Impeller Flow Research Articles

Математическое моделирование течения в рабочем колесе вентилятора с меридиональным ускорением

The article considers a comparison of the methods for simulating the flow in the fan impeller with the meridional acceleration of the flow. The aim of this work is to compare the results of flow simulation obtained using the method of calculating the flow along axisymmetric current surfaces with variable thickness in relative motion with the solution obtained by the CFD method. The discrepancy between the results of determining the pressure for the test problem --- the flow in an elementary blade row is not exceeded 2 % with a continuous flow. The resulting distribution of velocity along the contour of the blade makes it possible to proceed to the calculation of the boundary layer on its surface and to take into account the profile losses in the rotor, as well as to clarify the location of the trailing points on the profile. The presented work shows the possibility of using the method of calculating the flow along axisymmetric current surfaces with variable thickness for profiling axial fans with meridional flow acceleration. The rotor was profiled using the method described in the article and a CFD calculation was performed, which confirmed the theoretical head coefficient Ht = 0.68 laid down during profiling at a given flow rate ca1 = 0.5, the total efficiency in the rotor was η∗f.i = 0.93

Particle image velocimetry in a centrifugal pump: Details of the fluid flow at different operation conditions

Centrifugal pumps are present in the daily life of human beings. They are essential to several industrial processes that transport single- and multi-phase flows with the presence of water, gases, and emulsions, for example. When pumping low-viscous liquids, the flow behavior in impellers and diffusers may affect the centrifugal pump performance. For these flows, complex structures promote instabilities and inefficiencies that may represent a waste of energetic and financial resources. In this context, this paper aims at characterizing single-phase water flows in one complete stage of a centrifugal pump to improve our understanding of the relationship between flow behavior and pump performance. For that, a transparent pump prototype was designed, manufactured and installed in a test facility, and experiments using particle image velocimetry (PIV) were conducted at different conditions. The acquired images were then processed to obtain instantaneous flow fields, from which the flow characteristics were determined. Our results indicate that the flow morphology depends on the rotational speed of the impeller and water flow rate: (i) the flow is uniform when the pump works at the best efficiency point (BEP), with streamlines aligned with the blades, and low vorticity and turbulence in the impeller; (ii) the velocity field becomes complex as the pump begins to operate at off-design conditions, away from BEP. In this case, velocity fluctuations and energy losses due to turbulence increase to higher numbers. Those results bring new insights into the problem, helping validate numerical simulations, propose mathematical models, and improve the design of new impellers.

Unsteady flow and pressure pulsation characteristics in centrifugal pump based on dynamic mode decomposition method

Considering the computing accuracy and resources of numerical calculation, a hybrid Reynolds-averaged Navier–Stokes/large-eddy simulations method based on the von Kármán scale and the corrected eddy viscosity has been used to study the unsteady flow structure and pressure pulsation characteristics in a centrifugal pump. The unsteady flow characteristics of the vertical two-stage marine centrifugal pumps with complex structure have been studied. The dynamic mode decomposition method is used to study the internal unsteady flow structure and analyze the mechanism of pressure pulsation in the centrifugal pump. The results show that the unstable flow in impeller is mainly affected by the inflow state, system rotation, and the structure of the impeller. Different inflow states lead to obvious differences of the internal flow states and unsteady flow structures between the first-stage and second-stage impellers. There are complex pressure pulsation characteristics dominated by different frequencies in different parts of a two-stage centrifugal pump. The impeller blade main pass frequency has different causes at different locations in the downstream flow passages. The mutual matching of different numbers of impeller blades and guide vane blades will result in a kind of impeller guide vane blade interaction frequency in guide vane and volute, which will excite higher harmonics of the impeller blade frequency. Other important characteristic frequencies in centrifugal pumps had been analyzed. The pressure pulsation mechanism analysis of the centrifugal pump will help researchers to optimize the design of the centrifugal pump and improve the operation stability of the centrifugal pump. Some possible improvement measures for typical frequency pressure pulsation are recommended.

