Research On Fluid-Structure Interaction And Vibration Characteristic Of Variable Speed Hydrodynamic Coupling

With the economy rapid development, the industry devices with large power areincreasing demanded, especially for the large-scale pumps and fans with variable speed andenergy-saving. Owning to the advantages of large power, variable speed and energy-saving,the hydrodynamic coupling is widely used and has been more and more concerned. For acertain input speed, the output power of the hydrodynamic coupling can be changed bychanging the filling rate of the working chamber. Therefore, when connected to otherdevices, the hydrodynamic couplings can achieve the smooth start and stepless speedadjustment, reduce the impulse and vibration and improve the transmission quality.Moreover, the energy saving effect of the hydrodynamic coupling is prominent, and thehigher power output has the better energy saving effect. However, there is a certain distanceto independently development the domestic hydrodynamic coupling. Supported by theNational863High-tech Project "Key Technological Research on Hydrodynamic VariableSpeed and Saving Energy of Large-scale Pump and Fan," this paper systematically studiesthe key techniques of the hydrodynamic coupling in the aspects of the fluid-structureinteraction and vibration characteristic, specific details are as follows:The theory and numerical computation methods related to fluid-structure interaction areintroduced. Aiming at the flow field characteristics of the hydrodynamic coupling, the fluidcontrol equation and impeller structural dynamic equation are deduced under the rotatingreference frame. Two numerical computation methods of integral solution method andsub-region solution method are specially introduced, and the description method,information transfer form and control conditions are declared for the fluid-structureinteraction surface in the numerical computation.Based on the numerical computation algorithm of the fluid-structure interaction andtaken the variable speed hydrodynamic coupling YOCQZ465as research subject, thefluid-structure interaction phenomenon is numerical simulated. Firstly, with the numerical computation method of the unidirectional fluid-structure interaction, the strain and stress ofthe hydrodynamic coupling impeller are analyzed, and the impeller strength is checked. Andthen with the numerical computation method of the bidirectional fluid-structure interaction,the flow field characteristic and the turbine blade dynamic feature are studied in thecondition of the braking working, which are analyzed both in the steady state and transientstate.Based on the potential fluid theory, the fluid-structure interaction of the hydrodynamiccoupling impeller and blade is numerical simulated with the modal solution method. Withthe modal solution method taking the pre-stress into consideration, the vibrationcharacteristics of the impeller are studied under different velocity ratio and different fillingrates, the possible resonant frequencies are obtained for impeller practical working, and thesensitive frequencies areas of the impeller vibration are also found.In order to validate the numerical simulation results, experiments are carried out to testthe strength of pump wheel and the vibration characteristic of the hydrodynamic couplingdriving device in its practical working. With the remote sensing method, the strength of thepump wheel are tested in different rotating speed. Compare the strain effective value of themeasuring points with the corresponding simulation results and validate the reliability of theremote sensing experimental result. In order to test the vibration characteristic of thehydrodynamic coupling driving device, ten measuring points are put in ten typical locationson the hydrodynamic coupling driving device, and the tested vibration signal of theacceleration in x, y, z direction are analyzed in time domain and frequency domain, which isused to estimate the vibration of the hydrodynamic coupling driving device in qualitative andquantitative.To sum up, according to numerical simulation and experiment validation, thefluid-structure interaction and vibration characteristic of the hydrodynamic coupling aresystematically studied. The study can be used to predict the flow field characteristic,calculate impeller structural dynamic and estimate the structure vibration feature, which hascertain significance for guiding the large power hydrodynamic coupling design.