scholarly journals Study on the Propagation Law of Water Hammer Wave in Underwater Blasting and the Reducing Effect of Air Curtain on Water Hammer Wave

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Chao Qi ◽  
Zuxiang Hu ◽  
Suihong Wang ◽  
Zhixiong Jiang ◽  
Haoyuan Wu ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Central Canal ◽  
Water Hammer ◽  
Inlet Section ◽  
Factors Affecting ◽  
Attenuation Law ◽  
Propagation Law ◽  
Reduction Effect ◽  
Water Depths ◽  
Bubble Curtain

The harmful effects (water hammer wave, flying stone, and broken quality of concrete) produced in the process of underwater drilling and blasting are the key factors affecting the safety of underwater drilling and blasting. In fact, the harm caused by the water hammer wave is the most significant. As a consequence, it is of great significance to study the propagation law of water hammer waves. Based on the background of the cofferdam demolition project at the inlet section of Shibishan Central Canal in Ningguo City, China, a three-dimensional numerical model was established based on Coupled Eulerian–Lagrangian (CEL) method. Besides, the propagation law of water hammer waves at different water depths with different millisecond times was studied. Meanwhile, the reduction effect of the water hammer wave at different positions of the bubble curtain was analyzed. The results showed that, in the direction of the minimum resistance line of the charge, the attenuation law of the water hammer wave is accorded with the Cole formula and attenuated exponentially. The attenuation speed of the water hammer wave increased at first and then decreased with the increase of the millisecond time. In addition, the attenuation rate of the peak pressure was the fastest when the millisecond interval 30 ms was used. The attenuation of the water hammer wave at different water depths decreased at first and then decreased with the increase of water depth. The attenuation law of the water hammer wave decreased linearly with the increase of the distance between the bubble curtain and the charge. The research results can provide particular guiding significance for similar on-site construction.

scholarly journals Three-Dimensional Navier–Stokes Analysis and Redesign of an Imbedded Bellmouth Nozzle in a Turbine Cascade Inlet Section

1996 ◽  
Vol 118 (3) ◽  
pp. 529-535 ◽  
Author(s):  
P. W. Giel ◽  
J. R. Sirbaugh ◽  
I. Lopez ◽  
G. J. Van Fossen
Keyword(s):  
Three Dimensional ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Inlet Section ◽  
Turbine Cascade ◽  
Blade Cascade ◽  
Inlet Geometry ◽  
Computational Fluid Dynamics Cfd ◽  
Transonic Turbine ◽  
Flow Nonuniformity

Experimental measurements in the inlet of a transonic turbine blade cascade showed unacceptable pitchwise flow nonuniformity. A three-dimensional, Navier–Stokes computational fluid dynamics (CFD) analysis of the imbedded bellmouth inlet in the facility was performed to identify and eliminate the source of the flow nonuniformity. The blockage and acceleration effects of the blades were accounted for by specifying a periodic static pressure exit condition interpolated from a separate three-dimensional Navier–Stokes CFD solution of flow around a single blade in an infinite cascade. Calculations of the original inlet geometry showed total pressure loss regions consistent in strength and location to experimental measurements. The results indicate that the distortions were caused by a pair of streamwise vortices that originated as a result of the interaction of the flow with the imbedded bellmouth. Computations were performed for an inlet geometry that eliminated the imbedded bellmouth by bridging the region between it and the upstream wall. This analysis indicated that eliminating the imbedded bellmouth nozzle also eliminates the pair of vortices, resulting in a flow with much greater pitchwise uniformity. Measurements taken with an installed redesigned inlet verify that the flow nonuniformity has indeed been eliminated.

