Study On Flow-induced Vibration Of Trashracks Of Pumped-storage Hydroelectric Plants

Cases have frequently occurred the trashracks of pumped-storage hydroelectric plants damage due to flow-induced vibration, experiments are the principle mean to study on trashracks currently. The entire hydroelasticity flow-induced vibration experiments are hardly to see under the restrictions of materials and conditions formerly. This paper mainly focuses on the research of trashracks flow-induced vibration in pumped-storage hydroelectric plants, combining with Pushihe pumped-storage hydroelectric plant, through hydroelasticity model experiment and finial element method.(1) Developing the materials to simulate the vibration of trashracks, the density of the trashrack bar is 5.64% smaller than the theory one, while the elastic modulus is 0.68% smaller, both meet the requirements for the experiment.(2) Developing the vibration signal processing system based on Matlab, solving the packed program cannot meet complex requirements of signal processing.making specialized analysis on the collected data of the flow-induced vibration, achieved well results.(3) According to the gravity-elasticity similar principle, the entire hydroelasticity flow-induced vibration test was taken, 60 strain survey spots on the trashrack have been measured under 24 conditions. Experiments show that the control condition is when the fluid flow at the trashrack shows the proliferation at the lowest water level, whether upward, downward reservoirs. The quadratic difference of maximum strain at the upward Trashrack is about as 3 times as the down one in this experiment. Totally speaking, the bars are the weak part of the trashrack.(4) The maximum deviation of strain gained in the entire hydroelasticity flow-induced vibration test is as 3 times as gained in the single hydroelasticity flow-induced vibration test. The former should take the influence by complex flow pattern and structure coupling into consideration. As a result, the single hydroelasticity flow-induced vibration test can't be a reliable prediction. Currently, the entire hydroelasticity flow-induced vibration test is a more reliable method.(5) According to the results of the entire hydroelasticity flow-induced vibration test, the analysis shows that the cyclical vortex force isn't the main vibratory source of the trashrack vibration under the condition when pumped on the upward reservoir. During the generating operation at the upward trashrack and every situation of the downward reservoir trashrack, the cyclical vortex force isn't the main vibratory source for some components, but for some other components.(6) Calculating the critical velocity of the galloping of the trashrack is 11.7m/s, far larger than the prototype of the status of the velocity, the galloping never happens in this paper.(7) Estimating on fatigue life of the bar, 392 years, this never happens.(8) With the application of the Levin formula and the Finite Element Method, the natural frequency of the single bar in the water is calculated, the difference is small; Also the natural frequency and the vibration mode in air and in water are calculated in the entire hydroelasticity flow-induced vibration test.(9) The natural frequency of the single bar is far larger than interference frequency, resonance is impossibly to happen; There is no situation of coincidence and lock between the natural frequency and interference frequency of the entire trashrack, difficult to resonant, however, it need to be further proved if it's necessary to raise the fundamental frequency of the entire trashrack.