In a recent paper it has been shown that the presence of liquid has an influence on Flow Induced Pulsations (FIPs) in closed side branches. Even larger effects of liquid in case of whistling in corrugated pipes were reported.
For this experimental study, the “Tandem configuration” with two closed side branches along a main pipe is considered. It is characterized by the distance between the two closed side branches equal to the double of their acoustic length.
The experiments reported in this paper aim at investigating the effect of the mixture water/gas on FIPs measured at the closed end of the two closed side branches. Different water flow rates are injected in the flow to obtain a mass factor rate in the range 0–10−4 m3/s. Furthermore, the relation between the multiphase flow pattern in the main pipe and the trend in the pulsation amplitude and Strouhal number is discussed, by comparison with the test for dry gas. To understand the effect of the type of flow, tests are performed with the injector far from and close to the upstream side branch.
For the far configuration, at both low and high injection rates, pulsations decrease for increasing injection rates. However, in the intermediate region, an increase of pulsations is observed. These different ranges can be attributed to different (multiphase) flow regimes.
Concerning the close configuration, only a decrease of the pulsations is observed over the full range. Furthermore, a decrease of the Strouhal number corresponding to the maximum pulsation level is observed.