Effect of an Axially Offset Impeller on the Transient Physics of Asymmetric Flow in a Double-suction Centrifugal Fan

Document Type : Regular Article

Authors

Zhejiang Key Laboratory of Multiflow and Fluid Machinery, Zhejiang Sci-Tech University, Hangzhou, Zhejiang 310018, China

10.47176/jafm.18.7.3184

Abstract

The impeller of a double-suction centrifugal fan may be subject to axial offset due to assembly or operational failure. The internal flow is asymmetric about the central disc and deteriorates the fan’s performance. In this work, the characteristics of flow were numerically investigated for the baseline model (Model-BM) and the axially offset impeller model (Model-Offset). The objective and motivation are to provide a detailed assessment and quantification of the effect of offset impeller on the fan’s performance and transient physics of the asymmetric flow. The numerical data reveal that the offset impeller generates highly asymmetric flow. The difference in mean flow rate at the two inlets of Model-Offset is 25.02m³/h, accounting for 6.8% of the total flow rate. The static pressure rise reduces by 2.40% for Model-Offset, and the static pressure efficiency is reduced by 2.11%. The leakage flow gets pronounced in the enlarged clearance with the inward and outward motion of air, while the narrowed clearance blocks it. The reversed flow is significant in the NA-side blade passages, especially close to the impeller end ring, where the leakage flow and the volute tongue confinement dominate. The reversed flow persists throughout the impeller, is still evident as the air first enters the volute, and is significant on the NA-side of the fan outlet.

