Research On The Characteristics Of Flow Field Of The Local Generator

Spiral flow can be seen frequently in nature. It was not only wildly used in industry, but also applied in daily life. Sediment transportation by spiral pipe flow has been used. It was a new way of sediment transportation with the advantage of high-concentration, energy-saving and high-efficiency.The paradox of concentration and energy of sediment transportation in smooth flow was conquered.In general, spiral pipe flows are generated by three means: tangentially inletting medium, guiding fluid by vanes with a certain angle and axially rotating pipe. In this paper, spiral pipe flows generated by locally installing guide blade were researched. Based on the previous research, the influences ofboundary layer of guide blade were considered. The characteristics of flow field in boundary layer are different from that of laminar flow and turbulence. So, it was not ignored. For the influences of Reynolds stress, the turbulence model was founded. And then, the formation and development of spiral pipe flow were studied by numerical simulations and experimental measures.Based on the Navier-Stockes equation, the finite difference method was applied to variance the simplified N-S equation on cylindrical coordinate system. Then, 3-D model of the spiral flow locally generated in circular pipe with steady and axial-symmetry condition was founded. The ordinary iterative method of Gauss-Seidel was induced. Finally, the velocity field and pressure field of different discharge was obtained.By means of experiment, experimental data of velocity and pressure of spiral flow generator-generating spiral flow locally in different discharge were acquired. By contrasting the result of numerical simulation with experimental data, the reliability of3-D model was tested.The main conclusions are as follows. The axial velocity distribution of the spiral flow generator is a logarithm-like function. Its maximal value is not at the central. The difference of the axial velocity between the maximum and the central value reduces with the attenuation of the spiral flow. The circumferential velocity distribution is basically a linear function. The maximum value closes to axes with the attenuation of the spiral flow. The pressure is minimum at the pipe centre and maximum near to the pipe wall. The radial difference of pressure is reducing with the attenuation of the spiral flow. Along the axes, the pressure near to the pipe wall is increasing and reducing at the pipe centre.Based on the experiment, research on the characteristics of the spiral flow by using numerical simulation is feasible. This paper enriched the theory of sediment transportation by spiral pipe flow. It also laid a foundation for applying in projects.KEY WORDS: spiral flow,boundary layer,turbulence model,numerical simulation...