Multibody dynamics analysis of a Kaplan turbine runner in full operating conditions

Low head hydraulic resources are important renewable energy, while the Kaplan turbine is an important equipment for developing it, and it provides important references for the development of tidal energy unit. The flow characteristics and the dynamic behavior of a prototype Kaplan turbine in full operating conditions have been analyzed on the basis of the fluid-structure interaction theory and the nonlinear multibody dynamics analysis method, and a kind of contour line which intuitively describes the behavior of the unit is proposed in this paper. The results show that the hydraulic torque and the torque caused by centrifugal force have opposite effect on the blade, wherein the hydraulic torque makes the blade tends to open and the torque caused by centrifugal force makes the blade tends to close. The dynamic response behavior of the multibody mechanism shows inconsistency between different components, while the dynamic stress and the combined torque show high consistency. The low head and large power operating condition is unfavorable to blade lever, with a mean stress of 130 MPa and an amplitude of 11 MPa. This paper is helpful for the in-depth understanding on the multibody dynamic behavior of the Kaplan turbine runner under the nonlinear effect and fluid-structure effect. The proposed contour lines of hydraulic excitation and dynamic stress in full operating conditions can provide guidance for the design and operation of the unit.