Correlation between depassivation and repassivation processes determined by single particle impingement: Its crucial role in the phenomenon of critical flow velocity for erosion-corrosion

2021 ◽  
Vol 89 ◽  
pp. 158-166
Author(s):  
L.L. Li ◽  
Z.B. Wang ◽  
S.Y. He ◽  
Y.G. Zheng
Keyword(s):  
Flow Velocity ◽  
Single Particle ◽  
Crucial Role ◽  
Critical Flow ◽  
Critical Flow Velocity ◽  
Erosion Corrosion

On the critical flow velocity for erosion-corrosion of Ni-based alloys in a saline-sand solution

Wear ◽  
2020 ◽  
Vol 458-459 ◽  
pp. 203417
Author(s):  
J.Z. Yi ◽  
H.X. Hu ◽  
Z.B. Wang ◽  
Y.G. Zheng
Keyword(s):  
Flow Velocity ◽  
Critical Flow ◽  
Critical Flow Velocity ◽  
Erosion Corrosion

scholarly journals Hybrid Scour Depth Prediction Equations for Reliable Design of Bridge Piers

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2019
Author(s):  
Hossein Hamidifar ◽  
Faezeh Zanganeh-Inaloo ◽  
Iacopo Carnacina
Keyword(s):  
Flow Velocity ◽  
Critical Velocity ◽  
Depth Estimation ◽  
Hybrid Models ◽  
Velocity Estimation ◽  
Bridge Piers ◽  
Critical Flow ◽  
Scour Depth ◽  
Critical Flow Velocity ◽  
Estimation Equations

Numerous models have been proposed in the past to predict the maximum scour depth around bridge piers. These studies have all focused on the different parameters that could affect the maximum scour depth and the model accuracy. One of the main parameters individuated is the critical velocity of the approaching flow. The present study aimed at investigating the effect of different equations to determine the critical flow velocity on the accuracy of models for estimating the maximum scour depth around bridge piers. Here, 10 scour depth estimation equations, which include the critical flow velocity as one of the influencing parameters, and 8 critical velocity estimation equations were examined, for a total combination of 80 hybrid models. In addition, a sensitivity analysis of the selected scour depth equations to the critical velocity was investigated. The results of the selected models were compared with experimental data, and the best hybrid models were identified using statistical indicators. The accuracy of the best models, including YJAF-VRAD, YJAF-VARN, and YJAI-VRAD models, was also evaluated using field data available in the literature. Finally, correction factors were implied to the selected models to increase their accuracy in predicting the maximum scour depth.

An Analysis of In-Flow Fluidelastic Instability Based on a Physical Insight

2014 ◽  
Author(s):  
Tomomichi Nakamura
Keyword(s):  
Flow Velocity ◽  
Flow Instability ◽  
Pressure Sensors ◽  
Measured Data ◽  
Critical Flow ◽  
Nonlinear Phenomenon ◽  
Critical Flow Velocity ◽  
Fluid Force ◽  
Tube Arrays ◽  
Fluidelastic Instability

Fluidelastic vibration of tube arrays caused by cross-flow has recently been highlighted by a practical event. There have been many studies on fluidelastic instability, but almost all works have been devoted to the tube-vibration in the transverse direction to the flow. For this reason, there are few data on the fluidelastic forces for the in-flow movement of the tubes, although the measured data on the stability boundary has gradually increased. The most popular method to estimate the fluidelastic force is to measure the force acting on tubes due to the flow, combined with the movement of the tubes. However, this method does not give the physical explanation of the root-cause of fluidelastic instability. In the work reported here, the in-flow instability is assumed to be a nonlinear phenomenon with a retarded or delayed action between adjacent tubes. The fluid force acting on tubes are estimated, based on the measured data in another paper for the fixed cylinders with distributed pressure sensors on the surface of the cylinders. The fluid force acting on the downstream-cylinder is assumed in this paper to have a delayed time basically based on the distance between the separation point of the upstream-cylinder to the re-attachment point, where the fluid flows with a certain flow velocity. Two models are considered: a two-cylinder and three–cylinder models, based on the same dimensions as our experimental data to check the critical flow velocity. Both models show the same order of the critical flow velocity and a similar trend for the effect of the pitch-to-diameter ratio of the tube arrays, which indicates this analysis has a potential to explain the in-flow instability if an adequate fluid force is used.

Sign in / Sign up

Export Citation Format

Share Document