Conceptual Design and Hydrodynamic Analysis of a High-Speed Deformable Trimaran

2012 ◽  
Vol 204-208 ◽  
pp. 4610-4615 ◽  
Author(s):  
Hong Sheng Yan ◽  
Xiao Ying Xu ◽  
Yan Xin Feng
Keyword(s):  
Conceptual Design ◽  
High Speed ◽  
Hydrodynamic Performance ◽  
Optimal Layout ◽  
Hydrodynamic Analysis ◽  
Cfd Method ◽  
Resistance Performance

This paper proposed a new high-speed deformable trimaran based on DTMB5415, and discussed its advantages and applications. We computed the hydrodynamic performance with CFD method and analyzed the wave-making interference and resistance performance for eight different arrangements of this trimaran. The results show an optimal layout for this high-speed deformable trimaran, which can decrease the resistance of per unit displacement mass about 32%.

scholarly journals Numerical Analysis on the Effect of Artificial Ventilated Pipe Diameter on Hydrodynamic Performance of a Surface-Piercing Propeller

2019 ◽  
Vol 7 (8) ◽  
pp. 240
Author(s):  
Gao ◽  
Yang ◽  
Li ◽  
Dong
Keyword(s):  
High Speed ◽  
Water Immersion ◽  
Active Role ◽  
Numerical Results ◽  
Hydrodynamic Performance ◽  
Pipe Diameter ◽  
Pressure Area ◽  
Cfd Method ◽  
Thrust And Torque ◽  
Surface Piercing Propeller

Under the condition of large water immersion, surface-piercing propellers are inclined to be heavy loaded. In order to improve the hydrodynamic performance of the surface-piercing propeller, the installation of a vent pipe in front of a propeller disc is more widely used in the propulsion device of high speed planning crafts. Based on computational fluid dynamics (CFD) method, this paper studied the influence of diverse vent pipe diameters on hydrodynamic performance of the surface-piercing propeller under full water immersion conditions. The numerical results show that, with the increase of vent pipe diameters, the thrust and torque of the surface-piercing propeller decrease after ventilation, and the efficiency of the propeller increases rapidly; the low pressure area near the back root of the blade becomes smaller and smaller gradually; and the peak of periodic vibration of thrust and torque can be effectively reduced. The numerical results demonstrate that the installation of artificial vent pipe effectively improves the hydrodynamic performance of surface piercing propeller in the field of high speed crafts, and the increase of artificial vent pipe diameter plays an active role in the propulsion efficiency of the surface-piercing propeller.

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.

Pure Yaw Simulations of Fast Delft Catamaran 372 in Deep Water

2020 ◽  
Author(s):  
Suleyman Duman ◽  
Sakir Bal
Keyword(s):  
Deep Water ◽  
High Speed ◽  
Point Of View ◽  
Hydrodynamic Performance ◽  
Marine Vehicles ◽  
Wave Interference ◽  
Force Moment ◽  
Unsteady Rans ◽  
Cfd Method ◽  
Turbulent Flow Conditions

Fast marine vehicles have become more important than ever before due to increasing need and population. In maritime sector, special ship types such as catamaran and trimaran have already been designed and/or built to the civil and naval areas of use. The hydrodynamic performance of these vessels is an interesting problem for naval architects due to the wave interference between the hulls. From this point of view, a generic high-speed catamaran hull form (Delft catamaran 372 or DC372) has been chosen for the numerical prediction of manoeuvring coefficients. To achieve this, the pure yaw captive manoeuvre simulations of the DC372 have been performed in deep water conditions at several oscillating frequencies by using CFD method. The unsteady RANS equations have been solved under incompressible, viscous and fully turbulent flow conditions. The uncertainty in the computations has been determined using proper techniques. Manoeuvring coefficients have been calculated by processing time dependent force/moment signals obtained numerically with the help of Fourier analysis. Due to the accurate grid structure used here, numerical ventilation has been prevented and wave deformations have been captured well.

scholarly journals Tuna locomotion: a computational hydrodynamic analysis of finlet function

2020 ◽  
Vol 17 (165) ◽  
pp. 20190590 ◽  
Author(s):  
Junshi Wang ◽  
Dylan K. Wainwright ◽  
Royce E. Lindengren ◽  
George V. Lauder ◽  
Haibo Dong
Keyword(s):  
High Speed ◽  
Cross Flow ◽  
The Body ◽  
Hydrodynamic Performance ◽  
Thunnus Albacares ◽  
Hydrodynamic Analysis ◽  
Kinematic Data ◽  
Hydrodynamic Function ◽  
Scombrid Fishes

