Machine Parts

a.        No slip at boundary. b.       Due to viscosity there is a shear between fluid layers which is given by Ʈ= µ du/dy for flow in X direction. c.        The flow is rotational. d.       Due to viscous shear, there is continuous dissipation of energy   and for maintaining the flow energy must be supplied by externally. e.        Loss of energy is proportional to first power of velocity and first power of viscosity. f.         No mixing between different fluid as long as pVl/ µ is less thsn critical value of Reynolds number.  Examples of Laminar or viscous flow: 1.       Underground flow. 2.       Flow past tiny bodies. 3.       Flow of oil in measuring instruments. 4.       Movement of blood in the arteries of a human body. 5.       Rise of water in plants through their roots.

SI Engine means Spurk ignition and CI engine means compression ignition.  1.       SI Engine based on Otto Cycle and CI engine based on Diesel cycle. 2.       SI engine petrol used as a fuel but CI engine used diesel oil as a fuel. 4.       In SI engines requires an ignition system with spark plug in the combustion chamber. But CI engine is self ignition due to high temperature caused by high compression of air when fuel is injected.  1.       In SI engine Fuel and air introduced as a gaseous mixture in the suction stroke. But CI engine Fuel in ijected directly into combustion chamber at high pressure at the end of compression stroke. 5.       In SI engine compression ratio is 6 to 10.5 but CI engine compression ratio is 14 to 22.  6.       In SI engine higher maximum revolution per minute due to lighter weight. But cases of CI engine maximum revolution per minute is lower. 7.       In SI engine maximum efficiency lower due to

1.       The latest possible inlet valve should be accumulated. 2.       The length of flame travel should be as short as possible. 3.       There should not be hot surface at the end of region –region of gas. 4.       The exhaust valve should be kept small. 5.       The highest flame front velocity should be created by creating correct amount of turbulence. 6.       The largest mass of charge small burn as soon as possible after ignition. 7.       The heat flow should be minimum in the zone around spark plug. 8.       In the end gas region surface to volume ratio should be large so that there is good cooling in detonation zone. 9.       The spark plug should be positioned that it will be scored by any exhaust residual products by the incoming charge. 10.   The exhaust valve heat should be well cooled. 11.   The spark plug should be sufficiently cooled. 12.   There should be good scavenging of exhaust gases. 13.   It is des