NUMERICAL SIMULATION AND ACCIDENT ANALYSIS ON THE INNER FLOW FIELD OF THE CENTRIFUGAL COMPRESSOR WITH LARGE SIZE INLET DIAMETER SHROUDED IMPELLER

摘要

This paper presents a numerical simulation on the inner flow field of large size inlet diameter shrouded impeller of an accident centrifugal compressor low pressure cylinder and an analysis of the cause of the accident. The investigation includes the performance account of the whole low pressure cylinder and the reliability certification of physical and mathematical model of the numerical simulation. Through analyzing the impact of the flow field towards the impeller and the numerical simulation of the operating condition (Especially the accident condition), the main causes of the accident were revealed. Because of the unreasonable location design of inlet guide vane and some extant of pre-swirl angle of the inlet guide vane, strong air-impact was found in the inlet of the impeller; While the velocity field of the impeller inlet was considerably disturbed by the trailing vortex of the inlet guide vane. Because the inlet width of the blade of large size inlet diameter shrouded impeller is relatively large, the interior flow presents strong three-dimensional property. The results show that the unsteady vortex, the air-impact and the excitation-vibration are the key factors which cause the fatigue failure of the blade roots.