OUTDOOR TESTS OF A TOWED BOAT MODEL WITH FUEL COMBUSTION IN A BOTTOM CAVITY

2020 ◽  
Author(s):  
S. M. FROLOV ◽  
◽  
S. V. Platonov ◽  
K. A. AVDEEV ◽  
V. S. AKSENOV ◽  
...  
Keyword(s):  
Drag Force ◽  
Direct Contact ◽  
Propulsion System ◽  
Hydrodynamic Drag ◽  
Atmospheric Air ◽  
System A ◽  
Bottom Cavity ◽  
Gas Cavity ◽  
System Power ◽  
Gas Supply

To reduce the hydrodynamic drag force to the movement of the boat, an artificial gas cavity is organized under its bottom. Such a cavity partially insulates the bottom from direct contact with water and provides “gas lubrication” by means of forced supply of atmospheric air or exhaust gases from the main propulsion system. A proper longitudinal and transverse shaping of the gas cavity can significantly (by 20%-30%) reduce the hydrodynamic drag of the boat at low (less than 3%) consumption of the propulsion system power for gas supply.

PULSED COMBUSTION OF FUEL-AIR MIXTURE IN THE CAVITY UNDER THE BOAT BOTTOM: SIMULATION AND OUTDOOR TESTS

2020 ◽  
Author(s):  
S. M. FROLOV ◽  
◽  
S. V. PLATONOV ◽  
K. A. AVDEEV ◽  
V. S. AKSENOV ◽  
...  
Keyword(s):  
Direct Contact ◽  
Hydrodynamic Drag ◽  
Atmospheric Air ◽  
Exhaust Gases ◽  
Gas Lubrication ◽  
Gas Cavity

For reducing the hydrodynamic drag of a boat, a gas cavity can be made under the boat bottom, which will partially isolate the bot- tom from direct contact with water and provide ¤gas lubrication¥ by forced supply of atmospheric air or exhaust gases from a boat motor.

Slip Length Measurement of Water Flow on Graphite Surface Using Atomic Force Microscope

2014 ◽  
Vol 941-944 ◽  
pp. 1581-1584 ◽  
Author(s):  
Da Yong Li ◽  
Da Lei Jing ◽  
Yun Lu Pan ◽  
Khurshid Ahmad ◽  
Xue Zeng Zhao
Keyword(s):  
Atomic Force Microscope ◽  
Water Flow ◽  
Drag Force ◽  
Silicon Surface ◽  
Slip Length ◽  
Graphite Surface ◽  
Length Measurement ◽  
Hydrodynamic Drag ◽  
Experimental Measurements ◽  
Atomic Force

In this paper, we present experimental measurements of slip length of deionized (DI) water flow on a silicon surface and a graphite surface by using atomic force microscope. The results show that the measured hydrodynamic drag force is higher on silicon surface than that on graphite surface, and a measured slip length about 10 nm is obtained on the later surface.

scholarly journals The North-South Gas Corridor in the Context of Poland’s Gas Transmission System—A Perfect Opportunity to Diversify Gas Resources

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7188
Author(s):  
Wiktor Hebda
Keyword(s):  
Energy Security ◽  
Field Research ◽  
Green Energy ◽  
Coal Production ◽  
The North ◽  
System A ◽  
State Of Affairs ◽  
High Level ◽  
Huge Challenge ◽  
Gas Supply

The energy sector in Poland is currently calling for dynamic redevelopment and cleaner energy. This country is world famous for its high level of coal production, from which it does not want to retreat in the next two decades. For this reason, it is safer to gradually reduce the use of coal while increasing the consumption of gas and simultaneously developing green energy. However, the Polish gas sector is still dependent on Russian gas supplied through the Yamal gas pipeline. Taking into consideration Polish geopolitics, this state of affairs poses a huge challenge and a threat to Poland’s energy security. That is why the concept of the North-South Gas Corridor was introduced. It is intended to be a network of gas pipelines that connect the countries of Central and South Europe to two gas terminals (in Poland and Croatia), which will supply gas from a chosen source. This article presents the current condition of the gas sector in Poland. It focuses on the North-South Gas Corridor project and its impact on the energy security of Poland. An analysis of documents and field research shows that the North-South Gas Corridor provides Poland with an opportunity to diversify the sources and directions of gas supply over the next few years.

Wave Devouring Propulsion System: From Concept to Trans-Pacific Voyage

2009 ◽  
Author(s):  
Yutaka Terao
Keyword(s):  
Propulsion System ◽  
Roll Motion ◽  
Wave Forces ◽  
Restoring Force ◽  
Hull Form ◽  
System A

In the spring of 2008, the Mermaid II began her historic voyage from Hawaii to Japan. According to the log of the vessel, the journey took 110 days and covered about 7800 km. The successful conclusion of the voyage demonstrated the possibility that Wave Devouring Propulsion System (WDPS) could be adapted to practical use. In order to capitalize on the success of this voyage, the author intended to design and tested a new WDPS hull within a year to build it. A WDPS is a thrust generator for a vessel that converts wave forces directly into forward thrust. Additionally it efficiently reduces hull pitch and roll motion, while also performing as a motion stabilizer. The Mermaid II, which is equipped with a WDPS, incorporates a specially designed catamaran hull form and twin hydrofoil system. A solid hydrofoil system that captures wave forces is set on the underside of the bow of the vessel. Those hydrofoils are connected to the hull with pin joints and are supported by soft springs that provide foil pitch restoring force.

