Hydraulic Laboratory Research Articles

UJI MODEL HIDROLIK FISIK (UMH-FISIK) PELIMPAH BENDUNGAN CIBEET DI KABUPATEN BOGOR

Among the vital components of a dam is the spillway structure. Therefore, the building requires testing of physical hydraulic models, one of which is carried out at the Water Hydraulics and Geotechnical Center laboratory. This physical hydraulic model test study aims to analyze the hydraulic behavior of the dam spillway, mainly the discharge curve and flow elevation, average flow velocity, flow direction pattern, and hydrostatic pressure. This study uses a physical hydraulic model (modeling), which is a research method that focuses on 3-dimensional physical modeling and using the initial design from the consultant (series 0) by modeling some of the core parts of the dam such as spillway structures, dam body structures, launch channels, energy dampers, some of the contours of the river upstream, and some of the contours of the river downstream. The research instrument used were: Thompson discharge measuring instrument, level meter as a means of predicting water level elevation, current meter velocity measuring instrument, floating object as a research aid, a piezometer to determine hydrostatic pressure. The results showed that the spillway capacity could drain the PMF return period discharge (QPMF = 2091,75 m3/s) with the available guard height of 1,25 m, meeting the planning criteria of 0,75 m. At the Q2th and Q25th discharges, there is no hydraulic jump in the energy reducer and leads directly to the transition channel. In contrast, at the Q100th and Q1000th discharges, a hydraulic jump occurs in the energy reducer. The flow velocity, downstream of the spillway, especially on the left side of the guide wall, was recorded at a relatively high velocity, allowing turbulence to occur. The flow direction pattern that occurs upstream of the reservoir is reasonably even towards the spillway, and there is no crossflow. There is negative pressure at the piezometer point P5 with a 2-year return discharge of -0,25 N/m2, a 25-year return discharge of -0,25 N/m2, and a 100-year return discharge of -0,15 N/m2, which is still within the safe limits and does not exceed the allowable provisions, namely -1.00 m (for pairs) and -4.00 m (for concrete).

FEM Strength Analysis of Circumferential Compensation with Integrated Lips in Gear Pumps

Currently, gear pumps are developed with a aim to increase their efficiency, reduce internal leaks, and increase their working pressures. This development direction requires new solutions which would compensate backlash while ensuring an optimal size of the gaps for the entire range of working pressures. One of the solutions intended to meet this demand is to design circumferential compensation with the so-called integrated lips. The presented backlash compensation method is the result of research performed as part of a project named Designing High-Pressure Gear Pumps. The project was granted funding under path A of the Applied Research Program, contract No. PBS3/A6/22/2015. The research works were performed in the Laboratory of Hydraulic Drives and Vibroacoustics of Machines at Wrocław University of Science and Technology, and in cooperation with Hydrotor SA.

IMPLEMENTASI TEKNOLOGI PETA VIRTUAL 3D GEDUNG E TEKNIK SIPIL DAN GEDUNG F LABORATORIUM HIDROLIKA FAKUTAS TEKNIK UNIVERSITAS LAMPUNG

Lampung University doing out routine activities every new academic year for students especially for new students college who majoring in Civil Engineering, Faculty of Engineering, Introduction about Campus Life for New Students (PKKMB), one of the main agendas of PKKMB is introducing about everyvbuildings and public facilities in Civil Engineering also every building and the room in it. The current state of the COVID-19 pandemic make the University of Lampung conduct learning activy by network (online). So, it's make every students activities not possible to perform direct tracing. Serving method information follows technological developments, one of which is 3D visualization techniques. With using the Multimedia Development Life Cycle (MDLC) system development method, 3D virtual map applications can be developed that can display building layouts and facilities in 3D. This research is Alpha Testing and Customer satisfaction. Alpha Testing provides test results The application can operate on versions in operation android system 7.1 to 10. The application can operate on smartphone with screen specifications from 5.0 inch to 6.5 inches. The application can operate on smartphones from minimum 3GB RAM to 8GB RAM. Customer Satisfaction Respondents stated that the 3D Virtual Map Application of Building E Civil Engineering and Building F of the Hydraulics Laboratory get good results with a percentage index between 87.5% to 95%.