Finlets are a series of small non-retractable fins common to scombrid fishes (mackerels, bonitos and tunas), which are known for their high swimming speed. It is hypothesized that these small fins could potentially affect propulsive performance. Here, we combine experimental and computational approaches to investigate the hydrodynamics of finlets in yellowfin tuna ( Thunnus albacares ) during steady swimming. High-speed videos were obtained to provide kinematic data on the in vivo motion of finlets. High-fidelity simulations were then carried out to examine the hydrodynamic performance and vortex dynamics of a biologically realistic multiple-finlet model with reconstructed kinematics. It was found that finlets undergo both heaving and pitching motion and are delayed in phase from anterior to posterior along the body. Simulation results show that finlets were drag producing and did not produce thrust. The interactions among finlets helped reduce total finlet drag by 21.5%. Pitching motions of finlets helped reduce the power consumed by finlets during swimming by 20.8% compared with non-pitching finlets. Moreover, the pitching finlets created constructive forces to facilitate posterior body flapping. Wake dynamics analysis revealed a unique vortex tube matrix structure and cross-flow streams redirected by the pitching finlets, which supports their hydrodynamic function in scombrid fishes. Limitations on modelling and the generality of results are also discussed.

Numerical Prediction Method of Resistance Performance of Catamaran Planing Vessels

2013 ◽  
Vol 344 ◽  
pp. 19-22 ◽  
Author(s):  
Hai Long Shen ◽  
Wei Lu ◽  
Yu Min Su
Keyword(s):  
High Speed ◽  
Optimization Design ◽  
Degrees Of Freedom ◽  
Prediction Method ◽  
Hydrodynamic Performance ◽  
Rans Equations ◽  
Six Degrees Of Freedom ◽  
Simulation Results ◽  
Planing Vessel ◽  
Resistance Performance

The classical approaches using CFD software to calculate the hydrodynamic performance of catamaran planing vessel still need to rely on the model test or empirical formula to make sure of the running attitude. So a theoretical calculate method of resistance performance of catamaran planing vessel is proposed in this paper based on RANS equations and the VOF method to couple six degrees of freedom equation of the catamaran planing vessel. Numerical simulation results indicate that using RANS equations can better forecast hydrodynamic performance of catamaran planing vessel at high speed, which provides a practicable numerical method for optimization design of the catamaran planing vessels hull.

Conceptual Design and Hydrodynamic Analysis of a High-Speed Sealift Adjustable-Length Trimaran

2008 ◽  
Author(s):  
K. J. Maki ◽  
L. J. Do ◽  
R. M. Scher ◽  
W. M. Wilson ◽  
S. H. Rhee ◽  
...  
Keyword(s):  
Conceptual Design ◽  
Model Test ◽  
High Speed ◽  
Test Program ◽  
Hydrodynamic Analysis ◽  
Numerical Predictions

This paper describes a novel adjustable-length trimaran design for service as a high-speed sealift vessel. Different numerical hydrodynamic tools were exercised to assess the performance of the vessel. An extensive model test program that included powering and seakeeping experiments was conducted to elucidate utility of the numerical predictions.

scholarly journals Test research on the resistance performance of high-speed trimaran planing hull

2013 ◽  
Vol 20 (4) ◽  
pp. 45-51 ◽  
Author(s):  
Weijia Ma ◽  
Huawei Sun ◽  
Jin Zou ◽  
Heng Yang
Keyword(s):  
High Speed ◽  
Model Tests ◽  
Hydrodynamic Performance ◽  
Test Results ◽  
Longitudinal Stability ◽  
Hull Form ◽  
Ship Model ◽  
Resistance Performance ◽  
Resistance Peak ◽  
Aerodynamic Lift

ABSTRACT In order to identify high-speed navigation ability of trimaran planing hull, as well as investigate the characteristics of its resistance and hull form, ship model tests were conducted to measure resistance, trim and heaving under different displacements and gravity centre locations. The test results were then used to study the influence of spray strips on resistance and sea-keeping qualities. Moreover, different planing surfaces were compared in the model tests which helped to look into influence of steps on hull resistance and its moving position. Also, the resistance features of monohull and trimaran planing hulls, both with and without steps, were compared to each other. From the tests it can be concluded that: the two auxiliary side hulls increase aerodynamic lift at high-speed motion, which improves the hydrodynamic performance; the trimaran planing hull has also excellent longitudinal stability and low wave-making action; when Fr∇ > 8, its motion is still stable and two distinct resistance peaks and two changes of sailing state (the second change is smaller) appear; spray strips are favourable for sea-keeping qualities at high speed. The change trends before the second resistance peak as to the resistance and sailing behaviour of trimaran planing hull without steps are the same as for monohull planing hull without steps. but when steps in both hulls exist the change trends are different; more specifically: trimaran planing hull with steps has only one resistance peak and its resistance increases along with its speed increasing, and the resistance is improved at the increasing speed as the number of steps increases.

