Yabin Liu

The University of Edinburgh | UoE · School of Engineering

Mitigating the impact of variable inflow conditions is critical for a wide range of engineering systems such as drones or wind and tidal turbines. Passive control systems are of increasing interest for their inherent reliability, but a mathematical framework to aid the design of such systems is currently lacking. To this end, in this paper a two-di...

Tip leakage flow in turbomachinery inherently generates intense unsteady features, named self-excited unsteadiness, which significantly affects the operating stability, aerodynamic efficiency, and noise but has not been well understood. A zonalized large eddy simulation is employed for a linear cascade, with wall-modeled large eddy simulation activ...

Tip leakage flow in turbomachinery inherently generates intense unsteady features, named self-excited unsteadiness, which has not been well understood. A Zonalised LES (ZLES) is employed around a linear cascade, with wall-modelled Large Eddy Simulation (LES) forced to be active in the tip region. The simulation is well validated and demonstrated th...

This paper presents the first blind prediction stage of the Tidal Turbine Benchmarking Project being conducted and funded by the UK's EPSRC and Supergen ORE Hub. In this first stage, only steady flow conditions, at low and elevated turbulence (3.1%) levels, were considered. Prior to the blind prediction stage, a large laboratory scale experiment wa...

We compute the loads on a model-scale tidal turbine with Blade Element Momentum (BEM) theory and Computational Fluid Dynamics (CFD) simulations, and we compare the results with towing tank tests. CFD simulations are wall-resolved, steady, Reynolds-averaged Navier-Stokes simulations with a k − ω SST turbulence model, where only a 120◦ wedge domain w...

Tidal currents are renewable and predictable energy sources that could prove fundamental to the transition to a sustainable use of renewable energy resources. Over a tidal period, changes in the flow speed in a tidal channel require that the blade pitch is adjusted to maximise power extraction. This is currently achieved with active pitch actuation...

Tidal energy has attracted great attention due to its massive potential and eco-friendly nature. Performance of ducted turbines used in tidal energy conversion is significantly influenced by tip clearance and associated leakage flow. In this work, a method of variable-depth (VD) groove is developed to suppress the tip leakage vortex (TLV) and the t...

Tip clearance results in the leakage flow from blade pressure side to suction side, which will further cause the tip leakage vortex (TLV). Moreover, the flow pattern in an impeller is seriously deteriorated due to the TLV and its interaction with the main stream. In the present work, the TLV in a mixed flow pump is investigated by numerical simulat...

A systematical investigation on hydraulic performance and unsteady flow characteristics around tip clearance in a mixed-flow pump is conducted based on experimental results and steady simulation. The 1mm increase of tip clearance size results in that the pump head reduces by 1.79m, and pump efficiency decreases by 5.49% at design flow rate. At larg...

Tip clearance in pump induces tip leakage vortex (TLV), which interacts with the main flow and leads to instability of flow pattern and decrease of pump performance. In this work, the characteristics of TLV in a mixed-flow pump are investigated by the numerical simulation using shear stress transport (SST) k-Ï ‰ turbulence model with experimental v...

Propellers, pumps, and turbines are widely applied in marine equipment, water systems, and hydropower stations. With the increasing demand for energy conservation and environmental protection, the high efficiency and the stable operation of pumps and turbine have been drawing great attention in recent decades. However, the tip clearance between the...

Influence of original and T-shape blade end on performance of a mixed-flow pump is investigated by using experimental measurement and numerical simulation. The new proposed T-shape blade end is formed at 95%–100% blade height with a linear increase of blade thickness. In comparison with original blade end, the efficiency of pump with T-shape blade...

Tidal energy induced by the gravitation between the earth and moon is the most widespread energy with great development potential by hydraulic machineries. Tip leakage vortex (TLV) has significant influence on the flow pattern and energy performance of hydraulic machineries. In the present work, a C groove method is proposed to suppress the TLV and...

Purpose The paper aims to investigate the effect of three-dimensional inlet guide vanes on performance of a centrifugal pump. Design/methodology/approach A design method for three-dimensional (3D) inlet guide vanes (IGVs) is proposed based on the controllable velocity moment, which is determined by a fourth-order dimensionless function. Numerica...

The pressure fluctuations and flow pattern in a mixed-flow pump are numerically investigated under design and off-design conditions. The accuracy and reliability are validated by good agreement of numerical results and experimental data of pump energy performance. At design flow rate, the dominant frequencies of pressure fluctuations are impeller r...

The energy performance and pressure fluctuations in a centrifugal pump with inlet guide vanes (IGVs) are investigated experimentally and numerically in a prewhirl angle range of −24 • to 24 • and in an axial distance range of 280 mm, 380 mm, and 460 mm. The reliability and accuracy of the numerical method are validated by the satisfactory agreement...

Cavitation phenomenon has strong transient characteristics and is highly influenced by geometric structure. In this study, the cavitation performance with influence of blade tip clearance for a mixed-flow pump is studied using the renormalization group (RNG) k–ε turbulence model and the Zwart–Gerber–Belamri cavitation model. The dominant frequency...

Tip clearance between blade end and shroud is inevitable in pump operation and of great importance on pump energy performance and pressure fluctuation. As the tip clearance size increases, the head and efficiency of the mixed flow pump drop accordingly. The simulation results show that the development of a leakage vortex is observed as the tip clea...

The role of blade rotational angle in the energy performance and pressure fluctuation of a mixed-flow pump is investigated through an experimental measurement and numerical simulation. The mixed-flow pump head increases at a blade rotational angle of 4° and decreases at a blade rotational angle of −4° compared with a blade rotational angle of 0°. M...

The energy performance and radial force of a mixed flow pump with symmetrical and unsymmetrical tip clearance are investigated in this paper. As the tip clearance increases, the pump head and efficiency both decrease. The center of the radial force on the principal axis is located at the coordinate origin when the tip clearance is symmetrical, and...