The Analysis Of Three-Dimensional Flow In High-Speed Pump And Research Of Its Fluid-induced Pressure Fluctuation

Due to its low price, small size and appropriated structure, the high-speed pump has widely been applied in spaceflight engineering. But with increasing speed, the flow-induced pressure fluctuation of the pump is a severe problem. Cracks in the inducer blades of some foreign spaceflight engines and the high-speed pump of the present work have been found, which are caused by flow-induced pressure fluctuation. Optimizing design and predicting the flow-induced pressure fluctuation of high-speed pump, which is useful to reduce the operation risk of high-speed pump, is a vital subject. To analyze the reason of cracks in the inducer blades, the Reynolds averaged N-S equations, the standard turbulence model, the RNG turbulence model, the sliding mesh technique, Fortran language program and Fluent program have been used to simulate the three-dimensional steady and unsteady turbulent flow in high-speed pump. The calculated results of three-dimensional steady flow not only offer the based dataset for flow diagnoses in the pump, but also indicate the design problem in some parts of the pump as well. The three-dimensional unsteady flow results reflected the influence of three-stage interaction coupled by rotor-stator row to the flow. And based on the results, the flow-induced pressure fluctuation of the high-speed pump is obtained. In the internal flow field of the inducer, the pressure fluctuation frequency of every point was kept consistency coinciding with three times passing frequency of the inducer. In addition, the flow characters in the gap between the static vane and impeller show completely the issue of interaction of rotor-stator rows.The experiment of energy and pressure fluctuation character on the pump is processed in a high-speed pump tig, so that the calculated results are validated. The net head and the discharge of the pump are measured in the energy experiment. And pressure fluctuation in the inducer is measured in the pressure fluctuation experiment. The experimental results are coincidence with the calculated results.In order to diagnose the reason of pressure fluctuation caused by flow in the high-speed pump and to check the validity of loss formulation, vorticity method, normalization helicity and the loss calculation of main part in the pump are presented in the paper. The vorticity method is used to analyze the reason of blades crack in the inducer from vorticity dynamics. And the normalization helicity method is used to calculate the vortex structure in different cross section, and analyze the internal flow field in the inducer.Finally, to analyze cracks on the inducer blades, the pressure fluctuation forces have been used as external force when three-dimensional unsteady stress calculation are conducted. The indirect sequentially coupled physical analysis method and the modal analysis method have been used to calculate the unsteady stress. From the results, the reason of the crack was found.