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1
Arndt, N., A. J. Acosta, C. E. Brennen, and T. K. Caughey. "Experimental Investigation of Rotor-Stator Interaction in a Centrifugal Pump With Several Vaned Diffusers." Journal of Turbomachinery 112, no. 1 (January 1, 1990): 98–108. http://dx.doi.org/10.1115/1.2927428.
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This paper describes an experimental investigation of rotor-stator interaction in a centrifugal pump with several vaned diffusers. Steady and unsteady diffuser vane pressure measurements were made for a two-dimensional test impeller. Unsteady impeller blade pressure measurements were made for a second two-dimensional impeller with blade number and blade geometry identical to the two-dimensional impeller used for the diffuser vane pressure measurements. The experiments were conducted for different flow coefficients and different radial gaps between the impeller blade trailing edge and the diffuser vane leading edge (5 and 8 percent of the impeller discharge radius). The largest pressure fluctuations on the diffuser vanes and the impeller blades were found to be of the same order of magnitude as the total pressure rise across the pump. The largest pressure fluctuations on the diffuser vanes were observed to occur on the suction side of the vane near the vane leading edge, whereas on the impeller blades the largest fluctuations were observed to occur at the blade trailing edge. However, the dependence of the fluctuations on the flow coefficient was found to be different for the diffuser vanes and the impeller blades; on the vane suction side, the fluctuations were largest for the maximum flow coefficient and decreased with decreasing flow coefficient, whereas at the blade trailing edge, the fluctuations were smallest for the maximum flow coefficient and increased with decreasing flow coefficient. Increasing the number of the diffuser vanes resulted in a significant decrease of the impeller blade pressure fluctuations. The resulting lift on the diffuser vanes was computed from the vane pressure measurements; the magnitude of the fluctuating lift was found to be larger than the steady lift.
2
Childs, D. W. "Pressure Oscillation in the Leakage Annulus Between a Shrouded Impeller and Its Housing Due to Impeller-Discharge-Pressure Disturbances." Journal of Fluids Engineering 114, no. 1 (March 1, 1992): 61–67. http://dx.doi.org/10.1115/1.2910001.
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An analysis is presented for the perturbed flow in the leakage path between a shrouded-pump impeller and its housing caused by oscillations in the impeller-discharge pressure. A bulk-flow model is used for the analysis consisting of the path-momentum, circumferential-momentum, and continuing equations. Shear stress at the impeller and housing surfaces are modeled according to Hirs’ turbulent lubrication model. In the present analysis, perturbations of the impeller discharge pressure are used to excite the fluid annulus. The circumferential variation of the discharge pressure is expanded in a Fourier series up to order n1, where n1 is the number of impeller blades. A precession of the impeller wave pattern in the same direction or opposite to pump rotation is then assumed to completely define the disturbance excitation. Predictions show that the first (lowest-frequency) “centrifugal-acceleration” mode of the fluid within the annulus has its peak pressure amplitude near the wearing-ring seal. Pressure oscillations from the impeller can either be attenuated or (sharply) magnified depending on: (a) the tangential velocity ratio of the fluid entering the seal, (b) the order of the fourier coefficient, and (c) the closeness of the precessional frequency of the rotating pressure field to the first natural frequency of the fluid annulus, and (d) the clearance in the wearing-ring seal.
3
Zhang, Wenwu, Zhiyi Yu, and Yongjiang Li. "Analysis of flow and phase interaction characteristics in a gas-liquid two-phase pump." Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 73 (2018): 69. http://dx.doi.org/10.2516/ogst/2018072.
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To analyze the characteristics of internal flow and phase interaction in a gas-liquid two-phase pump, the influence of Inlet Gas Void Fraction (IGVF), discharge coefficient, and medium viscosity were investigated using medium combinations of air-water and air-crude. Simulations were performed using ANSYS_CFX at different IGVFs and various values of discharge coefficient. Structured grid for the full flow passage was generated using ICEM_CFD and TurboGrid. Under conditions of IGVF = 0% (pure water) and IGVF = 15%, the reliability of numerical method was proved by means of the comparison with the experimental data of external characteristic. The results for air-water combination showed a uniform gas distribution in the inlet pipe, and formation of a stratified structure in the outlet pipe. The gas in impeller gathered at the hub because of the rotation of the impeller, also, the interphase forces increased with the increased IGVF. For the two medium combinations, the drag force was the largest interphase force, followed by added mass and lift forces, and then the turbulent dispersion force was the least, which can be neglected. Because of the larger viscosity of crude than that of water, the variation trend of interphase forces in the impeller is relatively smooth along the flow direction when the medium combination was air-crude.
4
Uy, Robert V., and Christopher E. Brennen. "Experimental Measurements of Rotordynamic Forces Caused by Front Shroud Pump Leakage." Journal of Fluids Engineering 121, no. 3 (September 1, 1999): 633–37. http://dx.doi.org/10.1115/1.2823516.
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Unsteady forces generated by fluid flow through the impeller shroud leakage path of a centrifugal pump were investigated. Different pump shroud geometries were compared, and the effect of leakage path inlet swirl (pump discharge swirl) on the rotordynamic forces was examined for various ratios of fluid throughflow velocity to impeller tip speed. A short axial length leakage path reduced the measured forces, while curvature appeared to increase the destabilizing forces when inlet swirl was present. It was observed that changing the inlet swirl velocity does not appear to significantly affect the measured forces for a given leakage flow coefficient, but any nonzero inlet swirl is destabilizing when compared to cases with no inlet swirl.
5
Pei, Ji, Wenjie Wang, Shouqi Yuan, and Jieyun Mao. "Numerical Investigation of Periodically Unsteady Pressure Field in a High Power Centrifugal Diffuser Pump." Advances in Mechanical Engineering 6 (January 1, 2014): 159380. http://dx.doi.org/10.1155/2014/159380.
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Pressure fluctuations are the main factors that can give rise to reliability problems in centrifugal pumps. The periodically unsteady pressure characteristics caused by rotor-stator interaction have been investigated by CFD calculation in a residual heat removal pump. Side chamber flow effect is also considered for the simulation to accurately predict the flow in whole flow passage. The pressure fluctuation results in time and frequency domains were considered for several typical monitoring points in impeller and diffuser channels. In addition, the pressure fluctuation intensity coefficient (PFIC) based on standard deviation was defined on each grid node for entire space and impeller revolution period. The results show that strong pressure fluctuation intensity can be found in the gap between impeller and diffuser. As a source, the fluctuation can spread to the upstream and downstream flow channels as well as the side chamber channels. Meanwhile, strong pressure fluctuation intensity can be found in the discharge tube of the circular casing. In addition, the obvious influence of operational flow rate on the PFIC distribution can be found. The analysis indicates that the pressure fluctuations in the aspects of both frequency and intensity can be used to comprehensively evaluate the unsteady pressure characteristics in centrifugal pumps.
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Baskharone, E. A., A. S. Daniel, and S. J. Hensel. "Rotordynamic Effects of the Shroud-to-Housing Leakage Flow in Centrifugal Pumps." Journal of Fluids Engineering 116, no. 3 (September 1, 1994): 558–63. http://dx.doi.org/10.1115/1.2910313.
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The fluid/shroud interaction forces acting on a pump impeller that is precessing around the housing centerline, are computed and the rotordynamic coefficients deduced. The numerical procedure utilized is an upgraded version of a finite-element-based perturbation model, initially devised for simple see-through annular seals. The computational model accounts for the complex flow structure in the shroud-to-housing secondary flow passage, which includes a tight-clearance face seal. The model also facilitates the mutual interaction between the primary and secondary flows near the impeller inlet and discharge stations. The numerical results are compared to existing experimental data, as well as the results of a simpler and widely used numerical model. Sources of discrepancies between the numerical results are identified, and a comprehensive assessment made in light of the experimental data.
