Experimental Study on Performance Deterioration of a Turbopump with Inducer Due to Precipitation of Dissolved Gas

In the present study, we conducted the performance experiments of a turbopump using water with dissolved CO₂ in a closed-loop cavitation tunnel. The inlet pressure was reduced step-by-step by a butterfly valve installed in a suction pipe; when the pressure decreases and CO₂ becomes oversaturated, it precipitates as a gas phase. The experiments were conducted in various conditions of the operating flow rate and the amount of dissolved CO₂. As a result, at all flow rate, the larger the amount of dissolved CO₂ was, the pump performance deteriorated at higher inlet pressure. The results also showed that, at high flow rates, the inflow of gas phase precipitated upstream, i.e. the suction of gas bubbles seemed to cause the performance deterioration, On the other hand, at low flow rate, the precipitation of dissolved gas occurred locally in the flow recirculation zone at the pump inlet as well as in the impeller before the upstream precipitation, forming local gaseous cavitation which seemed to be the main cause of performance deterioration.