Decomposition and Analysis of Pressure Pulsation Characteristics of Tubular Turbine under Dynamic and Static Matching Action
The development of low head tubular hydropower station is an important part to achieve the goals of carbon peaking and carbon neutrality in China.Because this kind of hydropower station is greatly affected by the incoming water,it is necessary to often adjust the opening of guide vanes and blades according to the actual situation in the operation process,and ensure that the opening degree of the two has a good matching relationship.In this paper,a low head turbine of a tubular hydropower station was selected,and its internal flow was numerically simulated under head of 7.22 m,when the guide vane opening is 60°,the blade opening is 36.29° and 57.24° respectively.The results show that the 36.29° blade has a good association with the guide vane in this case.The unit not only has an efficiency of 93.27％,but also has a good internal pressure pulsation.The variational mode decomposition(VMD)method was used to analyse the pressure pulsation,and the components of the pressure pulsation were reasonably determined.The pressure pulsation in the unit is mainly dominated by double blade frequency,and there is a low-frequency pressure pulsation with low intensity in the draft tube.Under the large opening blade,there is an obvious low-frequency pressure pulsation component in the unit,and there is an obvious unstable pressure pulsation in the draft tube as a whole.In this paper,a new method for analysing the pressure pulsation was presented,and the components of the pressure pulsation were demonstrated reasonably and clearly,which provides a new direction for the analysis of pressure pulsation.
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