スリット付き中空静翼の水膜分離性能

概要

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The presence of water droplets in the low-pressure stage of a steam turbine leads to erosion of moving blade, especially of an advanced long blade, because of the larger blade tip speed and higher wetness. This paper describes the effect of the separation of water film through suction slits on the blade pressure surface. By assuming a linear velocity distribution with water film, the mass flow and film thickness of water moving on the blade pressure surface were calculated in order to determine the location of slits. Water flow separated through suction slits was measured in a wet steam tunnel under the same conditions of a low-pressure steam turbine. Droplet size and velocity were also measured for dispersed water droplets in the wake of the blade with and without suction slits by means of a fiber laser Doppler velocimeter (LDV). Test results indicated that the water separation coefficient is strongly affected by the location of slits and pressure difference between cascade inlet and drain separator. Finally, the flow rates of dispersed water droplets in the wake of the blade with suction slits are 30〜40% lower than those in the wake of the blade without suction slits.
社団法人日本機械学会の論文
1991-12-25