scholarly journals Dynamic Characteristics of Flow Induced Vibration in a Rotor-Seal System

2011 ◽  
Vol 18 (1-2) ◽  
pp. 139-146 ◽  
Author(s):  
Nan Zhang ◽  
Ying Liu ◽  
Fulei Chu
Keyword(s):  
Fluid Flow ◽  
Dynamic Characteristics ◽  
Nonlinear Models ◽  
Point Of View ◽  
Nonlinear Phenomena ◽  
Flow Induced Vibration ◽  
Nonlinear Characteristics ◽  
Fluid Force ◽  
Synchronization Phenomenon ◽  
Unbalanced Rotor

Flow induced vibration is an important factor affecting the performance of the rotor-seal system. From the point of view of flow induced vibration, the nonlinear models of the rotor-seal system are presented for the analysis of the fluid force, which is induced by the interaction between the unstable fluid flow in the seal and the vibrating rotor. The nonlinear characteristics of flow induced vibration in the rotor-seal system are analyzed, and the nonlinear phenomena in the unbalanced rotor-seal system are investigated using the nonlinear models. Various nonlinear phenomena of flow induced vibration in the rotor-seal system, such as synchronization phenomenon and amplitude mutation, are reproduced.

Pulsating Flow Induced Vibration in the Seal System

2014 ◽  
Vol 602-605 ◽  
pp. 642-645
Author(s):  
Nan Zhang
Keyword(s):  
Fluid Flow ◽  
Nonlinear Models ◽  
Point Of View ◽  
The Self ◽  
Oscillating Flow ◽  
Nonlinear Phenomena ◽  
Flow Induced Vibration ◽  
Nonlinear Characteristics ◽  
Unbalanced Rotor ◽  
Excited Vibration

The oscillating flow is an important factor affecting the performance of the rotor–seal system. From the point of view of flow induced vibration, the nonlinear models of the rotor-seal system are presented for the analysis of the self-excited vibration, which is induced by interaction between the unstable seal fluid flow and the vibrating rotor. The nonlinear characteristics of flow induced vibration in the rotor-seal system are analyzed, and the nonlinear phenomena in the unbalanced rotor-seal system are investigated using the nonlinear model with the flow induced vibration.

Flow Induced Vibration in the Seal System

2014 ◽  
Vol 644-650 ◽  
pp. 390-393
Author(s):  
Nan Zhang
Keyword(s):  
Fluid Flow ◽  
Nonlinear Models ◽  
Point Of View ◽  
The Self ◽  
Oscillating Flow ◽  
Nonlinear Phenomena ◽  
Flow Induced Vibration ◽  
Nonlinear Characteristics ◽  
Unbalanced Rotor ◽  
Excited Vibration

The oscillating flow is an important factor affecting the performance of the rotor–seal system. From the point of view of flow induced vibration, the nonlinear models of the rotor-seal system are presented for the analysis of the self-excited vibration, which is induced by interaction between the unstable seal fluid flow and the vibrating rotor. The nonlinear characteristics of flow induced vibration in the rotor-seal system are analyzed, and the nonlinear phenomena in the unbalanced rotor-seal system are investigated using the nonlinear model with the flow induced vibration.

Pulsating Flow Induced Vibration in a Rotor-Seal System

2012 ◽  
Vol 542-543 ◽  
pp. 66-69
Author(s):  
Nan Zhang
Keyword(s):  
Fluid Flow ◽  
Numerical Simulations ◽  
Flow Velocity ◽  
Nonlinear Models ◽  
Sine Wave ◽  
Point Of View ◽  
Pulsating Flow ◽  
Flow Induced Vibration ◽  
Matlab Simulink ◽  
Pulsating Fluid

The pulsating flow is an important factor affecting the performance of the rotor-seal system. From the point of view of pulsating flow induced vibration, the nonlinear models of the rotor-seal system with the pulsating fluid flow are established. Based on the numerical simulations by Matlab/Simulink, the characteristics of pulsating flow induced vibration with the flow velocity in a form of sine wave or/and a constant have been quantitatively analyzed. The investigation also demonstrates that the proposed models, from the point of view of pulsating flow induced vibration, can be effectively applied to the analysis of the rotor-seal system.

scholarly journals Influence of Elastomeric Bearings in Tension on the Seismic Performance of Base-Isolated r.c. Buildings