7
Yu, Zhiyi, Wenwu Zhang, Baoshan Zhu, and Yongjiang Li. "Numerical analysis for the effect of tip clearance in a low specific speed mixed-flow pump." Advances in Mechanical Engineering 11, no. 3 (March 2019): 168781401983222. http://dx.doi.org/10.1177/1687814019832222.
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To study the influence of tip clearance on performance (external characteristics, pressure fluctuation and tip loss) of a low specific speed mixed-flow pump, unsteady simulation was performed for the whole flow passage with five tip clearance sizes ( δ0 = 0 mm, δ1 = 0.10 mm, δ2 = 0.25 mm, δ3 = 0.75 mm and δ4 = 1 mm). The reliability of the numerical methodology was verified in external characteristics (efficiency, head and power) and fluctuation. The performance of the pump was obtained under different discharges and tip clearance sizes using ANSYS CFX. The results showed that the variation of tip clearance size has greater effect on the external characteristics under large discharges. Meanwhile, along the flow direction, the fluctuation coefficients near the impeller shroud increase gradually with the smaller tip clearance sizes ( δ = 0.10 and 0.25 mm), while for the larger tip clearance sizes ( δ = 0.75 and 1.00 mm), the significant increase of fluctuation near the shroud of impeller inlet is closely associated with the clear leakage vortex and the large region of low pressure. Besides, with the increase of tip clearance size, the effect of tip clearance will become more remarkable under different discharge conditions. According to this study, for the optimization design of such pumps, the size of the tip clearance is suggested to be about 0.9% times the blade height at middle of the impeller passage.
8
Hernández Ramírez, Gabriel, Ángel Manuel León Segovia, Edison Salazar, Roberto Beltran Reina, and Julio Cesar Pino Tarragó. "Mathematical modeling of the coefficient of load correction of the pumping of hydromixtures lateritic." DYNA 86, no. 208 (January 1, 2019): 19–27. http://dx.doi.org/10.15446/dyna.v86n208.72006.
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The purpose of the present investigation was to determine the behavior correction coefficient of the characteristics of the centrifugal pump load curves, using mathematical models, taking into account the rheological properties. From experimental studies such as X-ray diffraction, X-ray fluorescence, particle size analyzer, rheological analysis and mathematical modeling we obtain the behaviors of the physical and chemical interactions that take place in non-Newtonian fluids. It is concluded that to obtain a mathematical model of the correction coefficient and the equations describing the behavior of the characteristic load - discharge curves of the networks and of the pumps to, by means of the joint analysis of these, obtain the frequency of rotation of the impeller that guarantees the required flow rates in energy efficient operating regimes.
9
Li, Yuan, Hua Chen, Xiangjun Li, Minghe Jiang, and Guinian Wang. "Influence of U-tube type casing treatment on pressure fluctuations of a centrifugal pump at low flow conditions." Modern Physics Letters B 35, no. 12 (March 9, 2021): 2150205. http://dx.doi.org/10.1142/s0217984921502055.
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The existence of pressure pulsations greatly increases the vibration and noise of pumps and harms their service life. In this paper, a casing treatment was employed to explore its impact on the pressure pulsations. A U-tube type groove was created at the inlet end-wall of a centrifugal pump and front cover of the impeller to connect the impeller with the inlet pipe by passing impeller leading edge. An unsteady numerical investigation was launched of the pump with and without this casing treatment, to study its influence on the pressure pulsations inside the pump and the mechanisms behind. The numerical results of the pump without casing treatment was first compared with the test performance of the pump to validate the numerical method, and gave excellent agreements with the test results. The CFD results also showed that the casing treatment increases the head coefficient and efficiency of the pump. Pressure pulsations at a reduced mass flow condition were studied by monitoring unsteady pressure signals generated by the CFD at various locations inside the pump. A Fast Fourier transform (FFT) was performed on the signals. The pump employs a double tongues volute with each tongue covering 180[Formula: see text] circumference. However, the two tongues are not identical with regard to the discharge of the pump. These geometric features of the volute and the pump’s operating condition generate several pressure pulsations in the frequencies of [Formula: see text], [Formula: see text], [Formula: see text] in the original pump. Due to the circumferential unifying capability of the casing treatment and its improvement to the impeller flow, these pulsations at impeller inlet are weakened or disappear when the U-tube is present. The pressure pulsation inside the impeller is less affected by the treatment. The [Formula: see text] pulsation at volute tongues also decreases or disappears for the same reasons, but [Formula: see text] pulsation increases slightly and this is due to the improved pressure recovery in the volute by the treatment which increases the pressure difference across one of the volute tongues. The unsteady radial force of the impeller exerting on journal bearings becomes more uniform and smaller when the casing treatment is employed.
10
Arndt, N., A. J. Acosta, C. E. Brennen, and T. K. Caughey. "Rotor–Stator Interaction in a Diffuser Pump." Journal of Turbomachinery 111, no. 3 (July 1, 1989): 213–21. http://dx.doi.org/10.1115/1.3262258.
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The interaction between impeller blades and diffuser vanes in a diffuser pump was investigated. Steady and unsteady pressure measurements were taken on the diffuser vanes, and the shroud wall of a vaned and a vaneless diffuser. Steady, unsteady, and ensemble-averaged unsteady data, as well as frequency spectra, are presented. The measurements were made for different flow coefficients, shaft speeds, and radial gaps between impeller blade trailing and diffuser vane leading edge (1.5 and 4.5 percent based on impeller discharge radius). The resulting lift on the vane, both steady and unsteady, was computed from the pressure measurements at midvane height. The magnitude of the fluctuating lift was found to be greater than the steady lift. The pressure fluctuations were larger on the suction side than on the pressure side attaining their maximum value, of the same order of magnitude as the total pressure rise across the pump, near the leading edge. Pressure fluctuations were also measured across the span of the vane, and those near the shroud were significantly smaller than those near the hub. The pressure fluctuations on the shroud wall itself were larger for the vaned diffuser than a vaneless diffuser. Lift, vane pressure, and shroud wall pressure fluctuations decreased strongly with increasing radial gap.
11
Krain, H. "Swirling Impeller Flow." Journal of Turbomachinery 110, no. 1 (January 1, 1988): 122–28. http://dx.doi.org/10.1115/1.3262157.
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The results of extensive laser measurements carried out in the blade passages of a newly designed backswept impeller are presented and discussed. Noticeable distortions of the throughflow patterns and a distinct swirling flow character were found inside the rotor. The measurement results and a simple theoretical approach suggest that the distorted throughflow patterns and the secondary flows are caused by a vortex flow. Although the relative flow has been significantly decelerated a comparatively smooth velocity profile has been identified at the rotor discharge that differed widely from the well-known jet/wake-type flow pattern.
12
Alpan, K., and W. W. Peng. "Suction Reverse Flow in an Axial-Flow Pump." Journal of Fluids Engineering 113, no. 1 (March 1, 1991): 90–97. http://dx.doi.org/10.1115/1.2926503.
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Experiments are carried out to determine the effects of different inlet geometries on the onset of suction recirculation and its associated power consumption in an axial-flow pump. The critical flow rate is determined by both the “string” visual technique and “pressure” method. The results are correlated with the inlet area and flow velocity distribution upstream of the impeller. Four different conical covers matching the impeller leading edge are employed to cover the impeller inlet completely or partially. Covering the inlet area reduces the critical flowrate corresponding to the onset of suction recirculation and eliminates all recirculation at higher flowrates. The power consumption associated with the suction recirculation flow for the uncovered impeller is determined by comparing the shaft powers with and without inlet covers. At the shut-off condition, the power is estimated from a comparison with the shaft power measured with the impeller inlet completely covered. Experimental studies conclude that the power consumption due to suction recirculation is mainly controlled by the impeller inlet area and is insensitive to the inlet pipe configuration. At shut-off condition, the power coefficient correlates well with the parameter based on the hydraulic radius of inlet area. At a finite through flowrate the analytical model recommended by Tuzson (1983) is adequate, except for a proportionality coefficient determined from the test data.
