As a low-cost scheme for small-scale hydropower generation, pump as turbines (PATs) are used at different hydrosites around the world. Nevertheless, big number of recently conducted studies on PAT performance have mainly focused centrifugal type, despite fact that axial-flow type has comparatively large flow capacity, thus disposing higher power density. Therefore, this article seeks to investigate dynamics an and associated energy loss characteristics, under both turbine operating modes. It...

We present a semi-automatic and efficient method for producing full polygonal models of range scanned trees, which are initially represented as sparse point clouds. First, skeleton the trunk main branches tree is produced based on Due to unavoidable incompleteness clouds by scans steps taken synthesize additional produce plausible support crown. Appropriate dimensions each branch section estimated using allometric theory. Using this information, mesh around skeleton. Finally, leaves...

Air-core vortices are a ubiquitous phenomenon in the intakes of hydropower stations. Due to transient and instability two-phase vorticial flow, prediction air-core vortex formation is challenging, understanding mechanism remains elusive. In this study, large eddy simulation (LES) method coupled level-set volume-of-fluid (CLSVOF) performed study benchmark reservoir with horizontal intake pipe. The process can be classified into an inception stage, stability stage. surface repeatedly goes...

Cavitation is a complex flow phenomenon that hinders the efficient, safe, and stable operation of hydraulic machinery. To investigate effect cavitation on energy performance characteristics machinery, cavitating in slanted axial-flow pump based entropy production theory vortex dynamics studied. The results show impeller chamber primary region loss generation under different conditions, including incipient, growing, wedge-shaped stages. In incipient stage, as degree strengthens, at blade...

Abstract Tip leakage flow (TLF) is a typical phenomenon in the internal of axial-flow pumps that has serious impact on their safety and stability. In this study, numerical simulations are performed to investigate influence various tip clearances operating conditions characteristics vortex (TLV) energy loss prototype vertical pump. First, based entropy production theory, TLV-induced quantitatively studied. The rate caused by turbulence dissipation (EPTD), which pulsating velocity, contributes...

Abstract. Physical parameterizations in general circulation models (GCMs), having various uncertain parameters, greatly impact model performance and climate sensitivity. Traditional manual empirical tuning of these parameters is time-consuming ineffective. In this study, a "three-step" methodology proposed to automatically effectively obtain the optimum combination some key cloud convective according comprehensive objective evaluation metrics. Different from traditional optimization methods,...

Background Lung cancer has the highest incidence and mortality of all cancers in China. Patients after a lobectomy experience serious physical psychological symptoms during chemotherapy. Studies are lacking about symptom clusters (SCs) sentinel postoperative chemotherapy period lung patients. Objective The aim this study was to explore SCs cycles 1 2 patients with cancer. Methods Using longitudinal design, treatment for were measured at separate points following lobectomy: cycle 2. MD...

When axial flow pumps-as-turbines (PATs) operate under off-design conditions, unstable and unsteady structures appear in the internal field, resulting suboptimal functioning. These operating conditions not only decrease efficiency of hydraulic machines but also affect their mechanical reliability. This study establishes relative streamline coordinates, based on blade's mean camber line, to investigate instabilities PATs from a new perspective. Numerical simulations an PAT were performed...

Due to the existence of an inlet elbow, transmission shaft, and other structural components, inflow axial-flow pumps as turbines (PATs) becomes non-uniform, resulting in complexity internal flow adverse effects such vibration. In this paper, numerical methods were employed explore non-uniform on impeller forces field characteristics within PAT. The study results indicated that caused uneven pressure distribution inside impeller, which leads imbalance radial offsetting center forces. With...

In deep stormwater tunnel systems (DSTSs), entrapped air pockets are prone to pressurization and deformation during rapid filling, resulting in pressure surges that threaten system security. This study investigates the effects of structural inflow parameters on peak pressures. To simulate pockets, a rigid-column model was developed for simplified DSTS configuration comprising two shafts one tunnel. The global sensitivities pocket, structure, were calculated using Extended Fourier Amplitude...

Axial-flow pumps have complex hydraulic performance under diverse conditions, especially low-flow which may occur rotational stall and brings serious system vibration. By combining experiments numerical simulation analysis, the fine features of local internal flow field in multi-flow rate conditions are accurately reflected, revealing mechanism changes axial-flow different at conditions. As decreased, backflow velocity near wall area inlet pipe circumferential swirl increased gradually, tip...

Spillway and drainage tunnels have an open-channel flow pattern when operating under unpressured condition, above which air is driven resisted by water flow, wall friction, pressure difference. Unpressured present many airflow-related safety environmental issues, including fluctuation, gate vibration, shaft cover blow-off, odor emission; therefore, it valuable to study predict their airflow velocity. Given the difficulty in accurate prediction of velocity complicated influences hydraulic,...