摘要: 研究典型株型沙生灌丛周围的流场分布，旨在为干旱、半干旱地区合理选择不同株型的防风沙植被提供理论依据。本文利用FLUENT软件对3类典型株型（坛形、梭形、帚形）灌丛周围的流场进行数值模拟，分析不同植株形态对风沙流的影响，并加以风洞试验验证，结果表明：（1）3类株型周围流场可分为5个区，且株后均存在3个涡流。受涡流强度的影响，在积沙初始阶段，梭形、帚形植株主要在株后6~7 H处积沙，而坛形植株在3 H附近积沙。（2）受植株最大侧影面积高度层的影响，3类株型灌丛株后1 H处的风速极小值依次出现在0.3 m、0.4 m、0.8 m高度处，最优防护高度依次为0.2~0.4 m、0.3~0.6 m、0.8~1 m。3类株型株后的空气动力学粗糙度逐渐减小，且坛形的粗糙度明显高于其他株型。（3）3类株型在-2~10 H范围内均可有效降低风速，株后近地表区防风效益表现为坛形＞梭形＞帚形，而中高空区防风效益均随株距增加而减小。（4）在T=10 s时，3类植株周围总积沙长度分别为8.5 H、6H、4.5 H，梭梭、沙拐枣分别在距入口5~5.5 m、4.5~6 m处存在不同程度的风蚀现象。对比其他植株，白刺（Nitrariasphaerocarpa）具有较好的阻沙效果，在防风固沙工程建设中建议将其与梭梭（Haloxylon ammodendron）、沙拐枣（Cal⁃ligonum mongolicum）结合，既能发挥白刺的阻沙作用，又可利用梭梭、沙拐枣较好的中高空防风效果。
Abstract: The purpose of this study was to provide a theoretical basis for the rational selection of different vegetation types for wind and sand control in arid and semiarid areas. Fluent software was used to numerically simulate the flow field around three types of typical strains (altar-shaped, shuttle-shaped, and broom-shaped) of scrub to analyze the influence of different plant forms on wind and sand flow and verify the results using existing wind tunnel tests. Results showed that (1) The flow field around the three types of plants can be divided into five zones, and three eddies exist behind the plants. Due to the intensity of the eddies, during the initial phase of sand accumulation, shuttle- shaped and broom- shaped plants accumulated sand primarily at 6-7 H after the plant, whereas altar-shaped plants accumulated sand at 3 H. (2) Affected by the height layer of the maximum profile area of the plant, the minimum wind speed at 1 H after the three types of plant shrubs appeared at heights of 0.3, 0.4 m, and 0.8 m, and the optimal protection range of height was 0.2- 0.4 m, 0.3- 0.6 m, and 0.8- 1 m, respectively. The aerodynamic roughness of the three plant types decreased gradually, and the roughness of the altar-shaped plants was significantly higher than that of the other two plant types. (3) All three types of strains could effectively reduce wind speed in the range of -2-10 H. The wind protection benefits in the near-surface area after the strains are altar-shaped > shuttle-shaped > broom-shaped the wind protection benefits in the midaltitude area all decrease with increasing plant distance. (4) At T = 10 s, the total duration of sand accumulation around the three plants was 8.5 H, 6 H, and 4.5 H, respectively, and wind erosion existed to different degrees at 5- 5.5 m and 4.5-6 m from the entrance for Haloxylon ammodendron and Calligonum mongolicum, respectively. Compared with other plants, Nitraria tangutorum exerted a better sand-blocking effect. Hence, it is recommended to combine N. tangutorum with H. ammodendron and C. mongolicum in the construction of wind and sand fixation projects, so that the sand- blocking property of N. tangutorum can be effectuated, and the better windblocking effect of H. ammodendron and C. mongolicum can be utilized at medium and high altitudes.
| [V1] | 2023-05-30 19:21:04 | ChinaXiv:202305.00246V1 | 下载全文 |
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