scholarly journals Numerical Prediction Method for Local Scour with 3D Body-Fitted Coordinates

1995 ◽  
Vol 39 ◽  
pp. 683-688
Author(s):  
Satoru Ushijima ◽  
Nobukazu Tanaka
Keyword(s):  
Prediction Method ◽  
Numerical Prediction ◽  
Local Scour

scholarly journals An Equivalent Damping Numerical Prediction Method for the Ring Damper Used in Gears under Axial Vibration

Symmetry ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1469 ◽  
Author(s):  
Shuai Wang ◽  
Xiaolei Wang ◽  
Yanrong Wang ◽  
Hang Ye
Keyword(s):  
Structural Parameters ◽  
Great Influence ◽  
Prediction Method ◽  
Forced Response ◽  
Numerical Prediction ◽  
Axial Stiffness ◽  
Response Analysis ◽  
Axial Vibration ◽  
Equivalent Damping ◽  
Vibration Loads

In aircraft gas turbine engines, gears in the transmission system are typically cyclic in structure and inevitably encounter large dynamic loads, such as meshing excitation, resulting in high vibration loads in resonance. To prevent gear resonance failure, a ring damper is employed to reduce the resonance response. As relative motion between the gear and the ring damper occurs, vibration loads can be reduced by friction energy dissipation. Moreover, the gears in the aircraft engine are thin-walled and their axial stiffness is much smaller than radial stiffness; thus, it is easier for axial vibration to cause resonance failure. This paper proposes an equivalent damping numerical prediction method for a ring damper under axial vibration, which greatly shortens the calculation time and prevents the forced response analysis of nonlinear structures. Via this method, the influence of ring damper structural parameters on friction damping in gears under axial vibration is investigated. The results indicate that the friction coefficient and mass of the ring damper have a great influence on damping performance.

scholarly journals The Quantitative Forecast of Precipitation with the Numerical Prediction Method

1955 ◽  
Vol 33 (5) ◽  
pp. 205-216 ◽  
Author(s):  
M. Komabayasi ◽  
K. Miyakoda ◽  
M. Aihara ◽  
S. Manabe ◽  
K. Katow
Keyword(s):  
Prediction Method ◽  
Numerical Prediction

scholarly journals NUMERICAL PREDICTION METHOD FOR ARBITRARILY-SHAPED BODIES MOVING IN THREE-DIMENSIONAL FLUIDS

2007 ◽  
Vol 51 ◽  
pp. 847-852
Author(s):  
Satoru USHIJIMA ◽  
Akira FUKUTANI ◽  
Susumu FUJIOKA ◽  
Iehisa NEZU
Keyword(s):  
Three Dimensional ◽  
Prediction Method ◽  
Numerical Prediction

scholarly journals Scale Model Experiment on Local Scour around Submarine Pipelines under Bidirectional Tidal Currents

2021 ◽  
Vol 9 (12) ◽  
pp. 1421
Author(s):  
Zhiyong Zhang ◽  
Yakun Guo ◽  
Yuanping Yang ◽  
Bing Shi ◽  
Xiuguang Wu
Keyword(s):  
Tidal Current ◽  
Tidal Cycle ◽  
Engineering Application ◽  
Prediction Method ◽  
Tidal Currents ◽  
Local Scour ◽  
Scale Model ◽  
Hangzhou Bay ◽  
Scour Depth ◽  
Steady Current

In nearshore regions, bidirectional tidal flow is the main hydrodynamic factor, which induces local scour around submarine pipelines. So far, most studies on scour around submarine pipelines only consider the action of unidirectional, steady currents and little attention has been paid to the situation of bidirectional tidal currents. To deeply understand scour characteristics and produce a more accurate prediction method in bidirectional tidal currents for engineering application, a series of laboratory scale experiments were conducted in a bidirectional current flume. The experiments were carried out at a length scale of 1:20 and the tidal currents were scaled with field measurements from Cezhen pipeline in Hangzhou Bay, China. The experimental results showed that under bidirectional tidal currents, the scour depth increased significantly during the first half of the tidal cycle and it only increased slightly when the flow of the tidal velocity was near maximum flood or ebb in the following tidal cycle. Compared with scour under a unidirectional steady current, the scour profile under a bidirectional tidal current was more symmetrical, and the scour depth in a bidirectional tidal current was on average 80% of that under a unidirectional, steady current based on maximum peak velocity. Based on previous research and the present experimental data, a more accurate fitted equation to predict the tidally induced live-bed scour depth around submarine pipelines was proposed and has been verified using field data from the Cezhen pipeline.

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