scholarly journals Stern Twin-Propeller Effects on Harbor Infrastructures. Experimental Analysis

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1571 ◽  
Author(s):  
Anna Mujal-Colilles ◽  
Marcel·la Castells ◽  
Toni Llull ◽  
Xavi Gironella ◽  
Xavier Martínez de Osés
Keyword(s):  
Experimental Analysis ◽  
Water Tank ◽  
Subsequent Increase ◽  
Medium Scale ◽  
Erosion Rates ◽  
Experimental Campaign ◽  
Marine Traffic ◽  
Scouring Depth ◽  
Experimental Laboratory ◽  
Basin Area

The growth of marine traffic in harbors, and the subsequent increase in vessel and propulsion system sizes, produces three linked problems at the harbor basin area: (i) higher erosion rates damaging docking structures; (ii) sedimentation areas reducing the total depth; (iii) resuspension of contaminated materials deposited at the seabed. The published literature demonstrates that there are no formulations for twin stern propellers to compute the maximum scouring depth. Another important limitation is the fact that the formulations proposed only use one type of maneuvering during the experimental campaign, assuming that vessels are constantly being undocked. Trying to reproduce the real arrival and departure maneuvers, 24 different tests were conducted at an experimental laboratory in a medium-scale water tank using a twin propeller model to estimate the consequences and the maximum scouring depth produced by stern propellers during the backward/docking and forward/undocking scenarios. Results confirm that the combination of backward and forward scenario differs substantially from the experiments performed so far in the literature using only an accumulative forward scenario, yielding deeper scouring holes at the harbor basin area. The results presented in this paper can be used as guidelines to estimate the effects of regular vessels at their particular docking location.

scholarly journals Influence of topography and human activity on erosion in Yunnan, SW China

2016 ◽  
Author(s):  
Amanda H. Schmidt ◽  
Thomas B. Neilson ◽  
Paul R. Bierman ◽  
Dylan H. Rood ◽  
William B. Ouimet ◽  
...  
Keyword(s):  
Land Use ◽  
Human Activity ◽  
River Sediment ◽  
Agricultural Land ◽  
Erosion Rates ◽  
The North ◽  
Small Watersheds ◽  
Basin Area

Abstract. In order to understand better if and where long-term erosion rates calculated using in situ 10Be are affected by contemporary changes in land use and attendant deep regolith erosion, we calculated erosion rates using measurements of in situ 10Be in quartz from 52 samples of river sediment collected from three tributaries of the Mekong River (median basin area = 46.5 km2). Erosion rates range from 12–209 mm/kyr with an area-weighted mean of 117 ± 49 mm/kyr (1 standard deviation) and median of 74 mm/kyr. We observed a decrease in the relative influence of human activity from our steepest and least altered watershed in the north to the most heavily altered landscapes in the south. In the areas of the landscape least disturbed by humans, erosion rates correlate best with measures of topographic steepness. In the most heavily altered landscapes, measures of modern land use correlate with 10Be-estimated erosions rates but topographic steepness parameters cease to correlate with erosion rates. We conclude that in some small watersheds we sampled, those with high rates and intensity of agricultural land use, that tillage and resultant erosion has excavated deeply enough into the regolith to deliver subsurface sediment to streams and thus raise apparent in situ 10Be-derived erosion rates by as much as 2.5 times over background rates had the watersheds not been disturbed.

scholarly journals Numerical and Experimental Analysis of Portable Underwater Robots with a Movable Float Device

2021 ◽  
Vol 33 (6) ◽  
pp. 1234-1247
Author(s):  
Norimitsu Sakagami ◽  
Mizuho Shibata ◽  
Tomohiro Ueda ◽  
Kensei Ishizu ◽  
Kenshiro Yokoi ◽  
...  
Keyword(s):  
Experimental Study ◽  
Feedback Control ◽  
Experimental Analysis ◽  
Field Experiments ◽  
Static Stability ◽  
Control Device ◽  
Water Tank ◽  
Underwater Robots ◽  
Stability Curve ◽  
Numerical Simulator

