Amazing Hydromechanics

By V. I . Merkulov

In this book the basic laws of hydrodynamics, the science on liquid and gas flow, are considered in a popular form. Airplanes and ships, birds and dolphins, blood vessels and pipelines are among the research targets of this science. Application of various laws is demonstrated on numerous examples taken from the ambient life.
Description of the existing potential of hydrodynamics, novel technology solutions and inventions may kindle interest of many readers.
The monograph is very well illustrated that both complements the book and facilitates its understanding.
An adult reader will benefit from reading this book by broadening his horizons and discovering unknown facts. Boys and girls will further in choosing a profession that may become their fate.

• Language: English
• Publisher: AuthorHouse
• Release date: Aug 16, 2012
• ISBN: 9781477258835

V. I . Merkulov

Vladimir I. Merkulov Professor Vladimir I. Merkulov is a Doctor of Physical and Mathematical Sciences and Leading Research Fellow of the Institute of Theoretical and Applied Mechanics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia. V. Merkulov was born in South Ural (USSR) in February 1930. He graduated from Physics and Mathematics Department of Rostov State University in the city of Rostov-on-Don in 1953 and took a post-graduate course at the Institute of Mathematics of the USSR Academy of Sciences in 1958. V. Merkulov received his Ph.D. in Physics and Mathematics in 1960 and became a Doctor of Physics and Mathematics in 1972. Prof. Merkulov started his career in 1958 as an Assistant Professor at Hydromechanics Department of Kiev State University. From 1963 to 1978 he worked as Head of Laboratory on Process Control in Solid Medium at the Institute of Cybernetics, Ukrainian Academy of Sciences, Kiev, Ukraine. Over a period from 1978 to 1990 Prof. Merkulov headed the Laboratory on Fluid Flow Control at the Institute of Theoretic and Applied Mechanics, Siberian Branch of the Russian Academy of Science, Novosibirsk, Russia. Since 1990 up to present time Prof. Merkulov has been working as a Leading Research Fellow of the same Institute. Prof. Merkulov is a well known expert in the field of internal gravitational waves (buoyancy waves) in atmosphere and in vortex chambers. He has supervised scientific works of 12 Ph.D.s, 2 Doctors of Sciences and one Full Member of the Ukrainian National Academy of Science. He is an author of more than 100 publications and patents, including 4 books published in Russian. Some of his publications are devoted to physics of various natural phenomena: Popular Hydrodynamics, Buoyancy Waves as a Heat Pump, Tornado and Elasticity of Discrete Vorticity, Electrogravidynamic Model of UFO, Tornado and Tropical Hurricane, etc. «Amazing Hydromechanics» is his first book published in English. It tells about basic laws of hydrodynamics and science of liquid and gas flows in a comprehensible form. Airplanes and ships, birds and dolphins, blood vessels and pipelines are among the author’s research objects. Application of various laws is demonstrated on numerous examples taken from the ambient life. Description of the existing potential of hydrodynamics, novel technology solutions and inventions may kindle interest of many readers. The monograph is very well illustrated that both complements the book and facilitates its understanding. An adult reader will benefit from reading this book by broadening his horizons and discovering unknown facts. Boys and girls will further in choosing a profession that may become their fate.

Book preview

© 2012 by V. I . Merkulov. All rights reserved.

No part of this book may be reproduced, stored in a retrieval system, or transmitted by any means without the written permission of the author.

Published by AuthorHouse 08/10/2012

ISBN: 978-1-4772-5889-7 (sc)

ISBN: 978-1-4772-5882-8 (hc)

ISBN: 978-1-4772-5883-5 (e)

Library of Congress Control Number: 2012914568

Any people depicted in stock imagery provided by Thinkstock are models, and such images are being used for illustrative purposes only.

Certain stock imagery © Thinkstock.

Because of the dynamic nature of the Internet, any web addresses or links contained in this book may have changed since publication and may no longer be valid. The views expressed in this work are solely those of the author and do not necessarily reflect the views of the publisher, and the publisher hereby disclaims any responsibility for them.

