文丘里型导管对潮流涡轮机作用荷载和转速的影响

Effects of Venturi-type duct on imposed load and rotational speed of tidal current turbines

为了提高潮流能发电涡轮机的出力,设计了一种新型涡轮机叶片及其文丘里型导管。通过室内水槽试验,研究了文丘里型导管对低速来流的增速作用和对斜向来流的矫正作用,剖析了自由流不同偏流角、文丘里型导管不同长径比和不同面积比对涡轮机转速的影响。从理论上推导出作用于潮流涡轮机上荷载(推力、转矩和径向力)的计算公式,并结合试验结果分析了潮流作用于涡轮机上的荷载随自由流偏流角及文丘里型导管长径比和面积比的变化关系。结果表明,文丘里型导管可显著提高涡轮机的转速,其大小取决于导管的长径比和面积比;在不同偏流角情形下,转速在长径比为1.5~2.0时最大,即导管不宜太长或太短;转速随面积比的增大而增大,在偏流角为30°时达到极大值;转矩和径向力随面积比的增大而增大,但随长径比、偏流角的变化存在临界值,推力则随偏流角的增大而减小;与自由流情形相比,文丘里型导管不仅可以增大潮流速度,同时还具有矫正偏流的作用,从而提高输入涡轮机的功率。

In order to increase the power output of tidal current energy,a new type of turbine blades and a Venturitype duct were designed.Through in-door flume test,the roles of Venturi-type duct on increasing low velocity and rectifying oblique of the inflow were experimentally studied.The effects of different free stream drift angles,lengthdiameter ratios and area ratios of Venturi-type duct on the rotational speed of turbine were analyzed.Calculation formulas of the loads(thrust force,torque and radial force)exerted on the tidal current turbine were theoretically deduced.Changes in the relationship between the acting loads with free stream drift angles,length-diameter ratios and area ratios of the Venturi-type duct were analyzed combined with the experimental results.The results show that the Venturi-type duct can considerably increase the rotational speed of turbine,with the amplitude depending on the length-diameter ratio and area ratio of the guide duct.Under different drift angles,the maximum rotational speed occurs at the length-diameter ratios between 1.5 and 2.0,which means the guide duct should not be too long or too short.The rotational speed increases with the area ratio,and can reach the maximum value at the drift angle of 30°.The torque and radial force increase with the area ratio,but critical values exist for different length-diameter ratios and drift angles.The thrust force decreases with the drift angles.Compared with the case of free stream,the Venturitype duct can not only increase the tidal current velocity,but also can rectify oblique inflow,thus enhancing the power inputted into the tidal current turbine.