Definition of Vapour Pressure and Cavitation – Properties of Fluid – Fluid Mechanics
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Definition of Vapour Pressure and Cavitation – Properties of Fluid – Fluid Mechanics


hello brains here in this video we will see what is meant by vapor pressure and cavitation vapor pressure and cavitation first I’ll start with vapor pressure for vapor pressure I can explain it with the help of a diagram suppose we have a vessel which is closed inside that vessel we have water now Here I am considering water is at atmospheric pressure then we are heating this water inside a closed container by supplying heat externally when we are adding Heat this water it will evaporate and since it is at atmospheric pressure that temperature required for evaporation that would be hundred degree Celsius now when the temperature reaches 100 at that time water molecules will be converted into vapor and this vapor will exert a pressure on this liquid water and hence this pressure would be called as vapor pressure so here I can define that vapor pressure is the pressure exerted by the vapor on a liquid so here we have defined vapor pressure that vapor pressure is the pressure exerted by the vapor on a liquid now this vapor pressure it can change vapor pressure for atmospheric condition we know that water will boil at 100 degree Celsius but if we go on decreasing the pressure then water will boil at a temperature less than 100 so this vapor pressure value can change so this concept of vapor pressure it takes place even when the water is flowing and it is subjected to difference in temperature now let us see what is meant by cavitation see cavitation it means that if we have a pipe line and when the water is flowing through that pipe line when the water flows through the pipe line then suppose we have a low pressure region at this location suppose we have low pressure then because of the low pressure here the water would be converted into vapor that is here we would be having air bubbles at low pressure region some air bubbles would be formed now these air bubbles which are formed in the low pressure region when it goes to high pressure region Here I am denoting this as the high pressure region so from low pressure to high pressure where it moves these bubbles they would be collapsing they are they would be collapsing at this location and when the bubble they collapse there is tremendous rise of pressure so because of that the walls of the pipe the get fitted there there would be we can say that pitting action on the pipeline so cavitation it is a phenomena when liquid passes from low-pressure region to high pressure region so cavitation it is a phenomena when the liquid passes from low-pressure region to high pressure region there is collapsing of the bubbles and because of this collapsing there is pitting action or we can say there would be small small holes produced on the walls so cavitation needs to be avoided it means there should not be a region where air bubbles are formed in simple terms when the water is flowing in the pipeline we try to avoid air bubble formation because that air bubbles when they collapse suddenly there is tremendous rising pressure and because of that the walls of the pipeline will get pitted or it looks like it is corroded there is corrosion taking place so this forces the cavitation phenomena hence in this video we have seen what was meant by vapour pressure meter diagram what is cavitation with the help of a diagram I hope everything is clear

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