The efficiency of gas turbine engines is strongly affected by the clearance between the rotating compressor or turbine blades and the stationary annulus around them. The most critical area is the high pressure turbine which, unfortunately, is the area where it is most difficult to make measurements, as the turbine blades run at temperatures in the region of 1000°C with hot gases containing unburnt fuel, soot etc., flowing over them at high pressure and speeds approaching sonic. The current trend is towards unshrouded blades, the efficiency of which is more strongly affected by tip clearance as the absence of the shroud creates overtip leakage (figure 1).

Date Published: 1 June 1988
PDF: 4 pages
Proc. SPIE 0863, Industrial Optoelectronic Measurement Systems Using Coherent Light, (1 June 1988); doi: 10.1117/12.943486

Published in SPIE Proceedings Vol. 0863:
Industrial Optoelectronic Measurement Systems Using Coherent Light
William F. Fagan, Editor(s)