The ONR Program Manager was Dr. Ki-Han Kim. Centrifugal pumps are a most commonly used in different fields like industries, agriculture and domestic applications. Fig. We utilized a mathematical function that was a combination of a target efficiency (95%) and a target power requirement as an objective function. This allows the 14-bladed baseline B#1 impeller to be redesigned as the 11-bladed NEW impeller. Proceedings of the IASTED International Conference on Modelling, Simulation and Optimatization. This approach has been used to develop a set of load and resistance factors instead of just a single safety factor to address all the uncertainties. Two cases were considered for this study: impeller, and combined impeller and diffuser. The RSF model predicted the highest efficiency, while the RBNN had the highest prediction accuracy. (RANS) equations with standard SST (Shear Stress Transport) turbulence models. Figure 7 shows the predicted flow pattern through impeller B#1’s surfaces. The critical flow separation affecting performance happens at the shroud near the blade leading edge. (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. This procedure essentially improves the blade efficiency. The CFD predictions suggest that a Reynolds number effect exists between the model- and full-scale fans. Probabilistic design is done by explicitly accounting for the uncertainties in the different variables and their influence on structural performance. At the design point, 57% of the fan air flows through the lift diffuser to maintain the required lift pressure. The goal was to reduce power consumption while maintaining a specified output pressure at the lift-side volute exit. The use of streamline curvature or potential-flow/Euler codes would not accomplish the goals for the current redesign effort. A centrifugal pump is common in process plants, usually in large numbers. Fan efficiency is further reduced to the 74–78% range by including the volute losses. Centrifugal pump usage has increased over the past year due to its importance and efficiency. Additionally, It is very difficult and complex to analyze the hydraulic performance and characteristics of a centrifugal pump. 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. However, the impeller efficiency remains nearly constant while the width changes. This rise in pressure does not occur for the other two impellers. This reduction in power agrees with the 8.7% reduction obtained from the CFD predictions. Design and simulation were conducted using ANSYS CFX, using the Navier-Stokes equation. 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) Lastly, a rigorous design validation study was undertaken with a carefully designed test rig for the 1/5 scale model. 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%. The optimization improves the impeller efficiency from 92.6% to 93.7%. 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. as the operation phase, thus reducing the cost of maintenance. where lift, ()lift, , , and are defined as the lift flow rate, fan lift discharge static pressure, fan tip diameter, fan tip speed, and air density, respectively. Fan performance data obtained from impeller/volute coupling CFD with the shroud gap. Introduction Radial flow centrifugal pumps are widely used where M. Ajith and D. M Issa, "Design and Analysis of Centrifugal Pump Impeller using ANSYS FLUENT", International Journal of Science, Engineering and … 12. Also shown in Figure 16 is the performance data from the B#1 and B#2 impellers. Problems arise, and diagnosing pump problems is a difficult and often confusing process. 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. The grids were then passed to CRUNCH CFD and the performance of the altered designs was evaluated. The stress pattern due to centrifugal force is highly complex in back sheet, shroud and blades of the impeller. 15. the Design of Radial Flow Pump Impeller through CFD Analysis. Before the diffused fluid started separating at the hub while the impeller width was increased, Kim et al. Further the impeller was analyzed for both forward and backward curved vane. Centrifugal Pump Impeller An impeller is a wheel or rotor with a series of backward curved blades or vanes. Centrifugal fans use the kinetic energy of the impellersto increase the volume of the air stream, which in turn moves against the resistance caused by ducts, dampers and other components. Three basic types of impellers: open, semi-open, closed Impeller design is the most significant factor for determining performance of a centrifugal pump. It represents the blade trailing-edge span with the shroud terminating at the blade trailing edge. The significance of the feedback depends, however, on each individual design configuration. Similar reductions were predicted for the B#1 and B#2 impellers, that is, from 93% to 88%. centrifugal pump impeller. As a resuLt , the head curve of the impeIler by thls design methodsatisfied adesign point , and pump e 館 ciency was over 62 % more than conventjorlal single 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. Since impeller B#2’s blade performs better than the B#1 impeller as shown in the last section, the B#2 blade shape was used as the starting geometry and all changes to the blade shapes were made through a network of Bezier curves. 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. The impeller flow field is unsteady and periodic due to the interaction between each blade and the asymmetric volute casing (Figure 2), particularly at the two tongue locations. 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. 7. Hillewaert and Van den Braembussche [3] used numerical predictions of the 3D unsteady inviscid impeller flow interacting with the steady volute flow in centrifugal compressors at off-design conditions and found reasonable agreements with measurements. 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. 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. Side View of Pressure Distribution at 2500, Fig. 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. 2.0). Furthermore the deformation was propagated to the grid points of the CFD grid associated with the newly deformed blade shape within SCULPTOR. Keyword: CFD, Design, Impeller, Pump, Radial Flow, Vane. References [9–12] provide additional details. design a radial type vane profile based on the fundamental understanding of published procedures. The new 3D blade generated high head of 1.548 ref versus 1.471 ref with a higher efficiency of 95.08% versus 93.66% at the expense of a higher shaft power of 0.968 PWRref versus 0.936 PWRref. A schematic of the design optimization framework is shown in Figure 10. 