Advanced firtree and broach slot forms for turbine stage 1 and 2 buckets and rotor wheels

摘要

A turbine bucket and wheelpost assembly reduces the number of buckets in at least one of the stages of the turbine from 92 to 60 while reducing stresses at the assembly points of the buckets and wheelposts. The buckets and wheelposts being formed with complementary fillets and tangs that provide for the insertion of the bucket into the broach slot between two wheelposts. The angles of the tang surfaces on both the bucket and wheelpost range from 50° to 57°. The upper surface of the wheelpost is scalloped to reduce weight and the tangs and fillets of both the bucket and wheelpost are formed from curved and straight surfaces to reduce stresses on the assembly.