Experimental Study on Flow Conditions of Jiaogang Ship Lock during Sluice Gate Hoist

The physical model of Jiaogang Ship Lock is established. Through model test, the flow condition in lock chamber and approach channel is studied. The results indicate when the upstream water level keeps high and the water level difference between upstream and downstream is less than 0.5 meter, the main flow oscillates less during spring tide flux and reflux in the flood year. When the upper water level is 0.96 m and during spring tide flux and reflux in the flood year, the flow is from downstream to upstream and the flow is smooth. When the upper water level is greater than lower water level, the sluice gate hoist condition is tidal range less than 0.3m in tide flux and less than 0.4m in tide reflux. Under the critical water level conditions, the Jiaogang Ship Lock sluice gate can be hoisted safely.

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Experiment Study on Force of Hoisting Triangular Gate of Ship Lock in Tidal Reach

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.391.402 ◽

2013 ◽

Vol 391 ◽

pp. 402-405

Author(s):

Teng Wu ◽

Jian Ding ◽

Ling Li Wu

Keyword(s):

Water Level ◽

Spring Tide ◽

High Water ◽

Tidal Range ◽

Water Control ◽

Absolute Value ◽

Tidal Reach ◽

Lock In ◽

Lock Gate ◽

Ship Lock

A physical model of Jiaogang Ship Lock is established in the paper. Through model test, the force of triangular gate under the condition of opening is studied. The result shows when the upper water level is high water control and when absolute value of upper-lower tidal range is less than 0.5m during the spring tide flux and reflux in the flood season of the Yangtze River in the flood year, the ship lock gate can be opened. When the upper water level is medium water control, the absolute value of upper-lower tidal range to open the ship lock gate should be less than 0.4m. And when the upper water level is low water control, the critical tidal range value is also less than 0.5m.

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Study on Hydrodynamic Characteristics and Environmental Response in Shantou Offshore Area

Journal of Marine Science and Engineering ◽

10.3390/jmse9080912 ◽

2021 ◽

Vol 9 (8) ◽

pp. 912

Author(s):

Yuezhao Tang ◽

Yang Wang ◽

Enjin Zhao ◽

Jiaji Yi ◽

Kecong Feng ◽

...

Keyword(s):

Flow Field ◽

Water Level ◽

Tidal Current ◽

Sea Water ◽

High Tide ◽

Spring Tide ◽

River Estuary ◽

Tidal Range ◽

Offshore Area ◽

Tidal Constituents

As a coastal trading city in China, Shantou has complex terrain and changeable sea conditions in its coastal waters. In order to better protect the coastal engineering and social property along the coast, based on the numerical simulation method, this paper constructed a detailed hydrodynamic model of the Shantou sea area, and the measured tide elevation and tidal current were used to verify the accuracy of the model. Based on the simulation results, the tide elevation and current in the study area were analyzed, including the flood and ebb tides of astronomical spring tide, the flood and ebb tides of astronomical neap tide, the high tide, and the low tide. In order to find the main tidal constituent types in this sea, the influence of different tidal constituents on tide elevation and tidal current in the study area was analyzed. At the same time, the storm surge model of the study area was constructed, and the flow field under Typhoon “Mangkhut” in the study area was simulated by using the real recorded data. Typhoon wind fields with different recurrence periods and intensities were constructed to simulate the change in the flow field, the sea water level, and the disaster situation along the coast. The results showed that under normal sea conditions, the sea water flows from southwest to northeast at flood tide and the flow direction is opposite at ebb tide. The tidal range is large in the northwest and small in the southeast of the study area. The tides in the study area are mainly controlled by M2, S2, K1, and O1 tidal constituents, but N2, K2, P1, and Q1 tidal constituents have significant effects on the high water level. The water level caused by typhoons increases significantly along the coast of Shantou City. In the west area of the Rong River estuary, a typhoon with a lower central pressure than 910 hPa may induce a water increase of more than 2 m.

