The problem of hydraulic calculation of pressure distribution pipelines

Most production technologies require a uniform flow path of liquid from pressure distribution pipelines. To achieve this goal, it is proposed to introduce polymer additives into the liquid flow or to use converging distribution pipelines with a continuous longitudinal slot in the wall. To reduce the uneven operation of the distribution pipeline during discrete liquid dispensing, it is proposed to use cylindrical output rotary nozzles with a lateral orthogonal entry of the jet into the nozzle. The problem is the lack of methods for accurate hydraulic calculation of the operation of distribution pipelines. Adequate calculation methods are based on differential equations. Finding the exact solution of the differential equation of fluid motion with variable path flow rate for perforated distribution pipelines is urgent, because it still does not exist. The available calculation methods take into account only the right angles of separation of the jets from the flow in the distribution pipeline. These methods are based on the assumption that the coefficient of hydraulic friction and the coefficient of resistance of the outlets are constant along the flow. A calculation method is proposed that takes into account the change in the values of these resistance coefficients along the distribution pipeline. The kinematic and physical characteristics of the flow outside the distribution pipeline are also taken into account. The accuracy of calculating the value of the flow rate of water distributed from the distribution pipeline has been experimentally verified. The error in calculating the water consumption by the method assuming that the values of the resistance coefficients are unchanged along the distribution pipeline reaches 18.75 %. According to the proposed calculation method, this error does not exceed 6.25 %. However, both methods are suitable for the design of pressure distribution pipelines, provided that the jet separation angles are straight. Taking into account the change from 90° to 360° of the angle of separation of the jets from the flow in the distribution pipeline will expand the scope and accuracy of calculation methods.

Employing the dumbbell-shaped longitudinal slot antennas in the planar slotted antenna arrays

The dumbbell-shaped longitudinal slot antennas are employed as a replacement for the round-ended longitudinal slot antennas. Each dumbbell-shaped slot is excited by an iris and a septum that have offsets from the waveguide centerlines. All the slots are also cut along the waveguide centerlines. It is demonstrated that the resonant length of the proposed dumbbell-shaped slot antennas is much smaller than the round-ended longitudinal slot antennas. Hence, the end-to-end spacings between the adjacent radiating slots as well as the end-to-end spacings between the coupling and the radiating slots increased noticeably in comparison with the arrays consist of the round-ended longitudinal slot antennas. This fact indicates that one can neglect the mutual coupling between the neighboring slots that are associated with the exciting higher-order modes at the slot positions. To better demonstrate the effectiveness of the proposed dumbbell-shaped slot antennas, a planar array antenna consists of the proposed dumbbell-shaped slot antennas have been designed, implemented, and tested. The measurement and the simulation results confirm the effectiveness of the proposed slot antennas.