Development of technologies on innovative-simplified nuclear power plant using high-efficiency steam injectors. (8) Study on direct condensation heat transfer in steam injector

Stability of a water jet in a conduit where vapor flowed parallel with the jet and vapor was condensing on it was examined. When the water jet velocity was low and the steam velocity was high, the water jet collapsed even at the position close to the outlet of the water nozzle. At the position far from the outlet of the water nozzle, the water jet tended to collapse over the wide conditions. As the water jet velocity became low, the disruption tended to occur at the lower steam velocity. When the jet velocity was high, larger subcooling was required to cause the jet disruption. It was tried to correlate the water jet disruption conditions. As one indicator, enthalpy ratio of steam and water subcooling was taken in order to take into account the condensation effect. Other indicators were the Weber number which is usually used for the stability of the jet flowing out to the atmosphere and the critical wave length of the Kelvin-Helmholtz instability. The correlated results suggested possibility to draw some relation among these. Further examination is required. (author)