Simulation On Three-dimensional Flow And Structure Improvement Of Dynamic Mechanical Based On FLUENT

In the low-pressure stage of steam turbine, the steam temperature has been reducedto near saturation temperature. The expansion process will produce spontaneouscondensation and the water droplets will grow in the base of condensation nucleuscenter. Therefore, the flow of wet steam in the low-pressure stage are often complextwo-phase flow. The two-phase flow of wet steam mainly causes two effects: firstly, thenon-equilibrium condensation process will cause losses and affect thermodynamicefficiency; secondly, the water droplets depositing on the surface of the blade will hitthe blade and produce corrosion. So the reasonable control of the wet steamspontaneous condensation can not only improve turbine efficiency, but also reduce thecorrosion of the blade.In this paper, the wet steam and droplets are seen as continuous medium by Euler-Euler method. By volume averaging method, this paper establishs the control equationsof gas-liquid two-phase, including the gas-liquid two-phase continuity equation,momentum equation and energy equation. The number equation of droplets is alsoestablished to ensure the conservation equations closure and the turbulence model usesthe standard k-model. Finally, the source term of the governing equation andturbulence model equation are loaded in UDS to achieve the docking with FLUENTsolver. In the study of droplets deposition, use the Lagrange method to track the waterdroplets particles. To describe the interaction of the gas-phase and water dropletsparticles, we use the collision restitution coefficient of water droplets to describe thecollision, rebound and deposition phenomenon on the surface of stator blade, and theTabakoff model is selected as the blade erosion model.The gap desiccant dehumidification is one of the most effective methods to removewater droplets in the steam turbine. This paper simulates the two-phase flow of steamand water droplets deposition law in the three-dimensional last stator blade, and theresearch subjects are last stage stator blade prototype structure and three solutions ofdifferent slot modifications. The paper compares the dehumidification effect of statorblade prototype structure and three modifications solutions, and also studys the dropcascade deposition law in the stator blade channel. The research results show that theslot forms huge pressure gradient undercooling and then produce a strong suction effect,which sucks water droplets into the inner cavity of the stator blade. In contrast the statorblade prototype with the two slotted scheme, we can see the two slotted scheme cansignificantly reduces humidity than the prototype. And the whole flow field humidityin scheme2is smaller than scheme1, so scheme2is better than scheme1in thedehumidifying efficiency. Through the study of droplets deposition law we can derive that, the suction effect will be better with the dehumidification slot inlet width greater,but the influence to the mainstream increase accordingly; the dehumidification slotopening angle should try to ensure along the direction of the mainstream; the suctioneffect of slot opened on the suction surface will be the stronger with the slot closer tothe blade leading edge.