An investigation of finding the best arrangement of hot steam injection holes in the 3D steam turbine blade cascade

Steam turbines play a critical role in power generation systems. Therefore, increasing the efficiency of steam turbines is highly desirable, especially in LP stages. One of the suggested techniques to reduce wetness losses in LP stages is the hot steam injection. In the first section of the present study, the effect of 3D turbine blade span length on wet steam flow parameters is investigated. Then, the performance of various arrangements of hot steam injection holes (single slot, in-line no. 1, in-line no. 2, staggered no. 1, and staggered no. 2) is evaluated and compared. The results demonstrated that the in-line no. 1 arrangement is the best design for hot steam injection. In this arrangement, the wetness and condensation loss are reduced by 79% and 44%, respectively, and the kinetic energy loss is less than the other arrangements. However, the kinetic energy is still about 28% lower than in the no-injection case. Ultimately, excessive kinetic energy reduction due to hot steam injection is prevented by decreasing the injection pressure. As the injection pressure is reduced from 160 to 100 kPa, the kinetic energy, wetness, and condensation loss are reduced by 9%, 40%, and 17%, respectively, compared to the no-injection case.