An experimental and theoretical study has been made to investigate the transient processes which occur when hot liquid spray droplets are suddenly injected into a gas contained in a closed chamber. A novel experimental apparatus was employed in which hot water is injected via commercial solid cone spray nozzles into air enclosed in a cylindrical spray chamber, of 121 mm diameter and 190 mm height, at a pre-determined constant owrate, and for a set duration, under computer control. Measurements were made of the spray chamber pressure rise with time due to the combined effects of liquid-gas heat transfer, droplet evaporation and liquid accumulation in the chamber. The experimental results reported in the paper cover a range of nozzle sizes, in both single-nozzle and multi-nozzle con gurations, and the effects of liquid owrate, initial gas pressure and initial liquid-gas temperature difference are considered. A simple analytical model has been developed which subdivides the chamber volume into three zones: a liquid zone, a transfer zone where heat and mass transfer occurs, de ned by the spray cone angle, and a still zone outside the spray cone. The analysis gathers the important parameters governing droplet heat transfer in a single dimensionless group, denoted by K 2 . For the range of conditions investigated, reasonable agreement between the experimental results and the theoretical solutions were obtained with a value of K 2ˆ2 £ 10 ¡5 .

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SUMMARYA numerical study has been undertaken to examine the behaviour of a gas liquid interface in a vertical cylindrical vessel subjected to a sinusoidal vertical motion. The computational method used is based on the simpliÿed marker-and-cell method and includes a continuum surface model for the incorporation of surface tension. The numerical results indicate that the surface tension has very little e ect on the period and amplitude of oscillations of the interfacial waves. The stability of the interfacial waves has been found to depend on the initial pressure pulse disturbance, and exponential growth of the interfacial wave has been observed in some cases. The in uence of the amplitude and frequency of the forcing oscillations has also been investigated. The results are in good agreement with available experimental and analytical solutions.

This paper deals with the generation and the movement of the liquid phase in the last stages of large condensing steam turbines. Considering thermodynamic instability, the primary droplet size resulting from spontaneous condensation is dependent on radial position, the flow, and inlet parameters. The analysis of the liquid phase transport to the blade surface is given, and the stability and disintegration of the liquid films on the blade surface is discussed.

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