Comparative numerical study of the dynamic motion of OWC impulse turbine in the starting process

2022 ◽  
Vol 245 ◽  
pp. 110429
Author(s):  
Yongyao Luo ◽  
Ran Tao ◽  
Guangjie Peng
Keyword(s):  
Numerical Study ◽  
Impulse Turbine ◽  
Dynamic Motion ◽  
Starting Process

Numerical study on a modified impulse turbine for OWC wave energy conversion

2016 ◽  
Vol 111 ◽  
pp. 533-542 ◽  
Author(s):  
Z. Liu (刘臻) ◽  
Y. Cui(崔莹) ◽  
K.W. Kim(金吉元) ◽  
H.D. Shi(史宏达)
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Numerical Study ◽  
Wave Energy Conversion ◽  
Impulse Turbine

scholarly journals Numerical Study of the Effect of Wing Position on the Dynamic Motion Characteristics of an Underwater Glider

2021 ◽  
Vol 28 (2) ◽  
pp. 4-17
Author(s):  
Xiangcheng Wu ◽  
Pengyao Yu ◽  
Guangzhao Li ◽  
Fengkun Li
Keyword(s):  
Numerical Study ◽  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
Underwater Glider ◽  
Dynamic Motion ◽  
Biological Oceanography ◽  
Underwater Gliders ◽  
Movement Performance ◽  
Motion Characteristics ◽  
The Relationship

Abstract Underwater gliders are winged, autonomous underwater vehicles that are broadly applied in physical and biological oceanography. The position of the wing has an important effect on the movement performance of the underwater glider. In this paper, the dynamic motion of a series of underwater glider models with different longitudinal wing positions are simulated, which provides guidance for the design of underwater gliders. The results show that when the net buoyancy is constant, the wing position affects the gliding angle, but does not affect the relationship between the gliding angle and the gliding speed. In addition, the farther the wing position of the glider is from the buoyancy centre, the longer it takes for the attitude of a glider to change, whether the wing is in front of, or behind, the buoyancy centre.

scholarly journals DEVELOPMENT OF A NUMERICAL MODEL FOR THE STUDY OF AN OSCILLATING WATER COLUMN DEVICE CONSIDERING AN IMPULSE TURBINE

2019 ◽  
Vol 18 (1) ◽  
pp. 99
Author(s):  
A. L. dos Santos ◽  
L. A. Isoldi ◽  
L. A. O. Rocha ◽  
M. N. Gomes ◽  
R. S. Viera ◽  
...  
Keyword(s):  
Numerical Model ◽  
Energy Conversion ◽  
Water Column ◽  
Numerical Study ◽  
Velocity Ratio ◽  
Power Coefficient ◽  
Working Fluid ◽  
Speed Ratio ◽  
Oscillating Water Column ◽  
Impulse Turbine

The present work brings a numerical study of an energy conversion device which takes energy from the waves through an oscillating water column (OWC), considering an impulse turbine with rotation in the chimney region through the implementation of a movable mesh model. More precisely, a turbulent, transient and incompressible air flow is numerically simulated in a two-dimensional domain, which mimics an OWC device chamber. The objectives are the verification of the numerical model with movable mesh of the impulse turbine in the free domain from the comparison with the literature and, later, the study of the impulse turbine inserted in the geometry of the OWC device. In order to perform the numerical simulation on the generated domains, the Finite Volume Method (FVM) is used to solve the mass and momentum conservation equations. For the closure of the turbulence, the URANS (Unsteady Reynolds Averaged Navier-Stokes) model k-ω SST is used. To verify the numerical model employed, drag coefficients, lift, torque and power are obtained and compared with studies in the literature. The simulations are performed considering a flow with a Reynolds number of ReD = 867,000, air as the working fluid and a tip speed ratio of λ = 2. For the verification case, coefficients similar to those previously predicted in the literature were obtained. For the case where the OWC device was inserted it was possible to observe an intensification of the field of velocities in the turbine region, which led to an augmentation in the magnitude of all coefficients investigated (drag, lift, torque and power). For the case studied with the tip velocity ratio λ = 2, results indicated that power coefficient was augmented, indicating that the insertion of the turbine in a closed enclosure can benefit the energy conversion in an OWC device.

Numerical Study of Cage Dynamics Focused on Hydrodynamic Effects of Guidance Land Clearances for Different Ball-Pocket Clearances in Cryogenic Environments

2017 ◽  
Author(s):  
Bok Seong Choe ◽  
Jeon Kook Lee ◽  
Doyoung Jeon ◽  
Yongbok Lee
Keyword(s):  
Ball Bearing ◽  
Rotation Speed ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Cfd Analysis ◽  
Dynamic Motion ◽  
Light Load ◽  
Dynamic Forces ◽  
Inner Race

