ISSN Online: 2377-424X
ISBN Print: 0-89116-299-2
International Heat Transfer Conference 7
HEAT TRANSFER AT THE TIP OF AN UNSHROUDED TURBINE BLADE
Résumé
In gas turbine engines, the unshrouded blades of axial turbine stages rotate in close proximity to a stationary peripheral wall. The pressure difference between the suction and pressure sides of a blade induces a flow through the clearance gap between the blade tip and adjacent wall. Experience shows that the combination of temperature and heat transfer coefficient associated with the gap flow can often produce structural damage to the
blade tips. Knowledge of the basic heat transfer
characteristics of the gap flow are therefore important in design. The relative motion between the parallel walls of the gap is a complicating factor. This problem is of particular concern with smaller gap heights resulting from active clearance control used in some current engine designs. This paper presents theoretical arguments
and experimental results which help to specify the
probable temperature of the pressure side flow
entering the gap, and additionally show that the
blade tip heat transfer coefficients are essentially
independent of the relative motion between blade and stationary wall.