SIMULATION STUDY ON NON-HOMOGENOUS SYSTEM OF NON-INVASIVE ERT USING COMSOL MULTIPHYSICS

2015 ◽  
Vol 77 (17) ◽  
Author(s):  
Yasmin Abdul Wahab ◽  
Ruzairi Abdul Rahim ◽  
Mohd Hafiz Fazalul Rahiman ◽  
Leow Pei Ling ◽  
Suzzana Ridzuan Aw ◽  
...  
Keyword(s):  
Finite Element ◽  
Simulation Study ◽  
Direct Contact ◽  
Comsol Multiphysics ◽  
Finite Element Software ◽  
Non Invasive ◽  
System A ◽  
Process Tomography ◽  
Gas Medium ◽  
Air Medium

The non-invasive sensing technique is one of the favourite sensing techniques applied in the process tomography because it has not a direct contact with the medium of interest. The objective of this paper is to analyse the simulation of the non-homogenous system of the non-invasive ERT using finite element software; COMSOL Multiphysics. In this simulation, the liquid-air medium is chosen as the non-homogenous system. A different analysis of the non-homogenous system in term of the different position of the single air, different size of the single air and the multiple air inside the vessel were investigated in this paper. As a result, the location, size and multiple air inside the pipe will influence the output of the non-invasive ERT system. A liquid-gas medium of non-homogenous ERT system will have a good response if the air is located near the source, the size of the air is large enough and it has multiple air locations inside the pipe.

Translation and rotation of a porous spheroid in a spheroidal container

2010 ◽  
Vol 88 (9) ◽  
pp. 689-700 ◽  
Author(s):  
E. I. Saad
Keyword(s):  
Drag Force ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Spherical Shape ◽  
Solid Sphere ◽  
Brinkman Equation ◽  
Hydrodynamic Drag ◽  
Particle Volume ◽  
Special Cases ◽  
Spheroidal Surface

The flow problem of an incompressible axisymmetrical quasisteady translation and steady rotation of a porous spheroid in a concentric spheroidal container are studied analytically. The same small departure from a sphere is considered for each spheroidal surface. In the limit of small Reynolds number, the Brinkman equation for the flow inside the porous region and the Stokes equation for the outside region in their stream functions formulations and velocity components, which are proportional to the translational and angular velocities, respectively, are used. Explicit expressions are obtained for both inside and outside flow fields to the first order in a small parameter characterizing the deformation of the spheroidal surface from the spherical shape. The hydrodynamic drag force and couple exerted on the porous spheroid are obtained for the special cases of prolate and oblate spheroids in closed forms. The dependence of the normalized wall-corrected translational and rotational mobilities on permeability for a porous spheroid in an unbounded medium and for a solid spheroid in a cell on the particle volume fraction is discussed numerically and graphically for various values of the deformation parameter. In the limiting cases, the analytical solutions describing the drag force and torque or mobilities for a porous spheroid in the spheroidal vessel reduce to those for a solid sphere and for a porous sphere in a spherical cell.

scholarly journals Numerical Study of Hydrodynamic Forces for AFM Operations in Liquid

Scanning ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Tobias Berthold ◽  
Guenther Benstetter ◽  
Werner Frammelsberger ◽  
Rosana Rodríguez ◽  
Montserrat Nafría
Keyword(s):  
Drag Force ◽  
Numerical Study ◽  
Viscous Friction ◽  
Hydrodynamic Drag ◽  
Water Mixture ◽  
Ultrapure Water ◽  
Liquid Environment ◽  
Drag Forces ◽  
Organic Sample ◽  
Repulsive Forces

For advanced atomic force microscopy (AFM) investigation of chemical surface modifications or very soft organic sample surfaces, the AFM probe tip needs to be operated in a liquid environment because any attractive or repulsive forces influenced by the measurement environment could obscure molecular forces. Due to fluid properties, the mechanical behavior of the AFM cantilever is influenced by the hydrodynamic drag force due to viscous friction with the liquid. This study provides a numerical model based on computational fluid dynamics (CFD) and investigates the hydrodynamic drag forces for different cantilever geometries and varying fluid conditions for Peakforce Tapping (PFT) in liquids. The developed model was verified by comparing the predicted values with published results of other researchers and the findings confirmed that drag force dependence on tip speed is essentially linear in nature. We observed that triangular cantilever geometry provides significant lower drag forces than rectangular geometry and that short cantilever offers reduced flow resistance. The influence of different liquids such as ultrapure water or an ethanol-water mixture as well as a temperature induced variation of the drag force could be demonstrated. The acting forces are lowest in ultrapure water, whereas with increasing ethanol concentrations the drag forces increase.

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