This study presents the dynamic motion of a ball bearing cage submerged in a cryogenic fluid under high-speed conditions. The dynamic motion of the cage has been studied as a function of the race land–cage and ball–cage pocket clearances for different inner race rotation speeds under light load conditions. In addition, this study conducted computational fluid dynamics (CFD) analysis using commercial software to analyze the fluid dynamic forces on the cage. The hydraulic force obtained from the CFD analysis was coded in commercial ball bearing analysis software as a function of the eccentricity ratio and rotation speed of the cage. Finally, the dynamic motion of the ball bearing cage considering the effects of fluid dynamic forces has been studied. The results include the cage whirling amplitude, fluctuation of cage whirling speed, and cage wear for various cage clearances and rotation speeds. The cage outer guidance clearances studied were 1.14, 1.04, 0.94, 0.84, and 0.74 mm and the ball–pocket clearances were 0.62, 0.92, 1.22, 1.52, and 1.82 mm. The rotation speeds of the inner race were 5,000, 8,000, and 11,000 rpm. The cage whirling amplitude decreases as the outer guidance clearance decreases, and it decreases as the rotation speed increases up to 11,000 rpm because of the increasing hydrodynamic force of the liquid nitrogen (LN2). However, the probability density function (PDF) curves indicate that an increase in the rotor speed increases the standard deviation in the cage whirling frequency. The wear loss of the cage was greatest for the largest race land–cage and the smallest ball–cage pocket clearances, owing to the increased number of intermittent collisions between the cage and the ball bearings (ball–race). Consequently, the analysis results for various operating conditions (inner race rotation speeds, cage clearances, traction coefficients, etc.) are in good agreement with the reference results.

Numerical Study of the Starting Process in a Supersonic Nozzle

2005 ◽  
Vol 21 (2) ◽  
pp. 374-378 ◽  
Author(s):  
A.-S. Mouronval ◽  
A. Hadjadj
Keyword(s):  
Numerical Study ◽  
Supersonic Nozzle ◽  
Starting Process

LOADING, CHARGING AND THERMAL EFFECTS ON THE MECHANISM OF WATER–CARBON NANOTUBE TRANSMISSION

2013 ◽  
Vol 02 (03n04) ◽  
pp. 1350017 ◽  
Author(s):  
ZHONG-QIANG ZHANG ◽  
HONG-FEI YE ◽  
YONG-GANG ZHENG ◽  
GUANG-GUI CHENG ◽  
JIAN-NING DING ◽  
...  
Keyword(s):  
Thermal Effects ◽  
Slip Velocity ◽  
Electromechanical Coupling ◽  
Transmission Mechanism ◽  
Dynamics Simulation ◽  
Confined Water ◽  
Dynamic Motion ◽  
Starting Process ◽  
A Charge ◽  
Better Than

In this paper, the transmission mechanism of a charge-controlled water–carbon nanotubes (CNTs) fluidic transmitting nanodevice is investigated by using molecular dynamics simulation with the loading, charging and thermal effects on the starting process being considered. The results show that the external load on the driven CNT can slow down the startup speed of the nanotransmission while the transmitting stability is better than that in non-loading transmitting process. The startup speed of the water–CNTs transmission increases with the increase in the charge magnitude on CNTs since the charges on CNT atoms can increase the water–CNT interfacial coupling strength. The control of the water temperature can also affect the startup speed of the driven CNT attributed to the thermal effect on the slip velocity of confined water. The configuration, dynamic motion behaviors and temperature of the confined water in both the starting and steady transmitting processes are studied to understand the thermo-electromechanical coupling effects on the transmission mechanism of the water–CNTs charge-controlled fluidic transmitting nanodevice.

Numerical study of a thermoacoustic impulse turbine

2019 ◽  
Author(s):  
Dan Radulescu ◽  
Georgel Vizitiu ◽  
Marius Deaconu
Keyword(s):  
Numerical Study ◽  
Impulse Turbine

scholarly journals Numerical Study on Heat Distribution and Transfer Characteristics of a Manifold in a Coal Mine VAM TFRR Oxidation Bed

2015 ◽  
Vol 9 (1) ◽  
pp. 687-696 ◽  
Author(s):  
Zongli Li ◽  
Yongqi Liu ◽  
Jinhui Han ◽  
Zhiming Wang
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Maximum Error ◽  
Flow Reversal ◽  
Thermal Flow ◽  
Hot Gas ◽  
Coupled Heat Transfer ◽  
Homogeneous Porous Media ◽  
Fluent Software ◽  
Starting Process

A thermal flow-reversal reactor is candidate for utilizing low concentration ventilation air methane. In this paper, a numerical study is performed by using the FLUENT software to explore the details of the transient preheating and starting process of the thermal flow-reversal reactor oxidation bed. The bed was heated by hot gas, which was transported and distributed through the holes of manifolds to the middle of the bed. The homogeneous porous media and coupled heat transfer models were chosen; and the mass and heat flow distributions passing through the holes, the heat transfer on the outer surface of the manifold and the temperature distribution of the bed were calculated. The results indicate that the heat of the hot gas passing through the holes decreases gradually along the direction of the hot gas flowing in the manifold, causing the temperature of the bed decrease accordingly. The calculated temperatures of the oxidation bed are compared with the tested results. The maximum error between the calculation and the test was 8.9%.

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