2020 ◽  
Vol 11 (1) ◽  
pp. 82
Author(s):  
Fabio Mazza ◽  
Mirko Mazza
Keyword(s):  
Base Isolation ◽  
Nonlinear Models ◽  
Vertical Component ◽  
Computer Code ◽  
Nonlinear Phenomena ◽  
Isolation System ◽  
Elastomeric Bearings ◽  
Near Fault ◽  
Base Isolation System ◽  
Near Fault Earthquakes

Elastomeric bearings are commonly used in base-isolation systems to protect the structures from earthquake damages. Their design is usually developed by using nonlinear models where only the effects of shear and compressive loads are considered, but uncertainties still remain about consequences of the tensile loads produced by severe earthquakes like the near-fault ones. The present work aims to highlight the relapses of tension on the response of bearings and superstructure. To this end, three-, seven- and ten-storey r.c. framed buildings are designed in line with the current Italian seismic code, with a base-isolation system constituted of High-Damping-Rubber Bearings (HDRBs) designed for three values of the ratio between the vertical and horizontal stiffnesses. Experimental and analytical results available in literature are used to propose a unified nonlinear model of the HDRBs, including cavitation and post-cavitation of the elastomer. Nonlinear incremental dynamic analyses of the test structures are carried out using a homemade computer code, where other models of HDRBs considering only some nonlinear phenomena are implemented. Near-fault earthquakes with comparable horizontal and vertical components, prevailing horizontal component and prevailing vertical component are considered as seismic input. Numerical results highlight that a precautionary estimation of response parameters of the HDRBs is attained referring to the proposed model, while its effects on the nonlinear response of the superstructure are less conservative.

Study on Flow-Induced Vibration Characteristics of Hydraulic Hoist of Large-Span Upwelling Radial Steel Gate

2011 ◽  
Vol 117-119 ◽  
pp. 241-246
Author(s):  
Zhen Hai Gao ◽  
Gen Hua Yan ◽  
Peng Liu ◽  
Fa Zhan Chen ◽  
Fei Ming Lv
Keyword(s):  
Dynamic Characteristics ◽  
Vibration Characteristics ◽  
Vibration Response ◽  
Flow Induced Vibration ◽  
Structural Dynamic ◽  
Large Span ◽  
Response Characteristics ◽  
Lever Action ◽  
Structural Dynamic Characteristics ◽  
Steel Gate

In this paper we conduct study on flow-induced vibration of large-span upwelling radial steel Gate and its hydraulic hoist. Place an emphasis on vibration response characteristics under two working conditions of diversion and drainage, which proves the safety of hydraulic hoist gate vibration caused by gate vibration. Firstly, we study on dynamic characteristics of fluid-structure interaction of association system of gate and start and stop lever, reveals the discipline of the effect fluid having on structural dynamic characteristics. On this basis, flow-induced vibration characteristics under two conditions of with and without start and stop lever action considered. The results indicate that the gate vibration response with hydraulic hoist used decreases, which explains start and stop lever has certain effect of restraining vibration on gate vibration. In addition, under the working condition of drainage the vibration magnitude of start and stop lever is smaller than that of gate body, which explains there is damping action during transference of gate vibration through start and stop lever. The results find out that on the assumption of optimized gate structure and hydraulic arrangement, it is practicable, safe and reliable to adopt hydraulic hoist. The achievement has directive significance on similar projects construction in the future

scholarly journals Flow-Induced Vibration on the Control Valve with a Different Concave Plug Shape Using FSI Simulation

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Akram Zeid ◽  
Mohamed Shouman
Keyword(s):  
High Efficiency ◽  
Complex Structure ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Simulation ◽  
Control Valve ◽  
Low Noise ◽  
Flow Induced Vibration ◽  
Nonlinear Characteristics ◽  
Flow Phenomena

Control valves have always been recognised as being among the most crucial control equipment, commonly utilised in versatile engineering applications. Hence, the need has arisen to identify the flow characteristics inside the valve, together with the incurred vibration induced as a result of the flow passing through the valve. Thanks to the tangible and fast progress made in the field of the flow simulation and numerical techniques, it has become possible to better observe the behavior of the flow passing inside a valve with view to examining its performance. Hence, the paper at hand is mainly concerned with introducing the modeling and simulation of a control valve. On the contrary, the flow system in a control valve is marked by a complex structure and nonlinear characteristics. The reasons for those qualities could be attributed to its construction as well as the fluid flow phenomena associated with it. It is especially for the sake of investigating and observing the flow characteristics, pertaining to a control valve equipped with different concave plug shapes and different openings, that the three-dimensional FSI simulation is conducted. In addition, it would be possible to make use of the obtained results relating to the three-dimensional analysis to achieve low noise and high efficiency improvement. Furthermore, all results will be validated on experimental grounds.