Distribution of flow velocity in a shaft intake structure

Abstract Recently, the construction of shaft intake structures in Slovakia has increased. The shaft intake structures overcome significant vertical depth over short horizontal distance. The flow of water in these shaft intake structures is therefore very complicated. The velocity field at a shaft intake of a small hydropower plant was investigated on a physical model in a hydraulic laboratory using the particle image velocimetry method. The particle image velocimetry measurements were realized for different shaft depths and the results of this study can increase negative effects of not suitable the design of construction on the flow homogeneity in the turbine intake.

Investigation of scours on a physical model of the Hričov weir using photogrammetry

Abstract Scours creation in riverbed at the Hričov weir is a permanent problem since its construction. It is caused by the shortened stilling basin of the weir. In almost all cases of flow control at the weir the energy is not dissipated sufficiently. A 3D physical model was built in the hydraulic laboratory to investigate the measures for reduction of the scour creation. To simulate uneven loads on the downstream riverbed, a flood discharge controlled by the weir in symmetric and asymmetric operations was used for simulations. The scours were evaluated using short-range photogrammetry for contactless measurements. Based on this method digital models of the riverbed for each simulation were created and the scours were assessed to determine the effect of the investigated measures on scour reduction.

Modelling the Effects of Hydraulic Force on Strain in Hydraulic Structures Using ANN (Haditha Dam in Iraq as a Case Study)

The strain on any structure is a critical issue worldwide, resulting from loads on the structure. An exact prediction at all the expected strains ranges on the dam will pave the way for better dam management under different discharges. The main aims of the present paper are to study the behaviour of strains on the dam and create a model based on ANN techniques that can be used to predict the strain on the model of the Haditha dam. The ANN is a computational model that simulates the method neurons work in the human brain. The research includes a study of the strains on the dam body and the gate. The input of the present model includes gate opening, discharge, depth of upstream water, and force on the dam body and gate. The model has been applied by using 150 actual testes of strain in the hydraulic laboratory. The model has been achieved by using a MATLAB software with hyperbolic sigmoid transfer function and three nodes. The accuracy of the model was achieved by using some statistical indicators. The results show the ANN is capable of predicting the strain on the Haditha dam with high accuracy. The regression for both strains on the dam body and the gate was more than 89% for all training, validation, testing, and all samples.

On berm design of Icelandic-type breakwaters (case study: Sirevåg berm breakwater)

An experimental model of an Icelandic-berm breakwater has been set up in the hydraulic laboratory of Tarbiat Modares University using irregular waves. Experimental model tests have been carried out using a wide range of sea-state conditions and geometrical parameters to measure different parameters, such as the eroded area (Ae), the berm recession (Rec) and the depth of the intersection point of initial and reshaped profiles (hf). A stability formula is proposed to establish the relationship between the damage parameter of the Icelandic-berm breakwater (Sd) and the non-dimensional form of Rec and hf. The application of the given formula for estimating the berm recession in the phenomenon and practical cases was evaluated employing the Sirevåg berm breakwater. The results of the evaluation highlight the appropriate estimation of berm recession. Moreover, some recommendations are suggested to consider berm parameters, such as the berm width, the berm elevation from still water level and the height of class I stones, as an Icelandic-type berm breakwater design criterion for future engineers. Eventually, taking all the proposed formulae and recommendations into consideration, a design tool for engineers in berm design of berm breakwaters has been provided.

Collinear Interaction of Waves and Current in the Presence of Ripple in the U-Tube

Ripple formation and evolution as well as vortex separation along the bedform profile strongly influence surface waves and sediment transport. These features were investigated in a U-Tube at the Hydraulics Laboratory of the University of Messina. During the experimental campaign, tests in the presence of wave only, current only, and collinear wave plus current in wave dominated regime were carried out. The experiments involved both live bed and fixed bed conditions. It was observed that, when the current superimposes to the wave, a longer time is required for the bedforms to stabilize; the vortex separating at the ripple crest reduces with respect to the wave only case. Accordingly, in the fixed rippled bed case, velocity measured in current only condition is larger than that in the wave plus current flow. As vortex shedding influences the way sediments are transported close to the bed, the obtained results may improve the present knowledge on wave current interaction in the presence of bedforms with repercussions in turn on sediment dynamics.

