Influence of an Inlet Rotating Axial Device on the Cavitation Processes in a Low Specific Speed Centrifugal Pump | Journal of Engineering Sciences

Influence of an Inlet Rotating Axial Device on the Cavitation Processes in a Low Specific Speed Centrifugal Pump

Author(s): Moloshnyi O. M.1*, Szulc P.2, Sotnyk M. I.1

Affiliation(s):
1 Sumy State University, 2 Rymskogo-Korsakova St., 40007 Sumy, Ukraine;
2 Wroclaw University of Science and Technology, 27 Wybrzeze Wyspianskiego St., 50-370 Wroclaw, Poland

*Corresponding Author’s Address: o.moloshnyi@outlook.com

Issue: Volume 6; Issue 1 (2019)

Dates:
Paper received: December 1, 2018
The final version of the paper received: March 21, 2019
Paper accepted online: March 26, 2019

Citation:
Moloshnyi, O. M., Szulc, P., Sotnyk, M. I. (2019). Influence of an inlet rotating axial device on the cavitation processes in a low specific speed centrifugal pump. Journal of Engineering Sciences, Vol. 6(1), pp. E25-E32, doi: 10.21272/jes.2019.6(1).e5

DOI: 10.21272/jes.2019.6(1).e5

Research Area:  MECHANICAL ENGINEERING: Computational Mechanics

Abstract. The paper is devoted to the analysis of the cavitation processes in the flow section of the low specific speed centrifugal pump. A new conception of double-entry hermetic pump leads to the application of special shaped inlet device, which is a part of an electrical motor rotating element. Four flow geometrical models of the axial inlet device were taken into consideration. The first model, treated as referential and basic, has a cylindrical shape with small diffuser and a cone in front on the impeller. Other three models consist of the motionless cone, which was part of the housing, straight pipe, and diffuser section rotating analogously to the impeller and a spherical fairing. The research was conducted using physical experiments and numerical simulations of the workflow in the ANSYS CFX software environment. The analysis of the results shows that the pump with the basic model of the inlet device has NPSH 3 % above the average values. The comparison between CFD and experiment of the cavitation curves shape showed its similarity but determined by means of the physical experiment have higher values. Cavitation in the impeller starts earlier than in the axial inlet device. The zones of the cavitation in the axial inlet device are located after the cone, at the beginning of the diffuser section and near the fairing at the outlet of the diffuser section. The cavitation zone, which is located after the cone, is separated from the walls of the axial inlet device. The value of the NPSH 3 % increases, when the diameter of the axial inlet device decreases, as the result of the raise of head loses in the inlet structure.

Keywords: inlet chamber, inlet nozzle, intake section, suction casing, cone, diffuser, CFD, NPSH, cavitation performance.

References:

  1. Guo, X., Guo, X., Zhu, Z., Cui, B., & Li, Y. (2012). Analysis of cavitation performance of inducers, centrifugal pumps. Centrifugal Pumps, doi: 10.5772/26744.
  2. Jiang, J., Sun, Q., Liu, Y., Chen, Y., & Yi, W. (2015). Numerical simulation of cavitation performance on a high-speed centrifugal pump with a variable pitch inducer. The 13th Asian International Conference on Fluid Machinery, Tokyo, Japan, September 7–10, 2015.
  3. Tkach, P. Y, (2017). Influence of geometry parameters of inducer bush design on cavitation erosion characteristics of centrifugal inducer stage of pump. IOP Conference Series: Materials Science and Engineering, Vol. 233, doi: 10.1088/1757-899X/233/1/012012.
  4. Si, Q., Yuan, S., Yuan, J., & Bois, G. (2016). Investigation on the influence of jetting equipment on the characteristics of centrifugal pump. Advances in Mechanical Eng, Vol. 8(8), pp. 1–11, doi: 10.1177/1687814016660287.
  5. Tan, L.., Zhu, B., Cao, S., Wang, Y., & Wang, B. (2014). Influence of prewhirl regulation by inlet guide vanes on cavitation performance of a centrifugal pump. Energies, Vol 7, pp. 1050–1065, doi: 10.3390/en7021050.
  6. Tan, L., Zha, L., Cao, S. L., Wang, Y. C., & Gui, S. B, (2015). Cavitation performance and flow characteristic in a centrifugal pump with inlet guide vanes. International Symposium of Cavitation and Multiphase Flow (ISCM 2014) IOP Conference Series: Materials Science and Engineering, Vol. 72, http://iopscience.iop.org/1757-899X/72/3/032028.
  7. Skerlavaj, A., & Pavlin, R. (2014). Effect of vortical structures on cavitation on impeller blades in pumps with suction chambers. IOP Conference Series: Earth and Environmental Science, 27th IAHR Symposium on Hydraulic Machinery and Systems, Vol. 22, doi: 10.1088/1755-1315/22/5/052002.
  8. Nagahara, T., Sato, T., & Okamura, T. (2003). Measurement of the flow around the submerged vortex cavitation in a pump intake by means of PIV. Fifth International Symposium on Cavitation (cav2003).
  9. Sikora, R., Burecek, A., Hruzik, L., & Vasina, M. (2015). Experimental investigation of cavitation in pump inlet. EPJ Web of Conferences, Vol. 22, doi: 10.1051/epjconf/20159202081.
  10. Cunha, M. A. R., & Nova, H. F. V. (2013). Cavitation modelling of a centrifugal pump impeller. 22–nd International Congress of Mechanical Engineering, San Paulo, Brazil, pp. 1633–1644.
  11. Hergt, P., Nicklas, A., Mollenkopf, G., & Brodersen, S. (1996). The suction performance of centrifugal pumps possibilities and limits of improvements. Proceedings of the International Pump Users Symposium, Texas A&M University System, 13–26.
  12. Gulich, J. F. (2014). Centrifugal Pumps. Springer, Berlin, Heidelberg, New York, doi: 10.1007/978-3-642-40114-5.
  13. Limbach, P., Muller, T., Blume, M., & Skoda R. (2016). Numerical and experimental investigation of the cavitation flow in a low specific speed centrifugal pump and assessment of the influence of surface roughness on head prediction. International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, Hawaii.
  14. Moloshnyi, O., & Sotnyk, M. (2017). Cavitation in centrifugal pump with rotating walls of axial inlet device. IOP Conference Series: Materials Science and Engineering, Vol. 233, doi: 1088/1757-899X/233/1/012007.
  15. Moloshnyi, O., & Sotnyk, M. (2018) Influence of geometric dimensions of inlet device on the operating process of the pump. Industrial Hydraulics and Pneumatics, Vol 3(61) [in Ukrainian].

Full Text



© 2014-2019 Sumy State University.
Scientific journal "Journal of Engineering Sciences"
ISSN 2312-2498 (Print), ISSN 2414-9381 (Online).
All rights reserved.