| 植物网纹增厚导管流体力学建模与流动特性分析 |
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| 引用本文： | 徐天宇,张立翔.植物网纹增厚导管流体力学建模与流动特性分析[J].排灌机械工程学报,2020,38(1):76-82. |
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| 作者姓名： | 徐天宇 张立翔 |
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| 作者单位： | 昆明理工大学建筑工程学院,云南昆明650500;昆明理工大学建筑工程学院,云南昆明650500 |
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| 基金项目： | 国家自然科学基金;国家自然科学基金;高等学校博士学科点专项科研基金 |
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| 摘 要： | 为了研究植物内壁网纹增厚对导管水分运输的影响,采用计算流体力学结合伯努利方程的方法,对导管内径,螺旋线数量,螺纹间距,网纹高度和网纹宽度等因素进行分析,通过压降和等效损失系数的变化,探究网纹增厚导管内部微流动机理.计算结果表明,对于特定网纹增厚导管模型,随着螺旋线数量的增加,总压降增大约16.34%,等效损失系数增大约26.45%;随着网纹螺纹间距增加,总压降减少约5.49%,等效损失系数减少约9.83%;随着网纹高度增加,总压降增大约33.89%,等效损失系数增大约57.96%;随着网纹宽度增加,压降增大约9.56%,等效损失系数增大约15.30%.导管网纹增厚对水分输运影响是网纹结构和回旋流动区域共同作用,且回旋流动区域是影响水分输运的主要因素.对比3种不同导管增厚结构,网纹增厚导管结构流阻最大,环纹增厚导管次之,螺纹增厚导管最小.3种增厚导管的结构流阻与导管内径大小成正比,内径越大的增厚导管其传输效率就越接近理想光滑管道.
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| 关 键 词： | 木质部导管 网纹增厚 伯努利方程 水分传输 螺旋线数量模型 等效损失系数 |
| 收稿时间： | 2019-04-21 |
Fluid mechanics modeling and flow characteristics analysis of secondary wall thickening reticulated vessels in vascular plants |
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| XU Tianyu,ZHANG Lixiang.Fluid mechanics modeling and flow characteristics analysis of secondary wall thickening reticulated vessels in vascular plants[J].Journal of Drainage and Irrigation Machinery Engineering,2020,38(1):76-82. |
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| Authors: | XU Tianyu ZHANG Lixiang |
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| Institution: | Faculty of Civil Engineering and Mechanics, Kunming University of Science and Technology, Kunming, Yunnan 650500, China |
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| Abstract: | Effects of inner diameter, number of helical curls, spacing of helical curls, helical curl height and width in secondary wall thickening reticulated vessels on water transport in the xylem of vascular plants were analyzed in terms of pressure drop and equivalent hydraulic loss coefficient(flow resistance coefficient)by using computational fluid dynamics(CFD)combined with the Bernoulli equation to study micro-flow mechanism in the vessels. The results showed that the total pressure drop and flow resistance coefficient were increased by 16.34% and 26.45%, respectively, with increasing number of helical curls. With increasing helical curl spacing, however, the total pressure drop and flow resistance coefficient were decreased by 5.49% and 9.83%. The total pressure drop and flow resistance coefficient rose by 33.89% and 57.96% as the helical curl height was increased. Additionally, the total pressure drop and flow resistance coefficient ascended by 9.56% and 15.30% with increasing helical curl width. The interaction between helical reticulated curl structure and flow recirculation region in the vessels, especially the recirculation region, was mainly responsible for the effects of the secondary wall thickening on the water transport. Compared with three different thickening vessels, the helical reticulated curl vessel was subject to the greatest flow resistance, and the helical curl vessel was with the smallest resistance, but the flow resistance in the annular vessel was in between. The flow resistance was proportional to vessel inner diameter in three thickening vessels. The larger the inner diameter of a thickening vessel, the closer the transport efficiency of the vessel to that of an ideal smooth vessel. |
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| Keywords: | xylem vessel reticulated thickened Bernoulli equation water transportation number of reticulated spirals model flow resistance coefficient |
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