Study On The Characteristics Of Shallow Water Self-Propulasion Of River-sea Going Ship

The River-sea Going Ship is a new type of ship that emerged in the 1990s.The main features are:low operating costs,low cargo losses,and short turnaround times.Based on the above points,River-sea Going Ship can effectively make up for the shortage of cargo transportation in Chinese rivers and seas,in line with the development trend of modern logistics.The large-scale inland ship is the development trend of Chinese domestic river ships.As one of the typical inland river ships,River-sea Going Ship is a new type of ship that has been developed in China in recent years.Its large-scale trend will lead to shallow water effect when navigating in the shallow channel of the inland river,affecting its resistance and propulsion performance.In recent years,numerical calculations have mostly only analyzed the shallow water resistance performance in the study of shallow water effects of ships.There is no further discussion on flow field information,and few scholars have done research on shallow water self-propulsion.The lack of data in shallow water tests has led to the lack of certain reliability of previous studies on the shallow water effect.In view of the above problems,the combination of model test and numerical simulation is used to study the self-propulsion characteristics of shallow water in River-sea Going Ship.The main work includes:The numerical simulation of the open water and resistance of the propeller was carried out with KVLCC2 as the object,and the validity of the numerical method was verified.The numerical simulation of the self-propulsion was carried out by using the overall modeling method of the paddle and the body force method.The advantages and disadvantages of both have found that the body force method has higher computational efficiency,but there is a certain error in the flow field detail description and the partial self-propulsion factor calculation;by adding the distribution function of the force source along the circumferential direction based on the H-O body force model,the flow field details are better depicted,and the traditional body force method is also improved to some extent.Taking the River-sea Going Ship as the object,the model and numerical simulation of the open water model of the propeller were carried out,which provided the basis for the subsequent self-propelled forecast.Through the numerical simulation of the resistance,the influence of the water depth and the Fourier number on the drag coefficient and the navigational state was analyzed.It is found that as the water depth becomes shallower,the drag coefficient increases gradually,and the first tilt phenomenon is more obvious.By capturing the flow field details such as the wave shape and the bottom velocity of the ship,and analyzing it,it is found that the wavelength of the wave is significantly increased as the water depth becomes shallower.Large,the stern reflow speed increases;through the numerical simulation of self-propulsion,the influence of water depth and Fourier number on the self-propelled factor is discussed,and the velocity distribution of the propeller area under different water depth conditions is compared.It is found that as the water depth becomes shallower,the thrust decrement and the accompanying flow fraction increase,the propulsion efficiency decreases,and the circumferential accompanying flow unevenness is more obvious.Taking KVLCC2 and River-sea Going Ship as the object,comparing the same and different between single-propeller and double-propeller in shallow-water self-propulsion,it is found that compared with KVLCC2,River-sea Going Ship is wider under the condition that the water depth is similar.The flat ship type results in a more pronounced shallow water effect.By studying the influence of shallow water on the self-propelled performance of River-sea Going Ship,some rules can be used to provide a basis for river boat direct ship type optimization and propeller design.