Accurate calculation of steam bending stress on control stage blade has important guiding significance to development of efficient and reliable control stage blades.Numerical simulation on 3Dsteady flow of a control stage blade with admission chamber in an ultra supercritical unit steam turbine was conducted

and the node steam force on the surface was extracted.Furthermore

interpolation procedures were compiled to transform the node steam force to the node force applied in the blade finite element model

and the steam bending stresses under conditions of 4valves open and 1valve open were calculated.The results show that

the maximum static pressure on the rotor blade surface under the above two conditions was 22.65 MPa and 17.76 MPa

respectively;the maximum static pressure on the stationary blade surface was 23.93 MPa and 23.95 MPa

respectively;the maximum steam bending stress under 1valve open condition was about 10 times larger than that under the 4valves open condition.