Study on the critical loosening condition toward a new design guideline for bolted joints

2018 ◽  
Vol 233 (9) ◽  
pp. 3302-3316 ◽  
Author(s):  
Hao Gong ◽  
Jianhua Liu ◽  
Xiaoyu Ding
Keyword(s):  
Three Dimensional ◽  
Element Model ◽  
Simulation Method ◽  
Bolted Joints ◽  
Design Guideline ◽  
Factors Affecting ◽  
Dimensional Finite Element ◽  
Frictional Coefficients ◽  
Three Dimensional Finite Element ◽  
Fit Tolerance

An understanding of conditions that trigger the loosening of bolted joints is essential to ensure joint reliability. In this study, a three-dimensional finite element model of a typical bolted joint is developed, and a new simulation method is proposed to quantitatively identify the critical transverse force for initiating loosening. This force is used to evaluate the anti-loosening capacity of bolted joints. Using the proposed simulation method, the effects of factors affecting critical loosening are systematically studied. It is found that the preload, frictional coefficients at the thread and the bearing surfaces, clamped length, and fit tolerance mainly affected loosening. When the preload and friction coefficients are increased, and the clamped length and fit tolerance are reduced, loosening is inhibited. Experiments are performed to demonstrate the reliability of the results. Finally, a suggestion is proposed to improve the design guideline VDI 2230 for bolted joints, which considers the requirement of avoiding loosening under vibrational loading.

Factors Affecting Measured Axial Compressor Tip Clearance Vortex Circulation

1995 ◽  
Vol 117 (3) ◽  
pp. 487-490 ◽  
Author(s):  
S. A. Khalid
Keyword(s):  
Viscous Flow ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Tip Clearance ◽  
Radial Transport ◽  
Factors Affecting ◽  
Blade Tip ◽  
Tip Clearance Vortex ◽  
The Relationship ◽  
Principal Contributor

The relationship between turbomachinery blade circulation and tip clearance vortex circulation measured experimentally is examined using three-dimensional viscous flow computations. It is shown that the clearance vortex circulation one would measure is dependent on the placement of the fluid contour around which the circulation measurement is taken. Radial transport of vorticity results in the magnitude of the measured clearance vortex circulation generally being less than the blade circulation. For compressors, radial transport of vorticity shed from the blade tip in proximity to the endwall is the principal contributor to the discrepancy between the measured vortex circulation and blade circulation. Further, diffusion of vorticity shed at the blade tip toward the endwall makes it impossible in most practical cases to construct a fluid contour around the vortex that encloses all, and only, the vorticity shed from the blade tip. One should thus not expect agreement between measured tip clearance vortex circulation and circulation around the blade.

scholarly journals Performance characteristics of a small water-hammer head pump

2019 ◽  
Vol 12 (2) ◽  
pp. 59-64
Author(s):  
Krishpersad Manohar ◽  
Anthony Ademola Adeyanju ◽  
Kureem Vialva
Keyword(s):  
Water Hammer ◽  
Maximum Height ◽  
Pump Efficiency ◽  
Inlet Section ◽  
Flowing Fluid ◽  
Test Configuration ◽  
Small Water ◽  
External Power Source ◽  
Hammer Head ◽  
Head Height

Abstract. Many rural farming areas are located far from a reliable electricity supply; hence, obtaining a reliable source of water for crops and livestock can prove to be an expensive venture. A water pump operating on the water-hammer effect requires no external power source and can serve as an effective means of pumping water to a higher altitude once a reliable supply is available. A low-cost small water-hammer head pump was designed to operate on the water-hammer head effect created by the sudden stoppage of a flowing fluid. This design consisted of an inlet section followed by the pump body, a pressure section and an outlet. The experimental set-up for testing the water-hammer head pump was designed with a variable head input and an adjustable head output. For each test configuration, a total of 10 samples of pump supply water and pump exhausted water were collected. The water samples were collected for 30 s in each case. The results showed a non-linear variation of water flow with respect to pump outlet height. The pump was capable of delivering water to a maximum height of 8 to 10 times the height of the input head. The pump operated at average efficiencies of 26 %, 16 % and 6 % when the delivery height was 2, 4 and 6 times the input head height, respectively. There was a 5 % incremental decrease in pump efficiency as the delivery height increased in increments of the corresponding input head height.

