0
Research Papers

Large Eddy Simulation for a Deep Surge Cycle in a High-Speed Centrifugal Compressor With Vaned Diffuser

[+] Author and Article Information
Ibrahim Shahin

Mechanical and Industrial Engineering Department,
College of Engineering,
Qatar University,
Doha 2713, Qatar
Mechanical Engineering Department,
Shoubra Faculty of Engineering,
Benha University,
Benha, Egypt
e-mails: Ibrahimshahin@qu.edu.qa;
Ibrahim.shahin@feng.bu.edu.eg

Mohamed Gadala

Mechanical Engineering Department,
UBC-University of British Columbia,
Vancouver, BC V6T 1Z4, Canada
e-mail: gadala@mail.ubc.ca

Mohamed Alqaradawi

Mechanical and Industrial Engineering Department,
College of Engineering,
Qatar University,
Doha 2713, Qatar
e-mail: myq@qu.edu.qa

Osama Badr

Mechanical Engineering Department,
The British University in Egypt,
Alshorouk, New Cairo, Egypt
e-mail: osama.badr@Bue.edu.eg

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received September 20, 2014; final manuscript received June 2, 2015; published online June 23, 2015. Assoc. Editor: Ricardo F. Martinez-Botas.

J. Turbomach 137(10), 101007 (Jun 23, 2015) (15 pages) Paper No: TURBO-14-1249; doi: 10.1115/1.4030790 History: Received September 20, 2014

This paper presents a computational study for a high-speed centrifugal compressor stage with a design pressure ratio equal to 4, the stage consisting of a splittered unshrouded impeller and a wedged vaned diffuser. The aim of this paper is to investigate numerically the modifications of the flow structure during a surge cycle. The investigations are based on the results of unsteady three-dimensional, compressible flow simulations, using large eddy simulation (LES) model. Instantaneous and mean flow field analyses are presented in the impeller inducer and in the vaned diffuser region through one surge cycle time intervals. The computational data compare favorably with the measured data, from the literature, for the same compressor and operational point. The surge event phases are well detected inside the impeller and diffuser. The time-averaged loading on the impeller main blade is maximum near the trialing edge and near the tip. The amplitude of the unsteady pressure fluctuation is maximum for the flow reversal condition and reaches values up to 70% of the dynamic pressure. The diffuser vane exhibits high-pressure fluctuation from the vane leading edge to 50% of the chord length. High-pressure fluctuation is detected during the forward flow recovery condition as a result of the shock wave that moves toward the diffuser outlet.

Copyright © 2015 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 11

Dynamic pressure with the flow time at midspan point “1.08R2” for surge flow rate

Grahic Jump Location
Fig. 12

The FFT analysis for the pressure signal at surge flow rate

Grahic Jump Location
Fig. 13

Instantaneous static pressure in Pa at 95% span plane

Grahic Jump Location
Fig. 14

Dimensionless instantaneous velocity “V/U2” at 95% span plane

Grahic Jump Location
Fig. 4

Performance parameters at design flow rate with different number of computational nodes

Grahic Jump Location
Fig. 3

Mesh details at different locations inside the domain and boundary conditions

Grahic Jump Location
Fig. 2

Computational domain grid: (a) with casing removal and (b) without casing removal

Grahic Jump Location
Fig. 18

Dimensionless instantaneous axial velocity “Vaxial/U2” at 95% span plane

Grahic Jump Location
Fig. 16

Isosurface for instantaneous velocity in the diffuser

Grahic Jump Location
Fig. 10

Dynamic pressure with the flow time at midspan point “1.08R2” for design flow rate

Grahic Jump Location
Fig. 9

Area weighted average for the inst. static pressure at diffuser outlet plane and the mass flow rate at impeller with the flow time

Grahic Jump Location
Fig. 20

Impeller blade mean static pressure loading at: (a) 50% span and (b) 95% span

Grahic Jump Location
Fig. 8

Area weighted average for the mass flow rate at diffuser outlet

Grahic Jump Location
Fig. 7

Comparison of velocities measured [12] “right” and present simulation “left” in the vaned diffuser at different flow conditions during surge

Grahic Jump Location
Fig. 23

Diffuser vane RMS static pressure loading at: (a) 50% span and (b) 95% span

Grahic Jump Location
Fig. 6

Comparison of absolute velocities at 95% span plan at off design point: (a) URANS and (b) LES model

Grahic Jump Location
Fig. 5

Pressure ratio of the compressor stage for the present CFD results “URANS and LES models” and experimental results [11]

Grahic Jump Location
Fig. 17

Vorticity magnitude and relative velocity prior to surge

Grahic Jump Location
Fig. 1

The geometry of simulated parts: (a) 120 deg sector, (b) full domain, (c) enlarged view, and (d) view with casing removal

Grahic Jump Location
Fig. 21

Impeller blade RMS static pressure loading at: (a) 50% span and (b) 95% span

Grahic Jump Location
Fig. 22

Diffuser vane mean static pressure loading at: (a) 50% span and (b) 95% span

Grahic Jump Location
Fig. 19

Streamlines and velocity vectors in impeller inducer “95% span plane” at different surge phases

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In