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MAN B&W ME-B Engines | Study

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Added on  2020-02-24

MAN B&W ME-B Engines | Study

   Added on 2020-02-24

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IntroductionThe MANB&W 6S80 MC engine is a six cylinder two stroke enginehaving a bore of 800 mm, stroke of 3200 mm and connecting rod lengthof 3000 mm. It is a mechanically driven fuel injection type engine withexhaust valve and starting air valves. It is electronically controlled by aCamshaft and has a super long stroke (MAN B&W Diesel A/S, 2000). It hasa turbocharger located on the exhaust side. This engine is used to performthe first task. The second task is performed using a two stroke engine witha bore of 600 mm, having a rated rpm of 105 and a connected rod lengthof 3 m and stroke of 2.4 m. Task 1The force acting on a pneumatic cylinder could be expressed asForce = Pressure x Area. Therefore, if pressure and diameter of thecylinder are given Piston force could be calculated. Now Guide thrust iscalculated by multiplying the tangent of angle between the connectingrod and the vertical axes with the Piston Force. Connecting Rod Thrust iscalculated by dividing the piston force with the cosine of the anglebetween the connecting rod and the vertical axes. Figure 1 shows a plot ofthe piston force, guide thrust and connecting rod thrust versus the crankangle.
MAN B&W ME-B Engines | Study_1
01234567891011121314151617181920212223242526272829303540455055606570758085900100020003000400050006000700080009000Comparison of Piston Force, Guide Thrust and Connecting Rode Thrust Vs Crank AnglePiston Force (kN)Guide Thrust (kN)Connecting Rod Thrust (kN)Crank AnglePistonForce,GuideThrustandConnectingRodThrustFigure 1. Plot of Piston Force, Guide Thrust and Connecting Rod Thrust VsCrank AngleThe piston force and connecting rod thrust start from 6097.20 kN when the crankangle is at 0° and increase till the crank angle reaches 13° at which point the piston force is7600.14 kN and the connecting rod thrust is 7655.24 kN. Then they decrease respectively to4453.53 kN and 4620.84 kN till the crank angle reaches 30°. From this point they experiencean exponential decrease until the crank angle reaches 90° at which point piston force is 759kN and connecting rod thrust is 897 kN. Whereas the guide thrust starts at 0 kN when thecrank angle is 0° and increases to 1266.71 kN as the guide angle reaches 26°. After which itdecreases to 1232.23 kN as the crank angle reaches 30°, then it is subjected to an exponentialdecrease until it reaches 478.55 kN at a guide angle of 90°. There is no side component ofthrust when the gas load acts vertically downwards at the top dead center. But as the pistonsmoves downwards and the angle between the connecting rod and the vertical axes increasesthe thrust due to the side component also increases.Task 2In this task the instantaneous velocity, acceleration and displacement of two strokeengine is calculated. Figure 2 is a plot of displacement versus crank angle.
MAN B&W ME-B Engines | Study_2

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