Numerical Simulation of Magnetostriction-Induced Cavitation Flow

2013 ◽  
Vol 477-478 ◽  
pp. 271-276
Author(s):  
Dong Sheng Xia ◽  
Yan Yu ◽  
Hui Chen Zhang
Keyword(s):  
Pressure Fluctuation ◽  
Cavitation Erosion ◽  
Pressure Pulse ◽  
Wave Length ◽  
Cavitation Flow ◽  
Local Flow ◽  
Dynamic Mesh Technique ◽  
Symmetrical Pattern ◽  
Cavitation Intensity ◽  
Mesh Technique

The magnetostriction-induced cavitation flow was numerically simulated by using a full cavitation model with the SSTk-ωturbulence model and the dynamic mesh technique. The characteristics of ultrasonic cavitation flow and the cavitation erosion mechanism were revealed. The computational results show that the pressure fluctuation possesses the characteristics of pulse on the specimen. Intense pressure pluses and cavitation occur in the local flow adjacent to the specimen. As numerous bubbles collapse, intense pressure pulses form on the specimen. Cavitation intensity is serious at the center while it is slight at the edge. The pressure pulse and the vapor volumn fraction with the equal magnitude symmetrically distribute around the center, meaning that cavitatin erosion appears a symmetrical pattern around the center. The effective pressure fluctuation occurs in the local flow field within the distance of one third of the wave length to the specimen. It is validated that the wave energy dissipates very fast in the magnetostriction-induced cavitation flow.

Research on the Impacts of Screw Speed on All-Metal Screw Pump

2014 ◽  
Vol 703 ◽  
pp. 425-429
Author(s):  
Jun Fei Wu ◽  
Zhi Li ◽  
Fan Guo Meng ◽  
Ben Liang Yu
Keyword(s):  
Geometric Model ◽  
Constraint Condition ◽  
3D Flow ◽  
Screw Speed ◽  
Ansys Fluent ◽  
Screw Pump ◽  
Single Screw ◽  
Dynamic Mesh Technique ◽  
Fluent Software ◽  
Mesh Technique

Compared with traditional screw pump,all-metal screw pump have more advantages in the oil extraction. In this paper, all-metal single screw pump's geometric model was made by PROE software; then the dynamic mesh technique was applied to mesh the model and constraint condition was applied in the ANSYS-FLUENT software. 3D flow field was numerical analyzed In that software, the impacts of screw speed on volume flow and volumetric efficiency were concluded, the conclusion can offer some valuable guidances to the all-metal single screw pump's design.

scholarly journals Cavitation Simulation and Mechanism Analysis of Underwater Jet of Cleaning Equipment for Aquaculture Fishing Net

2019 ◽  
Author(s):  
Taiping Yuan ◽  
Xiaohua Huang ◽  
Yu Hu ◽  
Shaomin Wang ◽  
Haiyang Liu ◽  
...  
Keyword(s):  
Cavitation Erosion ◽  
Volume Fraction ◽  
Evolutionary Process ◽  
Mechanism Analysis ◽  
Cavitation Inception ◽  
Outlet Angle ◽  
Cleaning Equipment ◽  
Cavitation Intensity ◽  
Nozzle Structure ◽  
Erosion Zone

In order to reveal the mechanism and influencing factors of high pressure jet cavitation of nozzle in submerged environment, this study focused on the evolutionary process of cavitation bubbles and combined finite volume method and mixed multi-phase flow model to analyze the cavitation, velocity distribution and experimental cavitation intensity of fishing net cleaning equipment. Results show that the cavitation inception, growth and collapse mainly occurred in the peripheral region of the flow field. Ring-shaped cavitation erosion zone appeared on the test sample target. A lot of small dense erosion pits were densely distributed in the ring-shaped erosion zone, erosion marks were observed in the center. The cavitation erosion intensity was greatly affected by the nozzle structure. As the diameter of nozzle increased from 0.6 mm to 1 mm, the maximum gas volume fraction increased by 8.53%. The nozzle outlet enlargement angle greatly increased the cavitation intensity. The nozzle with an outlet angle of 30° exhibited the optimal cavitation erosion performance . The cavitation volume fraction of the nozzle with short necking structure was slightly larger than that of the nozzle with long necking structure at the same level in the necking length rang of 3mm to 7mm. In terms of the influence of nozzle structure on the cavitation erosion effect, the nozzle diameter D ranked the first, followed by the outlet angle α, and the necking length L was at the last.

Simulating growth of ash deposit in boiler heat exchanger tube based on CFD dynamic mesh technique

Fuel ◽  
2020 ◽  
Vol 259 ◽  
pp. 116083 ◽  
Author(s):  
Zhimin Zheng ◽  
Wenming Yang ◽  
Peng Yu ◽  
Yongtie Cai ◽  
Hao Zhou ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Dynamic Mesh ◽  
Heat Exchanger Tube ◽  
Dynamic Mesh Technique ◽  
Ash Deposit ◽  
Mesh Technique ◽  
Exchanger Tube

Transient Analysis of Stress-Wave Penetration in Plates

1959 ◽  
Vol 26 (4) ◽  
pp. 651-660
Author(s):  
Norman Davids
Keyword(s):  
Time Delay ◽  
Plane Wave ◽  
Time Distribution ◽  
Transient Analysis ◽  
Pressure Pulse ◽  
Wave Length ◽  
Expansion Method ◽  
Transient Stress ◽  
Reflected Waves ◽  
Forcing Function

