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MET 212Fluid Mechanics

Lecture # 3

Objective

Fluid Pressure Pressure at Point Basic Equation For Pressure Filed

Incompressible Fluid Compressible FluidExample

Pressure MeasurementManometer

Piezometer Tube U-Tube Manometer Inclined-Tube Manometer

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Fluid pressure

θ

θ

x

z

y

2zyx

yxzp

sxsp

y

s

x

`zzxyp

Pressure at Point

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Basic Equation For Pressure Filed

dz

dp

This equation indicate that the pressure gradient in vertical direction is negative that is the pressure decrease as we move upward in the fluid at reset

Incompressible Fluid ( ρ ) constant ( g )in most of fluid application is neglected

21 phP Compressible flow

( ρ ) is not constant TRp

0

1212

)(exp

RT

zzgpP

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Basic Equation For Pressure Filed

ExampleOpen

Gasoline

Water

17 ft

3 ft

A tank has a gasoline and water as shown in the Figure. If the SG of gasoline is 0.68 determine the pressure at the gasoline water interface and at the bottom of the tank

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Pressure Measurement

ManometerManometer has three types:

Piezometer TubeU-Tube ManometerInclined-Tube Manometer

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Piezometer Tube

11hPA

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U-Tube Manometer

1122 hhpA

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U-Tube Manometer

Example

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U-Tube Manometer

0.2 m

A+

B+

0.3 m

h ??

Water

OilMercury

0.17 m

h ?