Vapor Pressure, Viscosity, Cavitations

Q1. Describe some methods to determine the viscosity of a fluid. Q2. Explain the concepts of (i) vapour pressure (ii) partial pressure and (iii) surface tension. Q3. Explain how liquid surface behaves by itself and when it is in contact with other surfaces. Q4. Derive an expression for the capillary rise or depression, given the value of the contact angle and the density and surface tension of the liquid. Q5. A circular disc rotates over a large stationary plate with a 2 mm thick fluid film between them, the viscosity of the fluid being 40 cp. The torque required to rotate the disc at 200 rpm was 0.069 Nm. Determine the diameter of the disc. Answer: (200 mm) Q6. The torque to overcome viscous drag of the oil film of viscosity of 28 cp in collar bearing of 0.16 m ID and 0.28 m OD running at 600 rpm was 0.79 Nm. Determine the film thickness. Answer: (1.2 mm) Q7. A conical bearing of outer radius 0.4 m and inner radius 0.2 m and height 0.2 m runs on a conical support with a clearance of 1 mm all around. The support is rotated at 600 rpm. Determine the viscosity of the oil used if the torque required was 21.326 Nm. Also determine the power dissipated. Answer: (20.0 cP, 1340 W)