Conceitos básicos de Mecânica dos Fluidos | Notas mecânicas do portão

Basic concepts of Fluid Mechanics | Gate mechanical notes

Basic concepts of Fluid Mechanics Gate mechanical notes

1. The fluid particle velocity is maximum at the center of the pipe section.
2. Density is defined in terms of viscosity as dynamic viscosity/kinematic viscosity.
3. The Reynolds number for flow in the pipe is given as VDρ/µ.
4. The SI unit of viscosity is 10 times poise.
5. Kinetic viscosity is not a dimensionless parameter.
6. The critical upper importance of the Reynolds number for pipe flow is of no practical importance to designers.
7. A liquid compressed in a cylinder has a volume of 1 liter at 1 MN/m2 and a volume of 995 cm3 at MN/m2. The apparent modulus of elasticity is 200 MPa.
8. The length of the mercury column at a location at an altitude will change relative to the length of the mercury column, first slowly and then abruptly.
9. The volumetric variation of the fluid caused by resistance is called adhesion.
10. The property of a fluid by which its own molecules are attracted is known as cohesion.
11. The pressure at a point in a fluid will not be the same in all directions if the fluid is viscous and moving.
12. The Pitot tube can be used to measure the flow of water in a 3000 mm diameter pipe.
13. An ideal fluid is one that is frictionless and incompressible.
14. Uniform flow occurs when at all points the velocity vector is identical in magnitude and direction at any instant.

Basic concepts of Fluid Mechanics Basic concepts of Fluid Mechanics

15. The continuity equation for ideal fluid flow states that energy is constant throughout the fluid.
16. Neglecting the forces due to inertia, gravity and friction resistance, the sizing of a channel can be done by comparing the Froude number.
17. For smooth turbulent flow, the friction factor changes as Nr1/4.
18. To prevent vaporization in the piping, the piping over the ridge is placed so that it is no more than 6.4 m above the hydraulic gradient.
19. The continuity equation is applicable to the conservation of mass.
20. The rise or fall of head 'h' in a capillary tube of diameter 'd' and liquid surface tension 'σ' and specific weight 'w' is given by 4σ/wd.
21. The McLeod manometer used for measuring low pressure operates on the principle of Boyle's law.
22. The mass density of the liquid (ρ) is given by ρ = kg sec2/m4.
23. The escape speed of a Pelton wheel does not provide load speed when the governor mechanism fails.
24. A Kaplan turbine is a low head axial flow turbine.
25. The vector difference of two speeds is the relative speed.
26. A ship whose hull is 100 m long must travel at 10 m/s. For dynamic similarity, at a speed of 2 m/s, a 1:25 model will be towed through the water.
27. For a stable equilibrium of a floating body, its metacenter must be above the center of gravity.
28. The center of pressure on an inclined plane is below the centroid.
29. The line of action of the buoyant force always acts through the centroid of the displaced volume of fluid.
30. An equipotential line is one that has no velocity component tangent to it.
31. Hydraulic jump is used to reduce flow energy.
32. The lowest part of the storage basin, from which water is not removed, is dead storage.
33. The pitot tube is a device used to measure speed.
34. The hydrometer is used to determine the specific gravity of liquids.
35. The Mach number is significant in the case of supersonics, as with projectiles and jet propulsion.
36. The fluid forces taken into account in the Navier Stokes equation are gravity, pressure and viscosity.
37. Rocks that have excessive internal stresses, producing spalling, are called stratified rocks.
38. The permissible speed of water flowing through the concrete tunnel is generally 4-5 m/s.
39. The maximum continuous power available from a hydroelectric plant under the most adverse hydraulic conditions is called firm power.
40. The relationship between the maximum load and the nominal capacity of the plant is called the utilization factor.
41. Orifice refers to an opening in a hydraulic structure with regulatory provisions.
42. The value of the discharge coefficient compared to the velocity coefficient is less.
43. Spillway refers to an opening with partially full flow.
44. The pressure force, in Netwons, on the 15 cm diameter headlight of a car traveling at 25 m/s will be 6.8.
45. The power transmitted through a pipe is maximum when the head loss due to friction is one-third of the total head supplied.

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