Design and Experimental Validation of a Radial Air Turbine Wheel of an Air Starter for Fighter Aircraft Application

A radial Air Turbine Wheel (ATW) designed to operate at 60000 rpm has been analysed for LCF and HCF life. Frequency and mode shape evaluation including blade disk coupling at different nodal diameters is carried out to obtain a speed range without undesirable resonance conditions. Harmonic analysis evaluated the effects of forced response during resonance. Structural integrity during transient has been analysed and found free from set in of any transient effects. The ATW has been fabricated through forging route and its structural integrity has been validated at its operating speed as well as 15% and 22% overspeeds. Satisfactory performance during these tests without any distress has demonstrated the adequacy of design and qualification of the turbine wheel for fitment in the air starter. The turbine wheel is fitted in an air starter unit which was then successfully performed consistently over 100 start cycles before cleared for aircraft application.