This report describes a numerical and experimental study of a posture control device based on a movable float for portable underwater robots. We numerically analyzed the static stability using a stability curve and allowable spatial range of a center-of-gravity shift caused by a payload shift or manipulator configuration. Further, we proposed a feedback controller based on direct pitch and roll signals to change and maintain robot posture. We tested the feedback control using a numerical simulator and conducted experiments in a water tank using two portable underwater robots to demonstrate the effectiveness of the movable float device and proposed controller. The results of the field experiments showed that the device and proposed controller can be employed for effective underwater operations of portable underwater robots.

scholarly journals Experimental Campaign Tests on a Tesla Micro-Expanders

2019 ◽  
Vol 113 ◽  
pp. 03015 ◽  
Author(s):  
Avinash Renuke ◽  
Alberto Traverso ◽  
Matteo Pascenti
Keyword(s):  
Experimental Analysis ◽  
Rotational Speed ◽  
Compressed Air ◽  
Working Fluid ◽  
Experiment System ◽  
Disk Thickness ◽  
Experimental Campaign ◽  
Power Group ◽  
Speed Up ◽  
The Impact

This paper presents the experimental campaign on Tesla turbo expanders carried out at Thermo-chemical Power group (TPG) of University of Genoa, Italy. An experiment system is established using compressed air as a working fluid. A 200 W turbine is tested with rotational speed up to 40000 rpm. Experimental analysis focused mainly on the efficiency features of this expander, showing the impact on performance of different disk gaps, disk thickness, discharge holes, exhaust geometry, as a function of speed and mass flow. An improved version of 3 kW air Tesla turboexpander is built. Preliminary experimental results are discussed along with the effect of number of nozzles on the performance of the turbine.

Experimental Investigation in LIFUS5/Mod2 Facility of Spiral-Tube Steam Generator Rupture Scenarios for ELFR

2017 ◽  
Author(s):  
Alessio Pesetti ◽  
Alessandro Del Nevo ◽  
Andrea Neri ◽  
Stefano Cati ◽  
Valerio Sermenghi ◽  
...  
Keyword(s):  
Steam Generator ◽  
Tube Bundle ◽  
Quality Data ◽  
Water Tank ◽  
Spiral Tube ◽  
Pressure Transducers ◽  
Experimental Campaign ◽  
Evolution Path ◽  
Pressure Peak ◽  
Lower Temperature

In the framework of the European Commission LEADER project, an experimental campaign of seven tests was performed in the LIFUS5/Mod2 facility, at ENEA CR Brasimone, for investigating the postulated Steam Generator Tube Rupture (SGTR) event in a relevant configuration for the Spiral-Tube Steam Generator (STSG) of the European Lead Fast Reactor (ELFR). The LIFUS5/Mod2 facility is composed by a water tank of 15 L injecting subcooled water up to 200 bar into the reaction tank of 100 L (420 mm of diameter), which is connected by a 3 inch pipe to the dump tank of 2 m3. A dedicated test section was designed, assembled and implemented in the reaction tank. It is composed by 188 tubes, vertically disposed with triangular pitch inside a cylindrical support. This tube bundle is representative of a portion of the STSG of ELFR. The cylindrical support is closed at the lower and upper end by two tube plates and has a perforated lateral shell (300 mm of diameter and 400 mm high). The reaction tank is filled by Lead-Bismuth Eutectic alloy (LBE) at 400°C up to the top tube plate, with an argon cover gas at about 2 bar. The water is injected at about 180 bar and 270°C through the central tube, at middle height of the bundle. The water-LBE interaction is characterised by high quality data acquisition system: 6 fast Pressure Transducers (PTs) working at 10 kHz for precisely characterize the first narrow injection peaks, 70 low constant time Thermocouples (TCs) to understand the vapour evolution path and 13 strain gages (SGGs) for measuring the strain of the bundle and main vessel. The overall LEADER experimental campaign is constituted by seven tests, divided in three series (B1, B2 and B3), characterized by different injection orifice diameters of 4, 8.9 and 12.6 mm, respectively. This paper presents the experimental results of the first two tests of series B2 (B2.1 and B2.2) having 8.9 mm of injection orifice. The first test analysed showed a first narrow pressure peak of about 32 bar, some milliseconds after the cap rupture instant. The following pressurization due to the evaporation of water entered into the reaction vessel was of an analogues magnitude for both the tests (about 50 bar) and lasted some tenths of second. The water/LBE interaction lower temperature was reached on the inner ranks of tubes, about 150°C. The outer rank was cooled down to about 300°C. The strain gage measurements showed a decreasing deformation on the tubes toward the outer positions. No ruptures were observed on tubes surrounding the injector. The amount of LBE transported into the dump tank was strongly dependent on the LBE level in the reaction tank at the start of the tests and about 200 kg.