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Tidal studies on Aldabra

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1971.0008 ◽

1971 ◽

Vol 260 (836) ◽

pp. 93-121 ◽

Cited By ~ 26

Keyword(s):

Water Level ◽

Time Lag ◽

Spring Tide ◽

High Water ◽

Wire Mesh ◽

Tidal Range ◽

Masking Effect ◽

Phase Lag ◽

Central Pacific ◽

Du Bois

The oceanic tide at Aldabra possesses a very large range for an atoll owing to the influence of the Mozambique Channel. The mean spring-tide range, expressed as 2 ( M 2 + S 2 ), is 2.74 m. This is much greater than the 0.5 m common to the majority of central Pacific atolls, and the 0.7 to 1.7 m for Indian Ocean atolls. Ten tide-recording stations were set up by members of the expedition. Foxboro—Yoxall tide-gauge records were obtained from most sites, though there are few accessible rock ledges near deep water suitable for the instrument, especially in the lagoon. Visual records were used extensively in a detailed study of the tidal system in Passe Houareau. Tidal predictions for Aldabra found in Admiralty Tide Tables possess marked lagoonal characteristics. They originate from ‘Grand Poste’, a site well within Grande Passe. It is recommended that records for Passe du Bois be taken as standard since they most closely represent the oceanic tide. Empirically derived tide-predicting graphs are presented for key stations around the atoll, using Kilindini as standard port. Reduction in tidal range is pronounced in the lagoon and is conspicuous even near the mouths of the major channels. Within Passe Houareau spring-tide amplitudes may be a mere 1.2 m only 500 m from the channel mouth where the oceanic range is 3.3 m. Time lag increases lagoonwards more rapidly at Passe Houareau than at either Passe du Bois or Grande Passe, and is greater at low water than at high because of the very shallow nature of the lagoon floor. The greatest recorded phase lag occurs at the head of Bras Cinq Cases, where high water is delayed by 4 1/4 h at major spring tides: at neaps the whole region is dry at high water. Harmonic analyses are presented for one oceanic and two lagoonal stations. Computer synthesis of neap tides in the lagoon demonstrates a monthly masking effect produced by prominent shallow water harmonics. This results in the lagoon being virtually tideless on the smallest neap tides. Strong higher harmonics are indicated by visual records for Ilot Marquoix at the eastern end of the lagoon. These are characterized by a plateau-like high water, where the level commonly remains stationary for over 3 h. Lagoon tide curves are markedly asymmetrical, and often show linear ebb profiles, indicating that the lagoon behaves as a simple water-filled basin in many areas. Drainage off lagoon platforms is slow, water level falling by only 3 to 5 cm h -1 . This results in the tide ebbing for to 10 h out of the 12 1/2 h cycle. Towards spring tides more water enters the lagoon through Passe Houareau than can drain away before the next tide. Water level gradually builds up until at major springs a foot of water covers the lagoon platform at low tide. Extreme low water coincides with neap tides. Because of this ponding effect significant differences in insolation are experienced by marine bottom communities. On oceanic platforms extreme low water coincides with spring tides and occurs at midday: in the lagoon, platforms are most exposed between 06h00 and 08h00 and are always covered at noon. The effects of solar insolation are therefore minimal throughout much of the Aldabra lagoon, but are at a maximum around the coast. Tidal currents were measured in each of the Passes. In the western channels maximum values of 1.5 m s -1 (3 knots) were recorded in Passe du Bois. In Passe Gionnet a peak ebb value of 3.7 m s -1 (7.2 knots) was attained at high springs, with 3 m s -1 (6 knots) sustained for over 2 h. Flow/ebb current reversals are rapid, and in Passe Gionnet accompanied by the development of standing waves. Many channels are floored with trains of reversing sand megaripples. Elsewhere scour is appreciable; a wire mesh shark cage on the floor of Passe du Bois being undercut by 25 cm in 2 weeks. Transitory megarippled sandbanks occur on the eastern flank of Passe Houareau, and bottom facies throughout the lagoon are sculptured by the strong tidal scour.