In this book the basic laws of hydrodynamics, the science on liquid and gas flow, are considered in a popular form. Airplanes and ships, birds and dolphins, blood vessels and pipelines are among the research targets of this science. Application of various laws is demonstrated on numerous examples taken from the ambient life.

Description of the existing potential of hydrodynamics, novel technology solutions and inventions may kindle interest of many readers.

The monograph is very well illustrated that both complements the book and facilitates its understanding.

An adult reader will benefit from reading this book by broadening his horizons and discovering unknown facts. Boys and girls will further in choosing a profession that may become their fate.

Contents

Preface

1    Hydrostatics

1.1    Basic equation of hydrostatics

1.2    Pascal law

1.3    Surface tension

1.4    Hydrostatics at zero-gravity

1.5    Equilibrium of ships

1.6    High-speed yachts

1.7    Aerostatics

1.8    The ship of desert

1.9    Pneumatic wheel

1.10    Aerostatic gas transportation

1.11    Helistat

2    Air Cushion

2.1    How to move the fridge

2.2    Ski skims over the air

2.3    Air castor vehicle

2.4    Why does the wheel skid?

3    Aeroelasticity

3.1    The arrow hits the target

3.2    Flutter

3.3    Static and dynamic stiffness of construction

3.4    Damping of elastic oscillations

4    The man is WALKING

over the water

4.1    Calm applause under the water

4.2    Added mass

4.3    One can run over the water

4.4    Running over a thin ice

4.5    Crossing without a bridge

4.6    Secrets of squid’s floating

5    Dynamic effects in liquid and gas

5.1    The energy conservation law

5.2    Water pours out of a vessel

5.3    Boiling of cold water

5.4    Measuring the flow velocity

5.5    Collisions between the marine ships

5.6    A ball SUSPENDED in air

5.7    The magnus effect

5.8    Flettner ship

5.9    Meteor burns in air

5.10    Whirlwind and tornado

1.11    Electric-gravidynamic model of tornadoes and tropical hurricanes

Gravitational and electromagnetic analogies

Atmospheric electricity

UFO and ball lighting are the inhomogeneity of the physical vacuum

Tornados and tropical cyclones

Conclusion

6    Viscous liquid

6.1    Oil the wheels to get good deals

6.2    Hydrodynamic resistance

6.3    The paradox of d’alembert

6.4    Non-newtonian fluids

6.5    Elasticity of blood and waves in capillary vessels

7    Hydrodynamic machines

7.1    Airscrew

7.2    Water propeller

7.3    Hydroturbine

7.4    Buoy and channel hydrogenerators

7.5    Torque CONVERTER

7.6    Hydroblow

7.7    Pulsating water jet

7.8    Generator of air vortices

7.9    Wind power installations: insects against dinosaurs

8    The wave washes away the city

8.1    The origin of wave

8.2    Wave runs and water remains

8.3    Composition of the waves

8.4    Waves feel the seafloor

8.5    Tsunami

8.6    Waves in the internal fuel tank of the rocket

8.7    Hydrofoil craft

8.8    How to use the wave

9    Hydrodynamics of animals

9.1    CHAMPIONS of underwater swimming

9.2    Natural movers

9.3    Flapping wing

9.4    The secrets of high speed

9.5    The secret of fast and thrifty swimming of a swordfish

10    Flight in wildlife

10.1    Gliding FLIGHT

10.2    Sailing flight

10.3    Flapping flight

10.4    Pneumatic accumulating irrigation system

10.5    Subsurface air-water irrigation

11    Magnetic hydrodynamics

11.1    Magnetic hydrodynamic pump

11.2    MHD-thruster

11.3    Crucibleless melting

11.4    Crucibleless zonal melting

11.5    MHD generatior

11.6    Nuclear MHD generatiors

11.7    Djinn in a magnetic bottle

11.8    Thermonuclear fusion

11.9    Pinch-effect

11.10    Stability of plasma filament

11.11    Temperature stratification in the atmosphere and a vortex chamber

Prospects of hydromechanics

List of recommended literature

Preface

There are many various interesting sciences. Each science ontributes to the human progress. And there is no one science, one could manage without. And in this sense all sciences are equal.