A Comparative Study of Structural Analyses for Flat and Curved Mechanical Heart Valve Prostheses to Enhance Durability

2003 ◽  
Author(s):  
Young Joo Kwon
Keyword(s):  
Comparative Study ◽  
Heart Valve ◽  
Dynamic Characteristics ◽  
Mechanical Heart Valve ◽  
Rigid Body Dynamics ◽  
Valve Prosthesis ◽  
Fluid Force ◽  
Heart Valve Prostheses ◽  
Valve Prostheses ◽  
Dynamics Analyses

This paper addresses a comparative study of structural analyses for flat and curved mechanical heart valve prostheses. The same fluid force computed by the fluid mechanics analysis for the blood flow passing through the leaflets of a bileaflet mechanical heart valve prosthesis is used to both flat and curved mechanical heart valve prostheses for comparison. This fluid force is applied to both mechanical heart valve prostheses for the rigid body dynamics analyses to confirm the kinematic and dynamic characteristics of leaflet motions, the structural mechanics analyses for deformed leaflets of both flat and curved mechanical heart valve prostheses are executed to give quite different stress and deflection results even though they have the almost same kinematic and dynamic characteristics.

scholarly journals Features of calculation of steel structures of bridge cranes at variable loads

2019 ◽  
Vol 298 ◽  
pp. 00032
Author(s):  
A. L. Akhtulov ◽  
O. M. Kirasirov ◽  
M. O. Kirasirov
Keyword(s):  
Dynamic Characteristics ◽  
Entire Range ◽  
Steel Structures ◽  
Point Of View ◽  
Operating Conditions ◽  
Variable Load ◽  
Linear Summation ◽  
Static And Dynamic Characteristics

The article deals with the calculation of metal bridge cranes operating under the influence of variable loads. Requirements to static and dynamic characteristics of mechanisms of load-lifting cranes are caused by specifics of work, features of a design and operating conditions of the cranes working at variable loadings. Thus, it is proposed to perform calculations of parts of crane mechanisms for endurance, operating under non-stationary variable load, based on the principle of linear summation of damage, allowing the calculation from the point of view of the load equivalent to the entire range of operating loads.

scholarly journals Research on Fault Feature Extraction Method Based on NOFRFs and Its Application in Rotor Faults

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Yang Liu ◽  
Yulai Zhao ◽  
Jintao Li ◽  
Fangquan Xi ◽  
Shuanghe Yu ◽  
...  
Keyword(s):  
Early Stage ◽  
Recognition Rate ◽  
High Order ◽  
Nonlinear Phenomena ◽  
Contribution Rate ◽  
Output Frequency ◽  
Nonlinear Characteristics ◽  
Feature Extraction Method ◽  
Rotor Faults ◽  
Fault Feature Extraction

Rub-impact between the rotating and static parts is a more common fault. The occurrence of faults is often accompanied by the generation of nonlinear phenomena. However, it is difficult to find out because the nonlinear characteristics are not obvious at the beginning of the fault. As a new frequency domain-based method, nonlinear output frequency response functions (NOFRFs) use the vibration response to extract the nonlinear characteristics of the system. This method has a better recognition rate for fault detection. Also, it has been applied in structural damages detection, but the high-order NOFRFs have the characteristics that the signals are weak and the features are difficult to extract. On this basis, the concept of the weighted contribution rate of the NOFRFs is proposed in this paper. The variable weighted coefficients with orders are used to amplify the influence of high-order NOFRFs on the nonlinearity of the system so as to extract its fault characteristics. The new index RI is proposed based on Clenshaw–Curtis quadrature formula to eliminate the effect of artificially selected weighted coefficients on sensitivity. Especially in the early stage of the fault, the new index varies greatly with the deepening of the fault. Both simulation and experimental results verify the validity and practicability of the new index. The new index has certain guiding significance in the detection of mechanical system faults.

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