13
Chen, Xin, Shiyang Li, Dazhuan Wu, Shuai Yang, and Peng Wu. "Effect of Suction and Discharge Conditions on the Unsteady Flow Phenomena of Axial-Flow Reactor Coolant Pump." Energies 13, no. 7 (April 1, 2020): 1592. http://dx.doi.org/10.3390/en13071592.
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In order to study the effects of the suction and discharge conditions on the hydraulic performance and unsteady flow phenomena of an axial-flow reactor coolant pump (RCP), three RCP models with different suction and discharge configurations are analyzed by computational fluid dynamics (CFD) method. The CFD results are validated by experimental data. The hydraulic performance of the three RCP models shows little difference. However, the unsteady flow phenomena of RCP are significantly affected by the variation of suction and discharge conditions. Compared with that of Model E-S (baseline, elbow-single nozzle), the pressure pulsation in rotating frame of Model S-S (straight pipe-single nozzle) and Model E-D (elbow-double nozzles) is weakened in different degrees and forms, due to the more uniform flow fields upstream and downstream of the impeller, respectively. It indicates that the generalized rotor-stator interaction (RSI) actually exists between the rotating impeller and all stationary components causing the circumferentially non-uniform flow. Furthermore, improving the circumferential uniformity of the flow upstream and downstream of impeller (suction and discharge flow) also contributes to reducing the radial dynamic fluid force acting on the impeller. Compared with those of Model E-S, the dynamic FX and FY of Model S-S are severely weakened, and those of Model E-D also gain a minor amplitude decrease at fBPF. In contrast, the general pressure pulsation in fixed frame is mainly related to the rotating impeller and barely affected by the suction and discharge conditions.
14
Kaupert, K. A., P. Holbein, and T. Staubli. "A First Analysis of Flow Field Hysteresis in a Pump Impeller." Journal of Fluids Engineering 118, no. 4 (December 1, 1996): 685–91. http://dx.doi.org/10.1115/1.2835496.
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The measured pump pressure discharge characteristic for a high specific speed radial pump (ωs = 1.7) reveals distinct discontinuities in part load operation. These pressure discontinuities occur at different threshold volume fluxes when increasing or decreasing the pump discharge and make up a hysteresis loop. The pump impeller characteristic was evaluated experimentally and numerically by taking the difference between the integrated impeller outlet and impeller inlet total pressure. The experimental and numerical characteristics agree well including the volume flux location and magnitude of the pressure discontinuities in the hysteresis loop. For volume fluxes within the hysteresis loop two stable well converged flows were calculated numerically. The numerical calculations were made on coarse and fine grids using commercially available software with and without the impeller clearance leakage flow. Further experimental and numerical comparisons are made at the impeller inlet/outlet with emphasis on the changing flow field in the hysteresis loop flow regime and its coupling to the onset of reverse flow zones. This combined application of numerical and experimental tools provides insight for the hysteresis flow field of a pump impeller characteristic.
15
Yoshida, Masanori, Kohei Ishioka, Hiromu Ebina, Koki Oiso, Hayato Shirosaki, and Ryota Tateshita. "Efficacy of partial baffles for a vessel agitated by a Rushton turbine impeller." Chemical Industry and Chemical Engineering Quarterly 24, no. 3 (2018): 293–301. http://dx.doi.org/10.2298/ciceq170921001y.
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For a vessel agitated by a Rushton turbine impeller, the efficacy of partial baffles was evaluated through examination of the liquid flow and impeller power characteristics. The bulk flow formed a pattern having circulation loops of different intensity and largeness depending on the baffle condition: the baffle length relative to the liquid depth for the vessel. Consequently, the liquid flow within the vessel affected the impeller power number. The characteristic circulation loops, which generally reflect the baffle efficacy, were assessed in terms of the discharge flow through the impeller and the energy transmission within the vessel based on the flow velocity profiles. The shorter length of baffles fitted partially in the upper half of the liquid phase was revealed to be effective, supported in combination by a comparable discharge flow and a successful energy transmission.
16
Brozowski, L. A., T. V. Ferguson, and L. Rojas. "Impeller Flow Field Laser Velocimeter Measurements." International Journal of Rotating Machinery 2, no. 3 (1996): 149–59. http://dx.doi.org/10.1155/s1023621x96000024.
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Development of Computational Fluid Dynamics (CFD) computer codes for complex turbomachinery affords a complete three-dimensional (3-D) flow field description. While significant improvements in CFD have been made due to improvements in computers, numerical algorithms, and physical modeling, a limited experimental database for pump CFD code validation exists.Under contract (NAS8-38864) to the National Aeronautics and Space Administration (NASA) at Marshall Space Flight Center (MSFC) a test program was undertaken at Rocketdyne to obtain benchmark data for typical rocket engine pump geometry. Nonintrusive velocity data were obtained with a laser two-focus velocimeter. Extensive laser surveys at the inlet and discharge of a Rocketdyne-designed impeller were performed. Static pressures were measured at key locations to provide boundary conditions for CFD code validation.
17
Kysela, Bohuš, Jiří Konfršt, Ivan Fořt, and Zdeněk Chára. "CFD Simulation of the Discharge Flow from Standard Rushton Impeller." International Journal of Chemical Engineering 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/706149.
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The radial discharge jet from the standard Rushton turbine was investigated by the CFD calculations and compared with results from the Laser Doppler Anemometry (LDA) measurements. The Large Eddy Simulation (LES) approach was employed with Sliding Mesh (SM) model of the impeller motion. The obtained velocity profiles of the mean ensemble-averaged velocity and r.m.s. values of the fluctuating velocity were compared in several distances from the impeller blades. The calculated values of mean ensemble-averaged velocities are rather in good agreement with the measured ones as well as the derived power number from calculations. However, the values of fluctuating velocities are obviously lower from LES calculations than from LDA measurements.
18
Miner, Steven M. "Evaluation of Blade Passage Analysis Using Coarse Grids." Journal of Fluids Engineering 122, no. 2 (February 10, 2000): 345–48. http://dx.doi.org/10.1115/1.483263.
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This paper presents the results of a study using coarse grids to analyze the flow in the impellers of an axial flow pump and a mixed flow pump. A commercial CFD code (FLOTRAN) is used to solve the 3-D Reynolds Averaged Navier Stokes equations in a rotating cylindrical coordinate system. The standard k−ε turbulence model is used. The meshes for this study use 22,000 nodes and 40,000 nodes for the axial flow impeller, and 26,000 nodes for the mixed flow impeller. Both models are run on a SPARCstation 20. This is in contrast to typical analyses using in excess of 100,000 nodes. The smaller mesh size has advantages in the design environment. Stage design parameters for the axial flow impeller are, rotational speed 870 rpm, flow coefficient ϕ=0.13, head coefficient ψ=0.06, and specific speed 2.97 (8101 US). For the mixed flow impeller the parameters are, rotational speed 890 rpm, flow coefficient ϕ=0.116, head coefficient ψ=0.094, and specific speed 2.01 (5475 US). Evaluation of the models is based on a comparison of circumferentially averaged results to measured data for the same impeller. Comparisons to measured data include axial and tangential velocities, static pressure, and total pressure. A comparison between the coarse and fine meshes for the axial flow impeller is included. Results of this study show that the computational results closely match the shapes and magnitudes of the measured profiles, indicating that coarse CFD models can be used to accurately predict performance. [S0098-2202(00)02202-1]
19
Galerkin, Y., A. Drozdov, and A. Rekstin. "Centrifugal compressor impeller loading factor analysis." E3S Web of Conferences 124 (2019): 01005. http://dx.doi.org/10.1051/e3sconf/201912401005.