Using Tip Injection to Stability Enhancement of a Transonic Centrifugal Impeller with Inlet Distortion

This paper aims to understand the effects of circumferential inlet distortion and tip injection on a transonic impeller performance and flow field. For distorted inflow, the impeller is subjected to a stationary 120-degrees circumferential total pressure distortion. Full annulus unsteady three-dimensional analysis has been used to study the inlet distortion and tip injection effects on the impeller performance, stability and flow field. The results show that the circumferential inlet distortion reduces the impeller total pressure ratio and adiabatic efficiency; however, it has no significant impact on the safe operating range. Unlike the inlet distortion, the tip injection considerably increases the operating range. According to the results, the distortion and tip injection effect on the compressor performance is mainly due to changes in tip leakage flow. The inlet distortion has unfavorable influences on the flow field, especially near the impeller tip; however, the tip injection ameliorates the flow field in this region. In both the clean and distorted inflow, the tip injection causes downstream shock transmission, weakening the shock-tip leakage interaction. Hence, stall inception is postponed, and the impeller stability is improved in the presence of the tip injection.

Transient Characteristics of Three-Dimensional Flow in a Centrifugal Impeller Perturbed by Simple Pre-Swirl Inflow

The pre-swirl inflow generated by guide vanes could improve the hydrodynamic performances of centrifugal pumps as long as the inflow matches the patterns of internal flow of the impeller. In this work, we present a numerical investigation on the internal flow in a centrifugal impeller subjected to inflow artificially constructed with simple pre-swirling; unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations are performed at the designed flow rate with five values of rotating velocity of the inflow, i.e., Urot/Uref = −0.5, −0.3, 0.0, 0.3 and 0.5, where Urot and Uref denote the rotating and normal velocity component at the entrance of the inflow tube, respectively. The primary objective of this work is to reveal the three-dimensional characteristics of internal flow of the impeller as influenced by the superimposed pre-swirl inflow, and to identify the propagation of inflow within the impeller. The numerical data are presented and analyzed in terms of the streamline fields, the distributions of various velocity components along the circumferential and axial directions, the pressure distribution and limiting streamlines on the surfaces of a blade. Numerical results reveal that separation occurs around the leading edge of the blades and occasionally at the trailing edge, and the internal flow is more uniform in the central region of the channels. A noticeable fluctuation of both radial and circumferential velocities is observed at the outlet of the impeller as it is subjected to counter-rotating inflow, and the greatest fluctuation is close to the hub instead of the middle channel and shroud as for the co-rotating inflow. The boundary layer flow of suction surface is more sensitive to the inflow; occasional small-scale separation bubble occurs on the suction surface around the leading edge for some blades, and reattachment of separated flow is reduced for the counter-rotating inflow.

Research on pressure pulsation characteristics of a reactor coolant pump in hump region

The reactor coolant pump (RCP) is the machinery used in nuclear power facilities to move coolant. So RCP operation must be safe in order for nuclear power plants to operate reliably. It was discovered throughout the experiment that the flow rate of RCP was unsteady between 0.875 Q0 and 0.85 Q0 and the pressure pulsation increased dramatically. As the flow drops, the head no longer increases, but instead declines. The condition of pump is in the hump region. This research conducts tests to determine the characteristics of pressure pulsation and uses numerical simulation to investigate the causes of increased pressure pulsation. According to the study, when the pump was working in hump region, the amplitude of low-frequency (<fr) pressure pulsation increase dramatically. The impeller's flow separation created vortices, which propagated downstream and caused stalls in the diffuser. The A_RMS of the low-frequency signal increases as a result of this.

