Flow Measuring Techniques and Multiphase Flow

Flow measuring techniques provide insight into properties of flow fields, such as velocity, pressure, and temperature distributions, etc, which may in many cases be difficult to achieve by computational means. Research in the present field is performed taking advantage of special experience with two kinds of flow measuring techniques – optical techniques, based on interferometry, and a special kind of rheometry, which looks at the elongational behaviour of liquid filaments in uniaxial elongational flows. The former flow measuring techniques are in particular Laser-Doppler anemometry (LDA) and phase-Doppler anemometry (PDA). The latter rheometric flow measuring technique was developed and used for measuring the elongational viscosity of viscoelastic polymer solutions. Applications to medical problems with viscoelastic body fluids – such as saliva and hyaluronic acid – are planned. Multiphase flows occur in many technical applications and in nature. They are characterised by the occurrence of media with different state – solid, liquid, gaseous – in the flowing fluid. Technical multiphase flows are, e.g., flows in bubble columns, spray flows in spray drying and in fuel injection, and flows in waste-water treatment. The institute works on techniques for controlled spray formation, the process of bubble formation at submerged porous surfaces, and the collision of drops in sprays.