Abstract This paper carries out an analysis of the propagation of a transient stress pulse concentrated at a point on the boundary of a plate whose thickness is of the order of a wave length. It is based on an expansion method used by Caignard in geophysical-layer problems which obviates the contour-integration difficulties and whose terms represent successively reflected waves of increasing time delay. From the general formulas obtained in this paper for an arbitrary forcing function, the stress versus time distribution along the axis of a 1-in-thick aluminum plate is obtained for a 5-microsec exponentially decaying pressure pulse. Inside the plate it is found there is a compressed zone which is relieved by a negative front traveling with the distortional wave velocity. When this interferes with a certain reflected negative front, the stress reverses in sign. A comparison of the location of this reversal is made with those based on plane-wave assumptions. Limiting cases are discussed.

NUMERICAL ANALYSIS OF CAVITATION SUSCEPTIBILITY FOR STEAM GENERATOR INTEGRAL PREHEATER TUBES

2014 ◽  
Vol 3 (01) ◽  
pp. 37-46 ◽  
Author(s):  
S. Laroche ◽  
L. Sun ◽  
J. Pietralik
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Steam Generator ◽  
Cavitation Erosion ◽  
Saturation Temperature ◽  
Fluid Temperature ◽  
Baffle Plate ◽  
Subcooled Boiling ◽  
Local Flow ◽  
Flow And Heat Transfer

A new tube degradation mechanism was observed in a recirculating steam generator (SG) with an integral preheater tube at the clearance gap between the tube and the preheater baffle. The general pattern of the damage and material composition in the degraded region suggested that the degradation was cavitation erosion. Cavitation erosion occurs when vapour bubbles exist or form in the flowing liquid and then these bubbles collapse violently in the vicinity of a solid wall. The bubbles collapse when they contact water that is sufficiently subcooled, i.e., below the saturation temperature. In the clearance gap between the tube and the preheater baffle, secondary fluid flow exists due to the pressure difference across the baffle plate. Meanwhile, heat transfer occurs from the primary-side fluid to the secondary-side fluid within this clearance gap, driven by the primary-to-secondary temperature difference. Factors such as the tube position in the baffle hole and fouling may influence the local flow and heat transfer conditions and can cause subcooled boiling that results in cavitation. This paper presents a numerical analysis of flow and heat transfer phenomena to determine the factors contributing to cavitation erosion of tubes in the preheater of a recirculating SG. The analysis used the THIRST code for a 3-dimensional thermalhydraulic simulation of steam generator and the ANSYS Fluent® code for detailed calculations of flow and heat transfer in the clearance gaps. A detailed temperature distribution in the gap was obtained using this analysis to determine the regions where subcooled boiling could occur by comparing the local fluid temperature with its saturation temperature. The susceptibility to cavitation was found to increase with increased inclination (i.e., tilt) and eccentricity (i.e., off-centre) of the tube in the baffle plate gap, and increased fouling on baffle plate surfaces. This methodology could be applied to analyze the cavitation susceptibility for other preheater types with this “tube to baffle plate” gap, as these preheaters might have conditions where boiling followed by the rapid condensation of the steam bubbles are present.

Simulation on Three Dimensional Water-Exit Trajectory of Submarine Launched Missile

2013 ◽  
Vol 791-793 ◽  
pp. 1069-1072 ◽  
Author(s):  
Shao Zhu Wang ◽  
Han Ping Wang ◽  
Ming Yang ◽  
Lin Peng Wang ◽  
Guang Wei Wei
Keyword(s):  
Three Dimensional ◽  
Dynamic Mesh ◽  
Research Focus ◽  
Dynamic Mesh Technique ◽  
Mesh Technique ◽  
Trajectory Characteristic ◽  
Water Exit

Cool Launch project is an important launch mode of submarine launched missile, the water-exit trajectory characteristic of the missile in launching process becomes to research focus. Model of three dimensional water-exit trajectory of submarine launched missile was built based on dynamic mesh technique and simulation operation was carried out to obtain the characteristics of water-exit trajectory & attitude. The method adopted in the establishment of the model and the result has provided references to the research of water-exit trajectory.

Characterization of Cavitation Eroded Surfaces at Different Temperatures Using Wavelet Method

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
A. Abouel-Kasem ◽  
B. Saleh ◽  
K. M. Emara ◽  
S. M. Ahmed
Keyword(s):  
Wavelet Decomposition ◽  
Cavitation Erosion ◽  
Average Particle Size ◽  
Image Features ◽  
Average Particle ◽  
Wavelet Method ◽  
Wavelet Energy ◽  
Cavitation Intensity ◽  
Different Temperatures

In the present work, the image features of cavitation erosion surfaces at different temperatures are extracted using wavelet decomposition transform. The results obtained indicate that the extract parameters, wavelet energy, and entropy can characterize the cavitation intensity in a similar manner to that of the mass loss and average particle size at different temperatures. Based on the analysis of the eroded surface and particle morphologies for different temperatures, it was found that the predominant failure mode was fatigue.

Sign in / Sign up

Export Citation Format

Share Document