The tip leakage vortex (TLV) cavitating flow in an axial flow pump was simulated based on an improved shear stress transport (SST) k-ω turbulence model and the homogeneous cavitation model. The generation and dynamics of the TLV cavitation throughout the blade cascades at different cavitation numbers were investigated by the numerical and experimental visualizations. The investigation results show that the corner vortex cavitation in the tip clearance is correlated with the reversed flow at the pressure side (PS) corner of blade, and TLV shear layer cavitation is caused by the interaction between the wall jet flow in the tip and the main flow in the impeller. The TLV cavitation patterns including TLV cavitation, tip corner vortex cavitation, shear layer cavitation, and blowing cavitation are merged into the unstable large-scale TLV cloud cavitation at critical cavitation conditions, which grows and collapses periodically near trailing edge (TE).

The motivation for this review paper came from the developing countries where the economy is mostly dependent on agriculture and climate conditions. Based on current conditions and historical records, profitability in production farming depends on making a right and timely operational decision. Precision farming is a systematic program designed to maximize the productivity of agriculture by carefully tailoring the soil and crop management to meet the specific requirements in each field while preserving environmental quality. This review paper highlights the development of an automated irrigation system with portable wireless sensor networks and decision support methods to remotely measure the environmental parameters in an agriculture field. Radio satellite, mobile phones, sensors, internet-based communication, and microcontroller capture the ecological parameters such as soil moisture, temperature, humidity, and light intensity. The knowledge gained from the sensors is transferred directly to the cloud server by using IoT technology. Users from anywhere in the world can display them through an internet-enabled device. Development of sensor-based application in modern agriculture makes it cost-effective and potentially productive and increases the efficiency through precision agriculture farming. Different limitations have been reported in the previously reviewed publications like the shortage of power in the field that can be solved by using a solar panel that recharges the battery at the same time using electricity. Bluetooth application in the agriculture sector is mainly improved by design system optimization. Problems related to transmission and radio range frequency can be solved by using a power class upgraded antenna.

In this paper, the design methodology of a new type of three-dimensional surface return diffuser (3DRD) is presented and described in detail. The main goal was to improve the hydrodynamic performance of the deep-well centrifugal pump (DCP). During this study, a two-stage DCP equipped with two different type diffusers was simulated employing the commercial computational fluid dynamics (CFD) software ANYSY-Fluent to solve the Navier-Stokes equations for three-dimensional steady flow. A sensitivity analysis of the numerical model was performed in order to impose appropriate parameters regarding grid elements number and turbulence model. The flow field and the static pressure distribution in the diffusers obtained by numerical simulation were analyzed, and the diffuser efficiency was defined to quantify the pressure conversion capability. The prototype experimental test results were acquired and compared with the data predicted from the numerical simulation, which showed that the performance of the pump with 3DRD is better than that of the traditional cylindrical return diffuser (CRD) under all operating conditions. The efficiency and single-stage head of the pump with 3DRD have been significantly improved compared with the standard DCP of the same class.

A pump is one of the most important machines in the processes and flow systems. The operation of multistage centrifugal pumps could generate pressure fluctuations and instabilities that may be detrimental to the performance and integrity of the pump. In this paper, a numerical study of the influence of pressure fluctuations and unsteady flow patterns was undertaken in the pump flow channel of three configurations with different diffuser vane numbers. It was found that the amplitude of pressure fluctuation in the diffuser was increased gradually with the increase in number of diffuser vanes. The lower number of diffuser vanes was beneficial to obtain a weaker pressure fluctuation intensity. With the static pressure gradually increasing, the effects of impeller blade passing frequency attenuated gradually, and the effect of diffuser vanes was increased gradually.

A multistage deep-well centrifugal pump (DCP) with different impeller rear shroud radius have been investigated both numerically and experimentally under multiconditons, which aims at studying the influence of impeller rear shroud radius to the axial force and pump hydraulic performance. During this study, a two-stage DCP equipped with three different impellers was simulated employing the commercial computational fluid dynamics (CFD) software ANYSY-Fluent to solve the Navier-Stokes equations for three-dimensional steady flow. High-quality structured grids were meshed on the whole computational domain. Test results were acquired by prototype experiments, and then compared with the predicted pump performance and axial force. The static pressure distribution in the pump passage obtained by numerical simulation was analyzed. The results indicated that the appropriate impeller rear shroud radius could improve the pump performance and lower the axial force significantly.