• International Journal of Naval Architecture and Ocean Engineering
• /
• v.12 no.1
• /
• pp.928-942
• /
• 2020

The pressure responsiveness property of a skirt-cushion system, which is closely related to the overall performance of Air Cushion Vehicles (ACVs), has always been the difficulty and challenging problem involving cushion aerodynamics and flexible skirt dynamics. Based on a widely used bag and finger skirt-cushion system, the pressure responsiveness properties are investigated numerically. The physical process and mechanism are analyzed and a numerical method for evaluating the pressure responsiveness property is proposed. A cushion-skirt information communication platform is also presented for interchanging the force and the skirt configuration between cushion aerodynamics and flexible skirt dynamics. The pressure responsiveness of a typical skirt-cushion system is calculated and the results demonstrate that the pressure responsiveness property helps alleviate the influence of the cushion height changing on the overall performance of ACVs. Finally, the influences of skirt geometrical and cushion aerodynamic parameters on the pressure responsiveness properties are discussed systematically, giving insight into the design of skirt-cushion systems.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.36 no.2
• /
• pp.179-193
• /
• 2012

The development of modern transportation technology has required many people in spaces (such as vehicle seats, airports, and train stations) for long periods. The public seats provided in these places are manufactured in a standard size; however, fatigue sets in if the seats are unsuitable for the person's physical size. For this reason, this study developed an air cushion vest that would enhance the comfort of vehicle seats. Passengers in vehicles, trains, airplanes, and buses were observed and surveyed to understand the demand for seat comfort. Our analysis found that the greatest source of discomfort was involuntary nodding of the head while asleep and discomfort around the waist area. For this reason, the air cushion vest was designed to support the head and the waist. The neck cushion of this vest was designed to strengthen head support to counter forward nodding because existing commercial neck cushions had no support for forward nodding. For the waist cushion, at lumbar and below-lumbar parts were chosen as the key parts to be supported, the cushion was designed to contain air at those parts. To cover the embedded waist cushion, the vest was designed to be long. The closure was constructed with zippers from the neck to waistline, and with invisible snaps from the waistline to the hemline so that the wearer could open them easily while seated. A subjective comfort evaluation was conducted to verify the effectiveness of the developed vest. In the test, the developed cushions received a better evaluation than cushions currently available on the market. The volume of the vest could be adjusted by the inflow and outflow of air. It was proven that the vest was effective in terms of comfort and portability. This shows that the developed vest could enhance passenger comfort while sitting on vehicle seats.

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.2
• /
• pp.241-249
• /
• 2008

In this study, lateral vibration analysis has been conducted on a propulsion and lift shafting system for an air cushion vehicle using ANSYS code. The shafting system is totally flexible multi-elements system including air propeller, aluminum alloy of lift fan and thin walled shaft with flexible coupling. The analysis included the lateral natural frequencies, mode shapes and harmonic analysis of the shafting system taking into account three-dimensional models for propulsion and lifting shaft system. In case of ACV the yawing and pitching rate of craft will be quite high. During yawing and pitching of craft significant gyroscopic moment will be applied to the shafting and will generate high amplitude of lateral vibration. So, such a shafting system has very intricate lateral vibrating characteristics and natural frequencies of shafting must be avoided in the range of operating revolution. The control of lateral vibration is included in this study.

• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.6
• /
• pp.768-776
• /
• 2007

In this study, axial vibration analysis has been conducted on a propulsion and lift shafting system for an air cushion vehicle using ANSYS code. The shafting system is totally flexible multi-elements system including wood composite material of air propeller. aluminum alloy of lift fan and thin walled shaft with flexible coupling. The analysis calculated the axial natural frequencies and mode shapes of the shafting system taking into account an equivalent mass-elastic model for shafting system as well as the three-dimensional models for propeller blade and fan impeller. Such a flexible shafting system has very intricate vibrating characteristics and especially, axial natural frequencies of flexible components such as propeller blade and impeller of lift fan can be lower to the extent that causes a resonance in the range of operating revolution. The results for axial vibration analysis are presented and compared with the results of axial vibration test for lift fan conducted during Sea Trial.

• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.4
• /
• pp.335-342
• /
• 2007

A propulsion and lift shafting system in an air cushion vehicle is flexible multi-elements system which consists of two aeroderivative gas turbines with own bevel gears, four stage lift fan reduction gear, two stage propulsion reduction gear air propellers and high capacity of lifting fans. In addition, the system includes the multi-branched shafting with multi-gas turbine engines and thin walled shaft with flexible coupling. Such a branched shafting system has very intricate vibrating characteristics and especially, the thin walled shaft with flexible couplings can lower the torsional natural frequencies of shafting system to the extent that causes a resonance in the range of operating revolution. In this study, to evaluate vibrational characteristics some analytical methods for the propulsion and lift shafting system are studied. The analysis, including natural frequencies and mode shapes, for five operation cases of the system is conducted using ANSYS code with a equivalent mass-elastic model.

• Journal of the Korean Professional Engineers Association
• /
• v.14 no.2
• /
• pp.18-22
• /
• 1981

• Selected Papers of The Society of Naval Architects of Korea
• /
• v.2 no.1
• /
• pp.29-46
• /
• 1994

In this paper, the effect of a skirt deformation on the responses of an Air Cushion Vehicle in waves is investigated. The air in the bag and plenum chamber is assumed to be compressible and to have a uniform pressure distribution in each volume. The free surface deformation is determined in the framework of a linear potential theory by replacing the cushion pressure with the pressure patch which is oscillating and translating uniformly. And the bag-finger skirt assumed to be deformed due to the pressure disturbance while its surface area remained constant. The restoring force and moment due to the deformation of bag-finger skirt from equilibrium shape is incorporated with the equations of heave and pitch motions. The numerical results of motion responses due to various ratios of the bag and cushion pressure or bag-to-finger depth ratios are shown.

• International Journal of Automotive Technology
• /
• v.6 no.3
• /
• pp.251-257
• /
• 2005

Several air cells are installed in the seat cushion to adjust the stiffness of seat by changing the air pressure. To select proper air pressure in the air cells, two kinds of tests are performed. For the pressure distribution on the seat, the maximum pressure and mean pressure are compared. And for the dynamic ride values, SEAT (Seat Effective Amplitude Transmissibility) values are calculated and compared. These experiments are carried out with three different drivers, three different vehicle speeds on the highway and two different speed on the primary road, and three different air pressures. From the real car tests, optimum air cell pressure depending on the vehicle speed and driver's weight are recommended.

• Journal of the Korean Professional Engineers Association
• /
• v.34 no.3
• /
• pp.46-51
• /
• 2001

Patent Technology Map analysis of future ship type. Example ship type : Hydrofoil Craft. Air Cushion Vehicle Surface Effect Ship, Twin Hull Ship, Wing In Ground Effect Ship, Elelctrial Propulsion Ship, Icebreaking Ship, Submarine, LNG Ship Conclusion of future shipbuilding Technology Policy

• Ocean Systems Engineering
• /
• v.1 no.1
• /
• pp.17-28
• /
• 2011

The purpose of this paper is to demonstrate the efficacy of modeling a surface effect ship's air-cushion flexible seal utilizing a two-dimensional beam under steady state conditions. This effort is the initial phase of developing a more complex three-dimensional model of the air-seal-water fluid-structure interaction. The beam model incorporates the seal flexural rigidity and mass with large deformations while assuming linear elastic material response. The hydrodynamic pressure is derived utilizing the OpenFOAM computational fluid dynamic (CFD) solver for a given set of steady-state flow condition. The pressure distribution derived by the CFD solver is compared with the pressure required to deform the seal beam model. The air pressure, flow conditions and seal geometry are obtained from experimental analysis. The experimental data was derived from large-scale experimental tests utilizing a test apparatus of a canonical surface effect ship's flexible seal in a towing tank over a variety of test conditions.