Dynamic evolution process of rotating stall vortex based on high-frequency PIV system in centrifugal impeller

Rotating stall is a kind of strong unstable flow phenomenon, which plays a decisive role in stable operation of centrifugal pumps. Limited by the performance of the experimental system, so far there are rare experimental studies on the rotating stall phenomenon in impeller, especially the initial generation and the evolution process of the rotating stall vortex. Based on the experimental bench with refractive index matching and the high-frequency PIV system, the continuous instantaneous velocity fields were visualized in a five-blade impeller. Two kinds of experimental measurement methods were utilized to observe the formation process and study the transmission mechanism of rotating stall vortex between impeller passages. Meanwhile, the Proper Orthogonal Decomposition method is used to smooth the instantaneous velocity field. The results show that the generation of the rotating stall in impeller is a transient process. The flow rate in each passage adjusted quickly when the impeller enters the stall stage, and then the stall vortex moved periodically along the impeller at a certain frequency. Two kinds of frequency characteristics of the stall vortex were clearly observed at stall conditions. The relationship between the evolution frequency of the stall vortex under different impeller speeds and flow rate is reasonably explained.

Computational Fluid Dynamics Model of Continuous-Flow Total Artificial Heart: Right Pump Impeller Design Changes to Improve Biocompatibility.

Cleveland Clinic is developing a continuous-flow total artificial heart (CFTAH). This novel design operates without valves and is suspended both axially and radially through the balancing of the magnetic and hydrodynamic forces. A series of long-term animal studies with no anticoagulation demonstrated good biocompatibility, without any thromboemboli or infarctions in the organs. However, we observed varying degrees of thrombus attached to the right impeller blades following device explant. No thrombus was found attached to the left impeller blades. The goals for this study were: (1) to use computational fluid dynamics (CFD) to gain insight into the differences in the flow fields surrounding both impellers, and (2) to leverage that knowledge in identifying an improved next-generation right impeller design that could reduce the potential for thrombus formation. Transient CFD simulations of the CFTAH at a blood flow rate and impeller rotational speed mimicking in vivo conditions revealed significant blade tip-induced flow separation and clustered regions of low wall shear stress near the right impeller that were not present for the left impeller. Numerous right impeller design variations were modeled, including changes to the impeller cone angle, number of blades, blade pattern, blade shape, and inlet housing design. The preferred, next-generation right impeller design incorporated a steeper cone angle, a primary/splitter blade design similar to the left impeller, and an increased blade curvature to better align the incoming flow with the impeller blade tips. The next-generation impeller design reduced both the extent of low shear regions near the right impeller surface and flow separation from the blade leading edges, while maintaining the desired hydraulic performance of the original CFTAH design.

Numerical study on gas–liquid two phase flow characteristic of multistage electrical submersible pump by using a novel multiple-size group (MUSIG) model

Electrical submersible pumps (ESPs) face enormous challenges in the petroleum industry while handling gas–liquid two-phase flow. The major difficulty is caused by the accumulation of gas bubbles inside ESP-impellers, which results in mild to severe degradation in pump performance. Therefore, to analyze the influence of gas entrainment and bubble size, a combination of experimental and numerical analysis is performed on a five-stage mixed-flow ESP in the present study. The experiments are first conducted to analyze the performance of ESP under pure water conditions at different rotating speeds, followed by the gas–liquid two-phase flow experiments that are performed at constant rotating speed (1475 r/min) and for a wide range of inlet gas void fractions (IGVFs). For numerical calculations, a novel multiple-size group (MUSIG) model is applied in ANSYS CFX to analyze the performance and different flow patterns in ESP in different IGVFs and understand the coalescence and breakup phenomena of gas bubbles in the impeller flow passage. The simulation results from the MUSIG model are compared with the Euler–Euler two-fluid model and test results. The MUSIG model can more accurately predict the changes in the performance and internal flow-field of ESP under two-phase flow conditions. Moreover, when the MUSIG model is used to calculate the two-phase flow of the ESP, the first-stage impeller has a higher head than other stages because the flow inside the second and other stages is affected by the disoriented flow coming from the first-stage diffuser and other return channels. Furthermore, this study gives an insight into the comprehensive application of the novel MUSIG model for complex turbo-machine designs such as ESP.

