Research On Vibration Absorption Of Hydropower Station Units Based On Phononic Crystal Metamaterial

At present,the power station units are developing towards the situation of high head,high single installed base,multi-unit plant and multiple load cases,which causes increasingly obvious harm of vibration of Francis turbine units and growing attention to the demand of shock absorbing.In recent years,the vibration of unit has caused many accident at the hydropower station around the world,such as Hongshi Dam,Yantan Dam,Wuqiangxi Hydroelectric Power Station in China,and Grand Coulee Dam,Itaipu Dam,Sayano–Shushenskaya Dam and other hydropower stations in foreign countries.In particular,the big accident occurred at Russia’s sayang-shushensk Dam in 2009 shocked the world.Phononic crystal metamaterial are a kind of multi-scale material system with delicate design.Its unusual physical property stems from the design of the microstructure rather than from its composed materials.It is a periodic structural material that is arranged by the same microstructure according to certain rules and there is a special wave control phenomenon in it called phonon band gap.When the elastic wave is within a certain range,its propagation in this kind of material will be inhibited.In this paper,I study on introducing the maphononic crystal metamaterial into hydropower stations and using the control effect of phononic crystal on elastic wave to achieve vibration reduction for hydropower station.Main research works were carried out as follows.1)In order to verify the wave absorption and vibration suppression effect of phonon crystals,based on the Bloch theorem and Floquet periodic boundary condition,the band gap study of two-dimensional phonon crystal metamaterials was carried out,and the attenuation of elastic waves within the band gap frequency range was verified by using low-amplitude elastic wave propagation experiment and numerical simulation calculation.2)In order to obtain a wider band gap,the thermo-induced band gap tunability of two-dimensional phonon crystals was studied.Using the thermal sensitivity of photosensitive resin and the unevenness of temperature field distribution,it was verified experimentally that the band gap of a single phonon crystal could be widened by combining normal temperature and local heating.3)Considering the operability of engineering practice,a three-dimensional phonon crystal is designed,and the phonon band gap research is carried out.This research innovatively combines the phonon band gap of metamaterials with the vibration of hydraulic turbine units in practical production.It is a kind of method supplement to solve the problem of vibration of water turbine unit.It is also an extension of the practical application of phonon crystal metamaterials...