Analysis of Risks Associated With Water Pipes in Rapid Flow Waterways Through Waterway Modeling Experiments

In this study, waterway modeling experiments were conducted by incorporating the information obtained by analyzing accident sites to prevent frequent accidents of firefighters that occur during water rescue operations conducted near water pipes in rapid flow waterways. Based on the conducted experiments, it was observed that the flow velocity increased with decreasing distance from the water pipe. Furthermore, the maximum flow velocity was found to be 3.99 times higher at the posterior end than at the anterior end of the water pipe, and the flow velocity was found to be higher at the lower side than at the upper side of the water pipe’s anterior end. The maximum flow velocity was measured to be 1.65 m/s at a distance of 10 cm from the entrance to the pipe, 2.63 m/s at a distance of 5 cm from the entrance to the pipe, 7.12 m/s within the pipe, and 5.33 m/s at a distance of 5 cm from the pipe’s exit. The average flow velocity was measured to be 0.94 m/s at a distance of 10 cm from the entrance to the pipe, 5.53 m/s within the pipe, and 4.64 m/s at a distance of 5 cm from the pipe’s exit. Furthermore, in this study, relevant standard operating procedures and regulations were taken into consideration. Based on the results obtained from this study, recommendations and guidelines were then accordingly devised for preventing accidents of firefighters that occur during water rescue operations.

Optimized Vegetation Density to Dissipate Energy of Flood Flow in Open Canals

Vegetation along the river increases the roughness and reduces the average flow velocity, reduces flow energy, and changes the flow velocity profile in the cross section of the river. Many canals and rivers in nature are covered with vegetation during the floods. Canal’s roughness is strongly affected by plants and therefore it has a great effect on flow resistance during flood. Roughness resistance against the flow due to the plants depends on the flow conditions and plant, so the model should simulate the current velocity by considering the effects of velocity, depth of flow, and type of vegetation along the canal. Total of 48 models have been simulated to investigate the effect of roughness in the canal. The results indicated that, by enhancing the velocity, the effect of vegetation in decreasing the bed velocity is negligible, while when the current has lower speed, the effect of vegetation on decreasing the bed velocity is obviously considerable.

Enhancing Turbine Deposition Prediction Capability With Conjugate Mesh Morphing

A framework for performing mesh morphing in a conjugate simulation in the commercial Computational Fluid Dynamics (CFD) software ANSYS Fluent is presented and validated. A procedure for morphing both the fluid and solid domains to simulate the protrusion of deposit into the fluid while concurrently altering and adding to the solid regions is detailed. The ability to delineate between the original metal sections of the solid and the morphed regions which represent deposit characteristics is demonstrated. The validity and predictive capability of the process is tested through simulation of a canonical impingement jet. A single over-sized impingement jet (6.35 mm) at 894 K and an average flow velocity of 56.5 m/s is used to heat a nickel-alloy target plate. One gram of 0-5 μm Arizona Road Dust (ARD) is delivered to the target and a Particle Shadow Velocimetry (PSV) technique is used to capture the transient growth of the deposit structure on the target. Thermal infrared images are taken on the backside of the target and synchronized with the PSV images. The experiment is modeled computationally using the Fluent Discrete Phase Model (DPM) and the Ohio State University (OSU) Deposition Model for sticking prediction. The target is morphed according to the particulate volume prediction. The deposit regions are assigned an effective conductivity (keff) representative of porous deposit, and the fluid and thermal computations are reconverged. 10 mesh morphing iterations are performed accounting for the first half of the experiment. The morphed deposit volume and height are compared to the experiment and show reasonable agreement. The backside target temperatures are also compared, and the simulations show the ability to predict the reduction in temperature that occurs as the growing deposit insulates the metal surface. It is demonstrated that the assignment of unique thermal conductivities to the deposit and metal cells within the solid is critical. With a more robust and accurate implementation of the deposit keff, this conjugate mesh morphing framework shows potential as a tool for predicting the thermal impact of deposition.

