近年来，在多因素影响下全球海洋渔业资源明显衰退，人工鱼礁是改善海洋生态环境、提高渔业产量的有效措施，主要通过投放后产生的流场效应来发挥作用，该效应与人工鱼礁的形状构造、规模大小、空间布局等密切相关，因此，探究不同类型和规模的单位鱼礁水动力学特性具有重要意义。本文以渤海辽东湾拟投放的方形鱼礁和M型鱼礁的单位鱼礁为研究对象，采用PIV技术模拟了5种流速、4种布设间距（以原间距L为基准缩放）下单位鱼礁流场的水动力过程，共完成有鱼礁实验2*5*4=40组、无鱼礁5种流速5组实验，共计45组水槽实验。在此基础上，采用熵值法综合评价了两类鱼礁在不同间距下的流场效应，对人工鱼礁的空间布局提出了建议。取得的主要结论如下：

（1）以上升流和背涡流的长度、高度、面积等为特征值，两种鱼礁的上升流和背涡流特征值均随流速增加而增大。同一流速，方形鱼礁的上升流和背涡流特征值均随间距增大先增加后减小。M型鱼礁的上升流特征值随间距增大呈先减小后增大再减小，上升流和背涡流特征值均在1.25 L间距达到最大值。

（2）纵向流速场呈“上高下低”分布，垂向流速场以流动分离点为中心向外呈弧形分布。按相对于礁体的位置设置典型断面，单位鱼礁区域内，两种鱼礁各断面的纵向和垂向流速均可以某一相对水深为界分为两段或三段。相较之下，方形鱼礁在1.25 L和1.00 L间距、M型鱼礁在1.25 L间距对流速的阻减作用较好。

（3）紊动强度场呈“下高上低”分布。单位鱼礁区域内，方形鱼礁所有断面的紊动强度分为三个变化阶段，M型鱼礁所有断面以中间鱼礁组为界分两大类，分别分为三个和两个变化阶段。方形鱼礁在小流速下对紊流场的影响更剧烈，M型鱼礁不同流速间差异较小。

（4）基于水动力学特征对比分析发现，M型鱼礁的上升流和背涡流的强度规模、对流速的阻减作用及对水流的扰动程度都明显强于方形鱼礁，这是由于前者的形状构造优于后者，建议在实际建设中可根据需要优先选择M型鱼礁。

（5）采用熵值法基于水动力和经济成本评价了方形鱼礁和M型鱼礁在四种间距下的流场效应，综合得分均为1.25 L最高。因此，建议两种鱼礁在实际投放时均在原间距基础上扩大25%，为人工鱼礁建设提供了参考依据。

（6）调整后的方形鱼礁单位鱼礁的流场影响范围增大了29%。另外，通过对比分析建议进一步将M型鱼礁的鱼礁组改为由4个单体礁构成，调整后的单位鱼礁造价减少了10%，而流场影响范围增大了10%，以更少的经济投入获得了更大的生态效益。

In recent years, under the influence of many factors, the global marine fishery resources have declined significantly. Artificial reefs are effective measures to improve the marine ecological environment and increase fishery production. They play a role mainly through the flow field effect , which is closely related to the shape, structure, scale and spatial distribution of artificial reefs, after the launch. Therefore, it is of great significance to explore the hydrodynamic characteristics of different types and scales of unit reef. In this paper, the unit reefs of square reef and M-shaped reef in Liaodong Bay of Bohai Sea are studied, 45 flume experiments, using PIV technology, were carried out to simulate the hydrodynamic process of unit reef flow field under 5 velocity and 4 disposal spacing (zoom based on the original spacing L). On this basis, the entropy method is used to evaluate the flow field effect of the two types of reefs at different disposal spacing, and some suggestions are put forward for the spatial layout of reefs. The main conclusions are as follows:

(1) The length, height and area of upwelling and back vortex are taken as eigenvalues. The eigenvalues of upwelling and back vortex increase with the increase of velocity. At the same velocity, the upwelling and back vortex eigenvalues of square reef increase first and then decrease with the increase of spacing. The eigenvalues of upwelling of M-shaped reef decrease first, then increase and then decrease with the increase of spacing.

(2) The longitudinal velocity field presents the distribution of "high at the top and low at the bottom" with obvious boundary. The vertical velocity field takes the flow separation point as the center and extends outward in an arc distribution. Setting typical sections according to the position relative to the reef, in the unit reef area, the longitudinal velocity and vertical velocity on each section of the two reefs can be divided into two or three sections by a certain relative water depth. In contrast, 1.25 L and 1.00 L of square reef have better effect on the velocity reduction, while 1.25 L of M-shaped reef has the strongest effect.

(3)The turbulence intensity is "high in the lower part and low in the upper part". In the unit reef area, the turbulence intensity of all sections of the square reef can be divided into three stages, and all sections of the M-shaped reef can be divided into two categories with the second reef group as the boundary, which can be divided into three and two stages respectively. The influence of square reef on turbulence field is more severe at low velocity. M-shaped reef has little difference in different velocity.

(4) The scale of upwelling and back vortex flow field effect, the reduction of flow velocity and the disturbance degree to water flow of M-shaped reef are obviously stronger than those of square reef, which is more conducive to creating an environment suitable for marine life. This is because the shape and structure of M-shaped reef is better than that of square reef. It is suggested that M-shaped reef should be selected first according to the actual construction needs.

(5) Based on the hydrodynamic characteristics and economic cost, the entropy method is used to evaluate the flow field effect of square reef and M-shaped reef under four disposal spacings, and the comprehensive score is 1.25 L, which is the highest. Therefore, it is suggested that the disposal spacing of square reef unit reef and M-shaped unit reef should be increased by 25% on the basis of the original design, which provides a reference for the construction of artificial reefs.

(6) After adjustment, the influence range of the square reef unit reef increases by 29%. In addition, through comparative analysis, it is suggested that the reef group of M-shaped unit reef should be further changed into four reef monocases. After adjustment, the unit reef cost is reduced by 10%, and the influence range is increased by 10%, which can obtain greater ecological benefits with less economic input.