Influence of casing roughness on the aerodynamic structure of tip vortices in an axial flow turbine

Nikhil M. Rao, Baris Gumusel, Levent Kavurmacioglu, Cengiz Camci*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

16 Citations (Scopus)


The aerodynamic influence of casing surface roughness on over-tip-leakage flow was investigated in a large scale, rotating, axial turbine rig. Phase-locked measurements of the absolute total pressure in a cold flow turbine research facility were conducted at the turbine stage exit using a high-frequency-response total pressure probe. Time accurate measurements provided valuable aerodynamic information quantifying the near tip flow modifications imposed by artificially roughened casing inner surface. A partial segment of the turbine casing was roughened by using a roughness layer of two different mean roughness heights. A smooth wall as a baseline case was also investigated by attaching a smooth layer of equivalent thickness to the casing surface. Artificially roughening the casing surface significantly reduced the leakage mass flow rate and the momentum deficit in the core of the tip vortex. The reductions obtained in the tip vortex size and strength influenced the tip-side passage vortex and other typical core flow characteristics in the passage. The influence of casing roughness was studied in a range of tip clearance values.

Original languageEnglish
Title of host publicationProceedings of the ASME Turbo Expo 2006 - Power for Land, Sea, and Air
Number of pages11
Publication statusPublished - 2006
Externally publishedYes
Event2006 ASME 51st Turbo Expo - Barcelona, Spain
Duration: 6 May 200611 May 2006

Publication series

NameProceedings of the ASME Turbo Expo
Volume6 PART A


Conference2006 ASME 51st Turbo Expo


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