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Journal of Mechanical Science and Technology

, Volume 33, Issue 11, pp 5261–5269 | Cite as

Improvement in stable operating range of a centrifugal compressor with leaned diffuser vanes

  • S. M. GunadalEmail author
  • M. Govardhan
Article
  • 6 Downloads

Abstract

The stable operating range of the centrifugal compressor is limited by stall or surge at lower mass flow rates and by choke at higher mass flow rates. The type of diffuser used has a strong influence on the performance of a centrifugal compressor. This paper presents a numerical investigation of the effect of the leaned vanes in the low solidity vaned diffuser on the stable operating range of a centrifugal compressor. The vanes in the low solidity vaned diffuser were leaned in the direction of impeller rotation by reducing their inlet angle from hub to shroud uniformly. Four cases of leaned vaned diffusers were configured downstream of the same impeller with different lean magnitude. The compressor stage with 6° leaned vaned diffuser gave an improvement of 19.3 % and 12.2 % in the stall margin and the operating range, respectively, over the stage with low solidity vaned diffuser.

Key words

Centrifugal compressor Low solidity vaned diffuser Leaned diffuser vanes Stall margin Choke margin Stable operating range 

Nomenclature

Cp

Pressure recovery coefficient

m

Mass flow rate (kg/s)

mn

Normalized mass flow rate (= m/md)

P

Pressure (Pa)

r

Radius (m)

T

Temperature (K)

y+

Normalized wall distance

Greek symbols

α

Absolute flow angle from tangential direction (deg.)

αb

Diffuser vane angle from tangential direction (deg.)

γ

Stagger angle from the tangential direction (deg.)

Δ

Change in any quantity

Subscripts

b

Blade/Vane

d

Design

t-s

Total to static

0

Total quantity

1

Impeller inlet

2

Impeller outlet

3

Diffuser inlet

4

Diffuser outlet

Abbreviations

CM

Choke margin (= (mchoke − mdesign)/mdesign)

LE

Leading edge

LSLVD

Low solidity leaned vaned diffuser

LSVD

Low solidity vaned diffuser

M

Mach number

SM

Stall margin (= (mdesign − mstall)/ mdesign)

TE

Trailing edge

VLD

Vaneless diffuser

VND

Vaned diffuser

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Copyright information

© KSME & Springer 2019

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringIndian Institute of Technology MadrasChennaiIndia

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