Investigation of Tip Leakage Vortex Structure and Trajectory in a Centrifugal Pump with a New Omega Vortex Identification Method

Semi-open centrifugal pumps are widely used in various fields. However, the tip leakage vortex (TLV) has a malign effect on the impeller flow field. The structure and trajectory of a TLV under different discharge conditions were simulated and are discussed herein. Then, the characteristics of the TLV were analyzed using a new omega vortex identification method. The external characteristic and pressure fluctuation of the simulation and experiment were consistent. A secondary leakage vortex near the blade outlet was formed under the high-discharge condition. A leading-edge overflow phenomenon under the low-discharge condition and led to the formation of a reverse-flow vortex. The interface between the main flow and tip leakage flow moved toward the impeller upstream with decreased discharge. As a result, the peak of the entropy production curve moved upstream, and leading-edge overflow and reverse flow occurred. The tip leakage flow changed the blade pressure distribution, resulting in a decrease in the blade load.

Probabilistic CFD analysis on the flow field and performance of the FDA centrifugal blood pump

The present study is set out to systematically investigate the combined impact of operational, geometrical, and model uncertainties on the hemodynamics and performance characteristics in the U.S. Food and Drug Administration (FDA) benchmark centrifugal blood pump. Non-intrusive Polynomial Chaos Expansion (NIPCE) has been utilized to propagate the uncertainty of 12 random input variables in the flow field and the performance characteristics of the blood pump at three working conditions. The global sensitivity of the Quantities of Interest (QoI) to the uncertain input parameters was measured through the Sobol’ indices. The Multiple Reference Frames (MRF) approach and the SST k−ω turbulence model were employed to conduct the 3D CFD computations of the pump. In addition, we quantified the device-related hemolysis using the semi-empirical power-law model. The stochastic CFD results of the pump velocity field and hydraulic performance parameters showed a satisfactory agreement with measurements. Statistical analysis indicated that the effect of operational and geometrical uncertainties on the velocity field of the blood pump chiefly emerges at the outlet diffuser region, more specifically along the center-line of the fluid jet formed inside the diffuser. This study has also clarified that the uncertainties in the flow field and the hydraulic performance of the blood pump are mainly due to the variations of impeller diameter, rotational speed, radial clearance, and flow rate. By contrast, the hemolysis index is profoundly affected by the model parameters. Additionally, higher robustness against uncertainties was observed for hydraulic efficiency compared to the pump head. Eventually, it was shown that the maximum value of the distribution function of the relative hemolysis index lies within the bounds of the measurements.

Investigation and Visualization of Flow Fields in Stirred Tank Reactors Using a Fluorescence Tracer Method

AbstractIn this study, flow fields in stirred tank reactors are investigated by a fluorescence tracer method. For these measurements, a fluorescent dye is inserted into a stirred tank reactor and distributed by the impeller flow, following the characteristic main circulation pathways. By this means, the main flow fields can be detected and visualized. Originally developed and used for the investigation of viscoelastic fluids, the method was adapted for Newtonian fluids with low viscosity in this study, with impeller installation height and impeller Reynolds numbers selected as influencing parameters. The resulting flow fields in both single‐ and double‐impeller setups match the known structures from literature excellently. Therefore, the developed fluorescence tracer method has proven to be a promising supplement to the established repertoire of fluid investigation methods, with little effort in both experiment itself as well as the following data analysis steps.

