scholarly journals Study on Vibration Characteristics of Marine Centrifugal Pump Unit Excited by Different Excitation Sources

2021 ◽  
Vol 9 (3) ◽  
pp. 274
Author(s):  
Cui Dai ◽  
Yuhang Zhang ◽  
Qi Pan ◽  
Liang Dong ◽  
Houlin Liu
Keyword(s):  
Centrifugal Pump ◽  
Calculation Model ◽  
Vibration Characteristics ◽  
Superposition Method ◽  
Pump Unit ◽  
Electromagnetic Excitation ◽  
Main Frequency ◽  
Vibration Excitation ◽  
Modal Superposition Method ◽  
Vibration Mechanism

In order to study the vibration mechanism of a marine centrifugal pump unit and explore the contribution of vibration caused by different vibration excitation sources, a marine centrifugal pump with a specific speed of 66.7 was used for research. A numerical calculation model of the flow field and electromagnetic field of the pump unit was established to analyze the frequency spectrum characteristics and contribution of pump unit vibration caused by different excitation sources. Using the modal superposition method, the vibration characteristics of the pump unit caused by fluid excitation and electromagnetic excitation were analyzed. The results show that the main frequency of pump unit vibration caused by fluid excitation was at the 1× blade passing frequency. The main frequency of pump unit vibration caused by electromagnetic excitation was at the 2× utility frequency. The contribution of different excitation sources to the vibration of marine centrifugal pump unit was in the following order: fluid excitation on the inner surface of the pump > electromagnetic excitation > fluid excitation in the impeller.

Vibration characteristics analysis of disordered two-span beams with numerical and experimental methods

2017 ◽  
Vol 24 (16) ◽  
pp. 3641-3657 ◽  
Author(s):  
Shenglin Zhou ◽  
Fengming Li ◽  
Chuanzeng Zhang
Keyword(s):  
Time History ◽  
Frequency Equation ◽  
Vibration Characteristics ◽  
Experimental Investigations ◽  
Superposition Method ◽  
The Finite Element Method ◽  
Response Curves ◽  
Modal Superposition Method ◽  
Characteristics Analysis ◽  
Good Agreement

Numerical and experimental investigations on the vibration behaviors of the disordered two-span beams have been conducted. The dynamics model of the two-span beam is established and solved by means of the modal superposition method. According to the boundary conditions, the frequency equation of the two-span beam is obtained, and the natural frequencies, vibration modes, frequency response curves, and time-history responses of the structure are also obtained consequently. Considering the structural size disorder due to the two different sub-span lengths of the two-span beam, a disorder ratio is introduced in terms of the two sub-span lengths and its influences on the vibration characteristics of the structure are analyzed. By comparing the results from numerical calculation with those from the finite element method (FEM) and experiments, good agreement is observed, which verifies the validity of the present investigations.

scholarly journals Optimization of Powerful Two-stage Screw Centrifugal Pump

2018 ◽  
Vol 220 ◽  
pp. 03009 ◽  
Author(s):  
Oleg Baturin ◽  
Grigorii Popov ◽  
Daria Kolmakova ◽  
Vasilii Zubanov ◽  
Julia Novikova ◽  
...  
Keyword(s):  
High Pressure ◽  
Centrifugal Pump ◽  
Mathematical Optimization ◽  
Pressure Head ◽  
Low Pressure ◽  
Calculation Model ◽  
Pump Efficiency ◽  
Rotor Speed ◽  
Two Stage ◽  
Optimization Parameters

The article presents a refining method for a two-stage screw centrifugal pump by the joint usage of mathematical optimization software IOSO, meshing complex NUMECA and CFD software ANSYS CFX. The pump main parameters: high-pressure stage rotor speed was 13300 rpm; low-pressure rotor speed was 3617 rpm by gearbox; inlet total pressure was 0.4 MPa; outlet mass flow was 132.6 kg/s at the nominal mode. This article describes the process of simplifying the calculation model for the optimization. The parameters of camber lines of the low-pressure impeller, transition duct, and high-pressure impeller blades for two sections (hub and shroud) were chosen as optimization parameters. The blades of low-pressure impeller, transition duct and high-pressure impeller have changed during optimization. The optimization goal was the increase of the pump efficiency with preservation or slight increase in the pressure head. The efficiency was increased by 3%.