In Situ Underwater Average Flow Velocity Estimation Using a Low-cost Video Velocimeter

The development of a low-cost Video Velocimeter (VIV) to estimate underwater bulk flow velocity is described. The instrument utilizes a simplified particle image correlation technique to reconstruct an average flow velocity vector from video recordings of ambient particles. The VIV uses a single camera with a set of mirrors that splits the view into two stereoscopic views, allowing estimation of the flow velocity vector. The VIV was validated in a controlled flume using ambient seawater, and subsequently field tested together with an acoustic Doppler velocimeter with both mounted close to the coastal seafloor. When used in non-turbulent flow, the instrument can estimate mean flow velocity parallel to the front face of the instrument with root-mean-squared errors of the main flow within 10% of the ±20 cm/s measurement range when compared to an ADV. The predominant feature of the VIV is that it is a cost-effective method to estimate flow velocity in complex benthic habitats where velocity parallel to the sea floor is of interest.

Research on Vibrating L-Box Test and Yield Value of Low Water-Cement Ratio Concrete

The rheological properties of concrete have a great impact on the workability, and the L-box test can obtain the relationship between the morphology and the yield value of the material under free flow conditions. However, as an elastoplastic fluid, the low water-cement ratio concrete can hardly flow freely without the admixture. The vibrating process is often used in the production to meet the requirements, but the rheological properties of the material under vibration are difficult to measure. A new vibration test method for the flowability of low water-cement ratio concrete is proposed in combination with the L-box idea. The flow morphology and flow velocity of two kind of low water-cement ratio concrete in the L-box are observed under the condition of controlling the vibration frequency. After that, theoretically analyzing the yield value of the material under vibration is applied. The results show that with the increase of vibration frequency, the average flow velocity of the material increases, but the trend is gradually slower. With the increase of vibration frequency, the yield value of low water-cement ratio concrete is much lower than before. This test method can be used in related engineering applications of vibrating compacted concrete.

JUSTIFICATION OF THE EFFECTIVENESS OF THE PROLETARIAN MAIN CANAL DURING RECONSTRUCTION

Calculations of the main parameters of the Proletarsky main canal for a polygonal section during its reconstruction for various options are presented. A method for hydraulic calculation of the Proletarsky main canal has been carried out. The developed method of the hydraulic calculation is based on the determination of the coefficient of reduction of the polygonal shape of the section to the trapezoidal one according to the formula of A.A. Uginchus. Then the cross-sectional area of each element is found after reduction to a trapezoidal section, the wetted perimeters, hydraulic radius and Shezi coefficient of each section element are calculated. For the earthen channel of the canal, the obtained hydraulic characteristics closely matched the design data for the fl ow rate and average current velocity. The earthen channel of the canal with an ice cover has a significant decrease in hydraulic parameters from the design section, both in terms of flow rate up to 36.0 m3/s (or by 33%) and in terms of the average flow velocity up to 0.410 m/s. The widened asymmetrical earthen channel is characterized by an increased discharge up to 57.47 m3/s, an effective cross-section of 101 m2 and a wetted perimeter of 42.0 m in comparison with the design section. For the channel of the canal section with a protective strengthening made of a rock fill and gravel-pebble coating, reduced characteristics were obtained both in terms of flow rates and average flow rates which is due to their high value of roughness coefficients. At the same time, it was found that a decrease in the roughness coefficients of protective coatings during operation due to the colmatage of alluviums particles will lead to an increase in water consumption in the canal. However, the process of alluviums colmatage of the protective layer of stone material will be slow, for 10 years or more.

Investigation of ultrasonic flowmeter error in distorted flow using two-peak Salami functions

Results of investigating the additional error of ultrasonic flowmeters caused by the distortion of the flow are presented in the article. The location coordinates of acoustic paths were calculated for their number from 1 to 6 according to the different numerical integrating methods: Gauss (Gauss-Legendre, Gauss-Jacobi), Chebyshev (equidistant location of acoustic paths), Westinghouse method, method of OWICS (Optimal Weighted Integration for Circular Sections). This made it possible to realize the flowrate equation for multi-path ultrasonic flowmeters and to determine their additional error for different location of the acoustic paths. The average flow velocity along each path is calculated based on the flow velocity profile in the pipe cross section. Four two-peak Salami functions of velocity are used to calculate the velocity profile of the distorted flow caused by typical local resistances. According to the research results the recommendations were developed for choosing the number of the acoustic paths of the ultrasonic flowmeters and for using the methods for determining the location coordinates of the acoustic paths.

