0
TECHNICAL PAPERS

Flow Mechanism for Stall Margin Improvement due to Circumferential Casing Grooves on Axial Compressors

[+] Author and Article Information
Aamir Shabbir

 University of Toledo and NASA Glenn Research Center, 21000 Brookpark Road, MS 5-9, Cleveland, OH 44135aamir.shabbir@grc.nasa.gov

John J. Adamczyk

 NASA Glenn Research Center, 21000 Brookpark Road, MS 5-9, Cleveland, OH 44135

J. Turbomach 127(4), 708-717 (Mar 01, 2004) (10 pages) doi:10.1115/1.2008970 History: Received October 01, 2003; Revised March 01, 2004

A computational study is carried out to understand the physical mechanism responsible for the improvement in stall margin of an axial flow rotor due to the circumferential casing grooves. Computational fluid dynamics simulations show an increase in operating range of the low speed rotor in the presence of casing grooves. A budget of the axial momentum equation is carried out at the rotor casing in the tip gap in order to understand the physical process behind this stall margin improvement. It is shown that for the smooth casing the net axial pressure force at the rotor casing in the tip gap is balanced by the net axial shear stress force. However, for the grooved casing the net axial shear stress force acting at the casing is augmented by the axial force due to the radial transport of axial momentum, which occurs across the grooves and power stream interface. This additional force adds to the net axial viscous shear force and thus leads to an increase in the stall margin of the rotor.

Copyright © 2005 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

A side view of the low speed axial compressor taken from Prahst and Strazisar (2003)

Grahic Jump Location
Figure 2

Pressure rise across the rotor with and without the casing circumferential grooves

Grahic Jump Location
Figure 3

A sketch of the grid cell illustrating the nomenclature of Eqs. 1,2,3 by using the example of net axial pressure force

Grahic Jump Location
Figure 4

A sketch illustrating the control volume at the casing used for analyzing the axial momentum equation

Grahic Jump Location
Figure 5

The balances of the axial momentum equation for the smooth casing control volume defined in Fig. 4. Note that the summation nomenclature ∑ in the figure means ∑θ,z.

Grahic Jump Location
Figure 6

A sketch illustrating the balance of axial momentum equation for the casing control volume for smooth casing as defined in Fig. 4

Grahic Jump Location
Figure 7

An oblique view of the blade-to-blade plane at the casing showing the radial velocity distribution

Grahic Jump Location
Figure 8

The balances of the axial momentum equation for the grooved casing control volume defined in Fig. 4. Note that the summation nomenclature ∑ in the figure means ∑θ,z.

Grahic Jump Location
Figure 9

A sketch illustrating the balance of axial momentum on the casing control volume with casing grooves as defined in Fig. 4

Grahic Jump Location
Figure 10

Evolution of the cumulative sum in the axial direction for the axial shear force and the force due to the radial transport of momentum for the control volume shown in Fig. 4. Note that before doing the axial sum, these quantities have already been summed in the tangential direction and the summation nomenclature ∑ in the figure legend means ∑θ.

Grahic Jump Location
Figure 11

The normalized axial velocity contours in an axial plane just downstream of the rotor trailing edge for smooth and grooved casing

Grahic Jump Location
Figure 12

Comparison of blockage growth as function of flow coefficient for smooth and grooved casings. Flow blockage is defined as (ABlocked∕ATotalPassage)×100.

Grahic Jump Location
Figure 13

Speedline corresponding to zero shear at the casing wall

Grahic Jump Location
Figure 14

The normalized axial velocity contours in an axial plane just downstream of the rotor trailing edge for the case of zero shear at the casing wall. See Fig. 5 for scale.

Grahic Jump Location
Figure 15

Comparison of blockage growth as function of flow coefficient for smooth casing and zero shear casing. Flow blockage is defined as (ABlocked∕ATotalPassage)×100.

Grahic Jump Location
Figure 16

Comparison of the pressure rise coefficient of the four grooved casing with the five grooved casing

Grahic Jump Location
Figure 17

Evolution of the cumulative sum in the axial direction for the axial shear force and the force due to the radial transport of momentum for the control volume shown in Fig. 4 for the four casing grooves configuration

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