Many scientists work with great enthusiasm in their specific research areas. Years of hard work are domed by magnificent discoveries and defeats give place to victories. Probably everyone considers his science and his problem to be the most interesting and most important. Without such conviction they unlikely would be able to derive strength to overcome the difficulties that are hidden by nature on the way to its secrets.

And what is the attitude toward various sciences of those who are just preparing to start dealing with science? Their attitude is formed partly based on the knowledge gained at school, and partly drawing information from factual books, newspapers, magazine articles or movies.

Here we face disparity in sciences. While many books and movies are devoted to certain sciences, and they are glorified with romantic appeal, the others remain in the shadow. Curiously enough, but aerohydrodynamics, the science about liquid and gas flow, belongs to the latter ones. This circumstance is even more surprising because the objects studied in aerohydrodynamics surround us everywhere. Everything around us and we are moving either in the air (birds, cars, airplanes, etc.) or in the water (fish, dolphins, submarines, and ships). Man has to study air and ocean currents, tidal and wind waves, oil and gas flows in the long-distance tubes, blood flow in the microscopic blood vessels.

Everyone knows that designs of an aircraft or hydrofoil craft owe to achievements in aerohydrodynamics. But just few people know that the problem on descending of spacecraft into the atmosphere of the Earth or another planet can be solved by hydrodynamics as well. Design of spacecraft engine 15 million kW in capacity, capable to pull out the man from the strong embraces of the Earth, is the success of not only designers, metallurgists, chemists, but the aerodynamicists as well. And if over the times people will be able to get control over the thermo-nuclear energy, then this would merit not only physicists, but also hydro-mechanists.

Fluid mechanics, like any other science, was originated and is developing driven by practical needs. Responding to problems of ancient ship builders, Archimedes (287-212 years B.C.) formulated the laws of buoyancy and sustainability of floating bodies. Construction of canals, dams, sluices, fountains, the further development of ship building and navigation in the XVII-XVIII centuries served as a major incentive for the development of fluid mechanics. It was at this time the members of the St. Petersburg Academy of Sciences Daniel Bernoulli (1700-1782) and L. Euler (1707-1783) published their fundamental works. Bernoulli introduced the term fluid dynamics, and his book which was published in 1738 was given the same title. Euler derived the general equation of motion for inviscid fluid, which we use to date.

Origin and development of aviation in the late XIX and early XX centuries initiated expansion of the works in aircraft aerodynamics. Here, first of all, we should mention Professor Zhukovskii (1847-1921), the father of Russian aviation. Zhukovsky formulas and profiles still play an important role in aerodynamics.

Thirst for knowledge has always encouraged people to seek truth, perception of the nature of phenomena, often ahead of technical capabilities and practical demands of society.

What a great and wonderful world is opened up to artist, poet, or writer! But it will be even more beautiful and amazing, if you look at the world with the eyes of a scientist. For example, a bird leaving in the clouds will tell you about the laws of aerodynamics, the wave incident to the shore will be a good illustration to the theory of oscillations. How interesting is it—to see the essence of the process behind its external manifestation.

This book is not a systematic presentation of the concerned science. It is written in the form of independent studies on various topics of hydro- and aerodynamics, and introduces to the reader just some of the problems.

Presentation starts with the simplest problems being already solved. But even these problems have interesting and untapped latent opportunities. In these sections the author is trying to explain not only what is being done, but also how it’s being done. According to the presented formulas the reader can, if desired, verify the results or perform calculations himself. In the following sections author attracts attention only to actual problems still existing in hydrodynamics.

Just as one can not compose a symphony without resorting to note signs, so it is impossible to talk about air and fluid dynamics without resorting to mathematical formulas. In each chapter of the book, except for the laws of hydrodynamics and their physical manifestations, author proposes engineering solution to one or another problem.

