Underwater Grooved Surface Drag Reduction Characteristics

In this paper, adopted theoretical, simulative and experimental investigation of the drag reduction by riblet surface and traveling wave surface are carried out. Comparing the theoretical results with the experimental results, we can find that both are consistent with each other. The main contributions of the dissertation are summarized as follows:(1) Summarizing the theoretical and experimental backgrounds of the mechanism of turbulence and conclusion, two kinds of representative somewhat mechanisms of the drag reduction by riblets are described.(2) Based on the special configurations of riblets surface, bring forward the require about the high-precision standards of grids. And then build the high-precision suitable grids used the differential equation method in two riblets surface.(3) Based on forward mathimatics model of reducing drag, build the suitable simple model and using the one function turbulent model to calculate theoretical result. Then about 10 percent drag reduction by V-riblet-surface flow are obtained.(4) Using FLUENT software to compute the riblets surface flow field. Based on the characteristic of riblets surface, bring forward the principle of numerical simulation and its actualize way. Prove that two kinds of representative somewhat mechanisms of the drag reduction by riblets are very good action in drag reduction. The simulation result is about 10 percent; using FLUENT software to compute the traveling wave surface flow field firstly. The simulation result show that slow whirlpool is created by traveling wave can reduce the surface drag efficiently. The maximal quantity is about 8 percent.(5) Through the experimental investigation of the column whose surface there are V-riblets surface and traveling wave surface in water tunnel, the important results are given. The maximal drag reduction quantity of the V-riblets surface is about 6 percent, the traveling wave surface is about 5 percent. The result show that the drag reduction of riblets surface is form high to low when the velocity is to faster and faster. Different form the region of drag reduction of fluid velocity in different size of the riblets surface. And the best drag reduction of the fluid velocity is also different, the size is bigger, the best drag reduction of the fluid velocity is slowly.The theoretical and experimental investigation of drag reduction by riblets surface and the simulative and experimental about drag reduction by traveling wave surface in this paper have important to the theory instruction significance for future investigation about it.