Lgf And Lgb Engines

The oil crisis in 1973 and the resulting massive increase in fuel prices stimulated enginebuilders to develop newer engines with reduced specific fuel consumption. B&W's answer was the L-GF series combining constant pressure turbocharging with an increase in piston stroke: an increase in stroke of about 22 per cent results in a lowering of the shaft speed by around 18 per cent, leading to greater propulsive efficiency when using larger diameter propellers and around 7 per cent increase in thermal efficiency.

The design of the L-GF series engine was heavily based on that of the K-GF and the necessary changes were mainly those relating to the increase in piston stroke and modifications to components to embody thermodynamic improvements (Figure 13.11). A major component design change was the cylinder liner, made longer for the increased stroke, and featuring cooling bore drillings forming generatrices on a hyperboloid to ensure efficient cooling of the high liner collar without cross borings with high stress concentration factors.

The cylinder covers are of the solid plate type used for the K-GF, while the pistons also are of the original oil cooled type but with



Figure 13.11 Short and long stroke 67GF engines

somewhat improved cooling caused by the stronger 'cocktail shaker' effect resulting from the greater quantity of oil in the elongated piston rod. The design of the crankshaft, crosshead, bearings, and exhaust valve actuating gear are, in the main, similar to the components introduced with the K-GF series.

Figure 13.12 12L90GFCA engine of 34 800 kW at 97 rv/min

80 85 90 95 100

Figure 13.13 Load diagram for L90GFCA engine kW/cyl. BHP/cyl. F 4500

80 85 90 95 100

Figure 13.13 Load diagram for L90GFCA engine

3300 L 3200

- 3100 3000 2900 2800 2700

r 2600 2500 2400 2300 2200

- 2100 2000

Beat The Battle With The Bottle

Beat The Battle With The Bottle

Alcoholism is something that can't be formed in easy terms. Alcoholism as a whole refers to the circumstance whereby there's an obsession in man to keep ingesting beverages with alcohol content which is injurious to health. The circumstance of alcoholism doesn't let the person addicted have any command over ingestion despite being cognizant of the damaging consequences ensuing from it.

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