An Experimental Study on the Dynamic Response of a Vertical Cantilever Pipe Conveying Fluid

1980 ◽  
Vol 102 (3) ◽  
pp. 129-135 ◽  
Author(s):  
R. Shilling ◽  
Y. K. Lou
Keyword(s):  
Experimental Study ◽  
Dynamic Response ◽  
Flow Rate ◽  
Natural Frequencies ◽  
Internal Flow ◽  
Deep Ocean ◽  
Economic Loss ◽  
System Response ◽  
Environmental Damage ◽  
Ocean Thermal Energy

Transverse vibrations of elastic pipes conveying a fluid have been observed in pipelines and heat exchangers. These fluid-induced vibrations can be a serious problem and in some incidents have caused structural failure resulting in environmental damage and economic loss. For offshore applications such as marine risers, the Ocean Thermal Energy Conversion Plant and deep ocean mining vacuums, the problem is compounded by the existence of vortex shedding, wave excitations, currents, and platform motions. An experimental study was conducted to investigate the effects of internal flow rate and the depth of immersion on the dynamic response of a vertical cantilever pipe discharging a fluid. It was found that the internal flow rate and the surrounding fluid have a significant effect on the natural frequencies of the system. Specifically it was found, that depending on the relative value of the forcing frequency, in comparison to the system natural frequencies, an increase in flow rate may not necessarily result in a larger system response. Conversely, an increase in the length of pipe immersion does not necessarily decrease the response of the system. It is also observed that with increasing flow rate, an auspicious increase in the response of the higher harmonics is noted, indicating an increase fluid coupling of the system. System natural frequencies were observed to decrease with increasing flow rate.

Experimental Investigation of the Effects of a Pulsating Internal Flow on the Dynamics of a Submersed U-Shaped Flexible Pipe

2012 ◽  
Author(s):  
Marcio Yamamoto ◽  
Shotaro Uto ◽  
Tomo Fujiwara ◽  
Motohiko Murai
Keyword(s):  
Dynamic Response ◽  
Flow Rate ◽  
Deep Sea ◽  
New Technologies ◽  
Fluid Pressure ◽  
Internal Flow ◽  
Flexible Pipe ◽  
Hydrocarbon Production ◽  
Petroleum Production ◽  
Single Well

In the past of the offshore petroleum production, each riser had conveyed the hydrocarbon production from a single vertical well; the riser’s internal flow rate was relatively low and only the internal fluid pressure was taking into account for the riser analysis. Other internal flow effects, such as internal fluid’s linear moment, and Coriollis effects, were neglected. However, the paradigm for petroleum production in ultra-deepwater is shifting nowadays. New technologies, such as horizontal wells, have increased the production rate from a single well. In addition, a subsea booster system can increase both pressure and flow rate of the riser’s conveyed fluid. Further, the Offshore Mining is rising as a new industry and will demand riser systems to convey, at high flow rates, the mineral ore’s slurry from the seafloor up to the production support vessel. In a previous experiment, the effects of the internal flow on a vertical riser were investigated. In the current experiment, the main objective is to investigate the effect of the internal flow on the dynamic response of a pipe in “jumper configuration”. The experiment was carried out at the Deep Sea Basin of the National Maritime Research Institute using a 10 m long flexible pipe. The actual “jumper” is a piece of flexible riser, in U-shaped configuration, that connects the main structure of “Self-Standing Hybrid Riser” to the production vessel. During the experiment, fresh water was pumped into the model by positive displacement pump; and an oscillator applies a harmonic vibration on one pipe’s end. Then the pipe’s dynamic response is measured by the Deep Sea Basin’s 3D Visual Measurement System. Results for different internal flows and oscillations are compared.

Enhancement of Spray Flash Evaporation by Means of the Injection of Bubble Nuclei

1985 ◽  
Vol 107 (2) ◽  
pp. 176-182 ◽  
Author(s):  
O. Miyatake ◽  
T. Tomimura ◽  
Y. Ide
Keyword(s):  
Experimental Study ◽  
Power Systems ◽  
Flow Rate ◽  
Geothermal Energy ◽  
Liquid Flow Rate ◽  
Current Level ◽  
Liquid Temperature ◽  
Flash Evaporation ◽  
Electrolytic Current ◽  
Ocean Thermal Energy

Spray flash evaporators are being used or considered for power systems utilizing solar energy, ocean thermal energy, and geothermal energy. As part of an attempt to develop a compact, efficient flash evaporator, an experimental study of the effect of injection of bubble nuclei has been conducted. The bubble nuclei were generated by electrolyzing warm water, which was ejected from a simple tubular nozzle into a low-pressure vapor zone. Effects of electrolytic current level, nozzle diameter, liquid flow rate, liquid temperature, and superheat were investigated. The evaporator rates attained were superior to those in conventional multistage flash evaporators with open channels.

