erosion material .

Keywords: Erosion, turbines, pipes

1. Introduction

A multidisciplinary field concerned with the generation and application of knowledge relating to the composition, structure, and processing of materials to their properties and uses. This field needed the complete knowledge of material behavior. It forms a bridge of knowledge from the basic sciences to various engineering disciplines.

The study of metallic materials constitutes a major division of the materials science and engineering field. Most metals have a crystalline structure of closely packed atoms arranged in an orderly manner. In general they are good electrical and thermal conductors. Many are relatively strong at room temperature and retain good strength at elevated temperatures. Metals and alloys are often cast into the nearly final shape in which they will be used as different parts of fluid machinery. Ferrous metals and alloys contain iron as their major metallic element; nonferrous metals and alloys contain elements other than iron as their major metallic element. 

Erosion is described as the progressive loss of original material from a solid surface due to mechanical Interaction between the surface and a fluid which may be a multi-component fluid or impinging solid or liquid Particles. Corrosion is a material degradation process which occurs due to chemical or electrochemical action, while erosion is a mechanical wear process.^[1] But my study is based upon the only erosion. The erosion rate of blades is 10 times greater than the erosion wear of hub. The erosion rate is found to be more severe near the leading edge as compared to other parts of impeller. The simulations which were carried out on impeller show that particle size affects the erosion rate only up to certain size of particles and depends on the impact angle. Slurry is a mixture of solids and liquids. Its physical characteristics are dependent on many factors such as size and distribution of particles, concentration of solids in the liquid phase, size of the conduit, level of turbulence, temperature, and absolute (or dynamic) viscosity of the carrier. Microstructure investigation was carried out in order to reveal the nature of damage of the specimen under various test conditions using a scanning electron microscope. Although several factors influence the formation of deposits on turbine components, the general effect is the same no matter what the cause. Adherent deposits form in the water passage, distorting the original shape of turbine nozzles and blades. These deposits often rough or uneven which are at the surface increase resistance to the flow of steam. Distortion of water passages alters water velocities and pressure drops, reducing the capacity and efficiency of the turbine. Where conditions are severe, deposits can cause excessive rotor thrust. Uneven deposition can unbalance the turbine rotor, causing vibration problems.

COBRA AND THE CROW

Somewhere in the country, under a banyan tree, there lived a pair of crows, husband and wife.
Now, whenever the female hatched her eggs, a black cobra would come out of the hollow of the tree, climb up, and make a meal of them.
Nearby, under another banyan tree, there lived a jackal.
The crows told him everything,

'Friend', they said, 'the black cobra creeps out of the hollow of the tree, climbs up and eats up our children.
Tell us, what can we do to protect our children ? It's become dangerous for us to live here'.

'Don't give up hope', said the jackal, 'it is a fact that a powerful enemy can be destroyed by a trick.'
The crow said, 'Friend, do tell us how we can kill this wicked cobra.'

'Well', said the jackal, 'go to a city that is the capital of a kingdom.
Visit the house of some wealthy man, a minister or someone, and see if he has been careless enough to leave a gold chain or a necklace lying about.

Pick it up, and making sure that the servants are watching you, fly off slowly with it and drop it in the hollow of the tree where the cobra lives.
When the servants run after you to recover the necklace , they'll see the cobra e and it's certain, they'll kill him.'

The crows decided to take the jackal's advice and flew off.
As they were flying, the female crow noticed a lake, in which the women of the harem were swimming.

They had left gold and pearl necklaces with their clothes on the banks of the lake.
The female crow picked up a gold chain in her beak and started flying slowly to her nest.

When the eunuchs saw this, they picked up their sticks and started running after the female crow.
She let the gold chain fall near the hollow of the tree where the cobra lived and seated herself on a tree nearby.

When the king's servants arrived on the scene, they were confronted by a cobra with swelling hood, before the hollow of the tree.
They killed the cobra with sticks, recovered the gold chain and returned home.
And the crows lived happily ever

The wise indeed say: Even a very powerful enemy can be destroyed through deceit.

DONKEY WHO SANG A SONG

DONKEY WHO SANG A SONG

Once upon a time, there lived a washerman in a village. He had a donkey by the name of Udhata. He used to carry loads of clothes to the river bank and back home everyday. 

The donkey was not satisfied with the food, that was given to him by his master to eat. So he wandered into the nearby fields stealthily and ate the crops growing there. 

Once, the donkey, while wandering around, happened to meet a fox. Soon, both of them became friends and began to wander together in search of delicious food. 

One night, the donkey and the fox were eating water-melons in a field. The water-melons were so tasty, that the donkey ate in a large quantity. Having eaten to his appetite, the donkey became so happy that he was compelled by an intense desire to sing. He told the fox that he was in such a good mood that he had to express his happiness in a melodious tone. "Don't be a fool. If you sing, the people sleeping in and around this field will wake up and beat us black and blue with sticks:' said the fox worriedly. 