A new method to predict average flow velocity and conveyance capacity of meandering streams

This paper aims to be a contribution to the evaluation of the resistance factor of the alluvial meandering streams of natural origin. The well-known “divided resistance” approach, commonly adopted nowadays for straight streams with a bed covered by ripples and dunes is extended to include an additional term that considers the resistance due to the meandering of the stream. For the present analysis, 40 laboratory experiments and 285 field observations are evaluated, where it is found that the contribution of the meandering of the stream to its overall resistance may vary from negligible to very substantial, which depends on the stream geometric and flow conditions. In addition, it is determined that the most influential components for the resistance factor in meandering conditions depend on the relation between channel-averaged flow depth (hav) and the average grain size of the bed material (D50), the deflection angle of a meandering flow at the crossover Oi (θ0), and also the relation between flow width (B) and the channel-averaged flow depth (hav); these relations are used to develop a mathematical expression capable to predict the resistance to flow due to the meandering of the stream. It is shown that the equation introduced in this paper leads to considerably improved predictions of average flow velocity and conveyance capacity of meandering streams, which is of significance for an improved management of inland waterways.

The Cascade device – In vitro tests to assess coil protrusion into the parent vessel

Background Balloon and stent-assisted coiling of aneurysms have increased the number of aneurysms available for endovascular treatment. Newer devices that allow flow within the parent vessel but coverage at the neck have recently entered the market. The Cascade is a new non-occlusive fully retrievable neck-bridging support device that has been designed to provide temporary support during coil embolisation of intracranial aneurysms. Methods Using a silicone aneurysm model three different aneurysms were catheterised with the coiling microcatheter placed in three different positions within each aneurysm – at the neck, centrally, and looped within the aneurysm. Multiple different coils were then deployed within each aneurysm with the Cascade device deployed across the neck to provide protection. In total 480 attempted coilings were performed. Aneurysm flow was used to calculate the change in intra-aneurysmal flow with the Cascade device deployed across the neck of the aneurysm. Results We did not observe a single episode of coil protrusion through the Cascade mesh nor did we observe any coil protrusion into the parent vessel when the Cascade was deployed across the neck. There was an average flow velocity reduction of 23% with the Cascade device deployed across the neck of the aneurysm. Conclusion The Cascade device offers robust protection of the aneurysmal neck and parent vessel as well as inducing significant intra-aneurysmal flow velocity reduction.

Scour Depth Prediction for Asa Dam Bridge, Ilorin, Using Artificial Neural Network

Bridge Scour is the localized loss of the geomaterials around the foundation of a bridge as a result of the movement of water around it. Scour is a great risk to the stability of a bridge’s foundation, thus leading to collapse, loss of lives and setback in a nation’s socio-economic life. Artificial Neural Networks (ANN) are collections of simple, highly connected processing elements that learn according to sets of input parameters and use that to simulate the networks of nerve cells of humans or animal central nervous system. The Asa Dam Bridge, one of the longest bridges in Ilorin, Kwara State, Nigeria, has five (5) spans of 20m each. The bridge connects Ilorin to the Ogbomosho Express way (leading to the western part of the country) and the Eyenkorin-Jebba road (leading to the north). Thus, the bridge has a high economic value. In this research, factors such as flow depth, average flow velocity of the river and median sediment size were investigated to show how they affect the depth of scour around the bridge pile foundation. Data were taken for a period of 48 weeks and ANN was applied to predict and generate a model that shows how these factors relate to the scour depth of the riverbed. The model revealed that the hydraulic parameters and soil grading around the pile cap of Asa River Bridge bears significant influence on the scour depth of its foundation. The model was compared with five (5) other established scour equations.