Narrow Results

Dynamic characteristics and sensitivity analysis of a tubular pump unit during starting process are proposed in this paper. A dynamic model of the pump unit, suitable for describing its transient characteristics during starting process, is established by using rigid body dynamics, fluid dynamics and hydraulic theory. The extended Fourier amplitude sensitivity test (EFAST) analysis method is used to investigate the influence of unit parameters on system outputs. Simulation of the pump unit is carried out for the starting process to verify the sensitivity analysis and explore the dynamic characteristics of the pump unit. The dynamic responses of the system parameter (rotating speed, flow and head) are revealed by the start-up simulation. Research results provide theoretical guidance for the rational design and safe operation of tubular pump stations.

A stochastic dynamic model of a Kaplan turbine is established in this paper during the transient process. When the Kaplan turbine operates with fluctuating load, the synergistic relationship between the guide vanes and blades experiences random fluctuation resulting from the mechanical, hydraulic and signal factors. To study the effect of stochastic fluctuations of the synergistic relationship, Chebyshev polynomial approximation method is adopted to analyze the stochastic dynamic characteristics of the Kaplan turbine during the transient process. Using Chebyshev polynomial approximation, the stochastic model of the Kaplan turbine is simplified to its equivalent deterministic model, and the stochastic dynamic characteristics of the model are investigated in the transient process. The effects of stochastic intensity on the dynamic behaviors of the Kaplan turbine are analyzed by means of numerical simulation. Moreover, the influences of PID parameters on the stochastic dynamic characteristics of the Kaplan turbine are studied through bifurcation diagrams. Analysis of stochastic characteristics and dynamic behaviors suggests that transient performance improvement can be obtained by controlling the synergistic stochastic intensity and PID parameters.