Structural Shape Reconstruction of FBG Flexible Plate Using Modal Superposition Method

2017 ◽  
Author(s):  
Li Li ◽  
Ben S. Zhong ◽  
Zi Y. Geng ◽  
Wei Sun
Keyword(s):  
Mode Shape ◽  
Shape Reconstruction ◽  
Displacement Sensor ◽  
Superposition Method ◽  
Flexible Plate ◽  
Structural Shape ◽  
Modal Superposition ◽  
Displacement Mode ◽  
Modal Superposition Method ◽  
Strain Data

Structural shape reconstruction is a critical issue for real-time structural health monitoring in the fields of engineering application. This paper shows how to implement structural shape reconstruction using a small number of strain data measured by fiber Bragg grating (FBG) sensors. First, the basic theory of structural shape reconstruction is introduced using modal superposition method. A transformation is derived from the measured discrete strain data to global displacement field through modal coordinate, which is the same for strain mode shape superposition and displacement mode shape superposition. Then, optimization of the sensor layout is investigated to achieve the effective reconstruction effect. Finally, structural shape reconstruction algorithm using modal superposition method is applied in experiments. The experiment results show that the reconstructed displacements match well with those measured by a laser displacement sensor and the proposed approach is a promising method for structural shape reconstruction.

Seismic Analysis of Structures With Coulomb Friction

1983 ◽  
Vol 105 (2) ◽  
pp. 171-178 ◽  
Author(s):  
V. N. Shah ◽  
C. B. Gilmore
Keyword(s):  
Rigid Body ◽  
Coulomb Friction ◽  
Seismic Event ◽  
Seismic Analysis ◽  
Equations Of Motion ◽  
Relative Displacement ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Superposition Method ◽  
Modal Superposition Method

A modal superposition method for the dynamic analysis of a structure with Coulomb friction is presented. The finite element method is used to derive the equations of motion, and the nonlinearities due to friction are represented by pseudo-force vector. A structure standing freely on the ground may slide during a seismic event. The relative displacement response may be divided into two parts: elastic deformation and rigid body motion. The presence of rigid body motion necessitates the inclusion of the higher modes in the transient analysis. Three single degree-of-freedom problems are solved to verify this method. In a fourth problem, the dynamic response of a platform standing freely on the ground is analyzed during a seismic event.

scholarly journals DOWNHOLE REACTIVE POWER COMPENSATION

2015 ◽  
pp. 29-33
Author(s):  
V. A. Kopyrin ◽  
V. A. Iordan ◽  
O. V. Smirnov
Keyword(s):  
Centrifugal Pump ◽  
Power Supply ◽  
Reactive Power ◽  
Reactive Power Compensation ◽  
Pump Unit ◽  
Unit Power ◽  
Transformer Substation ◽  
Electrical Centrifugal Pump

The authors provide a method for compensation of the reactive power inside a well. In the environment Matlab/ Simylink a model was developed of the site of the electrical centrifugal pump unit power supply from the transformer substation. A comparison is made of the proposed method of downhole reactive power compensation with the existing method.

Non-Linear Coupled Dynamics of a Flexible Propeller-Shaft System Supported by Water Film Bearings

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Chang-Gang Lin ◽  
Ming-Song Zou ◽  
Can Sima ◽  
Li-Bo Qi ◽  
Yue Yu
Keyword(s):  
Nonlinear Vibration ◽  
Damping Ratio ◽  
Water Film ◽  
Vibration Characteristics ◽  
Superposition Method ◽  
Propeller Shaft ◽  
Chaotic Motions ◽  
Mode Superposition Method ◽  
Shaft System ◽  
Slice Method

Abstract A slice method to determine the boundary conditions between the stern bearing and shaft by dividing the journal in the stern bearing into several slice elements along the axial direction is proposed for the first time. A comprehensive finite element model considering the nonlinear force of the water film and the flexibility of the propeller blade is established for a propeller-shaft system. The long bearing approximation is adopted to calculate the pressure distribution around each journal element in the stern bearing. The mode superposition method is employed. The nonlinear equation of motion is solved iteratively using the Newmark method. A parametric study is implemented to analyze the nonlinear vibration characteristics of the system. It is shown that the real motion state of the journal in the stern bearing can be simulated more precisely by the slice method proposed. The responses of the system alternate among period-one, quasi-periodic, multi-periodic, and chaotic motions as the rotating speed increases. The damping ratio has a significant effect on the dynamic characteristics of the propeller-shaft system. The motion of the system is unstable when the damping ratio is very small. At this time, the modes of the flexible propeller blades can be excited readily. The slice method, which can also be extensively used in similar rotor-bearing systems in the engineering field, is very simple and efficient to analyze the nonlinear vibration characteristics of a flexible propeller-shaft system supported by water film bearings.