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Transition Mechanisms in Laminar Separated Flow Under Simulated Low Pressure Turbine Aerofoil Conditions

Journal of Turbomachinery ◽

10.1115/1.4006393 ◽

2012 ◽

Vol 135 (1) ◽

Cited By ~ 12

Author(s):

Jerrit Dähnert ◽

Christoph Lyko ◽

Dieter Peitsch

Keyword(s):

Reynolds Number ◽

Separation Bubble ◽

Separated Flow ◽

Low Pressure ◽

Main Flow ◽

Test Facility ◽

Flow Conditions ◽

Laminar Separation ◽

Free Stream Turbulence ◽

Low Pressure Turbine

Based on detailed experimental work conducted at a low speed test facility, this paper describes the transition process in the presence of a separation bubble with low Reynolds number, low free-stream turbulence, and steady main flow conditions. A pressure distribution has been created on a long flat plate by means of a contoured wall opposite of the plate, matching the suction side of a modern low-pressure turbine aerofoil. The main flow conditions for four Reynolds numbers, based on suction surface length and nominal exit velocity, were varied from 80,000 to 300,000, which covers the typical range of flight conditions. Velocity profiles and the overall flow field were acquired in the boundary layer at several streamwise locations using hot-wire anemometry. The data given is in the form of contours for velocity, turbulence intensity, and turbulent intermittency. The results highlight the effects of Reynolds number, the mechanisms of separation, transition, and reattachment, which feature laminar separation-long bubble and laminar separation-short bubble modes. For each Reynolds number, the onset of transition, the transition length, and the general characteristics of separated flow are determined. These findings are compared to the measurement results found in the literature. Furthermore, the experimental data is compared with two categories of correlation functions also given in the literature: (1) correlations predicting the onset of transition and (2) correlations predicting the mode of separated flow transition. Moreover, it is shown that the type of instability involved corresponds to the inviscid Kelvin-Helmholtz instability mode at a dominant frequency that is in agreement with the typical ranges occurring in published studies of separated and free-shear layers.

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Sedimentary Cladocera as indicators of past water-level changes in shallow northern lakes

Quaternary Research ◽

10.1016/j.yqres.2011.02.007 ◽

2011 ◽

Vol 75 (3) ◽

pp. 430-437 ◽

Cited By ~ 33

Author(s):

Liisa Nevalainen ◽

Kaarina Sarmaja-Korjonen ◽

Tomi P. Luoto

Keyword(s):

Water Level ◽

Lake Level ◽

Water Levels ◽

Sediment Record ◽

Inference Model ◽

Water Level Changes ◽

Long Term Changes ◽

Lower Water Level ◽

The Relationship

AbstractThe usability of subfossil Cladocera assemblages in reconstructing long-term changes in lake level was examined by testing the relationship between Cladocera-based planktonic/littoral (P/L) ratio and water-level inference model in a surface-sediment dataset and in a 2000-yr sediment record in Finland. The relationships between measured and inferred water levels and P/L ratios were significant in the dataset, implying that littoral taxa are primarily deposited in shallow littoral areas, while planktonic cladocerans accumulate abundantly mainly in deepwater locations. The 2000-yr water-level reconstructions based on the water-level inference model and P/L ratio corresponded closely with each other and with a previously available midge-inferred water-level reconstruction from the same core, showing a period of lower water level around AD 300–1000 and suggesting that the methods are valid for paleolimnological and -climatological use.

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Transition Mechanisms in Laminar Separated Flow Under Simulated Low Pressure Turbine Airfoil Conditions

Volume 7: Turbomachinery, Parts A, B, and C ◽

10.1115/gt2011-45690 ◽

2011 ◽

Author(s):

Jerrit Da¨hnert ◽

Christoph Lyko ◽

Dieter Peitsch

Keyword(s):

Reynolds Number ◽

Separation Bubble ◽

Separated Flow ◽

Low Pressure ◽

Main Flow ◽

Test Facility ◽

Flow Conditions ◽

Laminar Separation ◽

Free Stream Turbulence ◽

Low Pressure Turbine

Based on detailed experimental work conducted at a low speed test facility, this paper describes the transition process in the presence of a separation bubble with low Reynolds number, low free-stream turbulence, and steady main flow conditions. A pressure distribution has been created on a long flat plate by means of a contoured wall opposite of the plate, matching the suction side of a modern low-pressure turbine aerofoil. The main flow conditions for four Reynolds numbers, based on suction surface length and nominal exit velocity, were varied from 80,000 to 300,000, which covers the typical range of flight conditions. Velocity profiles and the overall flow field were acquired in the boundary layer at several streamwise locations using hot-wire anemometry. The data given is in the form of contours for velocity, turbulence intensity, and turbulent intermittency. The results highlight the effects of Reynolds number, the mechanisms of separation, transition, and reattachment, which feature laminar separation-long bubble and laminar separation-short bubble modes. For each Reynolds number, the onset of transition, the transition length, and the general characteristics of separated flow are determined. These findings are compared to the measurement results found in the literature. Furthermore, the experimental data is compared with two categories of correlation functions also given in the open literature: (1) correlations predicting the onset of transition and (2) correlations predicting the mode of separated flow transition. Moreover, it is shown that the type of instability involved corresponds to the inviscid Kelvin-Helmholtz instability mode at a dominant frequency that is in agreement with the typical ranges occurring in published studies of separated and free-shear layers.

