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Experiments and Computations on Large Tip Clearance Effects in a Linear Cascade

Williams, RJ; Gregory-Smith, DG; He, Li; Ingram, Grant


RJ Williams

DG Gregory-Smith

Li He


Large tip clearances typically in the region of 6% exist in the high pressure (HP) stages of compressors of industrial gas turbines. Due to the relatively short annulus height and significant blockage, the tip clearance flow accounts for the largest proportion of loss in the HP. Therefore increasing the understanding of such flows will allow for improvements in design of such compressors, increasing efficiency, stability, and the operating range. Experimental and computational techniques have been used to increase the physical understanding of the tip clearance flows through varying clearances in a linear cascade of controlled-diffusion blades. This paper shows two unexpected results. First the loss does not increase with clearances greater than 4% and second there is an increase in blade loading toward the tip above 2% clearance. It appears that the loss production mechanisms of the pressure driven tip clearance jet do not increase as the clearance is increased to large values. The increase in blade force is attributed to the effect of the strong tip clearance vortex, which does not move across the blade passage to the pressure surface, as is often observed for high stagger blading. These results may be significant for the design of HP compressors for industrial gas turbines.


Williams, R., Gregory-Smith, D., He, L., & Ingram, G. (2010). Experiments and Computations on Large Tip Clearance Effects in a Linear Cascade. Journal of Turbomachinery, 132(2), Article 021018.

Journal Article Type Article
Publication Date 2010-01
Journal Journal of Turbomachinery
Print ISSN 0889-504X
Electronic ISSN 1528-8900
Publisher American Society of Mechanical Engineers
Peer Reviewed Peer Reviewed
Volume 132
Issue 2
Article Number 021018