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Chen, Z. Y., He, H., Yang, H., Wei, Y. K., & Zhang, W. (2024). Asymmetric flow in a double-suction centrifugal fan induced by an inclined impeller. Physics of Fluids, 36, 017113. https://doi.org/10.1063/5.0178927
Chen, Z. Y., Yang, H., Wei, Y. K., He, H. J., Zhang, C. Y., Nie, T. H., Yu, P. Q., & Zhang, W. (2022). Effect of a radially offset impeller on the unsteady characteristics of internal flow in a double-suction centrifugal fan. Processes, 10, 1604. http://dx.doi.org/10.3390/PR10081604
Deng, Q. F., Pei, J., Wang, W. J., & Sun, J. (2023). Investigation of energy dissipation mechanism and the influence of vortical structures in a high-power double-suction centrifugal pump. Physics of Fluids, 35, 075147. https://doi.org/10.1063/5.0157770
Ding, J., Du, X., Zhang, L. X., Jiang, T., & Wang, S. T. (2012). Investigation of the effect of volute openness on aerodynamic characteristics of a centrifugal fan. Chinese Journal of Turbomachinery, 5, 22–26. (in Chinese). http://dx.doi.org/10.3969/j.issn.1006-8155.2012.05.005
Gangipamula, R., Ranjan, P., & Patil, R. S. (2022). Study of rotor-stator interaction phenomenon in a double-suction centrifugal pump with impeller vane trailing edge as a design parameter. Physics of Fluids, 34, 095131. https://doi.org/10.1063/5.0105576
González, J., Parrondo, J., Santolaria, C., & Blanco, E. (2006). Steady and unsteady radial forces for a centrifugal pump with impeller to tongue gap variation. Journal of Fluids Engineering, 128, 454-462. https://doi.org/10.1115/1.2173294
He, C., Han, W., Li, R., Dong, Y. & Zhang, Y. (2025) Multi-objective optimization and performance analysis of the splitter blades in a multiphase pump. International Journal of Fluid Engineering, 2, 013501. https://doi.org/10.1063/5.0229988
Jin, J. M., Jung, K. J., Kim, Y. H., & Kim, Y. J. (2020). Effects of gap between impeller and volute tongue on pressure fluctuation in double-suction pump. Journal of Mechanical Science and Technology, 34, 4897-4903. http://doi.org/10.1007/s12206-020-2102-3
Lee, Y. T. (2010). Impact of fan gap flow on the centrifugal impeller aerodynamics. Journal of Fluids Engineering, 132, 091103. https://doi.org/10.1115/1.4002450
Lei, L., Wang, T., Qiu, B., Yu, H., Liu, Y. Q., & Dong, Y. C. (2024). The influence of ring clearance on the performance of a double-suction centrifugal pump. Physics of Fluids, 36, 025133. https://doi.org/10.1063/5.0188087
Li, W. (2025) Performance of vortex pump in CFD simulations with rough walls. International Journal of Fluid Engineering, 2, 013902. https://doi.org/10.1063/5.0237732
Li, Z. H., Ye, X. X., & Wei, Y. K. (2020). Investigation on vortex characteristics of a multiblade centrifugal fan near volute outlet region. Processes, 8, 1240. https://doi.org/10.3390/pr8101240
Lilly, K. (1992). A proposed modification of the Germano subgrid-scale closure method. Physics of Fluids, 4, 633–635. https://doi.org/10.1063/1.858280
Liu, H., Jiang, B. Y., Wang, J., Yang, X. P., & Xiao, Q. H. (2021). Numerical and experimental investigations on non-axisymmetric D-type inlet nozzle for a squirrel-cage fan. Engineering Applications of Computational Fluid Mechanics, 15, 363–376. https://doi.org/10.1080/19942060.2021.1883115
Liu, X. M., Dang, Q., & Xi, G. (2008). Performance improvement of centrifugal fan by using CFD. Engineering Applications of Computational Fluid Mechanics, 2, 130–140. https://doi.org/10.1080/19942060.2008.11015216
Liu, Z., Wang, Z., Du, S., Yang, H., Wei, Y., & Zhang, W. (2024). Orthogonal optimization design of a Sirocco fan and numerical analysis on the internal flow characteristics, Journal of Power and Energy, 238, 90-110.https://doi.org/10.1177/09576509231195120
Lu, J., Qian, L., Liu, X., & Choi, Y. (2024) Characterization of energy loss in jet mechanism of a Pelton turbine. International Journal of Fluid Engineering, 1, 033502. https://doi.org/10.1063/5.0209402
Lv, Y. K., Zhang, B., & Cheng, B. (2014). The optimal research on impeller central location of centrifugal fan. Applied Mechanics and Materials, 668-669, 729-732. https://doi.org/10.4028/www.scientific.net/AMM.668-669.729
Madhwesh, N., Karanth, K. V., & Sharma, N. Y. (2018). Effect of innovative circular shroud fences on a centrifugal fan for augmented performance: A numerical analysis. Journal of Mechanical Science and Technology, 32, 185–197. https://doi.org/10.1007/s12206-017-1220-z
Morinushi, K. (1987). The influence of geometric parameters on F. C. centrifugal fan noise. Journal of Vibration and Acoustics, 109, 227-234. https://doi.org/10.1115/1.3269425
Myung, H. J., & Baek, J. H. (1999). Mean velocity characteristics behind a forward-swept axial-flow fan. JSME International Journal Series B, 42, 476–488. https://doi.org/10.1299/jsmeb.42.476
Okauchi, H., Suzuka, T., Sakai, T., & Whitfield, A. (2002). The effect of volute tongue and passage configuration on the performance of centrifugal fan. International Compressor Engineering Conference, Paper No. 1502.
Pan, D., Whitfield, A., & Wilson, M. (1999). Design considerations for the volutes of centrifugal fans and compressors. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 213, 401–410. https://doi.org/10.1243/0954406991522356
Patil, S. R., Chavan, S. T., Jadhav, N. S., & Vadgeri, S. S. (2018). Effect of volute tongue clearance variation on performance of centrifugal blower by numerical and experimental analysis. Materials Today: Proceedings, 5, 3883-3894. https://doi.org/10.1016/j.matpr.2017.11.643
Rui, X. C., Lin, L. M., Wang, J. K., Ye, X. X., He, H. J., Zhang, W., & Zhu, Z. C. (2020). Experimental and comparative RANS/URANS investigations on the effect of radius of volute tongue on the aerodynamics and aeroacoustics of a Sirocco fan. Processes, 8, 1442. https://doi.org/10.3390/pr8111442
Samarbakhsh, S., & Alinejad, J. (2011). Experimental and numerical analysis of eight different volutes with the same impeller in a squirrel-cage fan. 2nd European Conference of Control and Mechanical Engineering, 198-203.
Smagorinsky, J. (1963). General circulation experiments with the primitive equations. I. The basic experiment. Monthly Weather Review, 91, 99–164. https://doi.org/10.1175/1520-0493(1963)091%3C0099:GCEWTP%3E2.3.CO;2
Sonawat, A., Kim, S., Ma, S. B., Kim, S.-J., Lee, J. B., Yu, M. S., & Kim, J. H. (2022). Investigation of unsteady pressure fluctuations and methods for its suppression for a double suction centrifugal pump. Energy, 252, 124020. https://doi.org/10.1016/j.energy.2022.124020
Song, Y., Fan, H. G., Zhang, W., & Xie, Z. F. (2019). Flow characteristics in volute of a double-suction centrifugal pump with different impeller arrangements. Energies, 12, 669. https://doi.org/10.3390/en12040669
Sun, L., An, C., Wang, N., Zhe, C., Wang, L., He, S., & Gao, M. (2021). Effect of the rotor blade installation angle on the structure-borne noise generated by adjustable-blade axial-flow fans, Physics of Fluids, 33, 095107. https://doi.org/10.1063/5.0065356
Versteeg, H. K., & Malalasekera, W. (2007). An Introduction to Computational Fluid Dynamics. Pearson Education, Essex, UK.
Wu, L.N., Liu, X. M., & Wang, M. H. (2020). Effects of bionic volute tongue on aerodynamic performance and noise characteristics of centrifugal fan used in the air-conditioner. Journal of Bionic Engineering, 17, 780-792. https://doi.org/10.1007/s42235-020-0067-7
Yang, X., Chen, W. M., Yuan, M. J., Wen, X. F., & He, M. (2011). Experimental study on the effect of relative impeller to volute position on the performance of multiblade centrifugal fan. Fluid Machinery, 39, 1-5. (in Chinese) http://dx.doi.org/10.3969/j.issn.1005-0329.2011.07.001
Ye, J. J., Liu, W. W., Duan, P., Huang, X. Y., Shao, J. D., & Zhang, Y. (2018). Investigation of the performance and flow behaviors of the multi-blade centrifugal fan based on computer simulation technology. Wireless Personal Communications, 103, 563–574. https://doi.org/10.1007/s11277-018-5461-7
Younsi, M., Bakir, F., Kouidri, S., & Rey, R. (2007). Numerical and experimental study of unsteady flow in a centrifugal fan. Journal of Power and Energy, 221, 1025-1036. https://doi.org/10.1243/09576509JPE445
Zhang, J. H., Chu, W. L., Zhang, H. G., Wu, Y. H., & Dong, X. J. (2016). Numerical and experimental investigations of the unsteady aerodynamics and aero-acoustics characteristics of a backward curved blade centrifugal fan. Applied Acoustics, 110, 256-267. https://doi.org/10.1016/j.apacoust.2016.03.012
Zhou, S. Q., Wang, M., Li, Z. Y., & Zhang, S. C. (2018). Influence of volute retrofit design on performance of multiblade centrifugal fan. Transactions of the Chinese Society of Agricultural Machinery, 49, 180-186. (in Chinese) http://dx.doi.org/10.6041/j.issn.1000-1298.2018.10.020