جستجوی مقالات مرتبط با کلیدواژه "خطوط جریان" در نشریات گروه "آب و خاک"

Sliding valves are among the hydraulic structures that have many applications in irrigation and drainage and dam networks. Their most important application is to increase the water level in order to drain the upstream canals and increase the height of the dam weir in order to store more water and also to measure the flow discharge. Many researches have been done to determine the flow coefficient (Cd) of these valves, all of which have been for valves perpendicular to the channel axis. In this research, the data of the hydraulic model of the side sliding gate of the sharp edge of the hydraulic laboratory of the Faculty of Civil Engineering, Rourke University of India have been used, which includes 121 laboratory data related to the free flow regime with three valve width to flume width ratios of 0.60, 0.83 , 1.00 and the flow discharge is 25 to 120 liters per second and 80 laboratory data are related to the submerged flow regime with a ratio of valve width to flume width of 1 meter and flow range of 25 to 85 liters per second. Laboratory data include flow rates Q, water depth before valve y1, flow depth at the bottom yt and opening of valve a. Using the analytical method and dimensionless number a / y1, the critical depth value under the sliding valve ycs For free flow regime and immersion coefficient  For submerged flow regime, the amount of flow discharge was calculated directly. The results of validation of the extracted relationships show that the use of the critical depth parameter in determining the amount of flow discharge has a high accuracy.

The main application of spillway in rivers and dams reservoirs is control and diversion of flood and protection of their related structures. In this research, a laboratory study was performed to test 16 trapezoid piano key A type weir models with different pillars 10, 15 and 20 cm in a canal with 10 meters length, 0.6 m width and 0.6 m height. The proposed weirs were placed on the main canal wall with two arrangements. The results showed that the maximum overflow rate coefficient was corresponded to weirs with p=15cm in both arranments (1 and 2) and the dimentionless ratio of 0.4 <H/P> 0.2 0.4 and also to weir with dimentionless ratio of 0.5 <H/P and p=20cm. Finally, the trapezoid piano key weir with a p=15cm and a B=50cm identified to pass the most appropriate flow regime.

Investigation of the flow pattern in meandering rivers is much more complicated than straight ones. Also, most rivers in the path of bends are not uniform due to channel width variations. Therefore, the use of a robust numerical model for simulating flow pattern in rivers is necessary. In this research, SSIIM three-dimensional numerical model was used to simulate the flow pattern in a meandering reach of ​​the Doab river in Chaharmahal and Bakhtiari province. For this purpose, after doing field measurements and model calibration the velocity values ​​calculated by the model were compared with the measured values in a relatively uniform section of bend by using RMSE and MAPE error criteria. Results obtained showed that the values of these two criteria are 0.081 and 0.075, respectively. This indicates that the model performance is good. Moreover, various flow characteristics including vertical and horizontal velocity profiles, the velocity lines in longitudinal and transverse directions and also the distribution of bed shear stress in location of two converged and diverged the bends are compared. The results of this study indicate that velocity values in longitudinal direction in converged bend is higher than diverged one. the high accuracy of the model in the study of flow pattern in the river bend. Furthermore, the density of the stream lines and the values of bed shear stress at the interval reach of two bends are maximum. As result, it can be said that flow pattern simulated well with the model