Low frequency sound acoustic losses in a cooling box for steel production (Infrasonik, SSAB)

  • Due No due date
  • Points None

Background

Low frequency sound (infrasound) with high intensity is used for cooling steel at fast rate, to produce a high-quality steel. The equipment is basically a long resonance tube, with a diaphragm at the close end, driven by an electric motor. At the open end of the resonance tube the sound waves are directed into a cooling box where the steel plates are passed through. The sound waves passing through the cooling box, along a steel plate and cooling fins with narrow spacing. The narrow spacing is needed to produce high velocity of the air/sound pulsating back and forth, to produce high heat transfer rate from plate to cooling fins, but making the geometry narrow adds acoustic losses that in turns slow down the velocity.

Cross-section view of cooling box. Illustration.

Fig 1. Cross-section view of cooling box 

Aim of the thesis work

One part of the work will be a theoretical study of flow losses dependence on shape of cross-section. Another part will be experiments with various configurations of cooling box geometries attached to an infrasound generator. No cooling will be used, only the geometry will be studied. Measurements of produced sound pressure inside the infrasound generator will be used for quantifying the acoustic losses and the produced velocity inside the cooling box geometry. When combining the findings of the theoretical study of flow losses and the experimental measurements the aim is finally to conclude how to calculate flow losses from the input parameters shown in figure 1.  The method for calculating those flow losses will be essential in optimizing full-scale cooling equipment used in industry.

Estimated budget

Existing pulsators and resonance tubes can be used, either at Infrasonik office or in Lund. There will be some cost for transportation to Lund if that option is chosen. The cooling box geometry that must be manufactured will cost roughly 50 kSEK. It will have at least two different b, c, d and H (fig 1) and also a possibility to exchange the plate in the middle to 2-3 different surface roughness. The open cross-section of the cooling box geometry should be near the cross-section of the resonance tube used, to be able to study very high velocity.

Contact person and industrial supervisors

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