Impact of the inducer meridional length on the tandem impeller performance within a transonic centrifugal compressor

Tandem impeller configuration has the potential to improve the performance of highly loaded transonic centrifugal compressors, while the related research is still in the early stages and general design guidelines, such as the selection of inducer meridional length, are limited so far. In this paper, a highly loaded transonic centrifugal compressor with various tandem impeller configurations is numerically investigated. The objective is to evaluate the impact of inducer meridional length [Formula: see text] on the tandem impeller flow structure and performance, and further to look into the underlying flow mechanisms and design principles of the tandem impeller. The results indicate that the inducer meridional length [Formula: see text] has significant effect on the tandem impeller and compressor stage performance. There exits an optimized tandem impeller [Formula: see text] value of Appr. 38% that achieves a compressor stage pressure ratio and efficiency gain (at the P.E. points) of 2.6% and 1.8%, respectively, and deviating from the optimized [Formula: see text] value will lead to deteriorated compressor performance. In terms of the impeller performance, the inducer trailing edge determined by the inducer meridional length [Formula: see text] should be located downstream of the passage shock to reduce the shock and inducer wake losses. However, the inducer blade should also be placed in the impeller axial part to avoid the exudcer incidence angle deviation. In terms of the diffuser performance which is partly determined by the impeller discharge flow uniformity, the inducer meridional length [Formula: see text] directly affects the tandem impeller discharge flow uniformity by rearranging and controlling the secondary flow patterns, and the flow uniformity is prone to be insensitive to the [Formula: see text] variation when the [Formula: see text] value is large enough (i.e. ≥30%). Additionally, the [Formula: see text] value should be large enough (i.e. ≥20%) to generate intense inducer shedding vortexes, which can suppress the development of Coriolis vortex and finally improve the impeller flow uniformity.

Effect of Conical Spiral Flow Channel and Impeller Parameters on Flow Field and Hemolysis Performance of an Axial Magnetic Blood Pump

For a blood pump, the blood flow channel and impeller parameters directly affect the performance of the pump and the resulting blood circulation. The flow channel in particular has a great impact on the hydraulic performance of the pump (e.g., flow and pressure), which directly determines the overall performance of the blood pump. Traditional bearing-supported blood pumps can cause mechanical damage to blood cells, leading to hemolysis and thrombosis. In this study, therefore, we designed a conical spiral axial blood pump with magnetic levitation. The blood pump was supported by electrodynamic bearings in the radial direction and electromagnetic bearings in the axial direction. The impeller and the front and rear hubs were integrated to minimize blood stagnation and reduce the formation of thrombosis. The hub had a conical spiral flow channel design, which not only reduced the size of the impeller but also increased blood flow and pressure while meeting the design requirements. Computational fluid dynamics (CFD) analysis was used to analyze the flow field of the axial blood pump, a power function model was used to establish a hemolysis prediction model, and the particle tracking method was used to obtain the flow trajectories of individual blood cells, thereby predicting hemolysis-related performance of the blood pump. The simulation results showed that the main high shear stress area in the blood pump was located in the impeller inlet and the clearance between the top of the impeller and the inner chamber of the blood pump. When the hub taper angle of the blood pump was 0.72° and the clearance was 0.3 mm, the average hemolysis prediction value was 0.00216. This prediction value was smaller than that of traditional axial blood pumps. These findings can provide an important reference for the structural design of axial blood pumps and for reducing the hemolysis prediction value.

A PANS Method Based on Rotation-Corrected Energy Spectrum for Efficient Simulation of Rotating Flow

A partially averaged Navier–Stokes method with a new expression of fk based on the rotation-corrected energy spectrum is proposed. It is coupled with the shear-stress transport turbulence model to simulate two typical rotating flows: rotating channel flow and flow in a centrifugal pump impeller. The results of two traditional energy spectrum-based fk expressions (ES1 and ES2) and DNS/experimental results are used for comparison. The results show that the fk distribution predicted based on the rotation-corrected energy spectrum is more reasonable. In the region with enhanced turbulence, more turbulence scales exist, such as the pressure side in the rotating channel flow, where the fk value is low and more turbulence scales are resolved. While in the region with suppressed turbulence, fewer turbulence scales exist, such as the suction side, where the fk value is relatively high. The model with a new fk expression can produce better results since it can give a more reasonable fk distribution. At the same time, the new model is more efficient since it shows better calculation performance with the same mesh scale and low cost with comparable calculation performance.

