Full Content is available to subscribers

Subscribe/Learn More  >

Unsteady Entropy Measurements in a High-Speed Radial Compressor

[+] Author Affiliations
M. Mansour, N. Chokani, A. I. Kalfas, R. S. Abhari

Swiss Federal Institute of Technology, Zürich, Switzerland

Paper No. GT2007-27450, pp. 625-637; 13 pages
  • ASME Turbo Expo 2007: Power for Land, Sea, and Air
  • Volume 1: Turbo Expo 2007
  • Montreal, Canada, May 14–17, 2007
  • Conference Sponsors: International Gas Turbine Institute
  • ISBN: 0-7918-4790-X | eISBN: 0-7918-3796-3
  • Copyright © 2007 by ASME


The time-dependent relative entropy field at the impeller exit of a centrifugal compressor is measured. This study is part of a broader effort to develop comprehensive measurement techniques that can be applied in the harsh environment of turbomachines. A miniature unsteady entropy probe (diameter 1.8mm) is designed and constructed in the present study. The unsteady entropy probe has two components: a one-sensor fast response aerodynamic probe and a pair of thin-film gauges. The time-dependent total pressure and total temperature are measured from the fast response aerodynamic probe and pair of thin-film gauges, respectively. The time-dependent relative entropy derived from these two measurements has a bandwidth of 40kHz and uncertainty of ±2J/kg. The measurements show that at the near design operating condition, the impeller exit flowfield is highly three-dimensional. Adjacent to the shroud there are high levels of relative entropy and at the mid-span there are low & moderate levels. Independent measurements made with a two-sensor aerodynamic probe show that the high velocity of the flow relative to the casing is responsible for the high relative entropy levels at the shroud. On the otherhand, at the mid-span, a loss free, jet flow region and a channel wake flow of moderate mixing characterize the flowfield. At both the shroud and mid-span, there are strong circumferential variations in the relative entropy. These circumferential variations are much reduced when the centrifugal compressor is operated near the onset of stall. In this condition the impeller exit flowfield is less highly skewed; however, the time-averaged relative entropy is higher than at the near design operating condition. The relative entropy measurements with the unsteady entropy probe are thus complementary to other measurements, and more clearly document the losses in the centrifugal compressor.

Copyright © 2007 by ASME



Interactive Graphics


Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

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 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