Aiming at providing guidelines for design of suction slots of hollow stator blade under wet steam flow condition
experiments were implemented on a wet steam test rig with eight hollow stator blades to investigate the water removal performance by varying the position
shape and width of suction slots. The wetness fraction at the inlet section of the test cascade was consistent with the real running condition. It is shown that the amount of removed water is affected by the main flow Mach number and suction pressure difference. When suction pressure difference increases to a moderate value
vaporization of water film occurs and acts as an additional important factor leading to degraded water removal performance. With the position of suction surface slot moving from 0.24 to 0.42 of axial chord
the amount of removed water is continuously increased. Compared with the straight slot
the step-shaped slot cannot improve water removal performance. On the contrary
it results in poor performance when the Mach number is beyond 0.7 due to increased number of sharp corners
which leads to water vaporization. A suction slot with arc-shaped inlet is able to eliminate vaporization of water film and improve water removal performance. A suction slot of 0.35 mm width is apt to allow water film across
a suction slot of 2 mm width cannot form an effective suction pressure difference
and both lead to degraded water removal performance. Suction slots of 0.7 mm and 1 mm width have good water removal performance
but the later is more slightly influenced by water vaporization.
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references
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