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,”. Kim, J, Choi, J, & Kim, K. "Design Optimization of a Centrifugal Compressor Impeller Using Radial Basis Neural Network Method." New to this edition: examples and applications in Matlab, Ansys, and Abaqus; structured problem solving approach in all worked examples; new discussions throughout, including the direct method of deriving finite element equations, use of strong and weak form formulations, complete treatment of dynamic analysis, and detailed analysis of heat transfer problems; more examples and exercises; and, all figures revised and redrawn for clarity. 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. Pumps are the heart of any flow system. For the B#1 impeller, a sudden pressure rise exists near the design condition. The computational resources from the Naval Oceanographic Office Major Shared Resource Center (NAVOCEANO MSRC) were provided through the DoD High Performance Computing Modernization Program (HPCMP). (v)The width of the impeller is almost linearly related to the impeller total head generated. 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. and then, the number of blades has been varied to analyze the pump’s performance. 10. This may have been caused by the unstable gap-flow solution using the current steady calculation procedure. and compared among the three impellers. The blade shapes were defined by a complex network control points which form an arbitrary shape deformation (ASD) grid (Figure 11(a)) that was generated utilizing the SCULPTOR tool. finite element analysis, structural analysis, computational, calculation of the simulations faster, more accurate and more efficient [12. All these aforementioned studies mostly with a single discharge volute indicate a volute feedback to the impeller aerodynamics exists, particularly at the volute tongue location. The LNG centrifugal compressors typically use a combination of 2D and 3D impellers. For model Reynolds number (Re) to be similar to the full-scale value, the model test would ideally be run at 5-times the full-scale speed of 1692 rpm. 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. excess vibration, excess noise and heat, leakage, mechanical seal failure, occurs if the pressure of fluid falls below the vapour pressure, This will cause the vibration and n, entrance angle which are related to the velocity of the fluid, Design and Analysis of Centrifugal Pump Impeller. In addition, a computational method accounting for all the aerodynamic losses is required. The objective of the present study is to optimise the blade geometry, viz. This verifies the conclusion obtained in the previous section and confirms the feasibility of further reducing power consumption. order to proceed with the flow simulation in ANSYS CFX. The NEW impeller has the smallest performance variation in almost all the parameters predicted, particularly for the volute losses as pointed out previously. The flow field formulation was implemented within a 3D unstructured code CRUNCH. 10, pp. Yu-Tai Lee, Vineet Ahuja, Ashvin Hosangadi, Michael E. Slipper, Lawrence P. Mulvihill, Roger Birkbeck, Roderick M. Coleman, "Impeller Design of a Centrifugal Fan with Blade Optimization", International Journal of Rotating Machinery, vol. 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 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. The profile labelled with 0.0263 (local radius of curvature/D) corresponds to the B#2 impeller. Conventionally, design optimization can be carried out for such a problem by either performing a multiobjective optimization or by using constraints to limit the shaft power and to maximize the output power. Although the inlet was controlled with a velocity condition, the inlet pressure was predicted as part of the simulation since the pressure pertains to the upstream propagating characteristic. The test data of the lift-side pressure rise for the existing and new impellers agrees well with the CFD predictions based on the model Reynolds number. The standard high Reynolds number formulation of the - equations forms the basis for the turbulence modelling in CRUNCH. (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. Three-dimensional, steady-state flow equations are solved in ANSYS CFX along with Reynolds-Averaged Naiver- Stokes. The results show that for the optimized value, In this paper, a systematic numerical study was carried out of the aerodynamic characteristics of the existing impellers. To accurately capture the boundary layer and loading on the blade surface, the grid on the blade portion is structured and all other surfaces are either structured or unstructured as shown in Figure 5. 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. The two main components of a centrifugal blower are the impeller and the casing. Figure 6 shows the computed percent change in ShaftPWR versus the design power with the number of cells for the structured and unstructured grids ranging from 105,984 to 958,464 cells. Following that we provide details of the model-scale fan test [8] and comparisons with the coupled CFD predictions at design and off-design conditions. The grouping of control points was implemented in the spanwise direction to ensure that the integrity of the 2D shape was maintained. 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. 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. The NEW impeller reduces shaft power by 5.76% from the baseline. [18], Re based on and should be between 1.0 × 106 for the backward-swept centrifugal fans and 2.0 × 106 for airfoil-bladed centrifugal fans to reach the Re independent regime. The dominant frequency at the same monitor point was constant but with different amplitude at different operating conditions, the pressure fluctuation at the coupling interface had a lower strength at the position where far away from the volute tongue. 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. and tear, or the pump is damaged from the fl. In order to establish a design strategy within a constrained design window, two existing impellers B#1 and B#2 were first analyzed with a second-order accurate CFD method which solves a full compressible form of the Navier Stokes equations with preconditioning to obtain an efficient time-marching numerical scheme [9] for the incompressible flow. Figure 4 shows the assembly of the bellmouth and impeller for one half of the fan. Each impeller blade row has backward-swept blades mounted between a common back plate and shrouds.
2020 centrifugal impeller design