Integrating Visualization into Structured Public Involvement: Case Study of Highway Improvement in Central Kentucky

2002 ◽  
Vol 1817 (1) ◽  
pp. 50-57 ◽  
Author(s):  
Keiron Bailey ◽  
Joel Brumm ◽  
Ted Grossardt
Keyword(s):  
User Satisfaction ◽  
Public Involvement ◽  
Systems Approach ◽  
Three Dimensional ◽  
Factors Affecting ◽  
State Highway ◽  
Advanced Technologies ◽  
Design Options ◽  
State Highway Agencies

Public involvement in transportation infrastructure decision making is frequently mandated and is regarded as increasingly essential by a wide variety of stakeholders. The integration of advanced technologies, such as visualization, into this process is increasingly desired. However, public involvement processes often are regarded as problematic by many stakeholders and the state highway agencies charged with implementing them. Structured public involvement (SPI) is posited. SPI takes a systems approach toward the integration of advanced technologies into public involvement forums. Because the goal of public involvement is to increase user satisfaction with both the process and the outcomes, the characteristics of advanced technologies and their capacities for gathering useful feedback in public forums must be evaluated. Visualization is put forth as an enabling technology within an SPI framework. The properties, capacities, and transportation-related uses of three visualization modes are evaluated, and their operational features are discussed. A case study dealing with highway improvement in central Kentucky reveals that three-dimensional renderings are significantly preferred to twodimensional and virtual reality modes; the case study also shows that visualization should complement, not replace, other performance information. The role of electronic scoring as an integral component of this SPI protocol is emphasized, resulting in fast assessment and free expression of views. Factors affecting the efficiency of visualization are analyzed, and recommendations are presented for implementing SPI protocols that rely on visualization. These include investigating participants' previous experience with visualization, incorporating iterative public involvement in finalizing design options, and ensuring that the technologies are compatible with the chosen public involvement process.

scholarly journals Effects of Nozzle Die Angle on Extruding Polymethylmethacrylate in Open-Source 3D Printing

2018 ◽  
Vol 15 (2) ◽  
pp. 663-665 ◽  
Author(s):  
Nor Aiman Sukindar ◽  
Mohd Khairol Anuar Mohd Ariffin ◽  
B.T. Hang Tuah Baharudin ◽  
Che Nor Aiza Jaafar ◽  
Mohd Idris Shah Ismail
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Drop ◽  
3D Printing ◽  
Open Source ◽  
Flow Behavior ◽  
Three Dimensional ◽  
3D Printer ◽  
Element Analysis ◽  
Factors Affecting

Open-source 3D printer has been widely used for fabricating three dimensional products. However, this technology has some drawbacks that need to be improved such as accuracy of the finished parts. One of the factors affecting the final product is the ability of the machine to extrude the material consistently, which is related to the flow behavior of the material inside the liquefier. This paper observes the pressure drop along the liquefier by manipulating the nozzle die angle from 80° to 170° using finite element analysis (FEA) for polymethylmethacrylate (PMMA) material. When the pressure drop along the liquefier is varied, the printed product also varies, thus providing less accuracy in the finished parts. Based on the FEA, it was found that 130° was the optimum die angle (convergent angle) for extruding PMMA material using open-source 3D printing.

scholarly journals Relationship between Spacing Rasio and Stiffness Coefficient by Using Smoothed Particle Hydrodynamics Method to Simulate Water – Solid Interaction

2019 ◽  
Vol 95 ◽  
pp. 02011
Author(s):  
Anisa Wulandari ◽  
R.R Dwinanti Rika ◽  
Jessica Sjah ◽  
Herr Soeryantono
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Three Dimensional ◽  
Stiffness Coefficient ◽  
Factors Affecting ◽  
Fluid Behavior ◽  
Grid Approach ◽  
Spacing Ratio ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method

Scouring Phenomenon directly occurs on materials due to the motion of water flow and water borne sediments that researchers in the world continue to investigate. Scouring are then continuously developed in Computational Fluid Dynamics (CFD) to be able to estimate scouring effects by analyzing interaction between fluid and solid. Water and solid interaction can be researched by realizing three dimensional numerical modeling (3D) using Smoothed Particle Hydrodynamics Method which is modeling and visualizing fluid behavior with a Lagrangian approach in particle scale (micro scale), a more particle approach realistic than the grid approach. Using this method, the results of each particle can be reviewed either by their property values or visually so that the results are obtained more representatives. One of the factors affecting fluid-solid modeling is spacing ratio between solid particle and fluid particle. To obtain the correct physical results, it is required to consider the influence of spacing ratio and the value of Stiffness Coefficient (Ks) needed.