Experimental Study of a Vibrating Disk Submerged in a Fluid-Filled Tank and Confined With a Nonrigid Cover

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
David Valentín ◽  
Alexandre Presas ◽  
Eduard Egusquiza ◽  
Carme Valero ◽  
Mònica Egusquiza
Keyword(s):  
Experimental Study ◽  
Theoretical Model ◽  
Dynamic Response ◽  
Natural Frequencies ◽  
Pressure Sensors ◽  
Hydraulic Turbine ◽  
Added Mass ◽  
Test Rig ◽  
Damping Behavior ◽  
Hydraulic Turbines

Determining the dynamic response of submerged and confined disklike structures is of interest in engineering applications, such as in hydraulic turbine runners. This dynamic response is heavily affected by the added mass and damping as well as the proximity of solid boundaries. These solid boundaries are normally considered as completely rigid in theoretical or numerical calculations, however, this assumption is not always valid. Some hydraulic turbines have noncompletely stiff casings, which can modify the dynamic response of the runner itself, affecting specially its natural frequencies and damping behavior. To determine the influence of noncompletely rigid nearby surfaces in the dynamic behavior of a submerged structure, an experimental test rig has been constructed. This test rig is based on a disk attached to a shaft and confined in a tank covered with two different casings with different mass and stiffness. For both covers and different disk to cover distances, natural frequencies and damping ratios of the disk have been obtained experimentally. Accelerometers installed on the disk and covers as well as pressure sensors are used for this purpose. Results obtained for all the cases are discussed in detail and compared with a simplified theoretical model.

scholarly journals Effect of Clamping Torque on Large Deflection Static and Dynamic Response of a Cantilever Beam: An Experimental Study

2018 ◽  
Vol 15 ◽  
pp. 1-16
Author(s):  
Soumen Mondal ◽  
Sushanta Ghuku ◽  
Kashi Nath Saha
Keyword(s):  
Experimental Study ◽  
Dynamic Response ◽  
Cantilever Beam ◽  
Strain Gauge ◽  
Large Deflection ◽  
Static Load ◽  
Natural Frequencies ◽  
Dynamic Strain ◽  
Load Step ◽  
Different Thickness

The present paper reports an experimental study on the effect of finite clamping on static and dynamic characteristics of cantilever beam. The experiment is carried out with two different beams, each of which is clamped at two different locations resulting in two different geometry settings. Under each of these four settings, specimen is clamped under two different torque ratings giving rise to different finite clamping effect. Under the eight settings, coordinates of tip point under static loading are measured directly using scales and plumb at each load step; whereas, complete deflection profiles of loaded beam under each static load step are obtained through post-processing of images captured during experimentation. Such image processing is carried out manually using AutoCAD®and in-built AutoLISP®software. Strain measurements at each static load step are carried out by using strain gauge, a universal data acquisition system and the associated Catman Easy®software. To obtain loaded free vibration characteristics, loaded beam under each setting is disturbed by a rubber hammer and its dynamic response is recorded from strain gauge signal through Catman Easy®software. These dynamic strain readings of loaded beam are post-processed and FFT plots are generated in MATLAB®software and first two loaded natural frequencies of beam under each setting are obtained. Finally, effects of clamping torques on the static strain and deflection results and loaded natural frequencies for beam settings with the four different thickness to length ratios are reported in a suitable manner. The result reported may be useful as ready reference to develop a theoretical model of clamped beam like structures incorporating the effect of finite clamping.

scholarly journals Rapid Multi-Hybridisation FISH Screening for Balanced Porcine Reciprocal Translocations Suggests a Much Higher Abnormality Rate Than Previously Appreciated

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 250
Author(s):  
Rebecca E O’Connor ◽  
Lucas G Kiazim ◽  
Claudia C Rathje ◽  
Rebecca L Jennings ◽  
Darren K Griffin
Keyword(s):  
Semen Analysis ◽  
In Situ Hybridisation ◽  
Economic Loss ◽  
Environmental Damage ◽  
Fluorescence In Situ Hybridisation ◽  
Reciprocal Translocations ◽  
Chromosome Translocations ◽  
Farrowing Rate ◽  
Significant Economic Loss

With demand rising, pigs are the world’s leading source of meat protein; however significant economic loss and environmental damage can be incurred if boars used for artificial insemination (AI) are hypoprolific (sub-fertile). Growing evidence suggests that semen analysis is an unreliable tool for diagnosing hypoprolificacy, with litter size and farrowing rate being more applicable. Once such data are available, however, any affected boar will have been in service for some time, with significant financial and environmental losses incurred. Reciprocal translocations (RTs) are the leading cause of porcine hypoprolificacy, reportedly present in 0.47% of AI boars. Traditional standard karyotyping, however, relies on animal specific expertise and does not detect more subtle (cryptic) translocations. Previously, we reported development of a multiple hybridisation fluorescence in situ hybridisation (FISH) strategy; here, we report on its use in 1641 AI boars. A total of 15 different RTs were identified in 69 boars, with four further animals XX/XY chimeric. Therefore, 4.5% had a chromosome abnormality (4.2% with an RT), a 0.88% incidence. Revisiting cases with both karyotype and FISH information, we reanalysed captured images, asking whether the translocation was detectable by karyotyping alone. The results suggest that chromosome translocations in boars may be significantly under-reported, thereby highlighting the need for pre-emptive screening by this method before a boar enters a breeding programme.