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Effects of Wakes on Blade Endwall Heat Transfer in High Turbulence Intensity

Volume 5A: Heat Transfer ◽

10.1115/gt2019-91493 ◽

2019 ◽

Author(s):

Sehjin Park ◽

Ho-Seong Sohn ◽

Hyung Hee Cho ◽

Hee Koo Moon ◽

Yang Seok Han ◽

...

Keyword(s):

Heat Transfer ◽

Turbulence Intensity ◽

Horseshoe Vortex ◽

Main Flow ◽

Flow Conditions ◽

Heat Transfer Characteristics ◽

Trailing Edge ◽

Transfer Characteristics ◽

Passage Vortex ◽

High Turbulence

Abstract Different types of vortices, such as horseshoe vortex, passage vortex, corner vortex, cause high heat transfer distributions and complex heat transfer characteristics at the endwall of turbine blades. In addition, the endwall heat transfer is also affected when the main flow is highly turbulent and wakes are generated by the trailing edge of the vane. Detailed heat transfer measurements are necessary to protect the blades under harsh and complex flow conditions. Therefore, this study investigated the heat transfer characteristics on the blade endwall under flow conditions that simulate high turbulence intensity of the main flow and the generation of wakes by the trailing edge of the vane. The endwall heat transfer was measured using the naphthalene sublimation method. A turbulence generating grid was installed in a linear cascade to simulate the main flow with high turbulence intensity and a wake generator with a rod bundle was used to simulate the wakes generated by the trailing edge of the vane. In the case of high turbulence intensity without wakes, the main flow with high turbulence intensity (Turbulence intensity, T.I = 7.5%) had little impact on the effect of the horseshoe vortex and passage vortex on the heat transfer characteristics. However, increasing turbulence caused the endwall heat transfer to decrease near the pressure side of the blade and increase near the suction side of the blade. On the other hand, the wakes resulted in heat transfer characteristics similar to high turbulence intensity, but decreased heat transfer by horseshoe vortex and passage vortex. The endwall heat transfer distributions were similar regardless of the turbulence intensity (T.I = 1.2%, 7.5%) in the cases with wakes (Rod passing Strouhal number, S = 0.3). This means that the flow condition of S = 0.3 has a more significant influence on the endwall heat transfer than that of T.I = 7.5%.

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Modelling Study of Transport Time Scales for a Hyper-Tidal Estuary

Water ◽

10.3390/w12092434 ◽

2020 ◽

Vol 12 (9) ◽

pp. 2434

Author(s):

Guanghai Gao ◽

Junqiang Xia ◽

Roger A. Falconer ◽

Yingying Wang

Keyword(s):

Numerical Model ◽

Water Level ◽

Residence Time ◽

Exposure Time ◽

Neap Tide ◽

Spring Tide ◽

High Water ◽

Residence Times ◽

Severn Estuary ◽

Release Times

This paper presents a study of two transport timescales (TTS), i.e., the residence time and exposure time, of a hyper-tidal estuary using a widely used numerical model. The numerical model was calibrated against field measured data for various tidal conditions. The model simulated current speeds and directions generally agreed well with the field data. The model was then further developed and applied to study the two transport timescales, namely the exposure time and residence time for the hyper-tidal Severn Estuary. The numerical model predictions showed that the inflow from the River Severn under high flow conditions reduced the residence and exposure times by 1.5 to 3.5% for different tidal ranges and tracer release times. For spring tide conditions, releasing a tracer at high water reduced the residence time and exposure time by 49.0% and 11.9%, respectively, compared to releasing the tracer at low water. For neap tide conditions, releasing at high water reduced the residence time and exposure time by 31.6% and 8.0%, respectively, compared to releasing the tracer at low water level. The return coefficient was found to be vary between 0.75 and 0.88 for the different tidal conditions, which indicates that the returning water effects for different tidal ranges and release times are all relatively high. For all flow and tide conditions, the exposure times were significantly greater than the residence times, which demonstrated that there was a high possibility for water and/or pollutants to re-enter the Severn Estuary after leaving it on an ebb tide. The fractions of water and/or pollutants re-entering the estuary for spring and neap tide conditions were found to be very high, giving 0.75–0.81 for neap tides, and 0.79–0.88 for spring tides. For both the spring and neap tides, the residence and exposure times were lower for high water level release. Spring tide conditions gave significantly lower residence and exposure times. The spatial distribution of exposure and residence times showed that the flow from the River Severn only had a local effect on the upstream part of the estuary, for both the residence and exposure time.

