The phenomenon of water–jet pump stall can be ascribed to the development blade boundary layer separation with transition process playing a significant role in this separation. hydrofoil is usually used as simplified model impeller blade, and its flow field characteristics have important reference values for analyzing flow. Based on dynamic mode decomposition method, article presents results study that was carried out NACA0009 blunt trailing edge hydrofoil. surfaces at different angles...

The occurrence and development of centrifugal pump rotating stall is closely related to disturbance in the incoming flow. seal clearance leakage an inherent impeller flow pumps. In order investigate influence on characteristics, field numerical simulation a under conditions with without are carried out. It found that 0.4Q0 condition leakage, “λ” special shaped high-velocity region distribution along blade leading edges strengthened, which lead larger scale vortices. And periodicity...

The phenomenon of rotating stall in centrifugal pumps is closely associated with the evolution blade boundary layer. Aiming to accurately predict characteristics layer, this study investigates pump impellers using gamma (γ) transition model. accuracy numerical simulation was confirmed by comparing its conclusions results testing. In calculations considering characteristics, distribution low-pressure areas inside impeller relatively discontinuous, while pressure more uniform. However, without...

Objective: To investigate the trends in insulin resistance, as represented by triglyceride-glucose index (TyG index), among Chinese adult residents from 2010 to 2018 and explore influencing factors. Methods: China Chronic Disease Risk Factor Surveillance was conducted 2010, 2013, 2018, using a multi-stage stratified cluster random sampling method across all 31 provinces (autonomous regions municipalities) China. This study sampled 98 712 adults 176 534 184 876 aged ≥18 years, totaling 406...

Pumped storage hydro is a mature energy method [...]

Waterjet propulsion systems are the core power units of high-performance ships and widely used in marine engineering. This study uses entropy production theory to analyze influence geometric parameter changes on thrust efficiency a water jet system at low cruising speeds. The results indicate that, based original model, when intake duct inclination angle varies by 3°, an increase leads reduction velocity, thereby decreasing thrust, diminishing inflow quality pump, increasing hydraulic loss...

Rotating stall is an unsteady flow phenomenon, which always leads to instability and efficiency degradation. In order reveal pressure fluctuations in the impeller of centrifugal pump induced by cells, structures a volute-type were calculated using Large Eddy Simulation (LES) method. The predicted results numerical model compared with experimental flow-head curve. simulation good agreement results. phenomenon occurred when rate dropped 70% design rate. Three cells located at entrance passages...

Stall usually occurs in the hump area of head curve, which will block channel and aggravate pump vibration. For centrifugal pumps with guide vanes have a clocking effect, stall characteristic at different positions should be focused. In this paper, flow field under conditions is numerically simulated, rotor–stator interaction effects are studied. The double-hump found curve by using SAS (Scale Adaptive Simulation) model. close to optimal working condition caused hydraulic loss, while far...

Double-entry two-stage double-suction centrifugal pumps with high flow rates and heads are used in some large water supply applications. The pressure fluctuation of the impeller is a key factor influencing vibration pumps. In this paper, pump simulated verified by experiments, distribution two stage impellers obtained. study on time domain frequency demonstrates that first-stage single-suction affected twin volute. At 1.0 Q, dominant blade suction side twice rotation frequency. main...

The interaction of tip leakage flow and main in an axial pump can induce the vortex, which causes unstable complex cavitation structures. In present research, modified shear stress transport k–ω turbulence model was utilized to predict cavitating under design off-design conditions. Validations were carried out using high-speed photography techniques. Results show that simulation results about performance based on agree well with experimental results. Cavitation inception occurs more possible...

Hydrofoil shapes are used for the marine turbine blades to capture kinetic energy from water currents effectively. Predicting transitions is a critical concern when studying hydrofoil boundary layer. This paper analyzed transitional behavior of layer in National Advisory Committee Aeronautics (NACA) hydrofoil, NACA0009, with blunt trailing edge using Algebraic Local-Correlation-based Transition Modeling (Algebraic LCTM) model. First, through sensitivity analysis, effects maximum y+ (the...

Purpose Tip leakage vortex flow (TLV) is a common phenomenon in the axial-flow hydraulic machinery. High-efficiency simulation of TLV still not an easy task because complex turbulent vortex-cavitation interactions. As important basis CFD, turbulence model directly affects efficient computation TLV. The purpose this paper to evaluate newly developed MST predicting flows. Design/methodology/approach By using and ZGB cavitation model, numerical simulations generated by NACA0009 hydrofoil were...

As an indispensable part of water conservancy engineering construction, the importance pumping stations is reflected in several aspects [...]

In the realm of marine science and engineering, hydrofoils play a pivotal role in efficiency performance turbines water-jet pumps. this investigation, boundary layer characteristics an NACA0009 hydrofoil with blunt trailing edge are focused on. The effectiveness both two-equation gamma theta (γ-Reθt) transition model one-equation intermittency (γ) forecasting behavior is evaluated. When considering natural transition, these two models outperform shear stress transport (SST k-ω) turbulence...