Calculation on critical depth of horseshoe cross-section by iterative method
LV Hong-xing(College of Water Conservancy and Architectural Engineering,Northwest Sci-Tech University of Agriculture and Forestry, Yangling, 712100, China)
Horseshoe cross-section is one of commomly used sections for open-channe1 flow tunnel. Its geometricshape consists of four radial curves. The hydralic elements, including cross-section area, wetted perimeter, watersurface width, etc., can be expressed by piecewise functions respectively. The hydraulic calculation of horse shoecross-section in open-channel flows is difficult because of its complex sectional construction. The formulas of hy-draulic elements and iterative formulas of critical depths for standard I and II type horseshoe cross-sections arederived, and how to discriminate the demarcation discharges of range of critical depths is presented. The calculat-ed results of hydraulic elements at characteristic points are identical, therefore the continuity and correctness ofthe formlas at the characteristic points are proved.