Showing papers by "Hongjun Zhu published in 2020"
TL;DR: The paper summarizes the works led to the current wind energy and hydro energy harvesters based on the principle of flow- induced vibrations, including bladeless generator Vortex Bladeless, University of Michigan vortex-induced vibrations aquatic clean energy, Australian BPS company's airfoil tidal energy capture device bioSTREAM, and others.
313 citations
TL;DR: In this article, the effects of the downstream plate length and the arrangement of plates on the hydrodynamic forces, vibration response and flow wake were examined using the direct numerical simulation (DNS).
102 citations
TL;DR: In this paper, the effects of the coverage ratio and angular position of a pair of fin-shaped strips on the hydrodynamic forces and wake structures of a circular cylinder at both low and medium Reynolds numbers were numerically studied.
52 citations
TL;DR: In this article, the performance of an Aquatic Clean Energy Harvester (ACEH) under wake interferences of different arranged stationary cylinders is numerically studied, and the wake interference can induce the EHC to galloping at some particular positions.
36 citations
TL;DR: In this paper, the effects of the plate length and surface undulation on the hydrodynamic forces and vortex shedding behavior of a circular cylinder with a rear rigid wavy plate was examined.
24 citations
21 citations
TL;DR: In this article, the energy generated by vortex-induced vibrations is studied through numerical simulation, and the vibration characteristics of the energy-harvesting device are studied using a bidirectional coupled fluid-structure simulation.
12 citations
TL;DR: In this paper, a numerical investigation was conducted to examine the effect of injection velocity of a pair of air jets positioned at the two shoulders of a circular cylinder on the vortex shedding at a low Reynolds number Re ǫ = 100.
10 citations
TL;DR: In this article, the results of a numerical investigation in to the two-degree-of-freedom (2-DOF) flow-induced vibration (FIV) of two rigidly coupled tandem cylinders of unequal diameters at a low Reynolds number of 150.
10 citations
TL;DR: In this article, the evolution of the vortical structures in the wakes of four types of screen cylinders at a Reynolds number of about 3200 was studied in a water flume using Particle Image Velocimetry (PIV).
9 citations
TL;DR: In this paper, the flow induced vibration (FIV) responses of two rigidly connected cylinders in various arrangements have been studied numerically using the two-dimensional incompressible Navier-Stokes equations coupling with a fourth-order Runge-Kutta method.
25 Mar 2020
TL;DR: In this paper, flow-induced vibrations of bluff bodies with four different cross-sectional geometries (circle, square, triangle and semi-circle) arranged both in single and tandem (gap ratio equals to 3 and 5) configurations are investigated in a wind tunnel.
Abstract: In this paper, flow-induced vibrations of bluff bodies with four different cross-sectional geometries (circle, square, triangle and semi-circle) arranged both in single and tandem (gap ratio equals to 3 and 5) configurations are investigated in a wind tunnel. It is found that triangular and square cylinders have the higher amplitude than that of the semi-circular and the circular cylinders in the single configuration. When two cylinders are arranged in tandem, the circular cylinders have the highest amplitude among all tested cylinders. Furthermore, the semi-circular cylinder shows that its vibrating amplitude increases with the reduced velocity in the tandem system due to the galloping effect.
18 Dec 2020
TL;DR: In this paper, the slug flow-induced vibration (SIV) of an inclined sagged riser conveying upward air-water flows is experimentally investigated in a small-scale test loop with a section of a free-hanging catenary tube made of silica gel.
Abstract:
Subsea liquid-gas flows conveyed through a flexible riser or pipeline may develop into various flow patterns including slug flow. In this study, the slug flow-induced vibration (SIV) of an inclined sagged riser conveying upward air-water flows is experimentally investigated. A small-scale experiment is carried out in an air-water test loop with a section of a free-hanging catenary tube made of silica gel. Attention is placed on the effect of superficial gas and liquid velocities on SIV responses. Both pipe motions and flow patterns are recorded using non-intrusive high-speed cameras. Pressure variations are also measured at the pipe inlet and outlet by two pressure transducers. The SIV system is tested by employing different ratios of the superficial gas-liquid velocities. Occurrence of unstable slug flows is captured at the relatively high gas-to-liquid velocity ratios, leading to a large-amplitude SIV. Experimental results of the space-time varying riser responses and oscillation frequencies are reported together with the associated slug flow features. Depending on the gas-liquid superficial velocities, slug flow characteristics are observed to vary significantly. These entail an intermittent SIV with modulated amplitudes and frequencies along riser span, signalling a potential dynamic stress and fatigue-related concern. In all experimental cases, the riser responses are found to be multi-modal and dominated by the fundamental planar mode whereas an out-of-plane vibration is negligible. Experimental observations suggest the key interrelationships of the two-fluid flow conditions, the slug characteristics and the pipe dynamics. This finding is meaningful for a practical design of riser transporting internal multiphase flows.
Patent•
12 Jun 2020TL;DR: In this article, an arc-shaped wing plate with uneven surfaces was used for swinging power generation and vibration suppression by using a swirl-swinging system and a current collecting system.
Abstract: The invention relates to a device and a method for swinging power generation and vibration suppression by using arc-shaped wing plates with uneven surfaces. The device is formed by two parts: a swirlswinging system and a current collecting system. The swirl swinging system comprises a current collecting vertical pipe, a steering bearing, nanometer material arc-shaped power generating wing platesand flexible tail plates; and the current collecting system comprises a telescopic power generation cylinder, a waterproof electric slip ring and a waterproof power transmission line. According to thedevice, under the combined action that the nanometer material arc-shaped power generating wing plates divide a flowing space and adjust a flowing direction, the nanometer material arc-shaped power generating wing plates drive the flexible tail plates to swing so as to destroy a tail vortex street, and hemispheric bulges and trumpet-shaped deflector holes disturb a flow-around boundary layer, vortex-induced vibration suppression without energy consumption is realized; and in addition, the bending and the deforming of the nanometer material arc-shaped power generating wing plates, the deformingof the hemispheric bulges, and the reciprocating telescopic action of the telescopic power generation cylinder produce currents, so that the conversion of ocean current energy is realized synchronously.