Comparative Investigation of an Automated Oceanic Wave Surface Glider Robot Influence on Resistance Prediction Using CFD Method

2015 ◽  
Vol 710 ◽  
pp. 91-97
Author(s):  
Aladdin Elhadad ◽  
Wen Yang Duan ◽  
Rui Deng
Keyword(s):  
High Speed ◽  
Water Resistance ◽  
Comparative Investigation ◽  
Numerical Predictions ◽  
Calm Water ◽  
Oceanic Wave ◽  
Computational Fluid Dynamics Cfd ◽  
Wave Glider ◽  
Cfd Method ◽  
Solution Parameters

Thewave glideris composed of two parts: the float is roughly the size and shape of a surfboard that contains all the instrumentation needed for scientific experiments; the sub has wings and hangs 6 meters below on an umbilical tether. This difference allows wave energy to be harvested to produce forward thrust. According to the lake of design information and data for thewave glider, the main aim of the study is usingcomputational fluid dynamics (CFD)to present a method to predict calm water resistance for the floating part of thewave glider(the hull).Wigley parabolic hulland high speed round bilge form (NPL)have been investigated in order to estimate the hydrodynamic performances of the hull usingCFDsoftware fluent.Wave glideris designed with slender hull shapes in order to decrease the wave making resistance of the ship.In this paper a method is evaluated by comparing the numerical predictions forwigleyandNPLforms (2m) using the same mesh generation method under the same conditions to design the hull. Calculations fortotal calm water resistanceare carried out using three different mesh sizes for Froude numbers in the range of 0.10 to 0.40 and compared for accuracy of the solution parameters. The close agreement between the numerical predictions shows the importance ofCFDapplications in estimating the hydrodynamics performance to design the floating hull and the numerical method is useful in glider design. This means that the method discussed in this paper can be used for the resistance calculation of some hulls like the float of the glider.

Numerical Analysis for Resistance Calculations of NPL as a Floating Hull for Wave Glider

2014 ◽  
Vol 619 ◽  
pp. 38-43 ◽  
Author(s):  
Aladdin Elhadad ◽  
Wen Yang Duan ◽  
Rui Deng ◽  
H. Elhanfey
Keyword(s):  
Numerical Analysis ◽  
Mesh Generation ◽  
Numerical Scheme ◽  
Water Resistance ◽  
Numerical Predictions ◽  
Calm Water ◽  
Resistance Prediction ◽  
Wave Glider ◽  
Solution Parameters ◽  
Good Agreement

Thewave glideris an autonomous unmanned vehicle (AUV) which uses the power of the ocean to propel itself. The purpose of this study is using the well known slender modelNPLin developing hull in an attempt to design the floating hull ofwave glider.CFDandMaxsurfsoftware are used to present a method focused on mesh generation to predictcalm water resistancefor the hull. Calculations are carried out for Froude numbers in the range of 0.10 to 0.40. Three different mesh sizes are used forCFDto calculate the mesh effects. The results of numerical predictions under the same conditions obtained fromCFDandMaxsurfcalculations are obtained and compared for accuracy of the solution parameters. The comparison shows a good agreement between the results. The method is useful and acceptable and the overall numerical scheme is suitable for resistance prediction.

A Computational Fluid Dynamics Method for Resistance Prediction of the Floating Hull of Wave Glider

2014 ◽  
Vol 936 ◽  
pp. 2114-2119 ◽  
Author(s):  
Aladdin Elhadad ◽  
Wen Yang Duan ◽  
Rui Deng
Keyword(s):  
Fluid Flow ◽  
Total Resistance ◽  
Numerical Predictions ◽  
Exclusive Economic Zones ◽  
Calm Water ◽  
Wigley Hull ◽  
Wave Glider ◽  
The Cost ◽  
Economic Zones ◽  
Solution Parameters