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The loading factor performance modelling is an important part of centrifugal compressor performance calculation. The presented information on model stages’ test data confirms the fact that the loading factor versus flow coefficient at an impeller exit is a linear function independent of Mach number (subsonic flow). The test data and the design characteristics of the series of 10 model stages are compared with the calculation of an inviscid flow and with calculations done using the NUMECA software. Math models offered by the authors, and inviscid calculations solve the problem of a primary design. The CFD-calculation for final solution is non-satisfactory. If the loading factor is calculated by total temperature difference and flow coefficient is calculated by a continuity equation, the performance is not quite linear and lies much higher. For the considered stages CFD-calculation inaccuracy is + (0,06 … 0,12). CFD-calculated flow coefficient is inside 0,96 … 0,98 of the measured and of the calculated by the Math model.
20
Lei, Tan, Zhu Bao Shan, Cao Shu Liang, Wang Yu Chuan, and Wang Bin Bin. "Numerical simulation of unsteady cavitation flow in a centrifugal pump at off-design conditions." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 11 (December 2, 2013): 1994–2006. http://dx.doi.org/10.1177/0954406213514573.
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Unsteady cavitation flows in a centrifugal pump operating under off-design conditions are investigated by using a numerical framework combining the re-normalization group k–ɛ turbulence model and the transport equation-based cavitation model. The reliability and accuracy of the numerical model are demonstrated by the satisfactory agreement between the experimental and numerical values of the pump performance. Under partial discharge, the frequency spectra of the pressure fluctuation at the impeller inlet become more complex as the pump inlet pressure decreases. The maximum amplitude of pressure fluctuation at the blade leading edge for cavitation flow is 2.54 times larger than that for non-cavitation flow because of the violent disturbances caused by cavitation shedding and explosion. Under large discharge, the magnification on the maximum pressure amplitude is 1.6. This finding indicates that cavitation has less influence on pressure fluctuations in the impeller under large discharge than under partial discharge. This numerical simulation demonstrates the evolution of cavitation structure inside the impeller.
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Liu, C. H., C. Vafidis, and J. H. Whitelaw. "Flow Characteristics of a Centrifugal Pump." Journal of Fluids Engineering 116, no. 2 (June 1, 1994): 303–9. http://dx.doi.org/10.1115/1.2910272.
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Measurements of velocity have been obtained in a centrifugal pump in terms of angle-resolved values in the impeller passages, the volute, the inlet and exit ducts and are presented in absolute and relative frames. The pump comprised a radial flow impeller with four backswept blades and a single volute, and the working liquid had the same refractive index as the transparent casing to facilitate the use of a laser-Doppler velocimeter. The flows in the impeller passages were found to depart from the curvature of the blade surfaces at off-design conditions with separation from the suction surface and from the shroud. Secondary flows from the suction to pressure surfaces were dominated by the influences of the relative motion between the shroud and impeller surfaces and the tip leakage. Geometric differences of 0.5 mm and one degree in spacing of the four blades caused differences in passage velocity of up to 6 percent of the impeller tip velocity close to the design flowrate and up to 16 percent at the lowest discharge. The flowrate from each impeller passage varied with volute circumferential position by up to 25 percent at an off-design flowrate. Poor matching of the impeller and volute at off-design conditions caused swirl and separation in the inlet and exit pipes.
22
Shen, Simin, Zhongdong Qian, and Bin Ji. "Numerical Analysis of Mechanical Energy Dissipation for an Axial-Flow Pump Based on Entropy Generation Theory." Energies 12, no. 21 (October 31, 2019): 4162. http://dx.doi.org/10.3390/en12214162.
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Mechanical energy dissipation is a major problem affecting hydraulic machinery especially under partial-load conditions. Owing to limitations of traditional methods in evaluating mechanical energy dissipation, entropy generation theory is introduced to study mechanical energy dissipation with varying discharge and tip clearance intuitively through numerical simulations in an axial-flow pump. Results show that the impeller and diffuser are the main domains of mechanical energy dissipation, respectively accounting for 35.32%–55.51% and 32.61%–20.42% of mechanical energy dissipation throughout the flow passage. The mechanical energy dissipation of the impeller has a strong relation with the hump characteristic and becomes increasingly important with decreasing discharge. Areas of high turbulent dissipation in the impeller are mainly concentrated near the blades’ suction sides, and these regions, especially areas near the shroud, extend with decreasing discharge. When the pump enters the hump region, the distributions of turbulent dissipation near the shroud become disordered and expand towards the impeller’s inlet side. Unstable flows, like flow separation and vortices, near the blades’ suction sides lead to the high turbulent dissipation in the impeller and hump characteristic. Turbulent dissipation at the tip decreases from the blade leading edge to trailing edge, and regions of high dissipation distribute near the leading edge of the blade tip side. An increase in tip clearance for the same discharge mainly increases areas of high turbulent dissipation near the shroud and at the tip of the impeller, finally reducing pump performance.
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Majidi, Kitano. "Numerical Study of Unsteady Flow in a Centrifugal Pump." Journal of Turbomachinery 127, no. 2 (April 1, 2005): 363–71. http://dx.doi.org/10.1115/1.1776587.
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Computational fluid dynamics (CFD) analysis has been used to solve the unsteady three-dimensional viscous flow in the entire impeller and volute casing of a centrifugal pump. The results of the calculations are used to predict the impeller/volute interaction and to obtain the unsteady pressure distribution in the impeller and volute casing. The calculated unsteady pressure distribution is used to determine the unsteady blade loading. The calculations at the design point and at two off-design points are carried out with a multiple frame of reference and a sliding mesh technique is applied to consider the impeller/volute interaction. The results obtained show that the flow in the impeller and volute casing is periodically unsteady and confirm the circumferential distortion of the pressure distribution at the impeller outlet and in the volute casing. Due to the interaction between impeller blades and the tongue of the volute casing the flow is characterized by pressure fluctuations, which are strong at the impeller outlet and in the vicinity of the tongue. These pressure fluctuations are died away in the casing as the advancement angle increases. These reduced pressure fluctuations are spread to the discharge nozzle; the pressure fluctuations are also reflected to the impeller inlet and they affect the mass flow rate through the blade passages.
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Susilo, Sugeng Hadi, and Agus Setiawan. "Analysis of the number and angle of the impeller blade to the performance of centrifugal pump." EUREKA: Physics and Engineering, no. 5 (September 13, 2021): 62–68. http://dx.doi.org/10.21303/2461-4262.2021.002001.
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The paper discusses the performance of the pump in relation to the impeller. The impeller section is determined by the number and angle of the blades. Therefore, the purpose of this study was to analyze the role of the number and angle of impeller blades on the performance (discharge and discharge pressure) of centrifugal pumps based on experiments and simulations.
The method used is experiment and simulation. Using a centrifugal pump type GWP 20/4 SW, Maximum Output: 6.5 HP/3500 rpm, Inlet/Outlet: 2 Inch, Dimensions: 475x375x370 mm. Experiments and simulations by varying the number of blades 2, 4, and 6 with a blade tilt angle of 130°, 150°, and 160°. For flow simulation using solid works program.
The results show that pump performance is related to discharge pressure, impeller with 2-blades and an angle of 130° the pressure increases 0.45–2.45 bar, for 150° increases 0.14–2.96 bar, and 160° increases 0.29–3.07 bars. For a 4-blade impeller and an angle of 130°, the pressure increases by 0.48–3.12 bar, for 150° it increases by 0.39–3.39 bar, and for 160° it increases by 0.36–3.48 bar. While the impeller for 6-blades with an angle of 130° the pressure increases from 0.6 bar to 3.72 bar, for 150° increases from 1.36 to 4.34 bar, and 160° increases by 0.36–4.74 bar. While it related pump performance to flow rate, increasing the number of blades causes a decrease in flow rate. The highest flow rate is in a 2-blade impeller with a blade angle of 130° is 404.91 l/s. The lowest flow rate is on a 6-blade impeller with an angle of 160° is 279.66 l/s
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Zhu, Di, Ran Tao, Ruofu Xiao, Wei Yang, Weichao Liu, and Fujun Wang. "Optimization design of hydraulic performance in vaned mixed-flow pump." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, no. 7 (November 14, 2019): 934–46. http://dx.doi.org/10.1177/0957650919887584.
