Variable pitch blades with cooling air control

摘要

In a gas turbine engine having a variable pitch rotatable airfoil, cooling air control means comprise a platform 26 fixedly attached to a radially inner end of each airfoil. The platform is generally positioned on a rotatable annular surface 16, which surface defines radially outer and inner spaces. In a first position (Figure 2 not shown), an edge portion of the platform substantially conforms to the annular surface. In a second position, the edge portion 38 is displaced radially outwardly from the surface thereby allowing cooling airflow from the outer to the inner spaces via the opening 40. In an alternative embodiment the opening 40 communicates with a diffuser for increasing the static pressure of the air flow.