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为了提高网片水动力系数的计算精度,本文通过动水槽实验对5种网片的水动力学性能进行测试。测试的参数包括水流对网片的冲角、流速、网片的水平缩结系数ET等,网片的水动力学升力系数CL、阻力系数Cd、升阻系数比K等。结果表明:(1)当雷诺数Re小于1 500,冲角小于45°时,阻力系数呈现先增后减的趋势;而冲角大于45°时,阻力系数呈减小的趋势。雷诺数Re大于2 800时,阻力系数基本趋于稳定。(2)升阻系数比K最大值出现在20°附近;在30°~90°之间,K值呈减小趋势;(3)升阻力系数随d/a的增大先增大后减小;(4)升阻力系数随线面积系数的增大而减小;(5)通过多元非线性拟合得出升阻力系数的经验公式,拟合度较好。本实验经验公式为拖网阻力的计算提供了依据。
In order to improve the computational accuracy of hydrodynamic coefficients of mesh, this paper tests the hydrodynamic performance of 5 kinds of mesh through the motionless tank experiment. The parameters of the test include the angle of flow to the web, the flow rate, the horizontal shrinkage coefficient ET of the web, the hydrodynamic lift coefficient CL of the web, the drag coefficient Cd, the ratio of resistance to drag K, and the like. The results show that: (1) The drag coefficient increases first and then decreases when the Reynolds number Re is less than 1 500 and the angle of attack is less than 45 °. When the angle of attack is larger than 45 °, the drag coefficient decreases. Reynolds number Re greater than 2 800, the drag coefficient basically stabilized. (2) The ratio of the drag coefficient to the maximum value of K appears in the vicinity of 20 °. From 30 ° to 90 °, the value of K decreases. (3) The drag coefficient increases first and then decreases with the increase of d / a (4) The coefficient of drag reduction decreases with the increase of line area coefficient; (5) The empirical formula of drag coefficient is obtained by multivariate nonlinear fitting, and the fitting degree is better. The experimental empirical formula provides a basis for the calculation of drag resistance.