Hydro Science & Marine Engineering
EISSN : 2661-331X
Current Publisher: Bilingual Publishing Co. (10.30564)
Total articles ≅ 20
Latest articles in this journal
Hydro Science & Marine Engineering, Volume 3; doi:10.30564/hsme.v3i1.2795
This study examined impact of climate variability on reservoir-based hydro-power-generation in Jebba dam, Niger State of Nigeria. Data of rainfall, temperature, evaporation, reservoir inflow and outflow and power output for thirty-one years were obtained from Jebba Hydropower Station [JHP]. The Man-Kendall and Pearson’s Product Moment Correlation Coefficient (PPMCC) were used to establish the influence of weather parameters on the reservoir inflow and outflow. Findings showed increased electricity generation during dry season than wet season. The highest annual mean amount of the electricity generated was in 2016 having mean of 689.12mwh, dry season (352.26mwh) and wet season (336.86mwh). Reservoir inflow showed negative trend with severe fluctuations in 1998 (1436.42M3/Sec), 1999 (1581.08M3/Sec) and 2010 (1641.08M3/Sec) with steady increase in 2016 (1556.0042M3/Sec), 2017 (1556.4242M3/Sec) and 2018 (1635.7542M3/Sec). The reservoir outflow pattern showed tremendous and negative trend in fluctuation with increase in 1998 (1421.75M3/Sec) 1999 (1581.58M3/Sec) and 2010 (1641.16M3/Sec) and a steady increase in 2016 (1535.00M3/Sec), 2017 1558.83M3/Sec and 2018 (1632.00M3/Sec). Thus, rainfall and reservoir inflow had strong relationships with the amount of power generated than temperature and evaporation. Therefore, the government should increase the water carrying capacity of the reservoir construction by storing water to be used during dry periods.
Hydro Science & Marine Engineering, Volume 2; doi:10.30564/hsme.v2i2.2412
This paper presents a review on previous activities of mining on water resources of Ebonyi State, SE, Nigeria. As high demand for water increases due to population growth and rapid development across the state has made it necessary to monitor water resources within the study area. However, less information is available on evaluation of impact on mining activities on water resources. For the purpose of this research, related articles were downloaded from Google, published article on effect of mining on water resources was download and thoroughly studied to evaluate effect of mining on water resources of the study area. Results obtained from findings revealed that mining activities that was carried out in the past has negatively affected the geochemistry of water resources and caused acid mine drain within the study area.
Hydro Science & Marine Engineering, Volume 2; doi:10.30564/hsme.v2i2.2266
Declines in wind speed (u) (termed as “stilling”) has been reported in many regions of the world. To explore the temporal trends of u and its aerodynamics effects is vital to understand the changes in water resources. This study analyzed the changes of temporal trends for u and its aerodynamic effects using the data during 1959-2000 at 266 stations across China. The improved PanPen model was used to estimate Epan and quantify the contribution of radiative and aerodynamic components (aerodynamic component separated into wind speed u, vapour pressure deficit D, and air temperature Ta). Climate factors include Epan measured with the standard Chinese 20 cm diameter pan, u, Ta, relative humidity (rh) and sunshine hours (sh). The results showed: stilling occurred in most of stations (206 among 266) and 105 stations presented significant decreasing trends at 99% confidence level; stilling was the main cause for controlling the trends in Epan in most part of China, especially in the west and north of China. The results indicated that decreasing trends in Epan due to stilling would inevitably alter water resources, and should be put further investigation incorporation other factors.
Hydro Science & Marine Engineering, Volume 2; doi:10.30564/hsme.v2i2.1691
As a key supporting equipment for the construction of LNG carriers, the installation platform undertakes the support and guarantee of LNG carrier tank internal construction. This paper takes the secondary shielding installation platform of A-type tank as the object of study, the study firstly considers the semi-rigidity of the nodes and the material nonlinearity based on finite element software, and then the residual structure is calculated using static nonlinear method after single truss, two trusses and three trusses are invalid simultaneously. The research results show that the truss with higher components importance coefficient has greater impact on the residual structure when the truss is invalid; After the 2 trusses of installation platform become invalid completely, the further progressive collapse will not occur; When A1-HJ, A2-HJ and A2-HJ are dismantled at the same time, it will lead to the local progressive damage, which can cause the collapse of large-scale structures. The research findings can support the design and use of the installation platform.
Hydro Science & Marine Engineering, Volume 2; doi:10.30564/hsme.v2i2.2341
In the present study, the flow over the stepped spillway was numerically investigated by using Flow3D model. The effect of step angle on different properties of Nappe flow regime such as the water surface profile, location of free-surface aeration inception, Froude number at the spillway’s toe, and pressure, flow velocity, air concentration and cavitation index were evaluated. The realizable k–ε was applied as the turbulence model, and Volume of Fluid (VOF) model was used to determine the free surface flow profiles of the spillway. The model was verified using experimental data. In order to investigate the different characteristics of Nappe flow regime, 17 numerical runs was designed, in which, four step angles, four flow discharge were considered to investigate the flow characteristics over the stepped spillway. The results indicated that the numerical model is well suited with the experimental data over the stepped spillway (RMSE = 0.147 and ARE = 6.9%). In addition, with increasing the step angles, the aeration inception point is generally moved downstream. By increasing the step angles from zero to 10 degrees, the Froude number does not change significantly, however, at the angle of 15 degrees, the Froude number decreases by about 42 percent.
