The Effect of Centrifugal Force and Coriolis Force on Vehicle-Flexible Bridge Vertical Vibration

2012 ◽  
Vol 455-456 ◽  
pp. 1480-1485
Author(s):  
Xiang Xiao ◽  
Wei Xin Ren ◽  
Wen Yu He
Keyword(s):  
Centrifugal Force ◽  
Coriolis Force ◽  
Vertical Vibration

The Effect of Centrifugal Force and Coriolis Force on Vehicle-Flexible Bridge Vertical Vibration

2012 ◽  
Vol 455-456 ◽  
pp. 1480-1485
Author(s):  
Xiang Xiao ◽  
Wei Xin Ren ◽  
Wen Yu He
Keyword(s):  
Centrifugal Force ◽  
Coriolis Force ◽  
Mass Matrix ◽  
Interaction Model ◽  
Vertical Motion ◽  
Vertical Vibration ◽  
Time Deformation ◽  
Damping Matrix ◽  
Load Vector ◽  
Bridge System

Considering centrifugal force and Coriolis force caused by the real-time deformation of bridge, a vehicle-bridge interaction model is established. Take simply supported bridge subjected to an one-axle vehicle for example, the mass matrix, damping matrix, stiffness matrix and load vector of the vehicle-bridge system are derived via modal analysis method, thus the vertical motion equation of vehicle-bridge system, which can better reflect the operation characteristics of vehicles running on the bridge, has been established.

The effect of spanwise system rotation on Dean vortices

1994 ◽  
Vol 274 ◽  
pp. 243-265 ◽  
Author(s):  
O. John E. Matsson ◽  
P. Henrik Alfredsson
Keyword(s):  
Centrifugal Force ◽  
Coriolis Force ◽  
Travelling Waves ◽  
Streamwise Vortices ◽  
Longitudinal Vortices ◽  
Smoke Visualization ◽  
Rotation Rates ◽  
Dean Vortices ◽  
System Rotation ◽  
Secondary Instabilities

An experimental study is reported of the flow in a high-aspect-ratio curved air channel with spanwise system rotation, utilizing hot-wire measurements and smoke visualization. The experiments were made at two different Dean numbers (De), approximately 2 and 4.5 times the critical De for which the flow becomes unstable and develops streamwise vortices. For the lower De without system rotation the primary Dean instability appeared as steady longitudinal vortices. It was shown that negative spanwise system rotation, i.e. the Coriolis force counteracts the centrifugal force, could cancel the primary Dean instability and that for high rotation rates it could give rise to vortices on the inner convex channel wall. For positive spanwise system rotation, i.e. when the Coriolis force enhanced the centrifugal force, splitting and merging of vortex pairs were observed. At the higher De secondary instabilities occurred in the form of travelling waves. The effect of spanwise system rotation on the secondary instability was studied and was found to reduce the amplitude of the twisting and undulating motions for low negative rotation. For low positive rotation the amplitude of the secondary instabilities was unaffected for most regions in parameter space.

scholarly journals Numerical Flow Analysis in a Rotating Square Duct and a Rotating Curved-Duct

2000 ◽  
Vol 6 (1) ◽  
pp. 1-9
Author(s):  
Je Hyun Baekt ◽  
Chang Hwan Ko
Keyword(s):  
Laminar Flow ◽  
Viscous Fluid ◽  
Secondary Flow ◽  
Centrifugal Force ◽  
Coriolis Force ◽  
Axial Velocity ◽  
Numerical Study ◽  
Axial Direction ◽  
Square Duct ◽  
Rotation Rates

A numerical study is conducted on the fully-developed laminar flow of an incompressible viscous fluid in a square duct rotating about a perpendicular axis to the axial direction of the duct. At the straight duct, the rotation produces vortices due to the Coriolis force. Generally two vortex cells are formed and the axial velocity distribution is distorted by the effect of this Coriolis force. When a convective force is weak, two counter-rotating vortices are shown with a quasi-parabolic axial velocity profile for weak rotation rates. As the rotation rate increases, the axial velocity on the vertical centreline of the duct begins to flatten and the location of vorticity center is moved near to wall by the effect of the Coriolis force. When the convective inertia force is strong, a double-vortex secondary flow appears in the transverse planes of the duct for weak rotation rates but as the speed of rotation increases the secondary flow is shown to split into an asymmetric configuration of four counter-rotating vortices. If the rotation rates are increased further, the secondary flow restabilizes to a slightly asymmetric double-vortex configuration. Also, a numerical study is conducted on the laminar flow of an incompressible viscous fluid in a90°-bend square duct that rotates about axis parallel to the axial direction of the inlet. At a90°-bend square duct, the feature of flow by the effect of a Coriolis force and a centrifugal force, namely a secondary flow by the centrifugal force in the curved region and the Coriolis force in the downstream region, is shown since the centrifugal force in curved region and the Coriolis force in downstream region are dominant respectively.

