scholarly journals A Hydrodynamic Methodology And CFD Analysis For Performance Prediction Of Stepped Planing Hulls

2015 ◽  
Vol 22 (2) ◽  
pp. 23-31 ◽  
Author(s):  
Hassan Ghassemi ◽  
Mojtaba Kamarlouei ◽  
Sajad Taj Golah Veysi
Keyword(s):  
High Speed ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Characteristics ◽  
Geometrical Parameters ◽  
Cfd Analysis ◽  
Analysis Model ◽  
Marine Coatings ◽  
Resistance Reduction ◽  
Calculation Results ◽  
Fruitful Research

AbstractNowadays all efforts in planing hull research are focused on resistance reduction for achieving the highest speed in fast planing crafts. Furthermore, many fruitful research projects have been carried out on marine coatings, planing equipment, and optimization of propeller and hull form, which revolutionized industry of high - speed crafts and made them an efficient survival vehicle in coastal areas and rivers. In this paper the hydrodynamic performance of planing hulls are investigated by means of a modified Savitsky model for both non-stepped and stepped bodies. Meanwhile, in order to meet this goal reasonably, effective geometrical parameters of planing hull are investigated and then operational hydrodynamic characteristics of the craft are predicted by using a computational program. Finally, the calculation results are verified by means of a CFD-analysis model.

scholarly journals Thermo-Elastohydrodynamic Study on Textured Journal Bearing with High-Speed and High-Specific-Pressure

2019 ◽  
Vol 37 (4) ◽  
pp. 751-756 ◽  
Author(s):  
Lin Wang ◽  
Yu Zhang ◽  
Guoding Chen
Keyword(s):  
Elastic Deformation ◽  
High Speed ◽  
Journal Bearing ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Specific Pressure ◽  
Analysis Model ◽  
Navier Stokes Equation ◽  
Gear Transmission System ◽  
Load Carrying

The performance of supporting journal bearing of the star gear transmission system in the geared turbo fan engine (GTF) is analyzed. A thermal-elastohydrodynamic analysis model was developed for textured journal bearing used in high-speed and high-specific-pressure conditions. The Navier-Stokes equation, energy equation, and viscosity-temperature equation were calculated by the computational fluid dynamics method. The influence of elastic deformation on bearing thermal hydrodynamic performance was studied in detail. The results indicate that the elastic deformation has an influence on the distribution of oil temperature and oil pressure. Besides, a comparative thermo-elastohydrodynamic analysis was conducted between the textured bearing and the un-textured bearing, and the discrepancies of maximum oil pressure, load carrying capacity and the maximum oil temperature are few. However, the textured bearing has a lower elastic deformation than the un-textured bearing.

scholarly journals Utilization of Open-Source OpenFOAM Code to Examine the Hydrodynamic Characteristics of a Linear Jet Propulsion System with or without Stator in Bollard Pull Condition

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Parviz Ghadimi ◽  
Negin Donyavizadeh ◽  
Pouria Taghikhani
Keyword(s):  
High Speed ◽  
Water Jet ◽  
Propulsion System ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Characteristics ◽  
Propulsion Systems ◽  
Thrust Coefficient ◽  
Jet Propulsion ◽  
Marine Industry ◽  
Total Thrust

With the development of high-speed crafts, new propulsion systems are introduced into the marine industry. One of the new propulsion systems is linear jet which is similar to pump jet and has a rotor, a stator, and a duct. The main difference between this system and pump jet is the placement of linear jet system under the hull body and inside a tunnel. Since this system, like a water jet, is inside the tunnel, the design idea of this system is a combination of a water jet and pump jet. In this paper, hydrodynamic performance of linear jet propulsion system is numerically investigated. To this end, the OpenFOAM software is utilized and RANS steady equations are solved using a k - ε turbulent model. The linear jet geometry is produced by assembling a Kaplan rotor, stator with a NACA 5505 cross section, and a decelerating duct. The results of numerical solution in the form of thrust, torque coefficient, and efficiency are compared with available experimental data for a ducted propeller, and good agreement is displayed. Subsequently, the hydrodynamic parameters are computed in two conditions: with a stator and without a stator. By comparing the results, it is observed that the total thrust coefficient of the propulsion system with a stator at all advance ratios increases by at least 40%. It is further observed that addition of a stator also improves its efficiency.

scholarly journals Stiffness Characteristics of High-Speed Railway Turnout and the Effect on the Dynamic Train-Turnout Interaction

