Operation of diesel engine in direct ship propulsion

In the paper an identification of low speed diesel engine operation in direct propulsion plant equipped with fixed pitch propeller during ship manoeuvring. It was starting of engine and gathering speed of ship. Analysis of engine operation was based on changes of engine torque and time of ship bring up to speed. Operation of reciprocating internal combustion engine consists in converting the supplied fuel energy and delivering it to ship propeller. This condition implicates converting different amounts of energy in different time. The main attention was given to operation of engine caused by crank pin forces in wide range of revolutions and their influence on mechanical load of ship propulsion plant. The torque is the major component determining the engine load. As a matter of fact its mean value is low, but a passing torque can be four times higher than the rated torque. The second important component of propulsion engine operation is the time of ship acceleration from one speed to another. It determines dynamic properties of the ship describing its reductional feature. This time is determined in dependence on other parameters characterizing operation of ship propulsion plant and ship motion by means of dimensional analysis. These parameters were regarded as dimension quantities of three-dimensional space. Thus the three independent in dimension parameters can be noted in digital form in dimensional functions. The knowledge of operation parameters of ship propulsion plant and the knowledge of ship motion dynamics makes possible rational manoeuvring. It increases safety of ship motion and failure-free operation of ship propulsion engine. The proper operation of engine requires delivery to the propeller such amount of energy, which ensure the motion of ship with required speed in given sailing conditions.