The Research On Gas Film Drag Reduction Device Design For River-sea Ship

The technology of gas film drag reduction is the practical technology for energy saving and emission reduction of ships.The gas film drag reduction device design is the key of the technology application.The river-sea ship is developing fast because our country builds a comprehensive and convenient transportation system and implements the strategy of the Yangtse Rive Economic Belt.The research on gas film drag reduction device design takes river-sea ship as the object to save this ship’s energy.The research conforms to our country’s concept of development that human and nature ought to develop harmoniously and the beautiful scenery means wealth.Analyzing the current domestic and foreign research on gas film drag reduction,it could be found that research objects mainly focus on the middle and high speed ships in the past and the medium and low speed transport ships are researched in recent years.The research results about large low-speed river-sea ship are scarce.And the research contents focus on the theoretical research and lack the engineering application research.Thus the paper adopts comprehensive methods of theoretical analysis,model test and numerical simulation to research the key problems in gas film drag reduction device design for river-sea ship for engineering application.At first the paper analyzes the design points of gas film drag reduction device for river-sea ship,the modules of gas film drag reduction device of jet method and the key design parameters affecting the effect of drag reduction such as jet position,number of jet position,jet flow rate,jet angle,jet size and so on.Next the model test method is adopted to study the influence of the design parameters on drag reduction such as jet position,number of jet position and jet flow rate through the design of general experimental plan,experimental model and key experimental equipment.Then the experimental results are used to correct the numerical calculation model.The numerical simulation method is adopted to discuss the geometric similar ship resistance extrapolation of gas film drag reduction through supplementing the flow field information under the model test condition.And the influence of the design parameters on drag reduction such as jet angle and jet size is also studied.Aiming at the effect of energy saving of target ship,the paper evaluates the effect of gas film drag reduction device on the ship’s drag reduction,the propulsion efficiency and the energy consumption comprehensively.The design parameters of the gas film drag reduction device of the target ship are optimized: the jet positions are located at 30%L and 45%L from the bow;the number of jet position is two;the jet width is 0.4‰L;the jet angle is 90 degree;the jet flow rate is expressed by the Reynolds number of air injection and the Reynolds number of air injection is 178.The research results show that the design and application of gas film drag reduction device of jet method can effectively reduce the target ship’s energy consumption and achieve the effect of energy saving and emission reduction.