Experimental Study on the Avoidance and Suppression Criteria for the Vortex-Induced Vibration of a Cantilever Cylinder

2002 ◽  
Vol 124 (2) ◽  
pp. 187-195 ◽  
Author(s):  
Takaaki Sakai ◽  
Masaki Morishita ◽  
Koji Iwata ◽  
Seiji Kitamura
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Water Flow ◽  
Experimental Validation ◽  
Flow Direction ◽  
High Viscosity ◽  
Design Guideline ◽  
Vortex Induced Vibration ◽  
High Viscosity Oil ◽  
Effect Of Structure

Experimental validation of the design guideline to prevent the failure of a thermometer well by vortex-induced vibration is presented, clarifying the effect of structure damping on displacement amplitudes of a cantilever cylinder. The available experimental data in piping are limited to those with small damping in water flow, because of the difficulty in increasing structure damping of the cantilever cylinders in experiments. In the present experiment, high-viscosity oil within cylinders is used to control their structure damping. Resulting values of reduced damping Cn are 0.49, 0.96, 1.23, 1.98, and 2.22. The tip displacements of the cylinder induced by vortex vibration were measured in the range of reduced velocity Vr from 0.7 to 5 (Reynolds number is 7.8×104 at Vr=1). Cylinders with reduced damping 0.49 and 0.96 showed vortex-induced vibration in the flow direction in the Vr>1 region. However, in cases of reduced damping of 1.23, 1.98, and 2.22, the vibration was suppressed to less than 1 percent diameter. It is confirmed that the criteria of “Vr<3.3 and Cn>1.2” for the prevention of vortex-induced vibration is reasonably applicable to a cantilever cylinder in a water flow pipe.

Vortex-Induced Vibration of Catenary Moored Cylindrical Structures

2004 ◽  
Author(s):  
Brad Stappenbelt ◽  
Krish Thiagarajan
Keyword(s):  
Experimental Data ◽  
Flow Direction ◽  
Response Prediction ◽  
Discrete Vortex ◽  
Number Range ◽  
Vortex Induced Vibration ◽  
Cylindrical Structures ◽  
Rigid Cylinder ◽  
Non Linear ◽  
Experimental Rig

Mooring systems utilised for floating structures typically introduce non-linear load-excursion behaviour. This non-linear compliance and the accompanying amplitude dependent natural frequency, influences the Vortex-Induced Vibration (VIV) response of the structure. The application of linear compliance VIV modelling and experimental data has been demonstrated to produce significant uncertainties regarding VIV onset and response prediction of catenary moored cylindrical structures (Bjarke et al. 2003; Dijk et al. 2003). The vortex-induced vibration issues associated with catenary moored cylindrical structures were investigated through non-linearly compliant elastically mounted rigid cylinder experiments. In particular, third order polynomial, hard spring stiffness, (typical of catenary moorings) was considered. The effect on transverse VIV lock-in and vibration amplitudes was examined using a single degree of freedom experimental rig. The experimental rig consisted of a moderately damped, elastically mounted rigid cylinder, restricted in all but the cross-flow direction through use of linear slide mechanism. The linear and cubic compliance components were independently varied over the non-linear compliance ratio of 0 to 0.3. All experimentation was conducted within the stable sub-critical Reynolds number range. The experimental data was compared to numerical results produced by the VIV modelling software package VisFlo. The program utilises a vortex-in-cell discrete vortex numerical method that was modified to allow the inclusion of varying degrees of structural non-linearity.

Performance Study of an Oil-Immersed Power Transformer With Shallow Geothermal Cooling

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Gerd Schmid ◽  
Chien-Yeh Hsu ◽  
Yu-Ting Chen ◽  
Tai-Her Yang ◽  
Sih-Li Chen
Keyword(s):  
Experimental Data ◽  
Thermal Analysis ◽  
Heat Exchanger ◽  
Water Flow ◽  
Cooling System ◽  
Flow Direction ◽  
Water Flow Rate ◽  
Transformer Oil ◽  
Performance Study ◽  
Cooling Performance

This paper investigates the cooling performance of a shallow geothermal energy method in relation to the cooling system of a 75 kVA oil-immersed transformer. A thermal analysis of the complete system is presented and then validated with experimental data. The cooling performance of the shallow geothermal cooling method is indicated by its cooling capacity and average oil temperature. The results of this study show that the average oil temperature can be reduced by nearly 30 °C with the aid of an 8 m deep U-pipe borehole heat exchanger, thereby making it possible to increase the capacity of the transformer. By increasing the water flow rate from 6 L/m to 15 L/m, the average oil temperature could be lowered by 3 °C. In addition, the effects of changing the circulating water flow direction and the activation time of the shallow geothermal cooling system were investigated. The results of the thermal analysis are consistent with the experimental data, with relative errors below 8%. The results of the study confirm that a larger temperature difference between the cooling water and the transformer oil at the inlet of the heat exchanger can increase the overall heat transfer rate and enhance the cooling performance of the shallow geothermal cooling system.

