蒸気加減弁に生じる遷音速非定常流れに関する単純形状を用いた数値解析(流体工学,流体機械)

概要

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A steam control valve is used to control the steam flow from a steam generator to a turbine in power plants. The flow field in the steam control valve is usually complex and transonic. A flowinduced vibration can occur in the valve and may cause unexpected shutdown. In the present paper, a numerical study has been carried out to clarify the characteristics of the transonic unsteady flow in the steam control valve. The numerical results show reasonable agreement with the experimental results. Under the high pressure ratio, the transonic jet becomes asymmetric and reattaches on the downstream pipe wall. Such a flow pattern is unsteady and the circumferential location of the reattachment point varies at random. Under the low pressure conditions, a Mach disk occurs downstream the head and fluctuates with the frequency which is lower than that of the acoustic resonance. Influence of the initial condition has also been examined. The result shows that initial pressure ratio plays an important role to determine the eventual flow patterns.
2008-02-25