Numerical Verification Of Blade Desigh For A Million Uniits

Development of ultra supercritical steam turbine generator is one of the important measures to realize the national energy saving and emission reduction targets in the electric power industry. In order to reduce the manufacturing cost of the unit, the large enthalpy drop blades are often used in the core components of the unit. Through digestion and absorbing of the foreign advanced technology of large enthalpy drop blade design, the scientific and technical personnel of Harbin Turbine Co., Ltd. have designed the new type of 1000 MW ultra super critical unit with the large enthalpy drop blades. Before applying it to engineering practice, it is urgent to verify whether aerodynamic performance meets the design objectives. Under a medium pressure stage environment of the ultra supercritical 1000 MW unit, it was numerically studied that the change of aerodynamic performance with the incidence and Mach number in this paper.The results of numerical simulation show that, under the design Mach number and 0 degree incidence, it was used that after loading profiles at two ends of the large enthalpy drop blade and the front loaded profiles at the blade middle, the blade selection for this type of loading has ensured the high load and high efficiency of the cascade. The flow incidence is increased from-40o to +40o, and the aerodynamic load of the blade is increased. In the range of positive incidences, with the increase of incidence, the local pressure fluctuation at the leading edge of the blade suction side is increased, and the minimum pressure point is moved to the front. In the range of negative incidence, with the increase of the absolute value of incidence, the pressure in front of the pressure side has a sudden decrease and the increase, the minimum pressure point of suction side is little changed. Compared with the zero incidence, the channel vorticites are increased as the positive incidence increases, the increase rate of the secondary flow losses is more and more quickly,the aerodynamic performance of the cascade is rapidly deteriorated. On the contrary, the greater the negative incidence is, the lower the channel vorticites is, the higher the boundary layer losses are, the latter slightly more than the former, and the total flow loss of the cascade is increased slowly.The numerical evaluation of change Mach number in the Large enthalpy drop static cascade show that, with exit Mach number was increased from 0.1 to 0.6, the minimum pressure point at the suction side is shifted to the trailing edge, this shows that all profiles along the blade height are more and more after loading, the gas dynamic load of each blade decreases gradually, the whole cascade gas dynamic load increases due to the increase of mass flow through the cascade. Because of the increase of the Mach number, the thickness of the boundary layer decreases, and the profiles are further after loading, the profile losses and the secondary losses are all decreased. From the sizes of the total pressure loss coefficients and the uniformity of theirs distribution along the blade height, the aerodynamic performance of the cascade is the best as the outlet Mach number was equal to 0.4. When the outlet Mach number is greater than 0.4, the flow becomes into the automatic mode area, the total flow loss increased slightly, which is caused by that the increase of the mass flux through cascade induces the increase of the negative incidence.