The Percolation Analysis And Channel Simulation On Interfaces For Contacting Mechanical Seal

The stability and reliability of the mechanical seal are more important with the rapid development of the modern industry. Actually the roughness of the sealing interfaces makes their contacting condition not so ideal, and fluid may find the pore channels throughout the interfaces, which can cause leakage to occur under the action of differential pressure. Therefore, analyzing the leakage channel model between the sealing interfaces is extremely critical. The existing channel models simplified the pore between the sealing interfaces to parallel gap or circumferential curve channel which can great simplify the calculation process. But these simplified channel models neglected the pore channels that can’t pass through the contacting interfaces, which caused the leakage calculation values to be larger than the actual values and caused great error when they were applied to predict leakage. This dissertation makes the percolation analysis and channel simulation on interfaces for contacting mechanical seal. The main research work and analysis results are summarized as follows:(1)The structure analysis of micro channel between the sealing interfaces was made. The three-dimensional morphology of the sealing interfaces with fractal characteristics was achieved through the digital simulation for the mechanical dynamic and static ring face. The influence of morphology parameters, material parameters and working parameters on the micro channel distribution based on micro convex body deformation process of rough surface was obtained.(2)This dissertation analyzed the percolation characteristics of the leakage channel between the sealing interfaces. The sealing interfaces were divided to the 3d grid model based on the percolation theory. And the binarization processing for the 3d grid model was made according to the micro channel distribution between the sealing interfaces. Algorithm searching the maximum pore regiment was established using the MATLAB programming. The percolation characteristics of the micro channel between the sealing interfaces was analyzed based on the above work. The percolation probability curve between the sealing interfaces has a mutation stage with the increase of magnification. More pore units connect and merge into the connected group throughout the entire seal interfaces during the mutation stage.(3)The dimension of percolation point was calculated and analyzed. The 3d percolation channel model under the given parameters was built. The critical magnification that make the channel from non-leakage to leakage can be obtained based on the algorithm searching the maximum pore regiment, and the dimension of percolation point can be calculated from it. We analyzed the influence of the fractal dimension coefficient G, the fractal dimension of the soft ring surface Ds2, elastic modulus E2, Poisson ratio v2 and the face unit load P on the dimension of percolation point. At the same time, the fluid leakage minimum pore scale also was analyzed.(4)The 3d micro channel model was achieved, and the leakage channel simulation was made. The simulation of ideally fluid flow between the contacting mechanical seal was carried on using the UG/Open GRIP software and the Fluent software. And the channel leakage character computed by simulation was analyzed.