0
Research Papers: Flows in Complex Systems

Influence of Changing Casing Groove Parameters on the Performance of Centrifugal Compressors Near Stall Condition

[+] Author and Article Information
Taher Halawa

Mechanical Engineering Department,
UBC—University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
Mechanical Engineering Department,
Cairo University,
Giza 12316, Egypt
e-mail: taherhalawa@alumni.ubc.ca

Mohamed S. Gadala

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

Mohamed Alqaradawi

Mechanical & Industrial Engineering Department,
Qatar University,
Al Tarfa, Doha 2713, Qatar
e-mail: myq@qu.edu.qa

Osama Badr

Mechanical Engineering Department,
British University in Egypt,
Al-Shorouk City 11837, Egypt
e-mail: osama.badr@Bue.edu.eg

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received January 13, 2015; final manuscript received August 10, 2015; published online September 10, 2015. Assoc. Editor: D. Keith Walters.

J. Fluids Eng 138(2), 021104 (Sep 10, 2015) (13 pages) Paper No: FE-15-1050; doi: 10.1115/1.4031311 History: Received January 13, 2015; Revised August 10, 2015

The casing treatment is an effective method for increasing the stall margin of compressors and enhancing the flow distribution at the blades tip. The present numerical study focuses on making an optimization of the casing groove parameters which can enhance the centrifugal compressor performance during stall. The casing grooves parameters considered are the groove cross section aspect ratio (the groove height to width ratio), groove location, and the number of grooves. Five groove aspect ratios were considered ranging from 0.2 to 1.8. Three groove locations were studied: at full blades leading edge, at splitter blades leading edge, and after the splitter blades leading edge by a distance equals to the distance between the first and second groove locations. Comparisons were made among different cases with number of grooves starting from one up to seven grooves located at the most effective locations and have the optimum cross section dimensions as deduced from the results of the groove aspect ratio and groove location optimization. Results showed that by using groove aspect ratio less than one, the reinjected groove flow is relatively weak but when the aspect ratio is equal to one, there is enough space inside the groove for the flow to circulate and generate the reinjected groove flow with higher velocities. When the groove aspect ratio was increased to be more than one, the reinjected flow velocity was increased slightly and its effective area was increased in the circumferential direction. Results also indicated that the best location for the groove is at the full blades leading edge because the stall area can be minimized and controlled in a better way comparing with the other groove locations. Results showed that by increasing the number of grooves, the surge margin (SM) increases and the isentropic efficiency decreases, but the stall area at the shroud surface decreases in size and its location is shifted toward the blades trailing edge.

Copyright © 2016 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

NASA CC3 centrifugal compressor shape [29]: (a) cross section view and (b) internal 3D view

Grahic Jump Location
Fig. 2

The numerical model used for the simulations of the groove aspect ratio variation

Grahic Jump Location
Fig. 3

The numerical model used for the simulations of the groove location variation: (a) location 1, (b) location 2, and (c) location 3

Grahic Jump Location
Fig. 4

The numerical models used for the simulations of changing the number of grooves with: (a) one groove, (b) three grooves, (c) five grooves, and (d) seven grooves

Grahic Jump Location
Fig. 5

Mesh configuration for the model of using seven grooves

Grahic Jump Location
Fig. 6

Compressor pressure and efficiency maps (numerical results versus measurements [37])

Grahic Jump Location
Fig. 7

Mean velocity variation with the percentage of meridional distance (numerical results versus measurements [26])

Grahic Jump Location
Fig. 8

Normalized pressure variation with the normalized meridional distance at the impeller tip (numerical results versus measurements [38])

Grahic Jump Location
Fig. 9

Velocity profile from hub to tip at the vaneless region at radius ratio of 1.1 (numerical results versus measurements [39])

Grahic Jump Location
Fig. 10

Pressure and Mach number contours for the current model results and for the previous CFD model results [40]

Grahic Jump Location
Fig. 11

Velocity at the diffuser different times of the surge cycle (numerical results versus measurements [32]): (a) surge cycle curve (measurements), (b) surge cycle (numerical results), (c) point A (measurements), (d) point A (CFD results), (e) point B (measurements), (f) point B (CFD results), (g) point C (measurements), and (h) point C (CFD results)

Grahic Jump Location
Fig. 12

Velocity contours at a plane perpendicular to the axial direction with the clarification of the velocity vectors inside the groove for various groove aspect ratio values of: (a) 0.2, (b) 0.6, (c) 1, (d) 1.4, and (e) 1.8

Grahic Jump Location
Fig. 13

Radial velocity variation with the circumferential angle for three different groove aspect ratio values

Grahic Jump Location
Fig. 14

Mach number values at 99% of the impeller span for three different groove locations: (a) location 1, (b) location 2, and (c) location 3

Grahic Jump Location
Fig. 15

Static pressure variation in the circumferential direction at the blades leading edge at 99% of span

Grahic Jump Location
Fig. 16

Velocity stream lines at 98% of span with different number of grooves for the cases of: (a) smooth casing, (b) one groove, (c) three grooves, (d) five grooves, and (e) seven grooves

Grahic Jump Location
Fig. 17

Average velocity contours at the impeller meridional plane with different number of grooves for the cases of: (a) smooth casing, (b) one groove, (c) three grooves, (d) five grooves, and (e) seven grooves

Grahic Jump Location
Fig. 18

Pressure variation with the normalized meridional distance for the cases of smooth casing and for the cases with five and seven grooves

Grahic Jump Location
Fig. 19

The effect of using different groove parameters on the flow angle at the diffuser inlet

Grahic Jump Location
Fig. 20

Impeller blade loading for the case of smooth casing and for the case of seven grooves with aspect ratio of 1

Grahic Jump Location
Fig. 21

Pressure ratio variation with mass flow rate for cases with different number of grooves and for the smooth casing case

Grahic Jump Location
Fig. 22

Total-to-total isentropic efficiency for cases with different number of grooves at the last stable operating condition near surge

Grahic Jump Location
Fig. 23

Description of the stall onset mechanism for the smooth casing case and for other cases with different casing grooves parameters: (a) stall inception for the case of no grooves, (b) effect of changing groove location, (c) effect of changing groove geometry, and (d) effect of using multiple grooves

Grahic Jump Location
Fig. 24

Velocity vectors inside the grooves and at a plane near the shroud surface at the best efficiency operating condition

Grahic Jump Location
Fig. 25

Velocity vectors inside the grooves and at a plane near the shroud surface at the stall operating condition

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