Free end drop for measuring flow rate in striped sides triangular channels

Abstract

Free end water drop in striped sides triangular channels has been used as a tool for measuring end depth flow rate with its practical applications in triangular trenches. The current study’s laboratory work includes testing twelve channel models with striped sides in which strips have 1 cm x 1 cm square cross sections arranged in seven patterns of strips concentrations h_s/L_s ranging from 1/128 to 1/2 for various side slopes Z_T and channel slopes S_T. Five hundred fifty-four experiments are performed on the channel models covering a wide range of Froude numbers. It is important to note that roughness coefficient n_T achieves its maximum value at strips concentration = 1/8 across all channel slopes. Curves of the end drop discharge (EDD) are presented for varied channel’s side slopes and bed slopes at h_s/L_s = 1/8. Ratio of end drop water depth D_e to critical depth D_c (EDR) demonstrated straight line correlations. D_e/D_c grows as h_s/L_s decreases, reaching a maximum value at h_s/L_s = 1/8. Variations of D_e with uniform depth D_n yielded straight line connections. A quadratic equation was found to exist between D_e/D_c and S_T/n_T with determination coefficient R² = 0.997. An empirical correlation for the fluctuation of dimensionless discharge in terms of D_e/D_c and S_T/n_T is obtained for different channel side slopes, channel bed slopes, h_s/L_s = 1/8, and a Froude number range of 0.39 to 0.87. Two empirical approaches are proposed for predicting flow rate in striped sides triangular channels.