A self-priming centrifugal pump can be used in various areas such as agricultural irrigation, urban greening, and building water-supply. In order to simulate the gas-water two-phase flow process of a pump, unsteady numerical calculation typical was performed using ANSYS Computational Fluid X (ANSYS CFX) software. It found that whole divided into three stages: initial stage, middle final stage. Moreover, time stages accounts for small percentage process, while stage is main further determines...

The generation of stall conditions will directly affect the hydraulic and energy characteristics water jet propulsion pump. Utilizing entropy theory, this study conducts a comparative analysis loss distribution across each pump device component under varying flow conditions. investigation delineates variation with changes in rate, revealing that impeller inlet duct emerge as primary contributors to system. Through patterns rate design two for section, elucidates these sections. aims provide...

As an important over-current component of the waterjet propulsion system, main function a nozzle is to transform mechanical energy pump into kinetic water and eject flow obtain thrust. In this study, with different geometry parameters was simulated based on computational fluid dynamics simulation experiment. Numerical results show good agreement experimental results. The that circular shape outlet shrinks evenly. Under designed rate condition, velocity uniformity 0.26% 0.34% higher than...

The roof-attached vortices (RAVs), floor-attached (FAVs), and complex combined submerged (CSVs) excited in a closed pump sump will induce irregular pressure fluctuations that can decrease the energy efficiency of stability its input flow. This article presents an experimental investigation loss induced by these under various conditions. A transparent closed-loop test rig was used for high-speed visualization pressure-fluctuation tests. findings demonstrate as flow rate is increased, head...

Hierarchical zeolites formed by the aggregation of uniformly oriented nanocrystals are directly synthesized using a high yielding quasi-solid phase method without adding extra templates, and is scalable. The hierarchical also exhibit excellent catalytic performance for alkylation benzene with propylene.

Vortices always happen in the forebay and sump of a lateral pumping station, reducing its efficiency wasting extra electric power. This study utilizes computational fluid dynamics (CFD) technology model test method to investigate distribution vortices station Y-shaped channel. Since vortex is accompanied by energy dissipation, entropy production theory also introduced analyze behaviors anti-vortex bottom sill. The research results indicate that verify accuracy CFD. sill can effectively...

In a laterally asymmetric intake pumping station, the flow direction in forebay is not consistent with channel. Thus, adverse patterns, such as bias flow, large-scale vortex and occur frequently sump. Based on Reynolds-averaged Navier-Stokes (RANS) equation RNG k-ε turbulence model, recent pattern station was numerically simulated analyzed, effective elimination measures were proposed. For original scheme, seriously biased combined vortices observed several occurred To suppress clash inflow...

Rotating stall as a kind of ship causes noise, vibration and unstable operation waterjet propulsion system sometimes it can even cause fracture blades destruction other flow passage components.To investigate the suppression rotating stall, complete 3-D model has been developed which contains an inlet passage, pump nozzle.Hydraulic performance characteristics are predicted by using numerical simulation, is in good agreement with experimental results.For suppressing separators set outlet...

The shaft tubular pump device is widely used in low head pumping stations plain areas. N-S equation and the SST k-ω turbulence model are adopted. Then, investigation on influence of transition form inflow pattern hydrodynamic characteristics pre-shaft carried out. By designing three forms shafts, different patterns provided for device. characteristic parameters shafts external internal flow under compared analyzed. Finally, optimal selected tests, unsteady pressure pulsation studied. results...

The shaft-type tubular pumping station has the remarkable characteristics of a large flow rate and high efficiency. It can realize functions irrigation, pumping, drainage through generating conditions considering tides. Moreover, it is widely used in plain area eastern China tidal along marine region. Due to different topological features airfoil impeller, energy evolution during remain unclear. entropy generation theory was introduced numerically simulate pattern channel, straight channel...

Water jet propulsion pumps start at special stages such as mooring and sailing, the ship is in shallow water, underwater keen clearance (UKC) relatively small, which easy to induce suction vortex near inlet position cause violent vibration of pumping unit. The powerful effect water-jet pump can draw debris from bottom riverbed, causing damage pump. This research investigated water under different UKC conditions. A flow field analysis method based on entropy weight theory was constructed...

An automated multi-objective and multidisciplinary design optimization (MDO) of a transonic turbine stage to maximize the isentropic efficiency minimize maximum stress rotor with constraints on mass flowrate dynamic frequencies is presented in this article. The self-adaptive differential evolution (SMODE) algorithm studied developed seek Pareto solutions optimization, new constraint-handling method based concept applied for constraint handling. performance SMODE demonstrated using typical...

The unsteady flow process of waterjet pumps is related to the comprehensive performance and phenomenon rotating stall cavitation. To analyze on condition, a computational domain containing nozzle, impeller, outlet guide vane (OGV), shaft established. surface vortex blade unstable at valley point hydraulic zone. core morphological characteristics will change in small range with time. best efficiency start zone each turbo relatively stable. At zone, pressure fields are unstable, which causes...

Nanocrystalline ZnS has been successfully prepared through a hydrothermal method by the reaction of anhydrous ZnCl 2 and NH 4 SCN at above 160°C. X-ray powder diffraction (XRD) analysis indicates that product was cubic phase (sphalerite). Transmission electron microscopy (TEM) shows average particle size is ∼30 nm.