Influence of Main Swirler Vane Angle on the Ignition Performance of TeLESS-II Combustor

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Bo Wang ◽  
Chi Zhang ◽  
Yuzhen Lin ◽  
Xin Hui ◽  
Jibao Li
Keyword(s):  
High Speed ◽  
Inlet Temperature ◽  
Main Stage ◽  
Ignition Process ◽  
High Speed Camera ◽  
Fuel Distribution ◽  
Fuel Droplets ◽  
Planar Laser ◽  
Cfd Method ◽  
Vane Angle

In order to balance the low emission and wide stabilization for lean premixed prevaporized (LPP) combustion, the centrally staged layout is preferred in advanced aero-engine combustors. However, compared with the conventional combustor, it is more difficult for the centrally staged combustor to light up as the main stage air layer will prevent the pilot fuel droplets arriving at igniter tip. The goal of the present paper is to study the effect of the main stage air on the ignition of the centrally staged combustor. Two cases of the main swirler vane angle of the TeLESS-II combustor, 20 deg and 30 deg are researched. The ignition results at room inlet temperature and pressure show that the ignition performance of the 30 deg vane angle case is better than that of the 20 deg vane angle case. High-speed camera, planar laser induced fluorescence (PLIF), and computational fluids dynamics (CFD) are used to better understand the ignition results. The high-speed camera has recorded the ignition process, indicated that an initial kernel forms just adjacent the liner wall after the igniter is turned on, the kernel propagates along the radial direction to the combustor center and begins to grow into a big flame, and then it spreads to the exit of the pilot stage, and eventually stabilizes the flame. CFD of the cold flow field coupled with spray field is conducted. A verification of the CFD method has been applied with PLIF measurement, and the simulation results can qualitatively represent the experimental data in terms of fuel distribution. The CFD results show that the radial dimensions of the primary recirculation zone of the two cases are very similar, and the dominant cause of the different ignition results is the vapor distribution of the fuel. The concentration of kerosene vapor of the 30 deg vane angle case is much larger than that of the 20 deg vane angle case close to the igniter tip and along the propagation route of the kernel, therefore, the 30 deg vane angle case has a better ignition performance. For the consideration of the ignition performance, a larger main swirler vane angle of 30 deg is suggested for the better fuel distribution when designing a centrally staged combustor.

scholarly journals Numerical Investigation on Hydrodynamic Performance of a Portable AUV

2021 ◽  
Vol 9 (8) ◽  
pp. 812
Author(s):  
Lin Hong ◽  
Renjie Fang ◽  
Xiaotian Cai ◽  
Xin Wang
Keyword(s):  
Numerical Investigation ◽  
Dynamic Model ◽  
Autonomous Underwater Vehicle ◽  
Dynamic Performance ◽  
Plane Motion ◽  
Hydrodynamic Performance ◽  
Wave Forces ◽  
Modeling And Control ◽  
Experiment Platform ◽  
Cfd Method

This paper conducts a numerical investigation on the hydrodynamic performance of a portable autonomous underwater vehicle (AUV). The portable AUV is designed to cruise and perform some tasks autonomously in the underwater world. However, its dynamic performance is strongly affected by hydrodynamic effects. Therefore, it is crucial to investigate the hydrodynamic performance of the portable AUV for its accurate dynamic modeling and control. In this work, based on the designed portable AUV, a comprehensive hydrodynamic performance investigation was conducted by adopting the computational fluid dynamics (CFD) method. Firstly, the mechanical structure of the portable AUV was briefly introduced, and the dynamic model of the AUV, including the hydrodynamic term, was established. Then, the unknown hydrodynamic coefficients in the dynamic model were estimated through the towing experiment and the plane-motion-mechanism (PMM) experiment simulation. In addition, considering that the portable AUV was affected by wave forces when cruising near the water surface, the influence of surface waves on the hydrodynamic performance of the AUV under different wave conditions and submerged depths was analyzed. Finally, the effectiveness of our method was verified by experiments on the standard models, and a physical experiment platform was built in this work to facilitate hydrodynamic performance investigations of some portable small-size AUVs.

Machine learning-based performance analysis of two-axial-groove hydrodynamic journal bearings

2021 ◽  
pp. 135065012199289
Author(s):  
Biswajit Roy ◽  
Sudip Dey
Keyword(s):  
Journal Bearing ◽  
Journal Bearings ◽  
Hydrodynamic Performance ◽  
Support Vector ◽  
Oil Viscosity ◽  
Hydrodynamic Analysis ◽  
Supply Pressure ◽  
Input Parameters ◽  
Precise Prediction ◽  
Output Behavior

The precise prediction of a rotor against instability is needed for avoiding the degradation or failure of the system’s performance due to the parametric variabilities of a bearing system. In general, the design of the journal bearing is framed based on the deterministic theoretical analysis. To map the precise prediction of hydrodynamic performance, it is needed to include the uncertain effect of input parameters on the output behavior of the journal bearing. This paper presents the uncertain hydrodynamic analysis of a two-axial-groove journal bearing including randomness in bearing oil viscosity and supply pressure. To simulate the uncertainty in the input parameters, the Monte Carlo simulation is carried out. A support vector machine is employed as a metamodel to increase the computational efficiency. Both individual and compound effects of uncertainties in the input parameters are studied to quantify their effect on the steady-state and dynamic characteristics of the bearing.

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