A New Mechanistic Model To Predict Boosting Pressure of Electrical Submersible Pumps Under High-Viscosity Fluid Flow with Validations by Experimental Data

SPE Journal ◽  
2019 ◽  
Vol 25 (02) ◽  
pp. 744-758 ◽  
Author(s):  
Jianjun Zhu ◽  
Haiwen Zhu ◽  
Guangqiang Cao ◽  
Jiecheng Zhang ◽  
Jianlin Peng ◽  
...  
Keyword(s):  
Experimental Data ◽  
Fluid Flow ◽  
Viscous Fluid ◽  
Flow Direction ◽  
Mechanistic Model ◽  
High Viscosity ◽  
Flow Rates ◽  
Viscous Fluid Flow ◽  
Artificial Lift ◽  
Viscosity Fluid

Summary As the second most widely used artificial-lift method in petroleum production (and first in accumulative production), electrical submersible pumps (ESPs) increase flow rates by converting kinetic energy to hydraulic pressure. ESPs are routinely characterized with water flow, and water performance curves are provided by the manufacturers (catalog curves) for designing ESP-based artificial-lift systems. However, the properties of hydrocarbon fluids are very different from those of water, especially the dynamic viscosities, which can significantly alter the ESP performance. Most of the existing methods to estimate ESP boosting pressure under high-viscosity fluid flow involve a strong empirical nature, and are derived by correlating experimental/field data with correction factors (e.g., Hydraulic Institute Standards 1955). A universally valid mechanistic model to calculate the ESP boosting pressure under viscous fluid flow is not yet available. In this paper, a new mechanistic model accounting for the viscosity effect of working fluids on ESP hydraulic performance is proposed, and it is validated with a large database collected from different types of ESPs. The new model starts from the Euler equations for characterizing centrifugal pumps, and introduces a conceptual best-match flow rate QBM, at which the outlet flow direction of the impeller matches the designed flow direction. The mismatch of velocity triangles, resulting from the varying liquid-flow rates, is used to derive the recirculation losses. Other head losses caused by flow-direction change, friction, leakage flow, and other factors. are incorporated into the new model as well. QBM is obtained by matching the predicted H-Q performance curve of an ESP with the catalog curves. Once QBM is determined, the ESP hydraulic head under viscous-fluid-flow conditions can be calculated. The specific speed (NS) of the studied ESPs in this paper ranges from 1,600 to 3,448, including one radial-type ESP and two mixed-type designs. The model-predicted ESP boosting pressure with water flow is found to match the catalog curves well if QBM is properly tuned. With high-viscosity fluid presence, the model predictions of ESP boosting pressure also agree well with the corresponding experimental data. For most calculation results within medium to high flow rates, the model prediction error is less than 15%. Unlike the empirical correlations that take experimental data points as inputs, the mechanistic model in this study does not require entering any experimental data, but can predict ESP boosting pressure under viscous fluid flow with a reasonable accuracy.

An Experimental Study on the Tribological Properties of the Pressing Dies of WC and SKD11 in the High Viscosity Oil

2015 ◽  
Vol 642 ◽  
pp. 72-77
Author(s):  
Yuh Ping Chang ◽  
Huann Ming Chou ◽  
Gino Wang ◽  
Jin Chi Wang
Keyword(s):  
Experimental Study ◽  
Tribological Properties ◽  
High Viscosity ◽  
Poor Quality ◽  
Surface Wear ◽  
The Poor ◽  
Pressing Process ◽  
The Future ◽  
High Viscosity Oil

The poor quality of machining surfaces caused by the surface wear of the pressing dies and the corrosion of the pressing parts has been a major concern for manufacturing engineers. In order to decrease the surface wear of the pressing dies and the corrosion of the pressing parts, the drawing oil is always used during the pressing process. It is well known that the properties and the distributions of the drawing oil significantly influence lubrication, cool down, cleanness and stabilization for the pressing dies and parts. Therefore, it is very important for the operating limitation of the pressing process. This paper is base on the above statements to further investigate the effects of the high viscosity drawing oil on the tribological properties and the adhesions between the dies and parts. The results have not only an added advantage of technology of pressing process, but they are also very helpful in design the pair of the dies and parts in the future. Moreover, the purpose of better quality and faster product speed of the pressing process can then be obtained for the industry.

Experimental Study of High-Viscosity Oil/Water/Gas Three-Phase Flow in Horizontal and Upward Vertical Pipes

2013 ◽  
Vol 28 (03) ◽  
pp. 306-316 ◽  
Author(s):  
Shufan Wang ◽  
Hong-Quan Zhang ◽  
Cem Sarica ◽  
Eduardo Pereyra
Keyword(s):  
Experimental Study ◽  
High Viscosity ◽  
Phase Flow ◽  
Three Phase ◽  
Three Phase Flow ◽  
Oil Water ◽  
High Viscosity Oil ◽  
Water Gas
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