The wave glider is a surface vehicle with an attached sub-surface wing system which propels the surface component forward, negating the need for a motor. Wave glider could be used for intelligence, surveillance, passive monitoring of marine life, monitoring exclusive economic zones for fishing and other economic resources that are important and useful to coastal countries. Monitoring of coastal waters normally requires large amounts of expensive surveillance. They can be used to find and research resources and fisheries at a fraction of the cost of other methods. Since the wave glider can either be programmed for a journey or to keep station, it is looked at as an alternative for expensive moored buoys. In this paper we present a method focused on the mesh generation to predict calm water resistance for the floating part of the wave glider (the hull). In this study a wigley hull form (4m) used as the floating hull has been investigated in order to predict the fluid flow of the ship using computational fluid dynamics (CFD). Calculations for total resistance are carried out for Froude numbers in the range of 0.10 to 0.40. Commercial CFD software fluent is used to investigate the fluid flow of wigley hull. Three different mesh sizes are used in this study to calculate the mesh effects. The results obtained from CFD calculations for total resistance are compared with the experimental results for accuracy of the solution parameters. The comparison shows a good agreement between experimental and CFD results. The method is evaluated by comparing the numerical predictions for wigley hull form (2m) with wigley hull form (4m) using the same mesh sizes under the same conditions in an attempt to design the floating hull of wave glider . The results obtained from CFD calculations are compared for accuracy of the solution parameters and the method is useful and acceptable.

Aerodynamic Loading Induced by Muzzle Flows on Small Caliber Spin Stabilized Projectiles

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Chuanlin Chen ◽  
Hui Xu ◽  
Chenlei Huang ◽  
Zhongxin Li ◽  
Zhilin Wu
Keyword(s):  
High Speed ◽  
Exponential Relationship ◽  
Interior Ballistics ◽  
Aerodynamic Loading ◽  
Axial Forces ◽  
Pitch Moment ◽  
Temporal Pressure ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Element Method

Abstract In this study, we examined the aerodynamic loading on a small caliber rifle (spin stabilized) projectile moving in a muzzle flow field using an element method to analyze the loading and the effect of the angle of attack (for small angles from 0 to 3 deg) on the different components. The temporal pressure distribution on the projectile, which forms the basis of the element method, was computed using a computational fluid dynamics (CFD) analysis combined with a classical interior ballistics model. Then, a high-speed optical experiment was conducted to verify the results of the CFD method and ensure the accuracy of the calculations. The results were as follows: (a) similar to a large caliber projectile, the total axial force, which consisted primarily of the axial forces on the base and boattail, was found to have an inverse exponential relationship with time; (b) the overall lift was a combination of the lift of the base, boattail, cylinder, and nose; and (c) the interaction between the pitch moment of the base and that of the boattail was found to be the primary contributing factor to the total pitch moment. Based on these results, we recommend that the characteristics of the base and boattail be considered when specifying the geometric configuration of a projectile.

scholarly journals Numerical Analysis on the Hydrodynamic Performance of an Artificially Ventilated Surface-Piercing Propeller

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1499 ◽  
Author(s):  
Dongmei Yang ◽  
Zhen Ren ◽  
Zhiqun Guo ◽  
Zeyang Gao
Keyword(s):  
High Speed ◽  
Artificial Ventilation ◽  
Water Immersion ◽  
Numerical Results ◽  
Hydrodynamic Performance ◽  
Heavy Load ◽  
Computational Fluid Dynamics Cfd ◽  
Large Water ◽  
Cfd Method ◽  
Surface Piercing Propeller

When operated under large water immersion, surface piercing propellers are prone to be in heavy load conditions. To improve the hydrodynamic performance of the surface piercing propellers, engineers usually artificially ventilate the blades by equipping a vent pipe in front of the propeller disc. In this paper, the influence of artificial ventilation on the hydrodynamic performance of surface piercing propellers under full immersion conditions was investigated using the Computational Fluid Dynamics (CFD) method. The numerical results suggest that the effect of artificial ventilation on the pressure distribution on the blades decreases along the radial direction. And at low advancing speed, the thrust, torque as well as the efficiency of the propeller are smaller than those without ventilation. However, with the increase of the advancing speed, the efficiency of the propeller rapidly increases and can be greater than the without-ventilation case. The numerical results demonstrates the effectiveness of the artificial ventilation approach for improving the hydrodynamic performance of the surface piercing propellers for high speed planning crafts.