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Jingmang Xu ◽  
Ping Wang ◽  
Xiaochuan Ma ◽  
Yuan Gao ◽  
Rong Chen
Keyword(s):  
High Speed ◽  
Transient Analysis ◽  
Longitudinal Direction ◽  
Analysis Model ◽  
Lateral Direction ◽  
High Speed Railway ◽  
Calculation Results ◽  
Track Stiffness ◽  
Stiffness Characteristics ◽  
Railway Turnout

Track stiffness in railway turnouts is variable due to differences in structural composition along the longitudinal direction, which will lead to severe dynamic interaction between train and turnout. In this paper, a transient analysis model is presented to investigate the stiffness characteristics of high-speed railway turnouts based on the finite element method and is applied to optimise the stiffness of railway turnouts. Furthermore, the effect of the stiffness variations on the dynamic train-turnout interaction is analysed. The calculation results show that the track stiffness characteristics are similar in the main and diverging line of railway turnout, except for the check rail sections. Due to the existence of shared baseplates and spacer blocks between different rails, the stiffness variations in the crossing panel are most severe in high-speed railway turnouts. The stiffness differences (calculated as the ratio of the maximum and minimum stiffness) of the longitudinal and lateral direction for Chinese number 18 ballasted turnout are 216% and 229%, respectively. The graded stiffness of the tie pads has been redesigned to optimise the stiffness of railway turnout based on the transient analysis model and the stiffness differences of the turnout are decreased. Altogether, the dynamic train-turnout interaction is enhanced remarkably by considering the turnout’s stiffness characteristics.

Effects of step configuration on hydrodynamic performance of one- and doubled-stepped planing flat plates: A numerical simulation

2019 ◽  
Vol 234 (1) ◽  
pp. 181-195 ◽  
Author(s):  
Abbas Dashtimanesh ◽  
Fatemeh Roshan ◽  
Sasan Tavakoli ◽  
Ahmadreza Kohansal ◽  
Bahare Barmala
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Critical Role ◽  
Pressure Coefficient ◽  
Numerical Data ◽  
Hydrodynamic Performance ◽  
Step Height ◽  
Hydrodynamic Characteristics ◽  
Flat Plates ◽  
Marine Vehicles

Categorized as one of high-speed marine vehicles, stepped planing hulls have the potential to reach relatively high speed in the sea by decreasing wetted surface. There were and still are some challenges in modeling of these vessels and design of ideal situation of steps. In the current study, a numerical-based method has been used to provide understanding about the effect of step height and its location on hydrodynamic characteristics of double-stepped planing plates. At the first step, one-stepped planing plate is numerically simulated. Results are compared against exiting numerical data, suggesting that results of the current numerical simulation are similar to results of previous numerical simulations. Then, double-stepped planing plates are modeled and pressure distribution, wetted length, free surface elevation and drag over lift ratio are computed. It is seen that, ventilation length behind the step and pressure coefficient are increased when step height of one- and a double-stepped planing plates are increased. It has been shown that, unlike an one-stepped planing plate, drag coefficient of a double-stepped planing plate can be increased when the step height is increased. The effects of the location of the second step on the performance of the planing plate have been explored, showing that this position plays a critical role on hydrodynamic forces. It is demonstrated that when the smallest possible lift force is produced by the middle-body, the plate shows the best performance (highest lift over drag ratio).

Validation of a CFD Analysis Model for the Thermal-Hydraulic Response of PWR Steam Generator to a Steam Line Break

2016 ◽  
Author(s):  
Jong Chull Jo ◽  
Bok Ki Min ◽  
Jae Jun Jeong
Keyword(s):  
Steam Generator ◽  
Steam Line ◽  
Cfd Analysis ◽  
Analysis Method ◽  
Pressurized Water Reactor ◽  
Analysis Model ◽  
Pressurized Water ◽  
Calculation Results ◽  
Main Steam Line ◽  
Main Steam

This paper presents a validation of a computational fluid dynamics (CFD) analysis method for a numerical simulation of the transient thermal-hydraulic responses of steam generator (SG) secondary side to blowdown following a main steam line break (MSLB) at a pressurized water reactor (PWR). To do this, the CFD analysis method was applied to simulate the same blowdown situation as in an experimental work which was conducted for a simplified SG blowdown model, and the CFD calculation results were compared with the experimental results. As the result, both are in reasonably good agreement with each other. Consequently, the present CFD analysis model has been validated to be applicable for numerical simulations of the transient phase change heat transfer and flow situations in PWR SGs during blowdown.

