耿令波, 胡志强, 林扬, 衣瑞文, 王超. 尺度效应对水下合成射流推力特性影响研究[J]. 工程力学, 2017, 34(12): 219-228. DOI: 10.6052/j.issn.1000-4750.2016.07.0547
引用本文: 耿令波, 胡志强, 林扬, 衣瑞文, 王超. 尺度效应对水下合成射流推力特性影响研究[J]. 工程力学, 2017, 34(12): 219-228. DOI: 10.6052/j.issn.1000-4750.2016.07.0547
GENG Ling-bo, HU Zhi-qiang, LIN Yang, YI Rui-wen, WANG Chao. THE EFFECT OF SCALE ON THE THRUST CHARACTERISTICS OF UNDERWATER SYNTHETIC JET[J]. Engineering Mechanics, 2017, 34(12): 219-228. DOI: 10.6052/j.issn.1000-4750.2016.07.0547
Citation: GENG Ling-bo, HU Zhi-qiang, LIN Yang, YI Rui-wen, WANG Chao. THE EFFECT OF SCALE ON THE THRUST CHARACTERISTICS OF UNDERWATER SYNTHETIC JET[J]. Engineering Mechanics, 2017, 34(12): 219-228. DOI: 10.6052/j.issn.1000-4750.2016.07.0547

尺度效应对水下合成射流推力特性影响研究

THE EFFECT OF SCALE ON THE THRUST CHARACTERISTICS OF UNDERWATER SYNTHETIC JET

  • 摘要: 该文通过数值方法研究了尺度效应对水环境下合成射流推力及推进效率的影响,不同尺度下激励器的网格采用等比例缩放的方式得到,数值计算在fluent进行,且数值计算方法通过实验数据进行了验证。数值计算结果发现,当激励器尺度为0.1 mm时,推力曲线与速度曲线非常接近,此时平均推力及推进效率均较小。随着尺度增加,当激励器尺度大于1 mm时,推力曲线不对称度增加,且推力曲线的上升区间所占周期增加而下降区间所占周期减小,此时平均推力及推进效率都有明显提高。建立了合成射流的推力模型,该模型将合成射流推力分解为三部分:质量效应、加速效应及外部流场的压强效应。给出了不同尺度下的涡量图、速度分布图,通过对其分析可知,尺度较小时粘性作用较强,此时,内部流体的加速效应及外流场压强效应均很小,导致推进效率较低。随着尺度增加,粘性作用减弱,推进效率开始增加,当尺度增加到粘性可以忽略时,推进效率不再随尺度增加。

     

    Abstract: The thrust characteristics of underwater synthetic jet under different scales are numerically studied. The commercial code fluent is used for the numerical simulation. The numerical results are validated using experimental data. The numerical results show that when the scale is 0.1 mm, the variation of the thrust is close to that of the velocity. The average thrust and the propulsion efficiency is low on this scale. When the scale increases to 1 mm, the thrust becomes asymmetrical and both the average thrust and the propulsion efficiency are increased. A mathematical model of underwater synthetic jet is established. The model decomposes the thrust of underwater synthetic jet into three parts:the thrust induced by mass change, the thrust induced by fluid acceleration and the thrust caused by the pressure of the fluid outside the actuator. The vortical structures and the velocity distribution under different scales are given. The analysis of the flow field reveals that the viscous effect differs significantly for different scales. When the viscous effect is strong, the fluid acceleration and the pressure effect of the outside fluid is very weak. As a result, the efficiency of the actuator is low. With the increase of the size, the viscous effect is greatly reduced. The fluid acceleration and the pressure effect of the outside fluid increase, resulting in a larger efficiency.

     

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