Computational aeroelastic analysis of slowed rotors at high advance ratios

2014 ◽  
Vol 118 (1201) ◽  
pp. 297-313 ◽  
Author(s):  
J. de Montaudouin ◽  
N. Reveles ◽  
M. J. Smith
Keyword(s):  
High Speed ◽  
Rotor Blades ◽  
Vortex Interaction ◽  
Blade Loading ◽  
Blade Vortex Interaction ◽  
Aeroelastic Analysis ◽  
Computational Fluid Dynamics Cfd ◽  
Advance Ratio ◽  
Cfd Method ◽  
Model Rotor

Abstract The aerodynamic and aeroelastic behaviour of a rotor become more complex as advance ratios increase to achieve high-speed forward fight. As the rotor blades encounter large regions of cross and reverse flows during each revolution, strong variations in the local Mach regime are encountered, inducing complex elastic blade deformations. In addition, the wake system may remain in the vicinity of the rotor, adding complexity to the blade loading. The aeroelastic behaviour of a model rotor with advance ratios ranging from 0·5 to 2·0 has been evaluated with aerodynamics provided via a computational fluid dynamics (CFD) method. Significant radial blade-vortex interaction can occur at a high advance ratio; the advance ratio at which this occurs is dependent on the rotor configuration. This condition is accompanied by high vibratory loads, peak negative torsion, and peak torsion and in-plane loads. The high vibratory loading increases the sensitivity of the trim model, so that at some high advance ratios the vibratory loads must be filtered to achieve a trimmed state.

Analysis and Simulation of Inner Flow Condition of a Novel Rotary on/off Valve

2012 ◽  
Vol 220-223 ◽  
pp. 1698-1702
Author(s):  
Jian Chen ◽  
Zhu Ming Su ◽  
Qi Zhou ◽  
Jian Ping Shu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Condition ◽  
High Speed ◽  
Ansys Fluent ◽  
Revolution Speed ◽  
Pressure Profiles ◽  
Open Case ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

A novel hydraulic rotary high speed on/off valve is investigated. The function of the outlet turbine and the effect on revolution speed of valve spool are analyzed. The inner fluid flow condition under full open case of the on/off valve is simulated using computational fluid dynamics(CFD) method based on Ansys/Fluent and velocity and pressure profiles of fluid inside valve are obtained. Suggestions on optimizing the geometry of valve to decrease transition losses are given.

Virtual Model Basin for Resistance, Maneuvering, and Seakeeping: A RANS CFD Based Approach

2007 ◽  
Author(s):  
Balasubramanyam Sasanapuri ◽  
Viraj Suresh Shirodkar ◽  
Wesley Wilson ◽  
Samir Kadam ◽  
Shin Hyung Rhee
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Free Surface ◽  
Water Resistance ◽  
Primary Objective ◽  
Navier Stokes ◽  
Theory Method ◽  
Virtual Model ◽  
Calm Water ◽  
Computational Fluid Dynamics Cfd

A Virtual Model Basin (VMB) is developed based on a Computational Fluid Dynamics (CFD) approach to solving the Reynolds Averaged Navier-Stokes (RANS) equations along with the Volume of Fluid (VOF) method for predicting the free surface. The primary objective of this work is to develop methodologies for the VMB and to demonstrate the capabilities for a generic multi-hull ship geometry. The VMB is used to simulate various model basin tests for steady resistance, maneuvering and seakeeping. For a generic catamaran hull configuration, the methodologies are used for solving these problems and the results are discussed in this paper. VMB results are compared with the results of a benchmarked potential flow theory method for calm water resistance.

