| As a kind of green energy with large storage capacity,high energy density and strong sustainability,the development and utilization of hydraulic resources had attracted more and more attention.Hydraulic turbine was a mechanical device that captured and converted water energy,and it was the core device of the development of hydraulic resources.It was of great significance and value to develop a water energy capture device with high efficiency and wide application range.Based on the motion characteristics of the half-rotating mechanism and the existing turbine,a new type of the half-rotating impeller hydraulic turbine(HRIHT)was proposed.This paper focused on the start performance under static and low-speed conditions to provide practical guidance for the further research of he HRIHT.Firstly,a new type of water energy capture-conversion system was proposed,and the design requirements for the matching water energy capturing devices were proposed.According to the design scheme,a new type of the HRIHT was designed.The working principle of the device was briefly introduced and mechanism design of the main parts was carried out with the three-dimensional model of the parts and the assembly model of the whole prototype.Based on the design scheme of the HRIHT,the installation mode of the HRIHT was determined as floating type,and the installation platform was preliminarily designed after comparative analysis and comprehensive consideration.Secondly,the mathematical calculation model of HRIHT’s starting torque was established.The self-starting performance of the starting torque was studied by using CFD method of numerical simulation though XFlow software.By controlling variables,the inflow velocity,blade aspect ratio and arm length of the calculation model were changed separately to explore their effects on the self-starting performance of the HRIHT.The experimental results showed that the larger the aspect ratio of blade would bring the better self-starting performance,which also affected the best and worst position of self-starting.Increasing inflow velocity could greatly improve the self-starting performance of the device.Therefore,a flow-gathering device was designed and found that increasing the angle of folding relative to increasing the length of folding line could better increase the effect of speed increasing for the folded-line type flow gathering device.Then,the output performance of the HRIHT in low-speed situation was studied.The output torque model of the HRITT was established and the calculation equationof the inflow force and output torque of the half-rotating impeller at any position was derived.In order to verify the accuracy of the mathematical model,a simulation model of half-rotating impeller was established,and its hydrodynamic simulation calculation was carried out.The calculation results were compared with those derived from the theoretical formula to verify the accuracy of the mathematical model.Based on the deduced theoretical formula,the structural parameters of the half-rotating impeller were optimized by means of the optimization toolbox of MATLAB,which took the average output torque coefficient as the objective function.Under this condition,the minimum output torque in the period of half-rotating impeller is calculated,which provides a reference for adding external load in the later period.Finally,considering to the design scheme of the HRIHT,working environment and operation comprehensively,the prototype parts were processed,which included the selection,processing,assembly of parts and materials,and the physical prototype of the HRIHT was completed.Aiming at the physical prototype of the HRIHT,a simple experimental platform and a experimental scheme were designed to carry out the running experiment of the prototype,which simulated the blade was acted by incoming flow.The results verified the feasibility of the design scheme and the good self-starting performance of the device,and proved that the prototype of the HRIHT preliminarily achieved the design purpose. |
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