An Improved One-Dimensional Flow Model for Side Chambers of Centrifugal Pumps Considering the Blade Slip Factor

Abstract The blade slip factor significantly influences the prediction accuracy of the self-closure one-dimensional flow model for side chambers of centrifugal pumps. Wiesner's and Stodola's slip factors, which are used to formulate the blade outlet pressure and served as the boundary condition for the model, are examined, which is an improvement of the previous study (Gu et al., 2020, “A Pressure Model for Open Rotor–Stator Cavities: An Application to an Adjustable-Speed Centrifugal Pump With Experimental Validation,” ASME J. Fluids Eng., 142(10), p. 101301). Both computational fluid dynamics (CFD) simulations and experiments for the centrifugal pump are conducted to support the improvement. A good agreement exists between the performance at the best efficiency points (BEPs) of different rotating speeds obtained by simulations and experiments. Through the CFD analysis, the flow in the impeller remarkably deviates from the blade-congruent flow, especially in the quasi-triangular regions downstream of the throats. Meanwhile, the reason for pressure over-predictions of the side chamber one-dimensional flow model that embeds Wiesner's slip factor (FMW) is that Wiesner's expression underestimates the impeller flow deflection and overestimates pressure boundary. By contrast, the side chamber one-dimensional flow model with Stodola's slip factor (FMS) is closer to CFD in terms of relative flow angle and chamber inlet pressure. Compared with the side chamber pressure measurements, the accuracy of FMS is upgraded approximately by 3.5% than FMW. At the BEPs of different rotating speeds, FMS generates lower shroud thrust coefficients but slightly greater volumetric efficiencies than FMW. This work provides a simple approach to better calculate flow characteristics in the side chambers.

Numerical Study on Cavitation Phenomenon in an In-Line Centrifugal Pump

Cavitation in pumps causes unwanted consequences, such as noise, vibrations, and system oscillations. These result in reduced pump efficiency and unstable operation range. Therefore, this study investigates the cavitation behaviours of newly designed centrifugal pumps experimentally and numerically. Computational Fluid Dynamics (CFD) was used to analyse cavitation flow behaviours. The Rayleigh–Plesset expression for bubble dynamics was employed to capture the cavitation phenomenon inside the pump. Numerical simulations were performed and validated by experiments, and good performance characteristics were obtained. The estimated total head drop lines for different cavitation flow rates and performances were analysed numerically. Cavitation was observed near the impeller blade suction for the leading-edge condition in impeller flow passage; moreover, a lower pressure was observed near the impeller blade shroud than the hub in the steady-state condition.

Influence of Gas Content on Performance Effect on Shunt Vane Type Aviation Fuel Pump

In order to study the flow law of shunt vane type aviation fuel pump under the condition of gas-liquid mixture transportation, based on the RNG K-ε turbulence model and the Euler-Euler non-uniformity model, using the ANSYS CFX software to calculate an aviation fuel pump under different gas content conditions, and analyzing the flow of the fuel pump and the pressure law of the blade pressure. The research shows that the gas phase is mainly distributed in the front section of the long blade suction surface and the back section of the short blade pressure surface. The increased gas content will result in increased liquid velocity in the pump, which makes the gas phase gradually develop towards the suction surface of long and short blades and diffuse to the impeller flow path. The gas content mainly affects the pressure surface load of the fuel pump blades. The pressure load curve fluctuates at the relative position of the short blade (0.5-0.6) and long blade (0.3-0.6) as well as at the end of the blade and decreases with the increase in gas content. The change of pressure fluctuation of the blade is mainly reflected at the junction of long and short blades, and the pressure fluctuation amplitude of the front section of the short blade and middle section of the long blade fluctuates greatly. With the increase in gas content, the pressure fluctuation amplitude at each monitoring point reduces. The research results can provide some reference for the design of aviation fuel pumps.

