Design Of Flow Resistance Testing Equipment And Study On Coating Drag Reduction Property

In this thesis, a coating flow resistance testing equipment is designed according the requirement of study on coating drag-reducing property, which can be iteratively disassembled to perform the surface treatment process. It is scientific, accurate, convenient and suitable to evaluate the effect of drag reduction on the interior wall. The establishment of computer aided testing system enables us to proceed to continuously measure and collect data. The drag-reducing testing software is developed to realize the data collecting process automation. The drag-reducing properties of various materials are tested by the equipment. Moreover, the mechanism of drag reduction is discussed and studied. Main innovation and study achievements are described as follows:(1) The equipment is designed based on the requirement of interior wall coating and drag reduction property testing for surface treatment process with regard to pipes. The design of testing pipe with disassemble rectangle structure averts disadvantages caused by the previous occlude round pipe design and facilitates the spray coating and other surface treatment process practices, with extensive practicality.(2) Using Visual Basic software, a drag-reducing testing programme is designed on the Windows operation system to realize procedure control on data collection and improve the automation of the testing equipment. The design of the programme is friend to programme interface, simple to operation, oriented to object of good opening and convenient for function expansion.(3) According theories of hydromechanics, computational fluid dynamics and so on, applying CFD computer software FLUENT, it adopts the standard k-e model to simulate the interior fluid of the testing pipes. It verifies the rationality of structure design and sensor selection of the equipment through imitation analysis, providing the basis and the theory instruction for theoretically analysing the science value of data tested by flow resistance testing equipment, and saving manpower, material resoureces and time.(4) Using the equipment and the aided testing software, drag-reducing properties of epoxy resin, epoxy asphalt, low surface energy material are tested by means of measuring successive fluid pressure diversification in the interior of pipe through alternative inlet water pressure. The drag-reducing mechanism of materials is discussed and studied. It is concluded that the drag-reducing property of coating is relative to surface energy and wall roughness. Under this thesis test condition, the drag-reducing mechanism of coating is advanced that the combination of the delay of laminar-turbulent transition induced by low surface energy and suitable wall roughness realizes drag reduction.