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The Research of Navigation Flow Conditions and Improvement Measures on Entrance Area and Connecting Reach of Dahua Lock in Hongshui River

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.250-253.3624 ◽

2011 ◽

Vol 250-253 ◽

pp. 3624-3629

Author(s):

Dian Guang Ma ◽

Xin Liu ◽

Jia Qiang Zhao ◽

Xiao Fei Liu ◽

Shao Xi Li

Keyword(s):

Flow Conditions ◽

Guangxi Province ◽

Navigation Problem ◽

Model Combining ◽

Approach Channel ◽

Improvement Measures ◽

Navigation Lock ◽

Lock In ◽

Inflow Conditions ◽

Pattern Problem

The ship facilities didn’t be constructed in step with the construction of Dahua Terminal in Hongshui River of Guangxi province, while the argumentation didn’t be carried out when navigation lock was built out. In the condition above, when the navigation lock was completed, the navigation flow conditions in the entrance area of downstream and the linkage section was bad, so ships were difficult to enter the approach channel. The research of navigation flow conditions and nay navigation mechanism in the entrance area of downstream and the linkage section in current condition was implemented through physical model combining ship model. The method of using traditional navigation wall and navigation pier to improve flow conditions didn’t be adopted in renovation research. The new renovation idea of changing inflow conditions was used innovatively and bad flow pattern problem was solved by using deep pools terrain in the entrance area of downstream. After the implementation of the engineering, nay navigation problem was solved effectively and ships could pass the terminal successfully. This engineering provides a new way to solve similar terminal navigation problem.

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Uncertainty in coastal flooding: modelling and visualisation

10.5194/egusphere-egu2020-8390 ◽

2020 ◽

Author(s):

John Maskell

Keyword(s):

Water Level ◽

Storm Surge ◽

Return Period ◽

Flood Risk ◽

High Water ◽

Coastal Flooding ◽

Water Levels ◽

Tidal Range ◽

The Uk ◽

Flood Maps

Two case studies are considered in the UK, where uncertainty and drivers of coastal flood risk are explored through modelling and visualisations. Visualising the impact of uncertainty is a useful way of explaining the potential range of predicted or simulated flood risk to both expert and non-expert stakeholders.Significant flooding occurred in December 2013 and January 2017 at Hornsea on the UK East Coast, where storm surge levels and waves overtopped the town&#8217;s coastal defences. Uncertainty in the potential coastal flooding is visualised at Hornsea due to the range of uncertainty in the 100-year return period water level and in the calculated overtopping due to 3 m waves at the defences. The range of uncertainty in the simulated flooding is visualised through flood maps, where various combinations of the uncertainties decrease or increase the simulated inundated area by 58% and 82% respectively.Located at the mouth of the Mersey Estuary and facing the Irish Sea, New Brighton is affected by a large tidal range with potential storm surge and large waves. Uncertainty in the coastal flooding at the 100-year return period due to the combination of water levels and waves is explored through Monte-Carlo analysis and hydrodynamic modelling. Visualisation through flood maps shows that the inundation extent at New Brighton varies significantly for combined wave and surge events with a joint probability of 100 years, where the total flooded area ranges from 0 m2 to 10,300 m2. Waves are an important flood mechanism at New Brighton but are dependent on high water levels to impact the coastal defences and reduce the effective freeboard. The combination of waves and high-water levels at this return level not only determine the magnitude of the flood extent but also the spatial characteristics of the risk, whereby flooding of residential properties is dominated by overflow from high water levels, and commercial and leisure properties are affected by large waves that occur when the water level is relatively high at the defences.

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