高速气泡船减阻试验和理论研究

This project makes theoretical and experimental researches on "the friction reduction by air curtain for high-speed air cavity vessel "which is one of the leading subjects in transportation industry. In theory the friction reduction by microbubbles for flat plates is simulated using business-oriented software and the programs made by the author. Firstly, the rule of the microbubbles production and development is investigated, And then the viscous friction is calculated simulating the given exterior environment of the injection, At last an approximated vessel model is simulated. Results show that interphase pressure、interphase lift can be ignored, but the effect of gravity-buoyancy、interphase drag force and virtual mass must be considered. The Spherical bubble drag is superior to the Stokes. The second, the maximum deduction of flat plates friction coefficient is up to 80%. The local friction reduction rate decreases with increasing the distance from the injection to the end of the plate. As bubbles concentration is given, the efficiency of friction reduction is better with increasing inflow velocity in the range of some values. Finally, result demonstrates that the friction reduction of vessel plat bottom is in direct proportion to the air injection ratio, while in inverse proportion to the distance from the injection. And the maximum friction reduction is up to 49.8%.. Micro-bubbles are generated through the perforated plate in small-scale and large-scale vessel model test for the first time in China. The injecting mean is an innovation because it provides a very effective way to use high-speed air cavity vessel practically. In circulating water channel both small scale whole vessel model and segmented vessel model are investigated. Air curtain width, length, thickness, appearance and efficiency of friction reduction is measured as well as how the vessel pose(heeling、trimming)and the wave to influence high-speed air cavity vessel is studied with (and without) the wave suppression plate in different injecting mean、injecting mean, and position, air volume discharge and forms of steps. Results indicate that the efficiency of friction reduction with is better than that without the wave suppression plate. With the same draft and the same air volume discharge the effect of friction reduction increases with increasing inflow velocity. The overlay length of air curtain expands with increasing inflow velocity in the range of some values. However the change of overlay width is not great. As inflow velocity is given the friction reduction rate increases with increasing air volume discharge. Setting steps can prevent the bubbles shaping "arch"(the local bubbles thickness increases suddenly) and entering into boundary layer as the air volume discharge is excessive. With the wave suppression plate the microbubbles is not easy to spill from the ship bottom，while the bubbles may spill at the bow as the inflow velocity is small. The effect of the wave influence on microbubbles layer distribution is not great If the draft is larger. Nevertheless the microbubbles layer is easy to spill if the draft is very small.Among the all kinds of experiment plans, air curtain near the injection covers the full width of the vessel. The length of the curtain relates to inflow velocity and injecting air volume discharge. And the curtain appearance downstream is similar to normal distribution curve. The whole vessel model experiment indicates the reduction of the total friction is up to 30.63% and for the segmented ship model that is up to 33.29%. Succeeding to separate friction from total resistance not only solve a very difficult problem for high-speed air cavity craft but also provide an effective experimental method for researches on friction reduction experimentally. And this is another creative idea. From the above study and large-scale ship in the large towing basin show the reduction of the total resistance is as much as 32%.

在试验和理论上对高速气泡船进行气膜减阻研究，研究与船型相配合的高速气泡船的喷口位置、喷嘴方式、喷嘴装置等关键技术，研究船舶航行姿态、波浪对减阻的影响，理论预测喷气气膜在船舶边界层的扩散宽度、长度以及厚度等主要参数和计算船体摩擦阻力。本研究将填补我国高速气泡船研究的空白，对发展我国的高速气泡船事业具有重要意义。