Влияние наклона волноотражающего козырька на высоту защитной стенки резервуара типа «стакан в стакане»

PURPOSE. The article presents the results of experimental studies analysis on the influence of horizontal and inclined wave-reflecting visors proposed for installation on the protective wall of glass-in-glass tank type for reducing its height to or below the maximum possible level of liquid in the main tank. METHODS. In the process of the research work methods of similarity theory and hydraulic laboratory modeling, physical experiment, observation, comparison, finding empirical dependence based on mathematical processing of experimental data, description and generalization have been used. FINDINGS. It has been found that fitting a horizontal or inclined wave-reflecting visor on the protective wall of a “glass-in-glass” type tank is an effective method of reducing its height. At the same time, the best results are shown by a wave-reflecting visor at an angle of 135° to the protective wall which allows, in the interwalled distance ranged from 1.8 to 3 m given the length of its handling radius reducing the height of the protective wall to 85 % of the maximum possible level of liquid in the main tank. RESEARCH APPLICATION FIELD. The proposed method of reducing the height of the protective wall, design schemes and empirical dependencies can serve as the foundation for the development of a regulatory document on ensuring fire safety of “glass-in-glass” type tanks, as well as be used by design organizations to find optimal solutions for the design and placement of typical tanks with a nominal volume of 700 to 30.000 m3. CONCLUSIONS. The proposed design solution will allow designing and operating “glass-in-glass” type tanks, ensuring the required level of fire, industrial and environmental safety provided compliance with the requirements for stability of the protective wall and wave-reflecting visor to the effect liquid flow and collapsing structures in case of the accident of the main tank. At the same time, the application of an additional barrier is not required, since all liquid in case of possible destruction of the main tank will be held by the proposed structure of the protective wall with a wave-reflecting visor.

Response to the HL - 69 soil resistive moisture sensor in different substrates

The objective of this work was to evaluate the response of the soil moisture resistive sensor HL-69 to different substrates. The study was split into two experiments. These were conducted at the Hydraulics and Irrigation Laboratory of the Agricultural Engineering Department of the Federal University of Ceará. Forty polyethylene vases with a capacity of 1030 mL were used, arranged on a benchwork. The treatments corresponding to the substrates were T1 (soil + commercial substrate (1: 1)); T2 (soil + hydro-retainer (2 g kg-1); T3 (soil) and T4 (commercial substrate), with ten replicates per treatment. The readings of the Hl-69 sensors were carried out simultaneously with the weighing of the vases on an analytical scale. According to the most promising response, the second experiment was started with the adoption of the T3 treatment. The readings carried out in this work followed two different methodologies: Firstly, readings of the saturation condition until low moisture (wet-dry) were obtained, and later they were obtained from the low moisture point to saturation (dry-wet). The Hl-69 sensor shows poor performance in determining the water content in the adopted substrates, showing better performance for the T3 treatment. The methodology that obtained the best adjustment of the data was the soil readings in the wetting process (dry-wet).

Desain Layout Laboratorium Pneumatik Hidrolik Berbasis Line Produksi Untuk Meningkatkan Skill Otomasi di Era Industri 4.0

The laboratory is a means of student learning in improving competence. Competence is one of the important elements in determining the quality of human resources, especially in facing challenges in the era of the industrial revolution 4.0 which relies entirely on technology and speed. This study aims to design a production line-based Pneumatic Hydraulic Laboratory to improve the automation skills of students majoring in mechanical engineering in the industrial era 4.0. The method in this study uses descriptive quantitative research. Collecting data through observation, design, pretest and posttest. The analysis uses descriptive statistics to describe the results of improving student skills. Based on the results of the study, it can be concluded that a production line-based laboratory layout design is indispensable in the era of the industrial revolution 4.0. The planned production design in the study is an automation system for drilling, pressing, conveyor, pick and place robots with PLC and HMI, the application of layout design can increase the average value of automation knowledge and skills (programming and automation simulation). The increase in the average value of knowledge is 22.72%. Meanwhile, the increase in automation competence was 29.23%.

