Table 4 shows the impeller maximum stress results when (a) only centrifugal force, (b) centrifugal force and thermal load, (c) centrifugal force and aerodynamic pressure, and (d) combination of loads are applied to the impeller. When only centrifugal force is applied, the
maximum stress of the blade type A and B is 170.5 MPa and 114.3 MPa, respectively. When combination loads are applied, the maximum stress is 141.7 MPa and 75.8 MPa. The 53.5% of the maximum stress in the blade type A under combination loads occurred at the blade root in the blade type B which has thicker blade hub thickness. Therefore, the blade type B has less deformation and stress under working condition compared to the blade type A. The maximum hub bore stress of blade type A and B is 88.2 MPa and 75.7 MPa for combined loads, respectively.