Experimental study on the dynamic response of a water ballast type floating breakwater

2021 ◽  
Vol 233 ◽  
pp. 109012
Author(s):  
Zhiwen Yang ◽  
Xinran Ji ◽  
Mingxiao Xie ◽  
Jinzhao Li ◽  
Huaqing Zhang ◽  
...  
Keyword(s):  
Experimental Study ◽  
Dynamic Response ◽  
Floating Breakwater

scholarly journals Effect of Air Injection on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1182
Author(s):  
Seung-Jun Kim ◽  
Yong Cho ◽  
Jin-Hyuk Kim
Keyword(s):  
Flow Rate ◽  
Draft Tube ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Air Injection ◽  
Low Flow ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Vortex Rope

Under low flow-rate conditions, a Francis turbine exhibits precession of a vortex rope with pressure fluctuations in the draft tube. These undesirable flow phenomena can lead to deterioration of the turbine performance as manifested by torque and power output fluctuations. In order to suppress the rope with precession and a swirl component in the tube, the use of anti-swirl fins was investigated in a previous study. However, vortex rope generation still occurred near the cone of the tube. In this study, unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted with a scale-adaptive simulation shear stress transport turbulence model. This model was used to observe the effects of the injection in the draft tube on the unsteady internal flow and pressure phenomena considering both active and passive suppression methods. The air injection affected the generation and suppression of the vortex rope and swirl component depending on the flow rate of the air. In addition, an injection level of 0.5%Q led to a reduction in the maximum unsteady pressure characteristics.

scholarly journals Impact of Orifice-to-Pipe Diameter Ratio on Leakage Flow: An Experimental Study

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2189
Author(s):  
Tingchao Yu ◽  
Xiangqiu Zhang ◽  
Iran E. Lima Neto ◽  
Tuqiao Zhang ◽  
Yu Shao ◽  
...  
Keyword(s):  
Experimental Study ◽  
Flow Rate ◽  
Pipe Wall ◽  
Pressure Head ◽  
Diameter Ratio ◽  
Pipe Diameter ◽  
Leakage Flow ◽  
Leakage Flow Rate ◽  
Different Shapes ◽  
Real Scale

The traditional orifice discharge formula used to estimate the flow rate through a leak opening at a pipe wall often produces inaccurate results. This paper reports an original experimental study in which the influence of orifice-to-pipe diameter ratio on leakage flow rate was investigated for several internal/external flow conditions and orifice holes with different shapes. The results revealed that orifice-to-pipe diameter ratio (or pipe wall curvature) indeed influenced the leakage flow, with the discharge coefficient ( C d ) presenting a wide variation (0.60–0.85). As the orifice-to-pipe diameter ratio decreased, the values of C d systematically decreased from about 12% to 3%. Overall, the values of C d also decreased with β (ratio of pressure head differential at the orifice to wall thickness), as observed in previous studies. On the other hand, orifice shape, main pipe flow velocity, and external medium (water or air) all had a secondary effect on C d . The results obtained in the present study not only demonstrated that orifice-to-pipe diameter ratio affects the outflow, but also that real scale pipes may exhibit a relevant deviation of C d from the classical range (0.61–0.67) reported in the literature.

Heave Induced Internal Flow Fluctuations in Vertical Transport Systems for Deep Ocean Mining

2014 ◽  
Author(s):  
Stephan D. A. Hannot ◽  
Jort M. van Wijk
Keyword(s):  
Transport System ◽  
Internal Flow ◽  
Deep Ocean ◽  
Vertical Transport ◽  
Transport Systems ◽  
Ship Motions ◽  
Centrifugal Pumps ◽  
Mining System ◽  
Pump System ◽  
Ocean Mining

Deep ocean mining systems will have to operate often in harsh weather conditions with heavy sea states. A typical mining system consists of a Mining Support Vessel (MSV) with a Vertical Transport System (VTS) attached to it. The transport system is a pump pipeline system using centrifugal pumps. The heave motions of the ship are transferred to the pump system due to the riser-ship coupling. Ship motions thus will have a significant influence on the internal flow in the VTS. In this paper, the influence of heave motions on the internal flow in the VTS for a typical mining system for Seafloor Massive Sulfide (SMS) deposits in Papua New Guinea is analyzed. Data on the wave climate in the PNG region is used to compute the ship motions of a coupled MSV-VTS. The ship motions then are translated into forces acting on the internal flow in order to compute fluctuations in the internal flow. In this way, the workability of the mining system with respect to the system’s production can be assessed. Based on a detailed analysis of the internal flow in relation to ship motions, the relevance of a coupled analysis for the design of VTS is made clear. This paper provides a method for performing such analyses.

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