Recharge mechanism and salinization processes in coastal aquifers in Nam Dinh province, Vietnam

In Nam Dinh province, in the Red River delta plain in Northern Vietnam, groundwater in the shallow Holocene aquifer shows elevated total dissolved solids up to 35 km from the coastline, indicating a saltwater intrusion from the Gulf of Tonkin. High groundwater salinities have been encountered below and adjacent to the Red River in the deep Pleistocene aquifer. Since 1996, large-scale groundwater abstraction was initiated from the deep aquifer, and the observed elevated salinities now raise concerns about whether the groundwater abstraction is undertaken sustainably. We have conducted a study to obtain a fundamental understanding of the recharge mechanisms and salinization processes in the Nam Dinh province. A holistic approach with multiple methods including transient electromagnetic sounding and borehole logging, exploratory drilling, sampling and analyzing primary ion and stable isotope compositions of water and pore water, groundwater head monitoring, hydraulic experiments laboratory of clay layers, and groundwater modeling by using the SEAWAT code. Results reveal that saline river water is leached from the Red River and its distributaries into the shallow aquifers. The distribution and occurrence of salty pore water in the Holocene aquitard clay shows that meteoric water has not been flowing through these low permeable clay layers. Marine pore water has, however, been leached out of the Pleistocene clay. When this layer is present, it offers protection of the lower aquifer against high salinity water from above. Salinity as high as 80 % of oceanic water is observed in interstitial pore water of the transgressive Holocene clay. Saltwater is transported into the Pleistocene aquifer, where the Holocene clay is directly overlying the aquifer.

Наклонный волноотражающий козырёк для снижения высоты защитной стенки резервуара типа "стакан в стакане"

Introduction. The prospects for the construction of tanks with a protective wall of the "glass in a glass" type are due to the possibility of their use with increased safety requirements, in particular, when designing near residential areas or water areas. However, previous studies on the retention of fluid flow by a protective wall during the destruction of the internal reservoir have shown that in order to completely retain it, the wall height must be at least 10 % higher than the original liquid level in this tank. It is obvious that the construction of such high protective walls is economically impractical, while conditions can be created for the formation of zones of explosive concentrations both in its inter-wall space and behind the protective wall. In this regard, studies on an effective way to reduce the height by protecting the wall at the maximum level of filling the internal tank with a flammable liquid are relevant. In particular, it is proposed to consider the possibility of arranging on the protective wall an inclined wave-reflective visor facing the wall of the main tank. Goals and objectives. Experimentally prove the possibility of reducing the height of the protective wall of tanks with a protective wall of the "glass in a glass" type by arranging inclined wave-reflective visor on it. Obtain an empirical formula for finding the minimum height of the protective wall depending on the geometric parameters of the main tank, the interwall distance and the outbound length of the wave-reflecting visor. Methods. In the process of research, the methods of similarity theory and hydraulic laboratory modeling, physical experiment, observation, comparison, finding an empirical dependence based on mathematical processing of experimental data, description, generalization were used. Results and their discussion. It has been experimentally proven that the arrangement on the protective wall of inclined wave-reflective visor is an effective method aimed at reducing the height of the protective wall to or below the maximum level of flammable liquid in the main tank. An empirical dependence is obtained to find the optimal ratio between the outbound length of the wave-reflective visor and the inter-wall distance for the main tanks with a protective wall of the "glass in a glass" type, the nominal volume from 700 to 30000 m3. Conclusion. The proposed method of reducing the height of the protective wall and empirical dependence can be the basis for the development of the relevant provisions of the regulatory document on ensuring fire safety of tanks with a protective wall of the "glass in a glass" type, as well as used by design organizations to find optimal solutions for the design and placement of the types of tanks in question at production facilities. Keywords: "glass in a glass" tank, destruction, protective wall, inclined wave-reflective visor, laboratory modeling.

Горизонтальный волноотражающий козырек для снижения высоты защитной стенки резервуара типа «стакан в стакане»

