Predicting the velocity distribution of double horizontal axis tidal turbines (DHATTs) is significant for the effective development of tidal streams. This current research gives an account on double turbine wake theory and flow structure of DHATT connected to single support by using the joint axial momentum theory and computational fluid dynamics (CFD) method. Characteristics of single turbine wake were previously studied with two theoretical equations predicting the initial upstream velocity closer to the turbine, and it’s lateral distributions along the downstream of the turbine. This current works agreed with the previous wake equations, which was used for predicting the velocity region along the downstream of the turbines. Flow field separating the two turbines is complicated in nature due to the indirect disturbance of turbines and no report was found on this central region. The Central region in the downstream flow is initially suppressed due to the blockage effects with a high velocity close to the free stream. Lateral expansion of two turbine wakes penetrated the central region with velocity reduction and followed by the flow recovery further downstream. This work provides more understandings of the wake and its central mixing region for double turbines with a proposed theoretical model.

预测双水平轴潮汐涡轮机（DHATT）的速度分布对于有效开发潮汐流具有重要意义。本研究利用联合轴向动量理论和计算流体力学（CFD）方法，对双涡轮尾流理论和与单个支架相连的DHATT的流动结构进行了说明。以前已经使用两个理论方程式研究了单涡轮机尾流的特性，这些方程式预测了靠近涡轮机的初始上游速度及其沿涡轮机下游的横向分布。目前的工作与以前的尾流方程式相吻合，后者用于预测沿涡轮机下游的速度区域。由于涡轮的间接干扰，将两个涡轮分开的流场本质上是复杂的，并且在该中心区域未发现任何报道。下游流动的中心区域最初由于靠近自由流的高速阻塞效应而受到抑制。两个涡轮机尾流的横向膨胀以速度降低的方式穿透了中心区域，然后在下游进一步进行了流量回收。这项工作通过提出的理论模型提供了对双涡轮机尾流及其中央混合区域的更多理解。两个涡轮机尾流的横向膨胀以速度降低的方式穿透了中心区域，然后在下游进一步进行了流量回收。这项工作通过提出的理论模型提供了对双涡轮机尾流及其中央混合区域的更多理解。两个涡轮机尾流的横向膨胀以速度降低的方式穿透了中央区域，然后在下游进一步进行了流量回收。这项工作通过提出的理论模型提供了对双涡轮机尾流及其中央混合区域的更多理解。