Experimental Investigation on Vortex-Induced Vibration of Dual Pipes With Unequal Diameters in Tandem

2020 ◽  
Author(s):  
Mengmeng Zhang ◽  
Shixiao Fu ◽  
Zhiqi Zhang ◽  
Haojie Ren ◽  
Yuwang Xu
Keyword(s):  
Vibration Frequency ◽  
Reynolds Numbers ◽  
Superposition Method ◽  
Wall Surface ◽  
Flexible Pipes ◽  
Modal Superposition Method ◽  
Out Of Plane ◽  
Single Pipe ◽  
Dominant Vibration Frequency ◽  
Significant Interference

Abstract With the massive use of buddle risers and pipelines in deep-water oil production industries, the demand to focus on the research of interference effects of dual pipe has been greatly enhanced. This paper presents interference experiments of dual flexible pipes with unequal diameters under uniform flow with Reynolds numbers ranging from 1.8E3 to 1.1E4. The pipe with larger diameter was set to be the upstream pipe. Various tandem arrangements with wall surface-to-wall surface distances being 3D to 8D were tested, where D is the smaller pipe diameter. Fiber Bragg grating (FBG) strain sensors were used to measure both in-plane and out-of-plane strain responses. Modal superposition method was applied to reconstruct IL mean displacement. Significant interference effect was found under the condition that wall-to-wall gap is smaller than 8D, where CF and IL vibration frequency ratio of downstream pipe equals to 1.0 and IL mean displacement gets smaller compared to those of single pipe in isolation. Moreover, a special ‘capture’ phenomenon, that the dominant vibration frequency and mode of downstream pipe were as the same as that of the upstream pipe subjecting to the uniform flows, was found when wall-to-wall distances were 4D and 8D.

Prediction for Sound Radiated Power from Submerged Double Cylindrical Shells Based on Measuring Vibration of Inner Shell

2013 ◽  
Vol 779-780 ◽  
pp. 602-606 ◽  
Author(s):  
Chao Zhang ◽  
De Jiang Shang ◽  
Qi Li
Keyword(s):  
Prediction Error ◽  
Cylindrical Shells ◽  
Prediction Method ◽  
Superposition Method ◽  
Power Curve ◽  
Mean Square ◽  
Average Prediction Error ◽  
Radiated Power ◽  
Modal Superposition Method ◽  
Good Agreement

A prediction method for the sound radiated power from submerged double cylindrical shells based on measuring vibration of inner shell is presented. The prediction model of submerged double cylindrical shells is established by using modal superposition method. Applied the ratio of the measuring value and theoretical value of the acceleration in one point or mean square velocity of inner shell, and combined with the theoretical value of the sound radiated power, the predicted value of the sound radiated power is derived. The corresponding experiment is carried out in lake. And then the measuring power curve is compared with the predicted power curve based on this method. The result shows that they have good agreement and the average prediction error is less than 2dB.

An Error Compensation Method for Structural Responses and Sensitivities

2011 ◽  
Vol 421 ◽  
pp. 743-749
Author(s):  
Xiao Ming Wu ◽  
Chun Liu
Keyword(s):  
Error Compensation ◽  
Truncation Error ◽  
Compensation Method ◽  
Superposition Method ◽  
Truncation Errors ◽  
Modal Superposition ◽  
Modal Superposition Method ◽  
Structural Responses ◽  
Epsilon Algorithm ◽  
Modal Method

Abstract. The computation of the responses and their design sensitivities play an essential role in structural analysis and optimization. Significant works have been done in this area. Modal method is one of the classical methods. In this study, a new error compensation method is constructed, in which the modal superposition method is hybrid with Epsilon algorithm for responses and their sensitivities analysis of undamped system. In this study the truncation error of modal superposition is expressed by the first L orders eigenvalues and its eigenvectors explicitly. The epsilon algorithm is used to accelerate the convergence of the truncation errors. Numerical examples show that the present method is validity and effectiveness.

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