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Vaned mixed-flow pump is widely used in industrial and agricultural cases. Considering mixed-flow impeller and space guide-vanes, the impeller and guide-vane blade angles need optimization design. In order to conduct optimization, the global dynamic-criterion algorithm with the ability of parallel running, dynamic criterion and escaping from local-best trap was used in this case. Based on numerical simulation and experimental verification, the 18 parameters' combination was optimized using this algorithm to achieve higher-efficiency in a specific flow rate range around the design condition. The numerical results showed that the weighted efficiency increased from 87.32% to 89.26% and the head coefficient decreased from 0.720 to 0.693. The improved efficiency and reduced head under design requirement helps to reduce the shaft power and energy consumption. The optimized blade inlet angle matches the inlet angle and improves the uniformity of flow in the impeller. The impeller outlet angle matches the guide vane inlet angle. Therefore, the flow regime becomes smoother in the rotor stator interaction region. The experimental results verify that the optimized pump efficiency was 85.75%. The measured head coefficient was 0.643 which meets the design requirement. This study provides a successful work for the green design of impeller and guide-vane of mixed-flow pump.
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Wang, Yongsheng, Feng Lin, Chaoqun Nie, and Abraham Engeda. "Design and Performance Evaluation of a Very Low Flow Coefficient Centrifugal Compressor." International Journal of Rotating Machinery 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/293486.
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Very low flow coefficient centrifugal compressors are often applied as the last stages of multistage compressors. Due to the lower volume flow rate, the flow channels in the impeller and diffuser are so narrow that friction loss becomes the main factor, which leads to lower efficiency than that of other stages in the same compressors. In addition, most of design methods are generally based on medium flow coefficient centrifugal compressors. Taking on researches on the low flow coefficient centrifugal compressors is significant and necessary. One-dimensional (1D) code, consisting of design and analysis parts, is developed in this study to provide basic geometric data and predict the entire performance of centrifugal compressor. Three-dimensional geometry of the impeller is built. CFD simulation is carried out as well to be compared with 1D prediction. With the continuous geometry adjustment, the final performance of the centrifugal compressor will be fixed once the performance discrepancy between CFD and one-dimensional code is acceptable. The details on the flow field within impeller will be presented through CFD.
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Adkins, D. R., and C. E. Brennen. "Analyses of Hydrodynamic Radial Forces on Centrifugal Pump Impellers." Journal of Fluids Engineering 110, no. 1 (March 1, 1988): 20–28. http://dx.doi.org/10.1115/1.3243504.
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Hydrodynamic interactions that occur between a centrifugal pump impeller and a volute are experimentally and theoretically investigated. The theoretical analysis considers the inability of the blades to perfectly guide the flow through the impeller, and also includes a quasi-one dimensional treatment of flow in the volute. Flow disturbances at the impeller discharge and the resulting forces are determined by the theoretical model. The model is then extended to obtain the hydrodynamic force perturbations that are caused by the impeller whirling eccentrically in the volute. Under many operating conditions, these force perturbations were found to be destabilizing. Comparisons are made between the theoretical model and the experimental measurements of pressure distributions and radial forces on the impeller. The theoretical model yields fairly accurate predictions of the radial forces caused by the flow through the impeller. However, it was found that the pressure acting on the front shroud of the impeller has a substantial effect on the destabilizing hydrodynamic forces.
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Wang, Hong, and Hiroshi Tsukamoto. "Experimental and Numerical Study of Unsteady Flow in a Diffuser Pump at Off-Design Conditions." Journal of Fluids Engineering 125, no. 5 (September 1, 2003): 767–78. http://dx.doi.org/10.1115/1.1603305.
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An experimental and numerical study was developed for the unsteady phenomena at off-design conditions of a diffuser pump. Unsteady pressure measurements were made downstream of the impeller, and the pressure fluctuations were analyzed using the ensemble averaging technique as well as the statistical and chaotic time series analysis. The unsteady flow was classified into five ranges as a result of the statistical and chaotic time series analysis. And a two-dimensional vortex method was employed to investigate the unsteady flow structure due to the interaction between impeller and diffuser vanes in a diffuser pump at various off-design conditions. The numerical results of unsteady flow at a partial discharge range (approximately 83% of the rated flow rate) show an asymmetrical separation bubble near the pressure surface of the impeller vane. The intermittence of the separation bubble may be the main factor to cause the unstable characteristics of the test diffuser pump. The calculated unsteady flow at the lower partial discharge range (50% of the rated flow rate) presents a rotating stall in the impeller passage as well as in the diffuser passage, which can be main cause of unstable characteristics there.
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Pavesi, G., G. Cavazzini, and G. Ardizzon. "Time-Frequency Characterization of Rotating Instabilities in a Centrifugal Pump with a Vaned Diffuser." International Journal of Rotating Machinery 2008 (2008): 1–10. http://dx.doi.org/10.1155/2008/202179.
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This paper presents acoustic and flowdynamic investigations of large-scale instabilities in a radial pump with a vaned diffuser. Pressure fluctuations were measured with transducers placed flush at the inlet duct, at the impeller discharge, and in the vane diffuser walls. Two impeller rotation speeds were analyzed in the study, at design, and at off-design flow rates. A spectral analysis was carried out on the pressure signals in frequency and in time-frequency domains to identified precursors, inception, and evolution of the pressure instabilities. The results highlighted the existence of a rotating pressure structure at the impeller discharge, having a fluid-dynamical origin and propagating both in the radial direction and inside the impeller. The experimental data were then compared with the results obtained with help of ANSYS CFX computer code; focusing on the changing flow field at part load. Turbulence was reproduced by DES model.
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Miner, S. M., R. D. Flack, and P. E. Allaire. "Two-Dimensional Flow Analysis of a Laboratory Centrifugal Pump." Journal of Turbomachinery 114, no. 2 (April 1, 1992): 333–39. http://dx.doi.org/10.1115/1.2929147.
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Two-dimensional potential flow was used to determine the velocity field within a laboratory centrifugal pump. In particular, the finite element technique was used to model the impeller and volute simultaneously. The rotation of the impeller within the volute was simulated by using steady-state solutions with the impeller in ten different angular orientations. This allowed the interaction between the impeller and the volute to develop naturally as a result of the solution. The results for the complete pump model showed that there are circumferential asymmetries in the velocity field, even at the design flow rate. Differences in the relative velocity components were as large as 0.12 m/s for the radial component and 0.38 m/s for the tangential component, at the impeller exit. The magnitude of these variations was roughly 25 percent of the magnitude of the average radial and tangential velocities at the impeller exit. These asymmetries were even more pronounced at off-design flow rates. The velocity field was also used to determine the location of the tongue stagnation point and to calculate the slip within the impeller. The stagnation point moved from the discharge side of the tongue to the impeller side of the tongue, as the flow rate increased from below design flow to above design flow. At design flow, values of slip ranged from 0.96 to 0.71, from impeller inlet to impeller exit. For all three types of data (velocity profiles, stagnation point location, and slip factor) comparison was made to laser velocimeter data, taken for the same pump. At the design flow, the computational and experimental results agreed to within 17 percent for the velocity magnitude, and 2 deg for the flow angle. The stagnation point locations coincided for the computational and experimental results, and the values for slip agreed to within 10 percent.
