PRESSURE & HEAD (PART-1)

PLEASE NOTE THIS IS PART-1
By Referring or said Learning This Presentation You Can Clear Your Basics Fundamental Doubts about Fluid Mechanics. In this Presentation You Will Learn about Fluid Pressure, Pressure at Point, Pascal's Law, Types Of Pressure and Pressure Measurements.

1. ACTIVE LEARNING ASSIGNMENT PRESENTATION FLUID MECHANICS (2141906) TOPIC PRESSURE & HEAD (PART- 1 ) PREPARED BY MECHANICAL – 4B2 DEVANSU KHORASIYA ( 150120119066 ) GUIDED BY PROF. SHAIVAL PARIKH PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

2. INTRODUCTION So, Before Starting The Chapter Clear Some Doubts…. This Chapter Deals With Forces Applied By Fluid at Rest. When A Certain Mass of Fluid is held in static Equilibrium by confining Within Solid Boundaries, it exerts forces Against Boundary surfaces. The Forces Exerted always in The Direction normal to The Surface in The Contact. This is So because a fluid at Rest Cannot Sustain Shear Stress. No Shear Force is Present as Fluid Particles do not Move With Respect To One Another. Let’s Start The Journey… PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

3. First Of All… What is Pressure ?? Pressure is defined as a normal force exerted by a fluid per unit area. Pressure is the force per unit area, where the force is perpendicular to the area. Units of pressure are N/m 2 , which is called a Pascal (Pa). Since the unit of Pa is too small..! F or pressures Encountered in practice kilopascal (1 K Pa = 10 3 Pa) and megapascal (1 MPa = 10 6 Pa) are commonly used. p= A m 2 Nm -2 (Pa) N F The pressure measured in your tyres is the gauge pressure, p-p a . p a = 10 5 Nm -2 1psi =6895Pa 1  psi  = 1 lbf ( 1 in ) 2 ≈ 4.4482 N ( 0.0254 m ) 2 ≈ 6894.757 Nm -2 PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

4. Pressure in a fluid acts equally in all directions. Pressure in a static liquid increases linearly with depth P= Increase In Depth (M) Pressure Increase GH The pressure at a given depth in a continuous, static body of liquid is constant. p 1 p 2 p 3 p 1 = p 2 = p 3 A = 2 cm 2 1.5 kg P = 73,500 N/m 2 PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

5. Fluid exerts forces in many directions. Try to submerse a rubber ball in water to see that an upward force acts on the ball. Fluids exert pressure in all directions. F Fluid Pressure PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

6. Properties of Fluid Pressure Water seeks its own level, indicating that fluid pressure is independent of area and shape of its container . At any depth h below the surface of the water in any column, the pressure P is the same. The shape and area are not factors. The forces exerted by a fluid on the walls of its container are always perpendicular . The fluid pressure is directly proportional to the depth of the fluid and to its density . At any particular depth, the fluid pressure is the same in all directions . Fluid pressure is independent of the shape or area of its container. PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

7. What is Pressure Head ??? In a Static Liquid, Vertical Distance From Datum Line to the Free Surface of Liquid is Known as Pressure Head . In fluid mechanics,  pressure head  is the internal energy of a fluid due to the  pressure  exerted on its container. It may also be called static  pressure head or simply static  head  (but not static  head pressure ). PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

8. What is Pressure at a Point ? Pressure at any point in a fluid is the same in all directions. Pressure has a magnitude, but not a specific direction, and thus it is a scalar quantity. Scuba Diving and Hydrostatic Pressure PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

9. Pressure Variation In A Fluid At Rest h mg Area P = r gh Pressure at any point in a fluid is directly proportional to the density of the fluid and to the depth in the fluid . PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

10. Pascal’s Law F out F in A out A in Pressure in = Pressure out Pascal’s Law: “An external pressure applied to an enclosed fluid is transmitted uniformly throughout the volume of the liquid.” Or “ The Intensity of Pressure at any Point in a Fluid at Rest, is Same in All Directions” PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

11. Absolute Pressure Gage Pressure Vacuum Pressure Types Of Pressure Absolute Pressure Absolute Pressure: The sum of the pressure due to a fluid and the pressure due to atmosphere. Gauge Pressure: The difference between the absolute pressure and the pressure due to the atmosphere: Absolute Pressure = Gauge Pressure + 1 atm h D P = 196 kPa 1 atm = 101.3 kPa PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

12. Vacuum Pressure atm atm h Mercury P = 0 One way to measure atmospheric pressure is to fill a test tube with mercury, then invert it into a bowl of mercury. Pressure below atmospheric pressure are called vacuum pressure , P vac = P atm - P abs . Density of Hg = 13,600 kg/m 3 P atm = r gh h = 0.760 m P atm = (13,600 kg/m 3 )(9.8 m/s 2 )(0.760 m) P atm = 101,300 Pa Gage Pressure Most pressure-measuring devices are calibrated to read zero in the atmosphere, and therefore indicate gage pressure, P gage = P abs - P atm . PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

13. Absolute, Gage, And Vacuum Pressures PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

14. Pressure Measurement Pressure is an important variable in fluid mechanics and many instruments have been devised for its measurement. Many devices are based on hydrostatics such as barometers and manometers, i.e., determine pressure through measurement of a column (or columns) of a liquid using the pressure variation with elevation equation for an incompressible fluid Enlarged Leg Two Fluid Inclined Tube Inverted U-Tube U-Tube Manometer PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

15. Manometers are used for measuring pressures by balancing the fluid column of fluid against another column of fluid of known specific gravity. Manometers can be classified as: Simple manometers : It consists of a glass tube with one end open to the atmosphere and other end connected to a point at which pressure is to be measured. a. Piezometer It consists of glass tube connected to a vessel or pipe at which static pressure is to be measured. It is the simplest of all the manometers (Fig. 5.1). It is used to measure very low pressures. The pressure in  piezometer  is given by the following equation.   Where,   = density of liquid h = height of liquid in the  piezometer  from the centre of the pipe. g = acceleration due to gravity Fig. Piezometer b.U -tube manometer The manometer is named so because it consists of a glass tube having the shape of alphabet ‘U’. One end is open to the atmosphere and other end connected to a point at which pressure is to be measured. PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

16. Column Manometer One of the limbs in double column manometer is converted into a reservoir having large cross sectional area (about 100 times) with respect to the other limb.                                                              Fig. shows a vertical single column manometer. Initially, the both limbs of the manometer are exposed to atmospheric pressure. When the left limb with reservoir is connected to container, the liquid pressure of it pushes down the level A 1  B 1  to A 2  B 2 causing !l h downward movement of liquid in the reservoir. For any variation in pressure, the change in the liquid level in the reservoir will be very small, which may be neglected and hence pressure is given by the height of liquid in the other limb. PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

17. AT THE LAST……. One Humble Request to all of YOU…. Make sure Your House, School, College, Society, Road, State, Nation, World is Neat and Clean…… PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)

18. THANK YOU GUYS FOR LISTINING ME…… PRESENTATION & DESIGNED BY DEVANSU KHORASIYA (150120119066) MY AIM IS…. CLEAN INDIA GREE N I NDIA & MAKE IN INDIA . PREPARED BY : DEVANSU KHORASIYA(GIT-150120119066)