Abstract
CFD was employed to simulate the steam flow in 1.5-stage cascades with three different seal clearances. When the seal clearance is 0, there is no steam seal leakage, no obvious secondary flow in the cascade, and the stage efficiency reaches 88.27%. When the clearance of diaphragm seal and rotor tip seal is 1mm, the leakage of diaphragm seal strongly interferes with the flow in the cascade, which promotes the formation and development of the end-wall secondary flow near rotor hub, and the rotor tip leakage flow has little effect on next stage, and the stage efficiency drops by about 2 percentage points. When the seal clearance is 4mm, the end-wall secondary flow near rotor hub and next stator casing is strengthened significantly, and the attack angle loss increases, so the stage efficiency decreases by about 13 percentage points.
Highlights
The performance of steam turbine flow path is directly related to the economy and safety of the entire steam turbine unit, and naturally becomes the focus of experimental research, operation optimization and technological transformation
Due to the advanced development of aerodynamics and other theories and manufacturing technologies, currently the flow efficiency of steam turbine has reached high level, and the blade profile loss and secondary flow loss have been greatly reduced [2,3], so steam leakage loss has become an important factor restricting the improvement of turbine flow efficiency [4]
It is necessary to indepth study the impact of the internal seal leakage on flow performance, which will help site engineers to grasp the working characteristics and status of the steam seal, and guide the optimization or technological innovation of the steam turbine unit
Summary
The performance of steam turbine flow path is directly related to the economy and safety of the entire steam turbine unit, and naturally becomes the focus of experimental research, operation optimization and technological transformation. The flow loss in the flowpath of steam turbine cascade is mainly blade profile loss, secondary flow loss and steam leakage loss [1]. Due to the advanced development of aerodynamics and other theories and manufacturing technologies, currently the flow efficiency of steam turbine has reached high level, and the blade profile loss and secondary flow loss have been greatly reduced [2,3], so steam leakage loss has become an important factor restricting the improvement of turbine flow efficiency [4]. It is necessary to indepth study the impact of the internal seal leakage on flow performance, which will help site engineers to grasp the working characteristics and status of the steam seal, and guide the optimization or technological innovation of the steam turbine unit. Since it is not easy to directly measure the seal leakage in steam turbine stage [5], this paper chooses to use numerical simulation methods for research
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