A few words about the terminology used. Mechanics is the science which studies the movement and balance of material bodies under the action of various forces. By adding word hydro (water) we separate the part of mechanics that studies the movement of fluid or fluid flow. Historically hydromechanics dealt not only with fluids, but with gases as well. This is owing to the proximity of the motion laws for liquids and gases in case if gas velocity is less than the sonic speed (sonic speed in air is 340 m/s). As far as the speeds in aviation were grown, fluid mechanics gave origin to air mechanics and gas dynamics which are accounting for gas compressibility.

In cases where equilibrium (static) is excluded from consideration and only the motion under the action of certain forces (dynamics) is considered, we use the term hydrodynamics, aerodynamics, or combination thereof.

This book is supplemented and revised edition of the previous book Popular Hydromechanics published by Ukrainian State Publishing House Technika in 1976. The new title of the book appeared as a result of responses from readers of the first edition. Experts in hydromechanics highlighted the main feature of the first book—discovery of yet unknown opportunities and application areas of hydromechanics. However, they almost always expressed their doubts concerning the feasibility of the proposed technical solutions. To justify these solutions to some extent, the author, in many cases has led some simple mathematical calculations to prove the practical attainability of proposals, looking incredible at the first sight. Some chapters of the book are described in more detail. The book is supplemented by new sections such as Aeroelasticity, Windspout-tornado, and Helistat.

1    Hydrostatics

1.1    Basic equation of hydrostatics

It is natural to start introduction to fluid mechanics with its most simple part namely hydrostatics. And though the problems related to liquid and gas equilibrium are indeed more simple than the problems of motion, the range of these problems is rather extensive and exiting.

The simplest task of hydromechanics arises, if we want to understand what are the forces applied to the water in the glass (Fig. 1).

image002.jpg

Fig. 1. An arbitrary liquid column is in equilibrium produced by the pressure and gravity forces.

Let cut out a vertical column of water with a cross-section S. This column will be subjected by atmospheric pressure, which we denote as P0. Over the area S this pressure will cause the force pnS. The weight of the liquid column will be directed to the same direction. If the letter q denotes the fluid density, the letter g-acceleration of gravity and the letter h—the height of the column, then its weight can be defined as the following product ghS.

The fact that the liquid column does not fall down evidences the existence of pressure at the bottom of the column, which balances the force directed downward. This pressure is called hydrostatic pressure. Let denote it as p. Then the equilibrium condition of the liquid column will be written as:

SKU-000596407_TEXT.pdf

As expected, the area S is included in above equation as a common factor and can be reduces. Usually, co-ordinate of the point at which one wants to determine the pressure p is introduced instead of column height h. Taking this coordinate downwards from the free surface of liquid we obtain a negative value, which is denoted by z= - L. Introducing this notation and reducing the equation (1) by S, we will obtain the basic equation of hydrostatics:

SKU-000596407_TEXT.pdf

If the point with coordinate z is situated on the bottom of the glass, then р will be the pressure at the bottom. In general р is the pressure at the level z.

In contrast to the solid body the specificity of the liquid is that the pressure in the liquid does not depend on the orientation of the elementary area where pressure is being considered. Each column is subjected to the same lateral pressure which is balanced by the pressure of adjacent columns or pressure on the walls of the glass.

image004.jpg

Fig. 2. The water in the overturned glass is held by the atmospheric pressure. The sheet of paper prevents the water surface from inclination.

To better understand the laws of hydrostatics, let carry out the following test. Let pour the water into the glass to its top. Cover it with sheet of paper and, holding the paper with your palm, turn the glass upside down. Then release the palm. The water remains in the glass as if it was based on the bottom.

This test can be easily explained using equation (2). Let rewrite it in a following manner:

SKU-000596407_TEXT.pdf

Just note that in the inverted glass the coordinate z is taken from the free surface upwards and thus always is positive.

Analyzing the equation we may conclude that the pressure in the water should reduce with increase in coordinate z. However if the weight of the column gz is less than atmospheric pressure р0, the pressure р will remain positive, though less than atmospheric. Positive value of internal pressure in the liquid means presence of the forces compressing the liquid. These forces hold the liquid in the overturned glass.

From equation (2) we can determine column height which can be hold by atmospheric pressure.