Research on the energy characteristics of reactor coolant pump under flow coastdown transient

In order to research the energy characteristics in impeller, guide vane and volute of reactor coolant pump under flow coastdown transient. In four typical states the variation laws of dynamic–static pressure energy and entropy generation in hydraulic components were analyzed under flow coastdown transient. The results show that after the occurrence of flow coastdown transient, the decreasing rate of energy conversion efficiency of impeller is similar that of the rotating speed. With the development of flow coastdown process, the high dynamic pressure energy distribution of impeller deviates to the outlet of impeller. After 0.25TQi, the energy retained by impeller is basically consumed. In guide vane passage, the change of dynamic pressure energy first increases and then decreases, and the static pressure energy firstly decreases and then increases. After 0.75TQi, the diffusivity of the guide vanes to the fluid decreases rapidly. With the development of flow coastdown process, the main working area of guide vane gradually shifts from the middle of guide vane to outlet. High static pressure energy area at guide vane inlet is enlarged and then reduced. With the development of flow coastdown process, the dynamic pressure energy of V2 and V4 at the monitoring points of volute changes alternately, and the dynamic pressure energy of right tongue region of volute gradually exceeds 11.20 m, and the energy conversion effect of volute gradually weakens, and the low static pressure energy region of the right tongue gradually disappears. Compared with other conditions, at 1.0TQi, the loss of dynamic pressure energy in volute is faster, while the reduction rate of static pressure energy is more stable. Entropy generation in reactor coolant pump varies in a similar manner to flow rate and speed, and is closely related to dynamic-static pressure energy. Both Total Entropy Generation (TEG) and per unit volume of entropy generation (Sˈ) eventually approach zero. Entropy generation ratio of volute is much larger than that of other areas, accounting for more than 60%. Guide vane area generates more per unit volume of energy loss than other areas. The flow in impeller under 0.5TQi condition is more stable than that under other conditions. The unstable flow in reactor coolant pump at the initial stage of flow coastdown transient is more severe and has a greater energy loss than under other conditions. After flow coastdown, great damage may occur in the impeller blade inlet area, the guide blade inlet area, the left area of the volute and the volute tongue area.

Aerodynamic noise prediction of a high-speed centrifugal fan considering impeller-eccentric effect

ABSTRACT In this paper, the aerodynamic noise of a centrifugal fan with an eccentric impeller is investigated and analyzed by adopting a hybrid method combining detached-eddy simulation and the acoustic finite element method (FEM). The impeller-eccentric effect of high-speed centrifugal fans, frequently ignored in theoretical studies, is objective in practical engineering applications owing to machining and installation errors, which have a significant influence on flow characteristics and subsequently noise characteristics. An impeller-whirling model combined with the sliding mesh method is introduced to obtain the actual flow with an eccentric impeller. First, the internal flow field handled with different eccentricities is investigated. The total pressure and internal efficiency decline, and the flow field near the leading edge shows intense unsteadiness, inducing a rise in the pressure fluctuation amplitude at the rotating frequency (RF) in both impeller flow passage and volute domain. Second, the variational formulation of Lighthill’s analogy is implemented by acoustic FEM to better account for the interaction between the solid surface and aerodynamic sound, capturing a contribution by turbulence noise at the second RF. Under eccentric conditions, the sound source intensity shows a circumferential non-uniform distribution in a similar region to the flow field. The calculated sound pressure level captures the variation in the experimental result, which shows an obvious rise at RF induced by the impeller-eccentric effect. The characteristics of the noise spectrum and sound directivity change significantly, and the overall sound pressure level rises with the increase in eccentricity. This study provides an effective simulation strategy for predicting the aerodynamic noise of centrifugal fans under realistic conditions.