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| DOI：10.13522/j.cnki.ggps.2025188 |
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| Method for optimizing hydraulic sections of composite trapezoidal-parabolic channel |
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HE Zhengyu, HE Wuquan, LI Bo, ZHAO Keyi
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1. Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas of Ministry of Education,
Northwest A&F University, Yangling 712100, China; 2. Power China Northwest Engineering Corporation Limited, Xi’an 710065, China
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| Abstract: |
| 【Objective】Traditional trapezoidal channels are less hydraulically efficient and prone to frost heave, while parabolic channels have narrow openings and excessive depths making them unsuitable for use in medium-to- large-scale engineering projects. To address these limitations, we propose a composite channel with a parabolic bottom section for improving hydraulics and a trapezoidal slope for adaptability to large-scale project. 【Method】A hydraulic calculation model was developed for the composite channel, with water depth in the parabolic section as design variable. Optimal combination of the trapezoidal slope and parabolic section was determined using differential methods to minimize the hydraulic resistance and cross-sectional area. From this optimization, we established the correlations between water depth in the parabolic section and the trapezoidal section, and calculated the optimal water depth, cross-sectional area, wetted perimeter and water surface width. The model was validated against experimental data. 【Result】Under operating conditions of flow rate of 12 m3/s, roughness coefficient of 0.015, and channel slope of 1/6 000, the optimal composite channel had the following hydraulic parameters: total water depth was 2.838 m, water surface width was 6.122 m, wetted perimeter was 8.717 m, and cross-sectional area was 11.554 m2. Compared with traditional trapezoidal channel under the same operating conditions, the composite channel reduced cross-sectional area by 1.28% and wetted perimeter by 3.20%, while compared with traditional parabolic channel, it reduced cross-sectional area by 0.85% and the wetted perimeter by 1.68%. 【Conclusion】The proposed composite trapezoidal-parabolic channel integrates the advantages of both traditional designs. It improves hydraulic efficiency and is applaudable to medium-to-large-scale hydraulic engineering projects. The reduced cross-sectional area and wetted perimeter in the composite channel save land occupation and reduces engineering costs, thereby providing a practical and optimized alternative for channel engineering applications. |
| Key words: parabolic-bottom trapezoidal channel; composite cross-section channel; hydraulic optimum section; differential method; hydraulic calculation |
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