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., Samip Shah. "EFFECT OF FLOW COEFFICIENT AND LOADING COEFFICIENT ON THE RADIAL INFLOW TURBINE IMPELLER GEOMETRY." International Journal of Research in Engineering and Technology 02, no. 02 (February 25, 2013): 98–104. http://dx.doi.org/10.15623/ijret.2013.0202002.
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Hamkins, C. P., and R. D. Flack. "Laser Velocimeter Measurements in Shrouded and Unshrouded Radial Flow Pump Impellers." Journal of Turbomachinery 109, no. 1 (January 1, 1987): 70–76. http://dx.doi.org/10.1115/1.3262072.
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Shrouded and unshrouded versions of a four-vaned radial flow impeller with a design flow coefficient of 0.063 were tested in a volute pump using a two-component frequency-shifted laser velocimeter. Velocity profiles were measured at six flow rates and at four radial and six circumferential positions in the volute. The variations of the velocity from blade to blade and in the axial direction were measured and are presented. A passage vortex caused by tip leakage and relative casing wall velocity was found in the unshrouded impeller. The tip leakage did not accumulate in the suction wake region; the suction wake region was only 30 to 50 percent as large in the unshrouded impeller as compared to the shrouded impeller. The slip was 30 percent higher in the unshrouded impeller and the variation of slip with flow rate is presented. At no measured position in the impellers did the slip factor reach unity; the closest approach was 0.90. Reverse loadings of the vanes at outer radii were found for flow rates below the impeller/volute matching point for both impellers.
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Zhou, Shihao, Peifeng Lin, Wei Zhang, and Zuchao Zhu. "Evolution Characteristics of Separated Vortices and Near-Wall Flow in a Centrifugal Impeller in an Off-Designed Condition." Applied Sciences 10, no. 22 (November 19, 2020): 8209. http://dx.doi.org/10.3390/app10228209.
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Flow separation is undesirable and lowers the efficiency of centrifugal impellers. In this study, the evolution characteristics of separated vortices in a centrifugal impeller are studied under the off-designed flow rate condition. Unsteady Reynolds-Averaged Navier–Stokes (URANS) with standard k-ε turbulent model is applied to simulate the alternating stall in the six-blade centrifugal impeller. We present and analyze the distributions of pressure gradient (either adverse or favorable) and skin friction coefficients on both sides of the blade for the stalled and unstalled passages to study the relationship between pressure gradient and separation of boundary layer flow. The evolution of skin friction coefficient is also presented at various axial cross sections. Numerical results reveal that, for the stalled passage, the increase in adverse pressure gradient on the pressure surface near the middle of the blade (S/S0 = 0.4) is much larger than that of the suction surface during a vortex formation cycle. The skin friction coefficient on the pressure surface also increases in magnitude sharply and the variation shows a peak-valley trend, while the coefficient on the suction surface increases slowly. Comparing the distribution of skin friction coefficient on the pressure surface of the same blade at different axial cross sections, it is found that the skin friction coefficient notably increases at S/S0 = 0.6 on the middle axial cross section (Z/b2 = 0.5). For the unstalled passage, both the pressure and suction surfaces produce favorable pressure gradients. The skin friction coefficient on the pressure surface shows an increasing trend around S/S0 = 0.5, and a large vortex can be seen at the exit of the impeller. The variation of skin friction coefficient on the suction surface is relatively mild; thus, the flow is relatively stable. It is clarified that the effect of adverse pressure gradient and wall shear stress jointly cause separation of the boundary layer; thus, the separated vortices are generated in the rotating impeller and deteriorate the performance of the impeller.
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Hah, C., A. C. Bryans, Z. Moussa, and M. E. Tomsho. "Application of Viscous Flow Computations for the Aerodynamic Performance of a Backswept Impeller at Various Operating Conditions." Journal of Turbomachinery 110, no. 3 (July 1, 1988): 303–11. http://dx.doi.org/10.1115/1.3262196.
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Three-dimensional flowfields in a centrifugal impeller with backswept discharge at various operating points have been numerically investigated with a three-dimensional viscous flow code. Numerical results and experimental data were compared for the detailed flowfields and overall performance of the impeller at three operating conditions (optimum efficiency, choke, and near-surge conditions). The comparisons indicate that for engineering applications the numerical solution accurately predicts various complex real flow phenomena. The overall aerodynamic performance of the impeller is also well predicted at design and off-design conditions.
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Jin, Yong Xin, Wen Wu Song, and Fu Jie. "A Study on the Effects of Blade Thickness on the Performance of Low Specific Speed Centrifugal Pump." Advanced Materials Research 1070-1072 (December 2014): 1957–62. http://dx.doi.org/10.4028/www.scientific.net/amr.1070-1072.1957.
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The effects of blade thickness on impeller performance is seldom considered when design the low specific speed centrifugal pump and only considered crowding coefficient when use the speed coefficient method calculate the head of the impeller was designed. It was didn't consider the fundamental relationship how leaf thickness and low specific speed centrifugal impeller performance effect each other. The three-dimensional of flow area would have large influence if the leaf thickness changes . Here the best true thickness of the low specific speed centrifugal impeller blade was obtained though study how the thickness of blade influence on the performance of low specific speed centrifugal pump.
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Liu, Cong, Xiaoyi Wang, Xiaofeng Yu, Yuhua Zhang, Zhizhen Qiu, and Xiangrong Xu. "Power Coefficient Analysis of Double-blade Half-rotating Impeller Tidal Turbine Operating at Yaw." E3S Web of Conferences 242 (2021): 03008. http://dx.doi.org/10.1051/e3sconf/202124203008.
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The double-blade half-rotating impeller tidal turbine (DHITT) is a new type of vertical shaft tidal current turbine with lift and resistance performance. The power coefficient of the DHITT is affected by the flow direction. In order to research the power coefficient (CP) of the DHITT under different flow direction, the optimal attack flow angle of a half-impeller turbine was explored, and the fluctuation of power coefficient of the DHITT operating at yaw was analyzed based on the optimal attack flow angle. The unsteady flow of the turbine was simulated by overlapping grid technique, and the fluctuation of the turbine’s power coefficient under different flow directions was analyzed, which was verified by experiments. The results have demonstrated that the power coefficient at the optimal angle of attack is 0.53. As the yaw angle greater than 30º, the power reduction is nearly 40%, but the average efficiency loss is only 3.7% in the range of -3º to 3º.
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Benisek, Miroslav, Dejan Ilic, Djordje Cantrak, and Ivan Bozic. "Investigation of the turbulent swirl flows in a conical diffuser." Thermal Science 14, suppl. (2010): 141–54. http://dx.doi.org/10.2298/tsci100630026b.
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Results of the theoretical and experimental investigations of the turbulent mean swirl flows characteristics change along straight conical diffuser of incompressible fluid (air) are presented in this paper. The main swirl flow characteristics review is given. In addition: the specific swirl flow energy, the energy loss, the mean circulation, the swirl flow parameter, the ratio between the swirl and axial flow loss coefficients change along the diffuser are presented. Among other values: the Boussinesq number, outlet Coriolis coefficient and swirl flow loss coefficient dependences on inlet swirl flow parameter are also given. The swirl flow specific energy and outlet Coriolis coefficient calculation procedure are presented in this paper, as well as experimental test bed and measuring procedures. The swirl flow fields were induced by the axial fan impeller. Various swirl parameters were achieved by the impeller openings and rotational speeds.
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Baun, Daniel O., Lutz Ko¨stner, and Ronald D. Flack. "Effect of Relative Impeller-to-Volute Position on Hydraulic Efficiency and Static Radial Force Distribution in a Circular Volute Centrifugal Pump." Journal of Fluids Engineering 122, no. 3 (May 15, 2000): 598–605. http://dx.doi.org/10.1115/1.1287852.