Prediction of Coolant Deflection Tendencies in Rotating Film Cooling

2010 ◽  
Vol 224 (11) ◽  
pp. 2435-2448
Author(s):  
B Yang ◽  
G Xu ◽  
P Childs ◽  
Z Tao ◽  
S Ding
Keyword(s):  
Boundary Layer ◽  
High Temperature ◽  
Centrifugal Force ◽  
Coriolis Force ◽  
Film Cooling ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Coolant Flow ◽  
Governing Equations ◽  
Pressure Surface

Film cooling is commonly used as an effective cooling technique to protect turbine blades from the thermal failure caused by operation in a high-temperature environment. The cooler air is injected into the high-temperature mainstream boundary layer on a blade surface and it generates a thin coolant film, which acts as a buffer to isolate the thermal loads effectively. In the present study, the classical boundary-layer theory is introduced into the analysis of the governing equations of film cooling under rotating operating conditions, and boundary-layer equations for film cooling are derived. Through simplification of the governing equations, it is demonstrated that four major governing parameters, the pressure gradient, viscosity, the Coriolis force and the centrifugal force, can significantly influence the coolant deflection phenomenon. Near the suction surface, the coolant deflects towards the high-radius locations noticeably. While near the pressure surface, the coolant can be driven to deflect centripetally and centrifugally according to the integrated effect of centrifugal force and Coriolis force. To judge the deflective direction of coolant flow near the pressure surface, a deflection ratio defined by the tangential to instantaneous ejection velocity components is proposed and validated numerically and experimentally. The experimental data and their comparison with the theoretical values indicate that this ratio provides an approach for distinguishing the coolant flow deflection in film cooling in regimes where the Coriolis and centrifugal forces are dominant in the flow field compared to the other forces. Use of the deflection ratio provides a design parameter for the arrangement of film-hole orientation on turbine blades.

Gravitoinertial Force Background Level Affects Adaptation to Coriolis Force Perturbations of Reaching Movements

1998 ◽  
Vol 80 (2) ◽  
pp. 546-553 ◽  
Author(s):  
James R. Lackner ◽  
Paul Dizio
Keyword(s):  
Centrifugal Force ◽  
Coriolis Force ◽  
Normal Gravity ◽  
Background Level ◽  
Mirror Image ◽  
Reaching Movements ◽  
Coriolis Forces ◽  
Straight Line ◽  
Gravitoinertial Force ◽  
Reaching Accuracy

Lackner, James R. and Paul DiZio. Gravitoinertial force background level affects adaptation to Coriolis force perturbations of reaching movements. J. Neurophysiol. 80: 546–553, 1998. We evaluated the combined effects on reaching movements of the transient, movement-dependent Coriolis forces and the static centrifugal forces generated in a rotating environment. Specifically, we assessed the effects of comparable Coriolis force perturbations in different static force backgrounds. Two groups of subjects made reaching movements toward a just-extinguished visual target before rotation began, during 10 rpm counterclockwise rotation, and after rotation ceased. One group was seated on the axis of rotation, the other 2.23 m away. The resultant of gravity and centrifugal force on the hand was 1.0 g for the on-center group during 10 rpm rotation, and 1.031 g for the off-center group because of the 0.25 g centrifugal force present. For both groups, rightward Coriolis forces, ≈0.2 g peak, were generated during voluntary arm movements. The endpoints and paths of the initial per-rotation movements were deviated rightward for both groups by comparable amounts. Within 10 subsequent reaches, the on-center group regained baseline accuracy and straight-line paths; however, even after 40 movements the off-center group had not resumed baseline endpoint accuracy. Mirror-image aftereffects occurred when rotation stopped. These findings demonstrate that manual control is disrupted by transient Coriolis force perturbations and that adaptation can occur even in the absence of visual feedback. An increase, even a small one, in background force level above normal gravity does not affect the size of the reaching errors induced by Coriolis forces nor does it affect the rate of reacquiring straight reaching paths; however, it does hinder restoration of reaching accuracy.

scholarly journals A discussion on the existence of the anomalous high and the anomalous low

2015 ◽  
Vol 33 (10) ◽  
pp. 1253-1261
Author(s):  
N. Li
Keyword(s):  
Pressure Gradient ◽  
Centrifugal Force ◽  
Coriolis Force ◽  
Air Flow ◽  
Formation Mechanisms ◽  
Gradient Force ◽  
Pressure Gradient Force ◽  
Gradient Wind ◽  
Reasonable Explanation ◽  
Classic Literature

Abstract. The air flow in a three-way balance between the Coriolis force, the centrifugal force and the pressure gradient force, i.e., the gradient wind, is discussed. The author studies formation mechanisms and possible existence of four types of gradient wind (the normal high, the normal low, the anomalous high and the anomalous low), and proposes reasonable explanation of the evolution of the gradient wind, especially for the anomalous high and the anomalous low, both of which are considered to be pure mathematical solutions and are overlooked in classic literature.

An Experimental Study on Rotational Coriolis Force upon Single Particle in Vertical Spiral Duct

2011 ◽  
Vol 138-139 ◽  
pp. 123-127
Author(s):  
Zhen Wei Mu ◽  
Zhi Yan Zhang
Keyword(s):  
Centrifugal Force ◽  
Coriolis Force ◽  
Single Particle ◽  
Tangential Velocity ◽  
Small Scale ◽  
Rotational Flow ◽  
Force Analysis ◽  
Particle Movement ◽  
Order Of Magnitude ◽  
Exponential Relation

An experiment of a single particle movement in vertical spiral rectangular duct has investigated with the aim to study the rotational Coriolis force based on kinetic model of single granular. The results indicate that: the dominant forces upon the particle are the centrifugal force, rotational Coriolis force, effectual gravity and drag force. There is exponential relation between λ and ζ, where λ stand for the ratio of tangential velocity of particle and water velocity, ζ stand for the ratio of rotational the Coriolis force and the centrifugal force. The probability of rotational Coriolis force and centrifugal force in the same order of magnitude is three-quarter. Therefore, the rotational Coriolis force should not be ignored on force analysis of a particle in small-scale rotational flow.

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