Numerical Study of Welding Sequence on the Residual Stress Field in a Thick-Walled Tee Joint

2011 ◽  
Vol 219-220 ◽  
pp. 1211-1214
Author(s):  
Wei Jiang
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Numerical Study ◽  
Three Dimensional ◽  
Element Model ◽  
Residual Stress Field ◽  
Factors Affecting ◽  
Welding Sequence ◽  
Welding Sequences ◽  
Three Dimensional Finite Element

Finite element simulation is an efficient method for studying factors affecting weld-induced residual stress distributions. In this paper, a validated three-dimensional finite element model consisting of sequentially coupled thermal and structural analyses was developed. Three possible symmetrical welding sequences, i.e. one-welder, two-welder and four-welder sequence, which were perceived to generate the least distortion in actual welding circumstances, were proposed and their influences on the residual stress fields in a thick-walled tee joint were investigated. Appropriate conclusions and recommendations regarding welding sequences are presented.

Measurement and Simulation of Water Hammer in Piping Systems Including Junction Coupling

2013 ◽  
Author(s):  
Stefan Riedelmeier ◽  
Stefan Becker ◽  
Eberhard Schlücker
Keyword(s):  
Three Dimensional ◽  
Water Hammer ◽  
Test Facility ◽  
One Dimensional ◽  
Beam Elements ◽  
Coupled Codes ◽  
Piping Systems ◽  
Complex Test ◽  
System Configurations

For the analysis of the effects of fluid-structure interaction (FSI) during water hammer in piping systems, a complex test facility was constructed. Resonance experiments with movable bends in two system configurations were carried out. The pressure and the displacement of the bend were recorded. The aim was to reproduce the results with two coupled codes: a one-dimensional solver based on the method of characteristics (MOC) for the hydraulic system and a three-dimensional solver based on the finite element method (FEM) working with one-dimensional beam elements for the structural system. The calculation included junction and friction coupling. The models were fine-tuned separately. For this purpose, special measurements were carried out. These included the determination of the structural damping, the friction factor, the influence of the bending of the anchorage, etc. After the validation of the models, the results of the coupled calculations were compared against the measurements, the performance of the coupled codes was evaluated and the most important physical effects were analyzed and are discussed.

Advanced Hydrodynamic Design of Vertical Diffuser Pumps Using Computational Fluid Dynamics

2002 ◽  
Author(s):  
Kristis V. Michaelides ◽  
Antonios Tourlidakis
Keyword(s):  
Development Process ◽  
Three Dimensional ◽  
Detailed Examination ◽  
Product Development Process ◽  
Design Parameters ◽  
Factors Affecting ◽  
Performance Predictions ◽  
Overall Performance ◽  
Industrial Use ◽  
Optimisation Procedure

The current paper describes an investigation into the industrial use of CFD and other computational technologies for the three-dimensional hydrodynamic design of vertical diffuser pumps and outlines the complete product development process. Detailed description of the complete design process is described and numerous CFD predictions of the flow are presented with detailed examination of the several factors affecting the hydrodynamics of impeller and diffuser and staging of the pump. Furthermore, variations of important geometrical design parameters based on the design optimisation procedure are discussed in accordance to the CFD results. The capabilities of the 3-D hydrodynamic design through CFD and the importance of the three dimensional blade geometry are demonstrated by the fact that two different pump impellers were designed based on strict design constraints affecting their basic dimensions. Finally, an overview of the functional prototypes development is described and comparisons are carried out between overall performance predictions and experimental results.

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