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The hydraulic performance and radial hydraulic force characteristics of a circular volute centrifugal pump are strongly affected by the impeller to volute relative position. For a typical design configuration the geometric center of the impeller will be coincident with the volute geometric center. However, assembling a circular volute pump with the impeller center eccentric from the volute center can radically alter both the hydraulic performance and the radial hydraulic force characteristics. In particular, at the design flow coefficient an optimum impeller to volute relative position exists where the efficiency is maximized and the resultant radial force is minimized. At the optimal relative position a 5 percent and a 3.5 percent increase in the efficiency was realized compared to the centered positions for the circular and spiral volutes, respectively. In addition the nondimensional resultant radial force at the design flow coefficient was reduced from 0.045 at the centered position to 0.005 at the optimal position for the circular casing. This value of radial thrust is similar in magnitude to the radial thrust for the spiral volute operating at the design flow coefficient. By assembling a circular volute pump with the appropriate relative impeller to volute position the design simplicity of a circular volute can be utilized without compromising pump hydraulic performance or radial force characteristics as compared to a typical spiral volute. [S0098-2202(00)02303-8]
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Akin, O., and D. Rockwell. "Actively Controlled Radial Flow Pumping System: Manipulation of Spectral Content of Wakes and Wake-Blade Interactions." Journal of Fluids Engineering 116, no. 3 (September 1, 1994): 528–37. http://dx.doi.org/10.1115/1.2910309.
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A unique, actively controlled pumping system allows independent control of inflow and impeller perturbations, as well as the phase shift between them. The basic configurations of an impeller and an impeller-diffuser blade system have been investigated, with the objective of manipulating the spectral content of the unsteadiness of the near-wake at the impeller discharge. Substantial alteration of the discrete spectral components can be attained. A central feature is the generation of a number of nonlinear interaction components, corresponding to sum and difference frequencies, of the forcing- and blade passing-frequencies and their harmonics. With proper choice of perturbation conditions, it is possible to attenuate the inflow perturbation, as well as to alter the magnitudes of the blade passing component and its harmonics.
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Šulc, Radek, Pavel Ditl, Ivan Fořt, Darina Jašíkova, Michal Kotek, Václav Kopecký, and Bohuš Kysela. "Local velocity scaling in an impeller discharge flow in T400 vessel agitated by tooth impeller in a fully turbulent region." EPJ Web of Conferences 180 (2018): 02102. http://dx.doi.org/10.1051/epjconf/201818002102.
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Hydrodynamics and flow field were measured in an agitated vessel using 2-D Time Resolved Particle Image Velocimetry (2-D TR PIV). The experiments were carried out in a fully baffled cylindrical flat bottom vessel 400 mm in inner diameter agitated by a tooth impeller 133 mm in diameter. The velocity fields were measured in the impeller discharge flow for impeller rotation speeds from 300 rpm to 700 rpm and three liquids of different viscosities (i.e. (i) distilled water, ii) a 28% vol. aqueous solution of glycol, and iii) a 43% vol. aqueous solution of glycol), corresponding to the impeller Reynolds number in the range 68 000 < Re < 221 000. This Re range secures the fully-developed turbulent flow of agitated liquid. In accordance with the theory of mixing, the dimensionless mean and fluctuation velocities in the measured directions were found to be constant and independent of the impeller Reynolds number. On the basis of the test results the spatial distributions of dimensionless velocities were calculated. The radial turbulence intensity was found to be in the majority in the range from 0.3 to 0.9, which corresponds to the high level of this quantity.
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Fu, Zong-Fu, Zhen Cui, Wen-Hong Dai, and Yue-Jun Chen. "Discharge Coefficient of Combined Orifice-Weir Flow." Water 10, no. 6 (May 28, 2018): 699. http://dx.doi.org/10.3390/w10060699.
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Baun, Daniel O., and Ronald D. Flack. "Effects of Volute Design and Number of Impeller Blades on Lateral Impeller Forces and Hydraulic Performance." International Journal of Rotating Machinery 9, no. 2 (2003): 145–52. http://dx.doi.org/10.1155/s1023621x03000137.
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A comparison is made between the characteristics of the measured lateral impeller forces and the hydraulic performances of a four- and a five-vane impeller, each operating in a spiral volute, a concentric volute, and a double volute. The pump's rotor was supported in magnetic bearings. In addition to supporting and controlling the rotor motion, the magnetic bearings also served as active load cells and were used to measure the impeller forces acting on the pump's rotor. The lateral impeller force characteristics, as a function of a normalized flow coefficient, were virtually identical in the four- and five-vane impellers in each respective volute type. The measured impeller forces for each volute type were compared with correlations in the literature. The measured forces from the double volute configurations agreed with the forces from a correlation model over the full flow range. Single volute configurations compared well with the predictions of a published correlation at high flow rates,ϕ/ϕn>0.5. Concentric volute configurations compared well with a published correlation at low flow rates,ϕ/ϕn<0.4. The head-versus-flow characteristics of the four-vane impeller in each volute type were stable over a greater flow range than the corresponding characteristics of the five-vane impeller. At higher flow rates in the stable region of the head's characteristic curves near the best efficiency point, the five-vane impeller produced higher head than did the four-vane impeller in each volute type.
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Zhao, Xiaoran, Zhengwei Wang, Yexiang Xiao, and Yongyao Luo. "Thermodynamic analysis of energy dissipation and unsteady flow characteristic in a centrifugal dredge pump under over-load conditions." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 13 (January 10, 2019): 4742–53. http://dx.doi.org/10.1177/0954406218824350.
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The present paper aims to investigate the energy dissipation related to unsteady flow phenomena inside a three-bladed impeller of a centrifugal dredge pump under over-load operating conditions. Three-dimensional unsteady numerical simulations of the centrifugal pump are performed by adopting the SAS SST-curvature correction turbulence model with the total energy equation. The simulating results are verified by comparing the performance results and pressure fluctuation with available experimental data. The unsteady flow patterns and energy dissipation in the rotating impeller are analysed by entropy distribution and pressure fluctuation spectra. A high-entropy area appears in the impeller flow passage when the discharge increases. It is indicated in the unsteady simulation results that a vortex flow with high entropy generates and detaches periodically, which causes the hydraulic energy loss under over-load operating conditions. In numerical simulations, a frequency as 3.3 times of rotating frequency is found in the pressure spectral analysis at 1.45 Q0 operating condition, which is related to the unsteady flow structure. The secondary flow near the volute tongue is found at 1.45 Q0 operating condition due to the large angle of attack when discharge increases.
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Shi, Xiaobing, Jinling Lu, and Lianming Zhao. "Investigations on the influence of tandem blades on inner flow and performance characteristics of centrifugal pump." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 234, no. 1 (October 23, 2019): 46–55. http://dx.doi.org/10.1177/0954408919883730.
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Although significant advances have been made in tandem-blade technology for axial and centrifugal compressors, little attention has been paid to its application in centrifugal pumps. In this study, we propose a new tandem-blade design method for improving inner flow characteristics and overall performance of a centrifugal pump. With the SST k − ω turbulence model, three-dimensional turbulent flow fields in the centrifugal pump with tandem blades are simulated and analyzed. The effects of tandem blades on the inner flow and performance characteristics of the centrifugal pump are investigated. The predicted velocity and pressure distributions and flow behavior of the tandem-blade impeller are compared with those of a conventional single row blade impeller. It is indicated that the centrifugal tandem-blade impeller exhibits a significant advantage in terms of the uniformity of the impeller discharge flow. The tandem blades improve the jet-wake structure and uniformity of velocity and pressure distributions at the impeller outlet, and thus reduce the pressure fluctuation and hydraulic loss. Moreover, the hump phenomenon is eliminated or alleviated under low flow rate conditions, and the tandem-blade impeller has better hydraulic performance within a wider operating range as well as high reliability. This study provides a basis for the further development of the centrifugal pump with tandem blades.
