470 / 2018-12-31 01:05:31

Effects of the Nozzle Group Linking-up Section Chamber Structure of the Control Stage on the Unsteady Aerodynamic Force

partial admission turbine；control stage；new optimized chamber structure；unsteady numerical analysis；aerodynamic exciting force/部分进汽透平；调节级；新型优化腔室结构；非定常数值分析；气流激振力

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In addition to the advantage of adjusting the aerodynamic load, partial admission is difficult to be replaced in terms of ensuring efficient operation of the turbine unit, thus it is still widely used currently. However, the rotor blades of partial admission turbine will be subjected to periodic airflow excitation, which will affect the blade fatigue life to a large extent. Based on the control stage model, this paper further improves the inlet chamber structure, and proposes a new optimized structure that effectively suppresses the local aerodynamic exciting force. The three-dimensional unsteady numerical method is used to analyze the flow parameters of the cascade and the variation of unsteady aerodynamic exciting force. The results show that by increasing the chamber structure of nozzle group linking-up section, the high-speed flow caused by the narrow flow space in the nozzle group linking-up section is greatly reduced, which effectively relieves the sudden change of pressure and increases the pressure in the low-pressure zone. The local axial aerodynamic exciting force is reduced by up to 59.4%. Meanwhile, the structure reduces the rotor inlet pressure value from the block section to the inlet section of the nozzle group linking-up section, and the local axial aerodynamic exciting force is reduced by 6.8%. It is worth noting that the chamber structure at the nozzle group linking-up section of the control stage does not have a significant impact on the aerodynamic performance, and the relative change rate of efficiency is 0.91%. Therefore, the new optimized chamber structure proposed in this paper can significantly improve the local aerodynamic exciting force in the nozzle group linking-up section.