Internship | Singing flexibles

Flexibles hoses are used in the energy industry to transport gas. A flow through these hoses can cause high amplitude sound (singing) due to flow detachment at the hose internals (corrugations). This phenomenon can damage the hoses and attached piping. This project aims to find how liquid injection can suppress the singing.

Flexibles hoses are used in the energy industry to transport gas. These type of hoses are used for the transport of for instance natural gas or CO2. Often these flexible hoses have an internally corrugated profile. At each corrugation, the boundary layer separates and an unstable shear layer is formed. This unstable shear layer can interact with an acoustic field and act as an amplifier. This can lead to the generation of a high amplitude tonal sound. This is also called ‘singing’ or ‘whistling’. The amplitudes can be that high that damages have occurred to attached piping. This phenomenon mainly occurs in dry gas (single phase) conditions. If some liquids are present in the gas, the corrugations are partially filled up and liquids will be present in the shear layer. Both effects reduce the source strength and no high amplitude sound is generated [4, 5, 6]. In the field, some successful campaigns were done to postpone the singing by liquid injection. However, in a recent campaign, suppression of the singing via liquid injection required much more liquid than anticipated. Therefore, the methods for the prediction of the behaviour of the liquid are not good enough. One hypothesis off the failed field case is that the cavities in this particular hose were much wider than in previous experiments.

Although the behaviour of the influence of liquid on the singing characteristics is a complex interaction between multiphase aspects, flow separation at the cavities and acoustic interaction, the focus in the student assignment is in the prediction of the liquid in and at the cavities. At this moment no experiments are foreseen and the focus is on CFD simulations of the liquid behaviour at cavities. If the CFD program is successful, experiments might be setup in the 2nd half of the internship for deeper analysis.

We are looking for a student who is enthusiastic, critical and a team-player. We expect you to work hard and independently on your own project, but ask for help if needed. Knowledge on fluid mechanics and CFD is highly preferred.

Duration: 6 to 9 months

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After the first CV selection, the application process will be conducted by the concerning department. TNO will provide a suitable internship agreement. If you have any questions about this vacancy, you can contact the contact person mentioned below.