"You are a dull fellow", the donkey said hearing the words of fox. "Singing makes one happy and healthy. No matter what comes, I'll definitely sing a song." 

The fox became worried to see the donkey adamant to sing a song in the midst of the field, while the owner was still sleeping only a little distance away. 

Seeing his adamance, he said to the donkey, "Friend, wait a minute before you start. First, let me jump over to the other side of the fence for my safety." 

Saying so the fox jumped over to the other side of the fence without losing a moment. 

The donkey began in his so-called melodious tone. Hearing, suddenly, a donkey braying in the field, the owner woke up from his sleep. He picked up his stick lying by his side and ran towards the donkey who was still braying happily. The owner of the field looked around and saw the loss caused by the donkey. He became very angry and beat him so ruthlessly that the donkey was physically incapacitated temporarily. He, somehow, managed to drag himself out of the field with great difficulty. 

The fox looked at the donkey and said in a sympathetic tone, "I'm sorry to see you in this pitiable condition. I had already warned you, but you didn't listen to my advice." 

The donkey too realised his folly and hung his head in shame.

HOLY MAN AND A SWINDLER

Once upon a time, in a lonely temple there lived a holy man called Dev Sharma. Many people used to visit him and present him with money and finely woven garments, which he sold and got very rich on the proceeds.

And by nature, he trusted nobody.

Night and day he kept the treasure purse under his armpit and would not part with it even for a second.

A swindler, who robbed other men of their money, noticed that the holy man always kept the treasure purse under his armpit.

He said to himself, 'How could I rob this holy man of his money! It's difficult to make a hole through the walls of the temple or to get in over the high gates, so what I'll do is, charm him with honeyed words so that he accepts me as his disciple.

And when he has put confidence in me, some day he'll fall into my clutches.'

When he had resolutely made up his mind, to carry out this plan, the swindler i approached the holy man, stood before him with reverence and said, 'Om Namaha Shivaya!'( I bow before Lord Shiva, the God of death)

With these words he threw himself humbly on the ground before the holy man and said, 'Oh Guruji! I am fed up of this life. Please do guide me so that I follow the right path in this life and find happiness .'

When the holy man heard this, he said kindly, 'My son, you are indeed blessed that you have come to me at this young age, surely I will guide you.'

When the swindler heard this, he fell on the ground before the holy man, touched his feet, and said, 'Oh, Guruji, please do accept me as your disciple.'

'My child! answered the holy man 'I will, but on one condition, that you will never enter the temple at night, because a holy man is recommended to stay alone at night without company and meditate . We will keep to it, you and I.'

'And so', continued the holy man, 'after taking the vow of initiation, you will have to sleep in a thatched hut at the gate of the temple.'

'I shall willingly carry out your wishes', said thr swindler

At bedtime, the holy man initiated the swindler according to the rituals and made him his disciple. The swindler massaged his hands and feet, waited upon him and made him happy but nonetheless the holy man did not part with his money bag even for a second.

After some time, the swindler began to think, 'He does not trust me at all! Shall I knife him in broad daylight, poison him or kill him like a wild animal?'  While he was thinking this over, the son of one of the holy man's disciples, from a nearby village, came to give him a personal invitation and said, 'Guruji,! Today the ceremony of the sacred thread takes place in our house.

Please come and sanctify it with your presence.'

The holy man accepted the invitation willingly and started off accompanied by the swindler

On the way, they came to a river.When the holy man saw the river, he folded his money bag in his robe and said, ' Oh my child! Look after this robe with the vigilance of a Yogi until I return.'

And he went into the bushes.The minute the holy man's back was turned, the swindler vanished with the money bag.After the holy man had answered the call of nature, he slowly returned, thinking about his money.When he got back, he failed to find the swindler but saw only his robe, lying on the ground.He peered anxiously inside but could not find his purse. He began to cry out, 'Alas! I have been robbed'. And he fell on the ground in a swoon.After sometime he returned to his senses.

He got up and began to shout ' Oh! Where are you, you rascal! Answer me!'

After he had shouted like this in a loud voice, he slowly trailed the swindler's footsteps until, just before evening, he came to a village.He stayed there for the night and in the morning, returned to his temple.

This wise indeed say : Do not be taken in by the sweet words of a swindler.'

