﻿ Savonius型水轮机减流特性数值模拟研究
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 哈尔滨工程大学学报  2020, Vol. 41 Issue (6): 870-876  DOI: 10.11990/jheu.201904013 0

### 引用本文

YAO Jianjun, LI Fengshen, WANG Xiancheng, et al. Numerical simulation of the Savonius turbine on the current reduction characteristics[J]. Journal of Harbin Engineering University, 2020, 41(6): 870-876. DOI: 10.11990/jheu.201904013.

### 文章历史

Savonius型水轮机减流特性数值模拟研究

1. 哈尔滨工程大学 机电工程学院, 黑龙江 哈尔滨 150001;
2. 浙江大学宁波理工学院 机能学院, 浙江 宁波 315100

Numerical simulation of the Savonius turbine on the current reduction characteristics
YAO Jianjun 1, LI Fengshen 1, WANG Xiancheng 2, CHEN Junhua 2, YU Jie 1
1. College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin 150001, China;
2. College of Mechanical and Energy Engineering, Ningbo Institute of Technology, Zhejiang University, Ningbo 315100, China
Abstract: To discuss the application of the Savonius hydrokinetic turbine (SHT) in the protection of marine aquaculture, we studied the effect of its flow velocity reduction on a wake flow field. Computational fluid dynamics numerical calculation was applied to simulate the rear flow field of the SHT. The reduction mechanism was explained by the detailed analysis of the velocity cloud map and vector graph, and the change rule of the velocity field was summarized. Then, we established the change law of a speed field and further studied the influence of different tip speed ratios (TSRs) on the performance of the current reduction and formulated the evaluation standard of flow characteristics reduction. Results show that the revolving SHT has a good effect on reducing the current speed, and the velocity distribution in the effective area of the flow reduction has a certain regularity. The TSR obviously affects the performance of the SHT on reducing the current speed, and the optimal range of the TSR is between 0.8 and 1.0. The best attenuation coefficient of 0.736 and relative reduced flow length of 15.6 are obtained when the tip speed ratios are 1.1 and 0.8.
Keywords: flow velocity reduction    tip speed ratio    Savonius hydrokinetic turbine    resistance type    computational fluid dynamics    power factor    speed attenuation coefficient    relative attenuation length

Savoniu型水轮机(S型水轮机)最早由芬兰工程师Savonius发明[1]，除早先用于风力发电外，近些年在潮流能发电领域也得到广泛应用。潮流能作为一种可再生能源，具有储量大、能源密度高且环境影响小等特点[2]。S型水轮机作为一种阻力型垂直轴水轮机具有转速低，启动力矩大以及结构简单制造成本低等优点。虽然阻力型垂直轴水轮机最大功率系数低于升力型垂直轴水轮机[3]，但阻力型水轮机是通过阻挡前方来流，使迎流的2个叶片形成的阻力差旋转做功，所以相比升力型水轮机，S型水轮机具有更好的减流效果。近些年随着海洋养殖业的不断发展，深海养殖渔场、海洋牧场等概念不断被提出，网箱已朝着深远海，大型化的趋势不断发展[4]。深远海一般存在风大浪急，流速较快的现象，容易造成养殖设施和物种的破坏，在养殖渔场外围应用S型水轮机不仅可以捕能供养殖渔场使用，还可以减流实现对网箱的保护作用，对远海养殖业发展具有重要的作用。

1 S型水轮机基本参数和仿真方法 1.1 基本参数

 Download: 图 1 S型水轮机工作示意 Fig. 1 Working dirgram of the Savonius trubine 注：U.来流速度；θ.当前水轮机旋转角度；ω.叶轮旋转速度；D.叶轮直径；d. 2个叶片之间的间隙。
 ${e = d/D}$ (1)
 ${\varepsilon = b/a}$ (2)
 ${{\rm{TSR}} = \frac{{\omega D}}{{2U}}}$ (3)

S型水轮机的减流性能则通过速度的衰减系数Ca和相对衰减长度La进行判断：

 ${L_a} = L/D$ (4)
 ${C_a} = \frac{{U - u}}{U}$ (5)

1.2 S型水轮机数值仿真模型建立

S型水轮机旋转时，在叶片周围及后方形成大量的涡流，促使流场运动变得十分复杂。本文采用CFD仿真软件Star-CCM对水轮机周围及后方流场进行数值模拟，此CFD软件具备较成熟的算法，丰富的物理模型，完善的多面体网格生成以及稳定的滑移网格技术，可在S型水轮机水动力学分析中，对流场中的湍流精确模拟，具有较高的仿真精度。由于仿真几何模型均采用直叶片，叶片展长方面的影响可以忽略，所以本文将采用二维CFD数值仿真计算，可大幅度地减少计算量，而又不影响计算精度。

1.4 仿真模型选择及验证

2 仿真结果分析 2.1 S型水轮机减流机理分析

 Download: 图 5 S型水轮机速度场及流线 Fig. 5 Velocity field and streamline of Savonius turbine

 Download: 图 6 S型水轮机旋转状态速度矢量 Fig. 6 Velocity vector field of rotating Savonius turbine
2.2 S型水轮机后方减流区域分布情况

 Download: 图 10 S型水轮机带有等值线的速度 Fig. 10 Velocity field with isoline of Savonius turbine
2.3 S型水轮机减流特性评价标准

 Download: 图 11 极限叶尖速比情况下各监测点平均速度 Fig. 11 Average velocity of probes at the limit TSR
2.4 叶尖速比对S型水轮机减流特性的影响

 Download: 图 12 不同叶尖速比S型水轮机的Ca和La Fig. 12 Ca and La of SHT at different TSR
3 结论

1) 由于叶片对来流水质点的阻挡、碰撞以及尾流场中涡流的作用，使得转动的S型水轮机在后方迎流面呈“剑”形区域内，具有很好的减流效果。

2) S型水轮机后方减流有效区域内速度场分布较为规律。纵向上越靠近0D处减流效果越好，并且凹面后方区域减流效果优于凸面；横向上随着与水轮机距离加大，减流效果先增加后减小再逐渐衰减至没有。

3) 叶尖速比对S型水轮机的减流效果有较大的影响，并通过比较各叶尖速比的AcLA发现减流最佳叶尖速比工作范围在0.8~1.0，其中最大速度衰减系数0.73以及最大有效相对衰减长度15.6分别在叶尖速比1.1和0.8处发现。

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