scholarly journals Numerical and Experimental Study on Seakeeping Performance of a High-Speed Trimaran with T-foil in Head Waves

2019 ◽  
Vol 26 (3) ◽  
pp. 65-77 ◽  
Author(s):  
Ang Li ◽  
Yunbo Li
Keyword(s):  
High Speed ◽  
Experimental Tests ◽  
Longitudinal Motion ◽  
Vertical Acceleration ◽  
Large Wave ◽  
Seakeeping Performance ◽  
Head Waves ◽  
Computational Fluid Dynamics Cfd ◽  
Motion Characteristics ◽  
Cfd Method

Abstract The longitudinal motion characteristics of a slender trimaran equipped with and without a T-foil near the bow are investigated by experimental and numerical methods. Computational fluid dynamics ( CFD) method is used in this study. The seakeeping characteristics such as heave, pitch and vertical acceleration in head regular waves are analyzed in various wave conditions. Numerical simulations have been validated by comparisons with experimental tests. The influence of large wave amplitudes and size of T-foil on the longitudinal motion of trimaran are analyzed. The present systematic study demonstrates that the numerical results are in a reasonable agreement with the experimental data. The research implied that the longitudinal motion response values are greatly reduced with the use of T-foil.

Experimental Analysis on Flow around Fin Assisted Semi SWATH

2015 ◽  
Vol 74 (5) ◽  
Author(s):  
Arifah Ali ◽  
Adi Maimun ◽  
Yasser M. Ahmed ◽  
Rahimuddin Rahimuddin ◽  
Mohamad Pauzi A. Ghani
Keyword(s):  
Froude Number ◽  
High Speed ◽  
Water Resistance ◽  
Wave Pattern ◽  
Resistance Test ◽  
Hull Form ◽  
Wave Interference ◽  
Calm Water ◽  
Water Test ◽  
Zero Degree

Demand on High Speed Craft (HSC) is increasing due to development of inland transportation. Therefore, many analysis have been conducted to evaluate performance of this modern ship. One of the important analysis is calm water resistance test. Resistance component of the hull and wave pattern around the hull are obtained from the calm water test. These criteria are important in analyzing flow around hull, especially on wave interference between the hulls. In this paper, flow around hull has been studied for one model of Semi SWATH hull form with fin stabilizers installation by performing calm water resistance test in deep water. The fore fin angle is fixed to zero degree while the aft fin angle is varied to 0, 5 and 15 degree. The effects of fin angle to resistance criteria and flow around hull are investigated. Wave height has been recorded using longitudinal wave probe during resistance test. For each configuration, the investigation is conducted with range of Length Froude Number from 0.34 to 0.69. From the analysis, it is found that flow around the hull of Semi SWATH is affected by fin angle and the effect is various depend on the Froude number.

scholarly journals Prediction of Propeller Open Water Characteristics for High Speed Boat by CFD Method

2019 ◽  
Vol 9 (1) ◽  
pp. 3701-3706
Keyword(s):  
High Speed ◽  
Open Water ◽  
Design Stage ◽  
Water Characteristics ◽  
Computational Evaluation ◽  
Mesh Density ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Commercial Solver ◽  
Computational Resources

Nowadays with the development of computational resources, calculating the open water characteristics of the propeller using Computational Fluid Dynamics (CFD) has been used widely at the initial design stage because of relatively accurate result, time and cost saving, in comparison with experimental approach. This paper presents the results of computational evaluation of propeller open water characteristics for high speed boat, based on steady RANSE flow model with rotating reference frame approach. The effects of mesh density, mesh generation are analyzed in order to improve obtained numerical results. The well-known Gawn propeller series, that is often used for high speed vessel is used to verify and validate the accuracy of case studies. In this study, the authors use the commercial solver Star CCM+ by SIEMENS

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