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Ishida, M., H. Ueki, and Y. Senoo. "Effect of Blade Tip Configuration on Tip Clearance Loss of a Centrifugal Impeller." Journal of Turbomachinery 112, no. 1 (January 1, 1990): 14–18. http://dx.doi.org/10.1115/1.2927412.
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According to the theory presented by the authors, the tip clearance loss of an un-shrouded centrifugal impeller mainly consists of two kinds of loss; one is the drag due to the leakage flow through the blade tip clearance and the other is the pressure loss to support the fluid in the thin annular clearance space between the shroud and the blade tip against the pressure gradient in the meridional plane without blades. The former is proportional to the leakage flow or the contraction coefficient of leakage flow. The authors have conducted performance tests using an impeller with 16 backward-leaning blades in three configurations of the blade tip: round edge, sharp square edge, and edge with an end-plate. The experimental tip clearance effects can be predicted by the theory assuming reasonable contraction coefficients. They are 0.91, 0.73, and 0.53 for the respective tip configurations. The impeller efficiency is improved by about 1.5 point by reducing the contraction coefficient from 0.91 to 0.53, providing that the tip clearance ratio at the exit of impeller is 0.1. More improvement is expected for an impeller with highly loaded blades where the leakage loss shares the major part of the tip clearance loss.
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Li, Xiaojian, Yijia Zhao, Zhengxian Liu, and Hua Chen. "A new methodology for preliminary design of centrifugal impellers with prewhirl." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, no. 3 (July 24, 2019): 251–62. http://dx.doi.org/10.1177/0957650919864193.
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The overall trend of centrifugal compressor design is to strive for high aerodynamic performance and high flow capacity products. A new methodology is derived to implement a preliminary design for high flow capacity centrifugal impeller with and without prewhirl. First, several new non-dimensional equations connecting impeller geometric and aerodynamic parameters are derived for the maximum flow capacity. The effects of prewhirl on mass flow function, inlet diameter ratio and work coefficient are discussed, respectively. Then, based on these equations, a series of design diagrams are drawn to extract the universal rules in centrifugal impeller design with prewhirl. Some physical limits of design maps are also discussed. Finally, the throat area of impeller is discussed under prewhirl, and the matching principle between prewhirl impeller and vaned diffuser is derived and validated. The proposed method can be used to design a new centrifugal compressor, or to evaluate the design feasibility and the challenge of a given design specification.
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Kartashov, Sergey, Yuri Kozhukhov, Vycheslav Ivanov, Aleksei Danilishin, Aleksey Yablokov, Aleksey Aksenov, Ivan Yanin, and Minh Hai Nguyen. "The Problem of Accounting for Heat Exchange between the Flow and the Flow Part Surfaces When Modeling a Viscous Flow in Low-Flow Stages of a Centrifugal Compressor." Applied Sciences 10, no. 24 (December 21, 2020): 9138. http://dx.doi.org/10.3390/app10249138.
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In this paper, we review the problem of accounting for heat exchange between the flow and the flow part surfaces when creating a calculation model for modeling the workflow process of low-flow stages of a centrifugal compressor using computational fluid dynamics (CFD). The objective selected for this study was a low-flow intermediate type stage with the conditional flow coefficient Փ = 0.008 and the relative width at the impeller exit b2/D2 = 0.0133. We show that, in the case of modeling with widespread adiabatic wall simplification, the calculated temperature in the gaps between the impeller and the stator elements is significantly overestimated. Modeling of the working process in the flow part was carried out with a coupled heat exchanger, as well as with simplified accounting for heat transfer by setting the temperatures of the walls. The gas-dynamic characteristics of the stage were compared with the experimental data, the heat transfer influence on the disks friction coefficient was estimated, and the temperature distributions in the gaps between disks and in the flow part of the stage were analyzed. It is shown that the main principle when modeling the flow in low-flow stage is to ensure correct temperature distribution in the gaps.
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Kaupert, Kevin A., and Thomas Staubli. "The Unsteady Pressure Field in a High Specific Speed Centrifugal Pump Impeller—Part I: Influence of the Volute." Journal of Fluids Engineering 121, no. 3 (September 1, 1999): 621–26. http://dx.doi.org/10.1115/1.2823514.
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An experimental investigation is presented regarding the unsteady pressure field within a high specific speed centrifugal pump impeller (ωs = 1.7) which operated in a double spiral volute. For this, twenty-five piezoresistive pressure transducers were mounted within a single blade passage and sampled in the rotating impeller frame with a telemetry system. The influence of varying volume flux on the pressure transducers was evaluated in terms of pressure fluctuation magnitudes and phase differences. The magnitude information reveals that the pressure fluctuations from the impeller-volute interaction grew as the volume flux became further removed from the best efficiency point and as the trailing edge of the impeller blade was approached. These fluctuations reached 35% of the pump head in deep part load. The upstream influence of the volute steady pressure field dominates the unsteady pressure field within the impeller at all off design load points. Acquired signal phase information permits the identification of the pressure field unsteadiness within the impeller passage as fundamentally synchronized simultaneously with the volute tongue passing frequency. Special emphasis was placed on the volume flux regime where the pump and impeller pressure discharge characteristic undergo hysteresis, as impeller inlet and outlet recirculation commence and cease. A synthesis of the rotating transducers was performed to obtain unsteady blade loading parameters. The value of the unsteady lift coefficient varies on the order of 200% for a single blade in part load operation (at 45% bep), an abrupt fluctuation occurring as the fore running blade suction side passes a volute tongue. The unsteady moment coefficient and center of pressure are also shown to vary significantly during the impeller-volute tongue interaction.
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Karanth, K. Vasudeva, and N. Yagnesh 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." International Journal of Rotating Machinery 2009 (2009): 1–8. http://dx.doi.org/10.1155/2009/293508.
Full textAbstract:
The flow between the impeller exit and the diffuser entry (i.e., in the radial gap is generally considered to be complex). With the development of PIV and CFD tools such as moving mesh techniques, it is now possible to arrive at a prudent solution compatible with the physical nature of flow. In this work, numerical methodology involving moving mesh technique is used in predicting the real flow behavior, as exhibited when a target blade of the impeller is made to move past corresponding vane on the diffuser. Many research works have been undertaken using experimental and numerical methods on the impeller-diffuser interactive phenomenon. It is found from the literature that the effect of radial gap between impeller and diffuser on the interaction and on the performance of the fan has not been the focus of attention. Hence numerical analysis is undertaken in this work to explore and predict the flow behavior due to the radial gap. This has revealed the presence of an optimum radial gap which could provide better design characteristics or lower loss coefficient. It is found that there is a better energy conversion by the impeller and enhanced energy transformation by the diffuser, corresponding to optimum radial gap. The overall efficiency also found to increase for relatively larger gap.
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Yablokov, Aleksey, Ivan Yanin, Aleksey Danilishin, and Anatoliy Zuev. "Ansys CFX numerical study of stages centrifugal compressor with low-flow rate coefficient." MATEC Web of Conferences 245 (2018): 09002. http://dx.doi.org/10.1051/matecconf/201824509002.
Full textAbstract:
The article presents results of applying the methods of computational fluid dynamics for model low-flow rate stages of centrifugal compressors with flow rate coefficient F = 0.028. The computational domain of a model centrifugal compressor for CFD-simulation consists of the following elements: inlet chamber, impeller, vaneless diffuser, return channel, outlet chamber, shaft seal labyrinth, front and back shroud leakage. Full-scale experimental studies were conducted to model stage 028 in air at an inlet pressure of p* = 1 atm. Numerical research for stage 028 held with flow rate coefficient F=(0.019-0.046) for three variants trailing edge of the impeller. According to the results of numerical research are constructed performances of stages centrifugal compressor and conducted verification of results. Estimated discrepancy between the results of numerical researches on the model with shaft seal labyrinth and without shaft seal labyrinth.