The Code Development for the Thermo-Hydrodynamic Characteristics Study of Reflood Phase

2014 ◽  
Author(s):  
Shipeng Niu ◽  
Yapei Zhang ◽  
Wenxi Tian ◽  
Suizheng Qiu ◽  
Guanghui Su
Keyword(s):  
Heat Transfer ◽  
Fuel Element ◽  
Theoretical Basis ◽  
Hydrodynamic Characteristics ◽  
Hydraulic Analysis ◽  
Analysis Model ◽  
Heat Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
System Pressure ◽  
Calculation Results

An thermo-hydraulic analysis model for the reflood phase was established in the paper, based on the flow and heat transfer characteristics of the reflood. A code based on the model was developed for the thermo-hydraulic analysis of reflood. By comparing and analyzing the calculation results with the experimental results, the influences of the system pressure and the subcooling of coolant on reflood phase were studied. The study also provided theoretical basis for safety analysis of fuel element of reflood phase.

Dynamic Analysis of DVG 850 High-Speed Machining Center

2012 ◽  
Vol 487 ◽  
pp. 203-207
Author(s):  
Gong Xue Zhang ◽  
Xiao Kai Shen
Keyword(s):  
High Speed ◽  
Simulation Analysis ◽  
Response Analysis ◽  
Improved Method ◽  
Analysis Software ◽  
Element Analysis ◽  
Harmonic Response ◽  
Machining Center ◽  
Calculation Results ◽  
Harmonic Response Analysis

Purpose, with the application of workbench finite element analysis software, get the analysis results of DVG 850 high-speed vertical machining center via the modal analysis and harmonic response analysis. Use the calculation results for reference, put forward the improved method, and prove the credibility of the simulation analysis by testing DVG 850 prototype.

Hydrodynamic characteristics of vertical and quadrant face pile supported breakwater under oblique waves

2021 ◽  
pp. 147509022110313
Author(s):  
T J Jemi Jeya ◽  
V Sriram ◽  
V Sundar
Keyword(s):  
Experimental Study ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Characteristics ◽  
Scattering Parameter ◽  
Oblique Waves ◽  
Test Conditions ◽  
Relative Water ◽  
Identical Test ◽  
Run Up ◽  
Water Depths

This paper presents the results from a comprehensive experimental study on the Quadrant Face Pile Supported Breakwater (QPSB) in two different water depths exposed to three different oblique wave attacks. The results are compared with that for a Vertical face Pile Supported Breakwater (VPSB) for identical test conditions. The paper compares the reflection coefficient, transmission coefficient, energy loss coefficient, non-dimensional pressure, and non-dimensional run-up as a function of the relative water depth and scattering parameter. The results obtained for QPSB are validated with existing results. The salient observations show that QPSB experiences better hydrodynamic performance characteristics than the VPSB under oblique waves.

The Mechanical Mechanism Analysis for Mortar Arch Framework Slope Protection Structure

2013 ◽  
Vol 859 ◽  
pp. 143-148
Author(s):  
Yang Xu ◽  
Ding Ling Li ◽  
Li Peng ◽  
Yan Xiao ◽  
Yi Hua Nie
Keyword(s):  
Finite Element Analysis ◽  
Mechanism Analysis ◽  
Analysis Model ◽  
Element Analysis ◽  
Finite Element Analysis Model ◽  
Vertical Loading ◽  
Total Displacement ◽  
The Finite Element Analysis ◽  
Calculation Results ◽  
Real Scale

The finite element analysis model was built as the real scale for mortar arch framework slope protection, and the displacement and strain at different points were collected by vertical loading pressure. So the mechanical mechanism can be studied, and the analysis was done between calculation results and testing results of solid miniature model. The studying results show that the point on the arch foot is the worst stress place for each arch, and the total displacement increase nonlinear as the distance from the slope top increases, and the bump phenomenon exists in the bottom of slope, the points are likely to be broken.

Seismic Response Analysis of Soil-Structure Interaction on Base Isolation Structure

2013 ◽  
Vol 663 ◽  
pp. 87-91
Author(s):  
Ying Bo Pang
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Soil Structure ◽  
Base Isolation ◽  
Soil Structure Interaction ◽  
Response Analysis ◽  
Analysis Model ◽  
Seismic Response Analysis ◽  
Structure Interaction ◽  
Calculation Results

As an effective way of passive damping, isolation technology has been widely used in all types of building structures. Currently, for its theoretical analysis, it usually follows the rigid foundation assumption and ignores soil-structure interaction, which results in calculation results distortion in conducting seismic response analysis. In this paper, three-dimensional finite element method is used to establish finite element analysis model of large chassis single-tower base isolation structure which considers and do not consider soil-structure interaction. The calculation results show that: after considering soil-structure interaction, the dynamic characteristics of the isolation structure, and seismic response are subject to varying degrees of impact.

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