Investigation of the Flow Pattern in the Inlet Part of Turbine Using Method of Mathematic Modelling
DOI:
https://doi.org/10.20998/2078-774X.2017.09.02Анотація
The article presents the results of a numerical investigation of the flow pattern in the input path of turbineK-200-12.7 including control valve, inlet pipe, nozzle segment. To determine the influence of each element in the total value of the energy loss, the calculations were carried out for the flow part of separate compartments: an isolated segment of the nozzle, inlet pipe-nozzle segment and the control valve-inlet pipe-nozzle segment. Each compartment was investigated for the modes, corresponding to the flow at low, medium and high valve opening. When calculating the model, a computational grid of tetrahedral type with prismatic sublayer and SST turbulence model was used. The results of the calculation showed that the total energy loss in the joint work of these elements exceed the loss in their isolated work. The main reason is the presence of increasing losses nonuniformity of input parameters generated in the previous path element. The most non-uniform distribution of flow parameters for all the investigated modes is observed in the outlet section of the valve diffuser. The stream thus formed enters the inlet pipe where it receives additional turbulence. As a result, the coefficient of irregularity of the total pressure at the nozzle inlet with a low valve opening reaches 0,137, and with a high valve opening – 0,035. In conclusion, it noted that the formation of the stream in the flow channel of the valve has a significant impact on the effective operation of the following elements of steam input path. An additional increase in the level of energy losses in the nozzles was 20.7–23.2 %. Increase internal loss coefficient in the inlet pipe was 33.6–83.3 %.
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