Experimental Study On The Effect Of Blade Openings On Hydrodynamic Performance Of Hydraulic Turbines

Compared with other forms of energy,tidal current energy in ocean energy has incomparable advantages,mainly embodied in: concentrated energy and high energy density;strong predictability;small fluctuation;abundant energy reserves.Tidal power resources in China's coastal areas account for about 46.7% of the world's total.At present,the utilizing efficiency of tidal energy is not high.If tidal energy can be used more effectively,it will effectively alleviate the energy demand tension.Therefore,the study on hydrodynamic performance for tidal current energy devices has important theoretical significance and engineering application value.Based on the ship towing tank,experiment study about the influence from blade opening position on the hydrodynamic performance of a vertical axis turbine is carried out in this paper.The main research contents are as follows:(1)Under different flow velocities,the influence of blade opening position on energy utilization ratio of vertical axis turbine is studied.The results show that the energy utilization ratio increases first and then decreases with the increase of the sharp speed ratio;the sharp speed ratio corresponding to the maximum energy coefficient is basically the same,which shows that the opening has no effect on the energy utilization ratio of the turbine;the maximum energy coefficient decreases with the increase of the distance between the opening position and the leading edge;the influence of opening position on energy coefficient is less than that of aperture size at low speed.(2)Under different rotational speeds,the influence of blade opening position on energy utilization ratio of vertical axis turbine is studied.The results show that the energy utilization ratio increases firstly and then decreases with the increase of the sharp speed ratio;the sharp speed ratio corresponding to the maximum energy coefficient is basically the same,which shows that the opening has no effect on the energy utilization ratio of the turbine;the maximum energy coefficient decreases with the increase of the distance between the opening position and the leading edge;the influence of opening position on energy coefficient is less than that of aperture size at low speed;Under the condition that the incoming flow remains unchanged,there exists a position which has the greatest influence on the energy coefficient.(3)Through comparing the effects of flow speed and rotational speed on the energy utilization ratio of turbine,it can be seen that under the condition of high tip-speed ratio and constant flow speed,properly increasing rotational speed is beneficial to enlarging tip-speed ratio and improving energy utilization ratio.Under the condition of fixed speed or the same inflow,blade opening will reduce the energy utilization rate of the turbine.