Hydro Science & Marine Engineering, Volume 2; doi:10.30564/hsme.v2i2.2448
This study investigated coal-mine drainage (AMD) and municipal wastewater (MWW) contaminant concentrations and conducted the combined treatment in phases I and II: phase I, evaluating effects of mixing the two based on extent of acid neutralization and metals removal; phase II: conducting anaerobic batch reactor treatment of AMD and MWW under varying COD/sulfate ratios (0.04-5.0). In phase I, acid mine drainage water quality conditions are as follows: pH 4.5, acidity 467.5 mg/L as CaCO3, alkalinity 96.0 mg/L as CaCO3, Cl- 11.8 mg/L, SO42- 1722 mg/L, TDS 2757.5 mg/L, TSS 9.8 mg/L, BOD 14.7 mg/L, Fe 138.1 mg/L, Mg 110.8 mg/L. Mn 7.5 mg/L, Al 8.1 mg/L, Na 114.2 mg/L, and Ca 233.5 mg/L. Results of the mixing experiments indicated significant removal of selected metals (Fe 85~98%, Mg 0~65%, Mn 63~89%, Al 98~99%, Na 0~30%), acidity (77~95%) from the mine water and pH was raised to above 6.3. The Phase II results suggested under the wide range of COD/sulfate ratios, COD and sulfate removal varied from 37.4%-100% and 0%-93.5% respectively. During biological treatment, alkalinity was generated which leads to pH increase to around 7.6-8.5. The results suggested feasibility of the proposed technology for co-treatment of AMD and MWW. A conceptual design of co-treatment system which is expected to remove a matrix of pollutants has been provided to utilize all the locally available water resources to achieve the optimum treatment efficiency. The technology also offers an opportunity to significantly reduce capital and operating costs compared to the existing treatment methodologies used.
Hydro Science & Marine Engineering, Volume 2; doi:10.30564/hsme.v2i1.1579
Pre-stressed structure and its application for civil engineering. Specificity of external loads of ships. Corresponded specificity of controllable pre-stressing. An example of pre-stressed structure and an decreasing estimation of its mass (about 10% of the full displacement). Possibility of wider application.
Hydro Science & Marine Engineering, Volume 2; doi:10.30564/hsme.v2i1.1504
Vortex-induced vibration (VIV) of multiple circular cylinders elastically connected together in a side-by-side arrangement subject to steady flow is investigated numerically at a low Reynolds number of 150 and a mass ratio of 2. Simulations are conducted for two-, five- and ten-cylinder systems over a wide range of reduced velocities. The aim of the study is to identify the high-amplitude response range of the reduced velocity for the multiple degree of freedom vibration system and identify the difference between the responses of the single- and multiple-degree-of-freedom vibrations. Unlike the single cylinder case, distinct lock-in between the response frequency and any of the structural natural frequencies in a wide range of reduced velocity is not observed in the multiple-cylinder cases. Instead, the response frequency increases continuously with increasing reduced velocity. High response amplitudes are found when the response frequency is between the first and the highest modal frequencies. In a multiple-cylinder system, the single-mode response, where the vibration is dominated by one mode, can be only found in low reduced velocity range. In the single-mode branch, the dominance of a single mode shape in the response can be clearly identified except at the boundary reduced velocity between two modes. The maximum response amplitude occurs in the multiple-mode response and interaction between the vortices in the wake of the cylinders is strong when the response amplitudes are high.
Hydro Science & Marine Engineering, Volume 2; doi:10.30564/hsme.v2i1.1598
A three dimensional model to predict the hydro-mechanical state of unsaturated and deformable material during hot air drying has been proposed. The material viscoelastic behaviour was formulated using Bishop’s effective stress theory for partially saturated material using the liquid saturation as the Bishop parameter. The hydro-thermal and mechanical equations were coupled by the fluid pressure and the solid matter velocity. The model was applied to a deformable material (innovative clay-cellulose fibers composite) subjected to convective drying. A generalized Maxwell model with five elements, whose parameters were measured experimentally and correlated to water content was used to describe the material’s viscoelastic behavior. The hydro-thermal part of the proposed model was validated on the basis of a comparison of experimental and simulated drying rate curves. The Von Mises stress was simulated and compared to the experimental tensile strength in order to predict the time and the region of material failure. For a drying process at95°C, the region of failure risk was identified. The failure may occur on the lateral surface of the slab in contact with air at a drying time of 2.5h.
Hydro Science & Marine Engineering, Volume 2; doi:10.30564/hsme.v2i1.1690
The independent LNG (Liquified Nature Gas) containment is widely used for small or medium-sized LNG carrier and ship using LNG as fuels. The common tank pattern includes single-spherical-cylindrical tank and double-spherical-cylindrical tank, which is the key to design the hull structure and its support. The support is designed to connect the hull structure and LNG tank. Its main functions are heat transferring and force loading. This paper focus on the temperature field distribution of hull and its support structure. The thermal boundary conditions are simulated according to the heat transfer action, such as thermal convection, heat conduction and thermal radiation. The method on how to carry out thermal analysis is presented for an independent LNG containment. The case study is carried out with two typical independent LNG tanks. One is a tank with double spherical cylindrical in the LNG carrier, and the other is a tank with single spherical cylindrical on the deck of the ship using LNG as fuels. The result shows the method presented in this paper is a good reference for the structural design with independent LNG containment.