抄録
Recently, we have experienced the industry issue of overheating failures in turbine-valve drain piping. The cause of the overheating has been believed to be thermo-acoustic phenomenon, which is known as H-S tube, but there have been little information about the thermo-acoustic failures. This report shows test results obtained by impinging jet air to a tube having close end that is simulating the drain pipe. The tube length is up to 2m, much longer than the previous works. The relationship between the heating rate and the pressure fluctuation in the tube is examined experimentally. The results show that there are two heating states, standing-wave type and non standing-wave type, which are similar as the previous works about shorter tubes. The relationship is also organized in dimensionless expressions, to be able to estimate the amount of heat generated in the steam. Finally, two countermeasures are proposed: one is to open the drain valve slightly, and the other is to add a muffler. In the case of the muffler, it should be noted that the upstream side of the muffler will still be overheated.