Purpose. The article states the possibility of lowering the protective wall of the “glass-in-glass” tank type thanks to fitting out a horizontal wave-reflecting visor facing the main tank wall. The empirical formula obtained on the basis of the processed experimental data for determining the optimal height of the protective wall depending on the geometrical dimensions of the main tank, interwall distance and length of the wavereflecting visor departure is presented. ABSTRACT Methods. In the process of the research work methods of similarity theory and hydraulic laboratory modeling, physical experiment, observation, comparison, finding empirical dependence based on mathematical processing of experimental data, description and generalization have been used. Findings. It has been found that fitting out a horizontal wave-reflecting visor on the protective wall of a “glass-in-glass” tank type is an effective method aimed at lowering the protective wall height to or below the maximum level of combustible liquid in the main tank. The empirical dependence has been obtained for finding the optimal ratio between the wavelength of the wavereflecting visor and the interwall distance for main tanks with the nominal volume from 700 to 30 000 m3. Research application field. The proposed method of lowering the height of the protective wall and empirical dependence can serve as a background for developing the relevant conditions of the regulatory document on ensuring fire safety of “glass-inglass” tanks type, and it can also be used by engineering companies to find optimal solutions for designing and locating the considered types of tanks. Conclusions. The proposed design solution will allow designing and operating “glass-in-glass” tanks type, providing the standard level of fire safety under observance of compliance with the requirements for stability of protective wall and wavereflecting visor to the hydrodynamic effect of liquid flow and dynamic impact of collapsing structures of the main tank in case of on accident. As an upcoming trend of the research, the fitting of the wave-reflecting visor of an inclined shape on the protective wall in relation to the wall of the main tank can be considered.

Study on Array Floating Platform for Wind Energy and Marine Space Optimization

The concept of multiline anchor, whose application is mainly considered in water depths beyond 100 m and analyzed only by numerical simulation, has been discussed for half a decade, yet previous studies have not conducted the wave basin experiment. Thus, this paper set this concept firstly with a shallow water mooring system designed for a Taiwan offshore water area, where the suitable water depth for floating offshore wind turbine is located from 50 to 100 m, and then conducted a 1:144 scaled model wave basin experiment to validate the results from numerical simulation. In this paper, the numerical model simulated and analyzed three identical DeepCwind OC4 semi-submersible platforms equipped with NREL 5MW wind turbines in OrcaFlex and the experiment carried out by using three 1:144 scaled semi-submersible platforms with equivalent disks which simulated different operations of wind thrusts. To consider the possible influence of the wake effect, the minimum turbines spacing was set at 750 m in a full scaled model and the length of mooring lines was redesigned according to the catenary theory. This paper utilized OrcaWave to calculate hydrodynamic parameters and input it into OrcaFlex to simulate the line tension and the three degrees of freedom (surge, heave, and pitch) of the platforms under regular and irregular wave tests, and coordinate with scaled model tests carried out in Tainan Hydraulics Laboratory (THL). In addition to the reduction in the number of anchors, the concept of multiline anchor was also discussed in this study for the spatial configuration of offshore wind farms. It shows that the wind farm composed of three floating wind turbines can reduce the ocean space by roughly 24% compared to that with a single-line anchor. According to the comparison of numerical and experimental results, this study finally optimized the mooring lines by changing the diameter to increase the stability and the threshold of Minimum Breaking Load (MBL) and proposed a multiline anchor configuration for shallow offshore water area in Taiwan based on the results obtained.

LOADING RESPONSE OF STERN TAB MOTION CONTROLS IN SHALLOW WATER

The ride control systems of high-speed vessels frequently use active stern tabs for both motion control and maintenance of correct trim at various speeds and sea conditions. This paper investigates the effect of water depth on the lift force provided by stern mounted trim tabs, of the type fitted to INCAT high speed wave-piercer catamaran vehicle ferries and similar vessels. This investigation was carried out at model scale with the use of a test apparatus in a flume tank in the University of Tasmania hydraulics laboratory. The lift force magnitude and location were measured over a range of tab angles and flow depths. This was used to calculate the lift coefficient of the tab and asses the performance of the tab over the range of flow depths. It was found that the lift force increased and the force location progressed further forward of the hinge as flow depth decreased. The lift curve slope of the stern tab increased by a factor of over 3 relative to the deep water value when the water depth below the hull was approximately equal to the tab chord. The deep water lift curve slope appears to be approached only when the water depth exceeded 4 or more tab chord lengths. The centre of pressure of the lift force was more than two chord lengths ahead of the tab hinge, showing that most of the lift produced by the tab was under the hull rather than on the surface of the tab itself.

