.com/detecting-pu. The measured lift-side static pressure coefficient versus the lift-side flow coefficient is plotted in Figure 21 for the three impellers. The impeller design will depend on the aerodynamic duty and the operating conditions. Based on this concept, the B#2 11-bladed impeller blades were extended inward radially at the leading edge and its angle measured from the shroud was modified from 0 degree for a 2D blade like the B#1 blade to 10 degrees. 9. At the design point, 57% of the fan air flows through the lift diffuser to maintain the required lift pressure. The widths for the two existing impellers shown in Figure 2 are 0.1207 D and 0.1350 D, respectively. This blade shape generated a total head of 1.459 ref at 93.68% efficiency and requires a shaft power of 0.926 PWRref. The final unconventional 2D design from the GA design iteration is shown in Figure 14. As a result, system factors are developed for inclusion in structural design, Nongye Jixie Xuebao/Transactions of the Chinese Society of Agricultural Machinery. Reference [16] provides further details for the effects of the gap on the impeller aerodynamics. The fitness plot in Figure 13 is an inverse measurement of the defined objective function shown in (7). Two cases were considered for this study: impeller, and combined impeller and diffuser. For this case, the targeted ShaftPWR and output power were set at 581 and 552 kWs, respectively. Pressure Distribution of Centrifugal Pump Impelle, Figure 9 and 10 show the overall pressure distribution of the. The width for the NEW impeller was chosen to be 0.1213 D. In order to evaluate the fan performance, it is necessary to include the volute with each impeller. The uncertainty of the measured pressure was estimated to be within 0.25% [8] at design conditions. Since the impeller width plays an essential role in the impeller performance, a wider width impeller was generated for comparison and is labelled as the NEW-w impeller. This Reynolds number effect is larger for the existing impellers as compared to the new impeller. The unstructured cells help to reduce the overall size of the grid thereby reducing turnaround time for the calculations. In the following sections, we provide details of the strategy and methodology for redesigning the impeller using the impeller-only CFD calculations. 2.0). The conditions at the interface serve as information exchange between the impeller and the volute and are obtained as a part of the solution. A variety of different techniques were utilized in the redesign process: for example, the hub was modified by streamline tracing; the bellmouth/shroud was modified by altering the local curvature near the blade whereas a formal genetic algorithm- (GA-) based optimization procedure was used to redesign the blade profile. Given the impeller diameter and the flow rate, this parameter controls the maximum achievable flow velocity. pump operation hugely depends on a large number of interdependent variables. This Reynolds number effect is larger for the existing impellers as compared to the new impeller. The width of the NEW impeller is determined by starting with the B#2 impeller width. This paper provides some brief guidelines for determining the nature of and solution to specific pump problems. A properly designed impeller optimizes flow while minimizing turbulence and maximizing efficiency. A centrifugal pump is common in process plants, usually in large numbers. Since the DDV is a structural constraint and required to be maintained in its shape, the baseline impeller and a dual bellmouth (or inlet duct) assembly are therefore redesigned to improve the fan performance. Table 1 compares the predicted power, the impeller (total) head, and the efficiency between the two impellers. The measured power reduction for the new impeller is 8.8% lower than the baseline. [15]. Create a centrifugal pump of outer volute radius 0.045m, the impeller of 0.04m radius, and an eye of 0.02m radius with the number of impeller vanes = 6. The fluid flow passage can be optimised by the blade thickness. In particular, both impellers were susceptible to flow separations near the leading edge of the blade and near the shroud region where the hub transitioned into the common backplate for the impeller system. Conversely, for a fixed impeller width, altering the blade geometry can play an important role in lowering shaft power and increasing impeller efficiency. The current low-specific-speed (≈0.2) baseline lift-fan impeller (named the B#1 impeller in the present paper) shown in Figure 1 is fitted with a double-discharge volute (DDV) shown in Figure 2 to provide air for both cushion lift and thrust vectoring. The impeller design package includes a geometry modelli procedure, aerodynamic analysis, stress analysis, and the direct generation of data for … The shaft power was calculated using (4) while imp was obtained by integrating the torque from all the impeller blades. The most centrifugal pump has a single suction design. In order to effectively manage the craft fuel consumption, a reduction in fan’s operating power is necessary. Fan efficiency is further reduced to the 74–78% range by including the volute losses. Copyright © 2011 Yu-Tai Lee et al. When the volute was coupled with the impeller, the impeller efficiency for the NEW impeller dropped from the impeller-design prediction of 95.5% to 89%. CFD predictions shown in Figure 21 for the FS and MS fans clearly demonstrate the Re effect, which is larger for the B#1 and B#2 impellers than the NEW impeller. It also occurs at the blade suction side of the tip trailing edge. A double-inlet, double-width impeller was modified to fit into a baseline double-discharge volute for a centrifugal fan. Finally, the internal flow fields were analyzed to understand the mechanism of efficiency improvement. Front View of Pressure Distribution at 1, Fig. Park, K. Ahn, and J. Baek, “Improvement of the performance of a centrifugal compressor by modifying the volute inlet,”, Y. T. Lee, “Impact of fan gap flow on the centrifugal impeller aerodynamics,”, A. Hildebrandt and M. Genrup, “Numerical investigation of the effect of different back sweep angle and exducer width on the impeller outlet flow pattern of a centrifugal compressor with vaneless diffuser,”. The fan output power and the total-to-total efficiency were calculated using the following formulae:FanPWRout=Δlift⋅lift+Δthruster⋅Qthruster,(8)fan=FanPWRoutShaftPWR. (RANS) equations with standard SST (Shear Stress Transport) turbulence models. The design modification was completed by decoupling the impeller from the volute.

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