Generalized Treatment of Surface Deformation for High-Speed Computational Fluid Dynamic Surrogates

Calculation of the resistance and trim of highspeed boat at planning regime is a complex hydrodynamic problem. At the planning regime, with the aid of lifting force, the boat is lifted over the water surface with high trim angle. Many methods have been applied to calculate the resistance and the trim of the high-speed boat at this planning regime. This paper will study the two typical methods, the first one is empirical method by Savitsky [1] and the second one is the computational fluid dynamic method (CFD). The calculation results of two methods are compared with experimental results.

Download Full-text

High-Speed Passenger and Intercity Train Aerodynamic Computer Modeling

10.1115/imece2000-2147 ◽

2000 ◽

Author(s):

Samuel Holmes ◽

Martin Schroeder ◽

Elton Toma

Keyword(s):

United States ◽

Wind Speed ◽

Computational Fluid Dynamic ◽

High Speed ◽

Fluid Dynamic ◽

The United States ◽

Motion Simulation ◽

High Speed Train ◽

Aerodynamic Loads ◽

Train Speed

Abstract With the onset of high-speed passenger train service in the United States, the Federal Railroad Administration (FRA) and railroad agencies are concerned with the aerodynamic effects these trains will have on lightweight freight equipment, such as empty double stack container cars. This paper presents the results of a research project that evaluated this interaction. In this study we conducted a series of computational fluid dynamic (CDF) calculations to characterize the aerodynamic loads on a container consist passed by a high-speed train. A train motion simulation program was used to determine resultant motion and risk of overturning or derailment of the container consist. Numerous cases were studied in which train speed and wind speed and direction were varied.

Download Full-text

Three-dimensional computational fluid dynamic analysis of high-speed water-lubricated hydrodynamic journal bearing with groove texture considering turbulence

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650121998519 ◽

2021 ◽

pp. 135065012199851

Author(s):

Huihui Feng ◽

Shuyun Jiang ◽

Yanqin Shang-Guan

Keyword(s):

Computational Fluid Dynamic ◽

High Speed ◽

Journal Bearing ◽

Fluid Dynamic ◽

Load Capacity ◽

Three Dimensional ◽

Operating Conditions ◽

Computational Fluid Dynamic Analysis ◽

Hydrodynamic Journal Bearing ◽

Groove Texture

Water-lubricated bearings have attracted increasing attention in the field of high-speed machine tools for their low friction due to low viscosity. However, new problems, in particular, insufficient load capacity, are on the way. To the point, groove-textured journal bearing is adopted in this study. Aiming at investigating the effects of groove texture on high speed, water-lubricated, hydrodynamic journal bearing precisely, and thoroughly, three-dimensional computational fluid dynamic analyses considering cavitation and turbulence are undertaken to assess the tribological performances of the bearing. To reduce the amount of three-dimensional modeling and meshing work, mesh deformation is presented. The numerical results are compared with experiments to verify the validity of the present models and calculation procedures. Pressure distribution, load capacity, and friction of groove-textured water-lubricated journal bearing are analyzed with respect to operating conditions and geometric parameters. Comparisons between groove-textured water-lubricated journal bearing and smooth bearing are carried out to find out the influence of groove texture. It is found that the groove texture can achieve a remarkable improvement of load capacity at a smaller eccentricity ratio and higher rotary speed. The load capacity is affected by the combined effects of groove depth, width, and length. However, generally, the friction force of water-lubricated journal bearing is slightly influenced by groove texture. Results can provide theoretical guidance for the optimal design of groove-textured water-lubricated journal bearing under different operating parameters.

Download Full-text

Effect of the Addition of Hydrofoil on Lift Force and Resistance in 60 M High-Speed Vessel

Kapal ◽

10.14710/kapal.v17i3.28772 ◽

2020 ◽

Vol 17 (3) ◽

pp. 95-106

Author(s):

Izzuddin Nadzir Ismail ◽

Parlindungan Manik ◽

Mahendra Indiaryanto

Keyword(s):

Froude Number ◽

Computational Fluid Dynamic ◽

High Speed ◽

Lift Force ◽

Fluid Dynamic ◽

Model Analysis ◽

Total Resistance ◽

High Speeds ◽

Sea Transportation ◽

Resistance Value

The development of sea transportation technology is needed to meet the demand for ships that can carry heavier loads and operate at high speeds. Modifications in the form of additional hydrofoil variations were conducted to produce higher lift and reduce the resistance generated by the ship so that the ship can go more efficiently at high speed. This study aims to obtain the effect of adding hydrofoil to ships with variations in the type and shape of foil and find out which types and shapes can reduce resistance on the ship. This research was conducted with several model analysis tests using Computational Fluid Dynamic (CFD) based software, namely Tdyn, at several different speeds. The results of this study show that of the six variation models analyzed, rectangular fully submerged foil models can reduce the total resistance value of the ship by 17.822% from the original ship on Froude Number (Fr) 0.670. The type and shape of the foil is very influential on the lift and resistance produced by the ship.

Download Full-text

Decreasing Airflow Velocity in High Speed Hard Disk Drive by Using Spoiler

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1061-1062.862 ◽

2014 ◽

Vol 1061-1062 ◽

pp. 862-865 ◽

Cited By ~ 1

Author(s):

Waranya Kankaew ◽

Kiatfa Tangchaichit ◽

Jarupol Suriyawanakul

Keyword(s):

Hard Disk Drive ◽

Computational Fluid Dynamic ◽

Rotational Speed ◽

High Speed ◽

Fluid Dynamic ◽

Hard Disk ◽

Disk Drive ◽

Airflow Velocity ◽

Commercial Software ◽

Airflow Simulation

This research aims at presenting the airflow simulation within the high speed Hard Disk Drive by installing the device called Spoiler which helps to reduce the airflow velocity before colliding with the read/write head. Due to the high speed airflow within the hard disk drive, it directly impacts on the vibration of the read/write arm and consequently causing the damage and inaccuracy function of the read/write head. The rotational speed of the platter is specified at 20,000 rpm (round per minute). According to this study, the length of Spoiler is divided into 4 values which are 15, 20, 25 and 30 millimeters respectively. Thereafter, apply each length of the Spoiler to the commercial software called Computational Fluid Dynamic (CFD) by using K-epsilon model. The result shows that the length of Spoiler at 30 millimeters can reduce the average airflow velocity by 57.18%.

Download Full-text