Nonlinear Dynamic Characteristic Analysis of the Shaft System in Water Turbine Generator Set

A 3D finite element vibration model of water turbine generator set is constructed considering the coupling with hydropower house foundation. The method of determining guide bearing dynamic characteristic coefficients according to the swing of the shaft is proposed, which can be used for studying the self-vibration characteristic and stability of the water turbine generator set. The method fully considers the complex supporting boundary and loading conditions; especially the nonlinear variation of guide bearing dynamic characteristic coefficients and the coupling effect of the whole power-house foundation. The swing and critical rotating speed of an actual generator set shaft system are calculated. The simulated results of the generator set indicate that the coupling vibration model and calculation method presented in this paper are suitable for stability analysis of the water turbine generator set.

Effects of Rotor Solidity on the Performance of Impulse Turbine for OWC Wave Energy Converter

Impulse turbine, working as a typical self-rectifying turbine, is recently utilized for the oscillating water column（OWC） wave energy converters, which can rotate in the same direction under the bi-directional air flows. A numerical model established in Fluent is validated by the corresponding experimental results. The flow fields, pressure distribution and dimensionless evaluating coefficients can be calculated and analyzed. Effects of the rotor solidity varying with the change of blade number are investigated and the suitable solidity value is recommended for different flow coefficients.

A NOVEL DESIGN OF COMPOSITE WATER TURBINE USING CFD

This paper presents computational investigation of a novel design of composite material axial water turbine using Computational Fluid Dynamics（CFD）.Based on three-dimensional numerical flow analysis,the flow characteristics through the water turbine with nozzle,wheel and diffuser are predicted.The extract power and torque of a composite water turbine at different rotating speeds were calculated and analyzed for a specific flow speed.The simulation results show that using nozzle and diffuser can increase the pressure drop across the turbine and extract more power from available water energy.These results provide a fundamental understanding of the composite water turbine,and this design and analysis method is used in the design process.

Performance experiment and numerical prediction on the optimization design of the micro-sized water turbine for the hose reel irrigator

In order to significantly improve the efficiency of driving water turbine used in hose reel irrigator,a new water turbine structure was proposed by the method of performance test and numerical calculation.The internal flow characteristics of original water turbine were analyzed,and it was found that unreasonable design of main flow passage components such as inlet,outlet and runner could not effectively translated pressure energy of upper stream into impact kinetic energy of blade,and gave rise to low energy conversion efficiency of water turbine.The inadequate internal flow and uneven pressure distribution were also not conducive to energy conversion efficiency.Then a new structure of water turbine structure was presented,in which the inlet has a tangential nozzle jet and the outlet is in axial direction.The computational analysis showed that the nozzle jet at the inlet of the new water turbine runner,which makes jet flow mainly concentrate in the impacted blade passage,can reduce the loss of flow kinetic energy.The axial outflow increases the distance of inflow in the runner,which is more conducive to the runner blades work.Performance experiments on both original and new water turbines showed that the highest efficiency of the new turbine is almost 20 percentages higher than that of the original turbine,and the new turbine is nearly triple output power over the original turbine.The internal flow characteristic analysis and the performance experiment were conducted to assess the feasibility of the replacement of the original water turbine by the new water turbine.

Performance of vertical axis water turbine with eye-shaped baffle for pico hydropower

t A series of inline pico hydropower systems,which could be used in confined space,especially for water distribution networks(WDNs),was designed and investigated.The turbine with an eye-shaped vertical water baffle was developed to evaluate the hydraulic performance.A three-dimensional dynamic mesh was employed and the inlet velocity was considered as the inlet boundary condition,whereas the outlet boundary was set as the outflow.Then,numerical simulations were conducted and the standard k-εturbulence model was found to be the best capable of predicting flow features through the comparison with the experimental results.The effects of the opening diameter of the water baffle and installation angle of the rotor on the flow field in the turbine were investigated.The results suggested that the water baffle opening at d=30 mm and the rotor at a 52°angle could achieve the highest efficiency of 5.93%.The proper eye-shaped baffle not only accelerates the fluid flow and generates positive hydrodynamic torque,but also eliminates the flow separation.The scheme proposed in this paper can be exploited for practical applications in the water pipelines at various conditions and power requirements.