It is evident that when

SKU-000596407_TEXT.pdf

water will pour our. Hence

SKU-000596407_TEXT.pdf

Substituting numerical values of р0 = g -10332 N/m2, = 1000 kg/m3, we get

SKU-000596407_TEXT.pdf

It follows from this calculation that, for example, pumping water from the well deeper than 10 m could be possible only by means of pump submerged into the well.

Let go back to formula (3). If we apply this formula to the liquid with the density higher than that for water, than value z will be less. Thus, for the mercury = 13 600 kg/m3 and z = 0.76 m.

Owing to the low column height at which mercury rises up, it is easy to carry out experiments on atmospheric pressure using mercury. To do this, let perform an imaginary experiment. Let fill with the mercury a thin glass tube more than 760 mm in length soldered at one end, close the hole from the other end with finger and submerge this end into the vessel with mercury. The height of mercury in a glass tube will show the atmospheric pressure in conventional units namely millimeters of mercury column.

From equation (3) we can derive both Archimedes and Pascal laws. But since the reader is familiar with these laws from school-time physics tuition, we will not consider derivation of these laws yet consider their applications.

1.2    Pascal law

Let us think why in the hydraulic machines we usually use the oil instead of water. It seems like for the purpose of cost efficiency we must use water. Also water corresponds more exactly to the name of the machine. As you might guess, the oil is used because on the one hand, it behaves like a liquid and transmits the pressure to all directions, and on the other hand, behaves like lubricant, which seals the gaps between the moving and immovable parts of the mechanism. The latter property displays only in case if the gap is small enough. Therefore, the joint parts of machines are treated very precisely, with a high grade of finish.

The reader must have seen on the city streets machine with telescopic mechanism intended for lifting the basket with the man to a certain height. The car stops. Steel tubes inserted one into another are installed vertically. After that, the pump starts to pump oil to the lower part of these tubes and the tubes, one by one move upwards. The basket with the man is fixed to the upper tube (the most thin one).

image008.jpg

Рис. 3. Car telehoist.

It would be great to take some concrete pipes, put them into each other, direct them vertically and pump the liquid into the pipes to make them moving up to the unprecedented height. But this dream never can come true because concrete tubes and even welded tubes are manufactured with rather low accuracy. Nested into each other they form such a gap that whole oil flows out through these slits. Stop! And why, actually, we have to use the oil? Is it possible to apply a different fluid which will seep through the gaps between the pipes quite slowly to allow pumps to feed liquid? Obviously, this fluid must have a high viscosity, such as pitch. But in this case we will face another problem. What kind of pump will be able to pump this pitch?

So, we need fluid, which would have a low viscosity when flowing inside the pump and have rather high viscosity when in the gaps between the pipes. It is quite appropriate to recall here some of the mud, which has the property of so-called thixotropy. This solution when mixing exhibit very low viscosity while at rest it turns into solid matter. Such clay solutions currently are used at drilling wells.

The use of thixotropic muds can solve the problem of vertical installation of concrete pipes (Fig. 4). Assume that there are ten concrete pipes each 10 m long having diameter which subsequently decreases from one tube to another. They are nestled in each other. Employing conventional construction and assembly mechanism these pipes are installed vertically on the prepared foundation, where the outer tube is rigidly fixed with cement mortar. Then radio or TV antennas or even a restaurant can be mounted on the top of the tube with smallest diameter. All this occurs at a height of 30 m and does not require any special lifting tools. After installation of the equipment, mud solution is pumped into the gap between the foundation and inner tubes. In the pump and in the pipeline, where the solution is intensively mixed, it behaves like a liquid with low viscosity. But in the gaps between the pipes, which are slowly moving relative to each other, the solution becomes almost solid, and internal pressure cannot push it through the slit. At that, the internal pressure can exceed the weight of the pipes, and they will start moving up gradually coming out from each other.

Even if their relative motion will be just 1 mm/s (at this sliding velocity liquid will not flow into the gap), less than 10 hours will be needed to rise the whole structure at the level of almost 300 m. In this position, the pipes are fixed by means