Effect of Different Screen Types on Head Loss in Deep Wells Used for Irrigation

Abstract

This research was carried out with the help of a deep well simulator, which is commonly utilized for irrigation studies. In this study, flow types based on Reynolds number, well drawdown, head losses, and cost changes of these head losses were analyzed for four different sieve types used in wells. In addition, the flow types and head losses for the types of screen used were examined as per the theoretical calculations.
 Theoretically, the turbulent head loss among types of screens was calculated at the highest (0.37 m) in the bridge slot screen (ST4) and at least (0.028 m) in the round slot (ST3). The drawdown is the sum of the head losses for deep wells. Among the well-types, the maximum drawdown (113.46 cm) was measured within the bridge slot well type (WT4), and the minimum drawdown (50.37 cm) was measured in the horizontal slot oblong well type (WT2). The least head loss per unit flow rate in the wells was measured in the well, which was formed with a horizontal oblong slot (WT2) screen. Here, gravel and screen hole position affected the percentage of clogging in the screens. Overclogging of the screens caused the narrowing of the opening area, increased flow velocity and turbulent head loss, and increased drawdown.
 It has been revealed that the use of a horizontal oblong slot screen minimizes the head loss in the wells, depending on the physical properties of the gravel used in this study. One of the most important factors to be considered in well designs is the compatibility of the screen type depending on the physical properties of the gravel. Even the change of the geometric shape among the screen types having similar apertures changed the blockage of the gravel, causing the head loss to change. The well-designers should pay attention to the selection of gravel depending on the screen type or the selection of the screen depending on the type of gravel used.