scholarly journals ORTHOGONAL WAVE CURRENT INTERACTION OVER A FIXED RIPPLED BED: PRELIMINARY RESULTS OF AN EXPERIMENTAL CAMPAIGN

2020 ◽  
pp. 44
Author(s):  
Carla Faraci ◽  
Alessia Ruggeri ◽  
Massimiliano Marino ◽  
Rosaria E. Musumeci ◽  
Enrico Foti
Keyword(s):  
Boundary Layer ◽  
Velocity Distribution ◽  
Water Tank ◽  
Current Case ◽  
Experimental Campaign ◽  
Current Interaction ◽  
Hydrodynamic Effects ◽  
Rippled Bed ◽  
A Current ◽  
The Eu

This paper reports some results obtained in the framework of the TA WINGS, funded by the EU through the Hydralab+ program. The project was aimed at investigating the hydrodynamic effects of an orthogonal wave onto a current in order to understand the nature of the velocity distribution along the water column over fixed ripples. Velocity profiles were acquired within the DHI shallow water tank by means of several Vectrinos in order to investigate the effects of wave-current interaction. A comparison between wave only case and wave plus current case showed that, when the current overlaps to waves, the recirculating cells formed near the bed are flatter than those formed in wave only. Moreover, the vorticity increases outside the boundary layer and decreases inside it when the current superposes to the wave.

scholarly journals EXPERIMENTAL ANALYSIS OF BEAM-TO-COLUMN JOINTS 1 EQUIPPED WITH SPRAYED ALUMINIUM FRICTION DAMPERS

2021 ◽  
Author(s):  
Massimo Latour ◽  
Gianvittorio Rizzano ◽  
Vincenzo Piluso
Keyword(s):  
Experimental Analysis ◽  
Steel Plates ◽  
Structural Detail ◽  
Friction Damper ◽  
Friction Dampers ◽  
Seismic Input ◽  
Experimental Campaign ◽  
Flexural Resistance ◽  
Thermally Sprayed ◽  
Sliding Force

In this paper, the results of an experimental analysis regarding beam-to-column joints equipped with friction dampers is presented. Even though the overall concept is not new, the connection structural detail and the friction pad material are different from previous proposals. In particular, the beam is connected to the column with a classical fixed T-stub fastening the upper flange and a friction damper located at the beam lower flange. The friction damper is composed of a stack of steel plates conceived to assure symmetrical friction. The friction pads are made of steel plates coated with thermally sprayed aluminium. The friction damper is designed in order to slide for a force level equal to or lower than the ratio between the nominal flexural resistance of the connected beam and the lever arm, i.e. the distance between the top T-stub and the friction damper. In this way, it is possible to obtain connections able to dissipate the seismic input energy almost without any damage to the steel elements, provided that all the joint components are designed with sufficient over-strength with respect to the actions corresponding to the friction damper sliding force. In this paper, such approach is validated reporting the results of an experimental campaign.

Experimental analysis of solar thermal storage in a water tank with open side inlets

2012 ◽  
Vol 89 (1) ◽  
pp. 401-412 ◽  
Author(s):  
E. Palacios ◽  
D.M. Admiraal ◽  
J.D. Marcos ◽  
M. Izquierdo
Keyword(s):  
Experimental Analysis ◽  
Thermal Storage ◽  
Solar Thermal ◽  
Water Tank ◽  
Open Side
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