PRESSURE DISTRIBUTION DUE TO STERN TAB DEFLECTION AT MODEL SCALE

Trim tabs form an important part of motion control systems on high-speed watercraft. By altering the pitch angle, significant improvements in propulsion efficiency can be achieved by reducing overall resistance. For a ship in heavy seas, trim tabs can also be used to reduce structural loads by changing the vessel orientation in response to encountered waves. In this study, trials have been conducted in the University of Tasmania hydraulics laboratory using a closed- circuit water tunnel to measure model scale trim tab forces. The model scale system replicates the stern tabs on the full- scale INCAT Tasmania 112 m high-speed wave-piercer catamaran. The model was designed for total lift force measurement and pressure tappings allowed for pressures to be measured at fixed locations on the underside of the hull and tab. This investigation examines the pressures at various flow velocities and tab deflection angles for the case of horizontal vessel trim. A simplified two-dimensional CFD model of the hull and tab has also been analysed using ANSYS CFX software. The results of model tests and CFD indicate that the maximum pressure occurs in the vicinity of the tab hinge and that the pressure distribution is long-tailed in the direction forward of the hinge. This accounts for the location of the resultant lift force, which is found to act forward of the tab hinge.

MEASURED LOADING RESPONSE OF MODEL MOTION CONTROL STERN TABS


 
 
 Active trim tabs are commonly used as part of the ride control systems of high-speed craft. This paper investigates the lift characteristics of rectangular stern tabs that are commonly fitted to INCAT wave-piercer catamarans. A test apparatus was developed to enable the testing of a model scale trim tab in a circulating water tunnel in the University of Tasmania hydraulics laboratory. The magnitude and location of the lift force produced by the tab were measured over a range of tab angles and flow velocities. From this the lift coefficient of the tab was calculated and the performance of the tab under varying conditions was analysed. The lift force produced by the tab was shown to increase with velocity and tab angle as expected, with the lift coefficient of the tab increasing linearly with tab angle and remaining relatively constant with increases in flow velocity. The magnitude of the measured lift coefficient was lower than had been previously estimated in shallow water tests and the force was found to act forward of the tab hinge, indicating that much of the lift force generated by the tab is due to the increased pressure on the underside of the hull forward of the tab.
 
 

Assessment of the effect of shapes of a shaft intake structure using the PIV method

The construction of shaft intake structures in Slovakia has increased. The shaft intake structures overcome significant vertical height over short horizontal distance. In their front horizontal section, the water flows with free surface, then in the vertical section the flow changes its direction and character to a pressurized flow. The flow of water in these shaft intake structures is therefore very complicated. A hydraulically suitable design of the intake structure is associated with achieving the required parameters of the small hydropower plant (SHPP), but due to the reduction of project costs, the shapes of shaft intake structures of SHPP are often not correctly hydraulically designed. One of the important aspects is the distribution of flow velocity of these intake structures. Uneven distribution of flow velocity causes negative effects on turbine performance. Therefore, the investigation of the effects of shaft intake structure design on flow velocity distribution has been realized. The velocity field at a shaft intake of a small hydropower plant was investigated on a physical model in a hydraulic laboratory using the PIV (Particle Image Velocimetry) method. The PIV measurements were realized for different shaft heights and proved negative effects of the design on the flow homogeneity in the turbine intake.

Flow Behavior of Boyong River as Revealed by Long-term Hydro-monitoring System

Boyong River is one of many rivers originating from Mt. Merapi, flows across three autonomy administrative of Sleman Regency, Yogyakarta City, and Bantul Regency. The river experiences flood in the form of lava flow several times, and the 1994 and 2010 occurrences were considered the biggest ones along with the river history. In line with the rapid development of information and communication technology, efforts to develop the early warning system due to the Mt. Merapi disaster have been implemented by the Hydraulic Laboratory of Gadjah Mada University 2006. This paper presents the study results of Boyong River flow behavior by analyzing the data obtained from the monitoring system. The Gemawang Weir at Boyong River was selected as the river control point understudy; those include the catchment boundary, the catchment characteristics, and the hydraulic features. Monitoring equipment consists of an automatic water level recorder (AWLR), the flow visualization using a Brinno camera, and the hydrophone monitoring system. The flow hydrograph characteristics and its corresponding sediment transport rate are considered two parameters for identifying the flow behavior. The results show that the precursive and recession times of the flood hydrograph are about 1-3 hours and 3.5-5 hours, respectively.