Samad Jafamadar - Faculty of Mechanical Engineering Department, Urmia University
Shahram Khalilarya - Faculty of Mechanical Engineering Department, Urmia University
Javad Kheyrollahi - PhD Candidate, Urmia University, Iran Heavy Diesel engine manufacturing Co.

The primary propulsion source of ships is the diesel engines and power required by the propeller to provideenough propulsion to the ship, defines engine running condition. When the ship accelerates, the propeller will besubjected to larger loads than during free sailing, power required for the propeller therefore, will be relativelyhigher than for free sailing, and the engine’s operating point will be heavy running, as it takes some time beforethe propeller speed reaches its new and higher level thus it is obvious that optimizing main engine workingcondition and torque curve comparing to design point of propeller is of so much importance. Effective brakepower of a diesel engine is proportional to the cylinder mean effective pressure and engine speed therefore, it isrequired to increase cylinder mean effective pressure in order to increase power diagram which suits forpropeller power usage. The goal of this study was to increase the power output of a marine diesel engine at lowengine speeds. This power increase was achieved by changing the design of engine intake system to get the bestpossible power margin at low speeds. Different turbocharging strategies were evaluated to optimize intakesystem and achieve the said target and best matching system is evaluated in practice. Simulations are performedusing GT power one‐dimensional software program in order to assess the effect of turbocharger performance onthe engine intake system as a whole. Simulations demonstrate that by changing compressor and turbineproperties, engine power curve is being affected. To get higher power curve line various sizes of compressorsand turbines are selected and result of current research shows that by using 10% smaller turbine and10%smaller compressor engine power curve is upgraded about 80% from idle to 800 rpm of engine speed.Result of simulation is evaluated at test cell after changing the engine intake build of the engine.

Marine application, Propulsion, Power law, Torque, Fixed and variable pitch propeller