Numerical Analysis Of The Flow Field With Moving Boundary In A Cylinder

The flow field with moving boundary in a complex cylinder is simulated numerically in this thesis. The purpose is to do some basic work of the simulation of the flow field with moving boundary in hydraulic elements, and to present useful numerical method and results for the designer who use the complex cylinder.The numerical simulation is one of the most important means to indicate possible ways to improve the properties of hydraulic elements. Although there are many papers on the numerical analysis of hydraulic-element flow fields, and make a good effect on improving the element properties, usually they only study steady flow field, which can not describe the whole moving process of hydraulic elements. Only by the simulation of the unsteady flow field with moving boundary, can the moving process be expressed faithfully. A steady flow field can be thought of and computed as a special case of the corresponding unsteady flow field.As far as the author knows, there are no published works in this area. With the development of computer and computational mechanics, The numerical simulation of unsteady flow with moving boundary will be a fruitful research area. In this thesis, some significant progresses have been achieved in the numerical simulation of complex-cylinder flow field with moving boundary.At first, the flow field in the complex cylinder is divided into several (for present case, five) basic flow field with moving boundary, which have similar structure and can be treated with the same algorithm. By coordinate transformation, the basic flow field with moving boundary is changed to a fixed domain, and solved numerically with the project method in this domain. The stable condition of the scheme of the difference equation is obtained through analysis.Then, the flow field composed of two basic flow field, which is a part of the complex- cylinder flow field, is analyzed numerically by solving each basic flow field respectively and coinciding them on their common boundary. After that, on the non-inertial coordinate, the other part flow field, of the complex cylinder, which is composed of three basic flow field, is simulated by the same method as above.At last, an experimental model is designed and made. With this device the experiments to show the flow field have been accomplished. The experimental and computational results agree well with each other. The conclusion is that the proposed method, i.e., to divide a complex- cylinder flow field into basic flow field, and then to solve them respectively and coincide them on the common boundary, is a good way to simulate the whole flow field. Further more, to solve basic flow field with the project method and coordinate transformation is suitable.