基于ADV的耙头周边主流流场测量实验

Measurement of Main Flow Field Around Drag Heads Based on ADV

在现有耙吸挖泥船的耙头研究中,关于其周边流场的测量数据较为匮乏。该文搭建了全透明耙头测试实验台,利用声学多普勒流速仪(ADV)对耙头周边主流区的流场进行测量。探讨了ADV在壁面附近的流速测量技巧方案,针对ADV的测量特点设计了移动调节装置,在确保测量数据准确可信的基础上,改变抽吸速度,在耙头吸口周边选择38个测量面,每个测量面在不同吸口边距和不同对地高度处测出流速值,共测量了342个测点。分析测量数据发现,耙头外左右两侧流场基本对称分布,主要分为前侧、左右两侧和相互干扰区,耙头抽吸效果主要由非干扰区流动决定,耙头前侧流速值小于两侧。在该文实验条件下,耙头周边各测量面流速随流量线性增加,随吸口边距基本线性减小,随测点升高而有所减小。在此基础上,分析了流场的形成原因,并探讨了耙头起动粒径的估算方法,以期为工程设计提供相关参考。

Measured date of the flow field around the drag head is deficient in the existing research on the Trailing Suction Hopper Dredgers.In this paper,a whole-transparent test bench about drag head is built for measuring the main flow field around the drag head with an Acoustic Doppler velocimetry(ADV).The skills of velocity measurement near the bed are discussed.According to the characteristics of ADV,a moving adjusting device is designed for ensuring the accuracy and credibility of the measured data.38planes around the suction port of the drag head are then selected to measure.With changing the suction velocity,a total of 342measured points'flow velocities are measured at different distances outside the suction edge and different heights above the bed.It is found from the measured data that the flow field of the drag head is basically axisymmetric and mainly composed of front,sides and interference region.The suction effect of the drag head is mainly determined by the flow in non-interference region.The velocities at the front side are lower than that on both sides.Under the test conditions of this paper,the velocity of each measured planes increases linearly with the flow rate,decreases nearly linearly with the distance outside the suction edge,and decreases as the measuring point rises.Moreover,the cause of the flow field is analyzed and the method is discussed for estimating the starting particle size of drag head,which can provide reference for the engineering design.