The Matching Research Of Ship Diesel Engine With Screw Propeller And Cooling System Optimization

The continuous development of national economy and increasing trade at home and abroad, brings the rapidly and sharply rising of sea transportation and ship building. Just in the past three years the total increment of the sea transportation of our country occupies more than 90% of that of the world. Meanwhile, ship building industry keeps its own rapidly increase tendency. From statistic, in the past half year of 2007, the completed ship buildings amount to 7.55 million tonnage, with the increment 43%, and the new order is 42.62 million tonnage, with the increment 165%, and the order in hand amounts to 105.4 million tonnage , exceeding 100 million tonnage for the first time. According to statistic data from Clarkson Research Studies to the total ship building of the world, the share market of completed ship building and new order and in hand order of our country are 19%, 42%, 28% separately, and each of the new order and in hand order exceeds Japan, takes the second place of he world. This all brings new opportunities of our ship industry.Nowadays diesel engine is the most source of ship power, and screw propeller is the propellant machine. And capability of the two and the matching will impact the transporting economic performance and ship security directly. While the cooling system ensures normally and efficiently work of the heated parts of the ship diesel engine, and so the design of cooling system will be an importance factor of the main engine power perform sufficiently or not. So the matching research of ship engine and screw propeller and cooling system in ship thrusting system are more and more regarded by world ship building and shipping as one of the most importance task in the ship technology field with the increasing transport tonnage and engine power.Currently the popular screw propeller matching design refers to plenty of charts and tables and various complicated calculation formulas, and such charts and tables have their own applied areas making against to apply. While the design of cooling water flow and pumps of ship cooling system mainly according to the rated point of the diesel engine, while in the real navigation diesel engine mainly works in part load condition, and this causes surplus of cooling capability and cooling water temperature too lower, and impacts the performance of main engine. So this paper takes the middle speed and small power of ship diesel engine as research object, and with the title of the matching research of ship diesel engine with screw propeller and the optimized design of cooling system to research the matching design of ship power system. And the main content of this paper is as the following:(1) The establishment of matching calculation platform of screw propeller and diesel engine.This paper starts with the analysis of balance of ship energy, and gets energy transfer relationship between ship diesel engine and screw propeller. And at this basement, analyzes the matching design between screw propeller and diesel engine, according design theory of screw propeller chart. Depending on the B-screw series new charts made by Holland ship model between 1973 and 1975, referring to resistance curve and screw propeller dimension of model ship calculates the engine power of the designed ship and chooses the type. And then according to the chose engine checks screw propeller dimension and calculates the maximum speed of the ship. And then analyzes the ship navigation capability and the main engine performance, establish the matching design platform of ship diesel engine and propeller. And in the end, evaluating the veracity of the calculate platform with 200 tonnage ship.(2) Analysis and optimization the cooling system of ship.This paper calculates the cylinder wall heat load changes at the full load and part load working condition based on thermal theory, and analyzes cylinder wall temperature at constant flow water and variable flow water condition, imposes methods to realize variable flow water. Analyze heat load of intercooler according to intake mass flow, environment temperature and working condition. And then design calculation and checking chart of seawater-freshwater heat exchanger according to the design theory of exchanger, and analyze seawater pump calculation flowchart according to main engine exchanger heat and heat load, and propose optimized methods according to environment and main engine working condition.