THE PEDIA OF PANCHTANTRA

The Panchatantra (IAST: Pañcatantra, Sanskrit: पञ्चतन्त्र, !پنچ تنتر}} 'Five Principles') is an ancient Indian inter-related collection of animal fables in verse and prose, in a frame story format. The original Sanskrit work, which some scholars believe was composed in the 3rd century BCE,^[1] is attributed to Vishnu Sharma. It is based on older oral traditions, including "animal fables that are as old as we are able to imagine", including the Buddhist Jataka Tales.^[2][3] It is "certainly the most frequently translated literary product of India",^[4] and these stories are among the most widely known in the world.^[5] To quote Edgerton (1924):^[6]

…there are recorded over two hundred different versions known to exist in more than fifty languages, and three-fourths of these languages are extra-Indian. As early as the eleventh century this work reached Europe, and before 1600 it existed in Greek, Latin, Spanish, Italian, German, English, Old Slavonic, Czech, and perhaps other Slavonic languages. Its range has extended from Java to Iceland… [In India,] it has been worked over and over again, expanded, abstracted, turned into verse, retold in prose, translated into medieval and modern vernaculars, and retranslated into Sanskrit. And most of the stories contained in it have "gone down" into the folklore of the story-loving Hindus, whence they reappear in the collections of oral tales gathered by modern students of folk-stories.

Thus it goes by many names in many cultures. In India, it had at least 25 recensions, including the Sanskrit Tantrākhyāyikā^[7] (Sanskrit: तन्त्राख्यायिका) and inspired the Hitopadesh. It was translated into Middle Persian in 570 CE by Borzūya. This became the basis for a Syriac translation as Kalilag and Damnag^[8] and a translation into Arabic in 750 CE by Persian scholar Abdullah Ibn al-Muqaffa as Kalīlah wa Dimnah^[9] (Arabic: كليلة و دمنة‎). A New Persian version from the 12th century became known as Kalīleh o Demneh^[10] (Persian: کلیله و دمنه‎) and this was the basis of Kashefi's 15th century Anvār-e Soheylī^[11] (Persian: انوار سهیلی‎, 'The Lights of Canopus'). The book in different form is also known as The Fables of Bidpai^[12][13] (or Pilpai, in various European languages) or The Morall Philosophie of Doni (English, 1570).

TORTOISE AND GEESE

a TORTOISE and two Geese lived together in a pond for many years. At last there came a drought and dried up the pond. Then the Geese said to one another,-

"We must seek a new home quickly, for we cannot live without water. Let us say farewell to the Tortoise and start at once."

When the Tortoise heard that they were going, he trembled with fear, and besought them by their friendship not to desert him.

"Alas," the Geese replied, there is no help for it. If we stay here, we shall all three die, and we cannot take you with us, for you cannot fly."

Still the Tortoise begged so hard not to be left behind that the Geese finally said,-

"Dear Friend, if you will promise not to speak a word on the journey, we will take you with us. But know beforehand, that if you open your mouth to say one single word, you will be in instant danger of losing your life."

"Have no fear," replied the Tortoise, "but that I will be silent until you give me leave to speak again. I would rather never open my mouth again than be left to die alone here in the dried-up pond."

So the Geese brought a stout stick and bade the Tortoise grasp it firmly in the middle by his mouth. Then they took hold of either end and flew off with him. They had gone several miles in safety, when their course lay over a village. As the country people saw this curious sight of a Tortoise being carried by two Geese, they began to laugh and cry out, - "Oh, did you ever see such a funny sight in all your life!" And they laughed loud and long.

The Tortoise grew more and more indignant. At last he could stand their jeering no longer. "You stupid . . . " he snapped, but before he could say more he had fallen to the ground and was dashed to pieces. 

the blue jackal..

chandaraka was a jackal living in a forest. One day, driven by hunger, he came to a nearby town in search of food. Seeing him, a group of mongrels began chasing and attacking him whenever possible. The jackal fled in panic and entering the house of a washer man hid in a vat full of blue used for bleaching clothes. When he came out, he became a blue animal. Thinking that he was not the jackal they chased, the mongrels dispersed. The jackal came back to the forest with his body dyed in blue. When the lions, tigers, panthers, wolves and other animals in the forest saw him, they took fright and ran in all directions. They thought to themselves, “We do not know his power and strength. It is better we keep a distance from him. Haven't the elders warned not to trust him whose conduct, caste and courage are not known. seeing them scared, the dyed jackal said, “Why do you run away like that. There is no need to fear. I am a special creation of God. He told me that the animals in the jungle here had no ruler and that he was nominating me as your king. He named me as Kakudruma and told me to rule all of you. Therefore all of you can live safely under the umbrella of my protection.” All the animals in the jungle accepted him as the king. He in turn appointed the lion as his minister, the tiger as his chamberlain and the wolf as the gatekeeper. After distributing office to the animals, the new king Kakudruma banished all the jackals in the forest. The lions, tigers and the wolves killed other animals and brought them as food for the king. Taking his share, Kakudruma would distribute the rest of the kill among his subjects. one day when the blue jackal was holding court, he heard a gang of jackals howling. Thrilled by the sound of his own ilk,Kakudruma began loudly responding in his natural voice. The lions and other animals immediately recognized that their king was after all a jackal and not a Godsend. They at once pounced on the blue jackal and killed him. "he who abandons his own folk will perish.”