On the influence of gas-liquid two-phase flow on Lorentz force velocimetry. - In: Measurement science and technology, ISSN 1361-6501, Bd. 29 (2018), 8, S. 085301, insges. 11 S.
Lorentz force velocimetry (LFV) is a contactless and non-invasive flow measurement technique for electrical conducting fluids. When the fluid passes a magnetic field, a Lorentz force will be generated. The force is proportional to the electrical conductivity, to the velocity of the fluid, and to the square of the magnetic flux density. It is possible to apply this technique over a range of conductivities varying from high values as for liquid metals to lower values as typically for electrolytes (e.g. salt water). The main challenge is measuring the force, which is six orders of magnitude smaller for electrolytes in comparison to liquid metals. It was shown that LFV is insensitive to the shape of different velocity profiles and especially to strongly asymmetric profiles as long as the volume flow is constant. However, the influence of a second gaseous phase on the force signal remains an open question. This is of fundamental interest especially for chemical and food processing industries. To examine this influence in detail, electrolyte flow with different volume flow fractions was investigated for the current study. By using frits, it is possible to generate a homogeneous distribution of the second (gaseous) phase in the electrolyte. Small electrolyte velocities or flow rates (v < 1.5 m s^-1, V1 = 225 l min^-1) enable the formation of slug flow and stratified wavy flow, and higher velocities (v > 1.8 m s^-1, V1 = 270 l min^-1) the formation of bubbly two-phase flow in the used test section. By this means, it is possible to study a wide range of flow patterns in a horizontal duct. The experimental results are in good agreement with the analytical estimations for fully dispersed flow. However, for a nonhomogeneous distribution of air the force signal deviates much stronger. An explanation can be the superposition of Lorentz forces and magnetic forces, caused by differences of the magnetic susceptibilities of water and air, which will be discussed in greater detail.
https://doi.org/10.1088/1361-6501/aaca8a
Sparsity order estimation from a single compressed observation vector. - In: IEEE transactions on signal processing, ISSN 1941-0476, Bd. 66 (2018), 15, S. 3958-3971
https://doi.org/10.1109/TSP.2018.2841867
Process characterization of powder based laser metal deposition on thin substrates. - In: Journal of laser applications, ISSN 1938-1387, Bd. 30 (2018), 3, S. 032506, insges. 6 S.
https://doi.org/10.2351/1.5040630
An analytical temperature-dependent design model for contour-mode MEMS resonators and oscillators verified by measurements. - In: Sensors, ISSN 1424-8220, Bd. 18 (2018), 7, 2159, insges. 21 S.
https://doi.org/10.3390/s18072159
Differential ultra-wideband microwave imaging: principle application challenges. - In: Sensors, ISSN 1424-8220, Bd. 18 (2018), 7, 2136, insges. 32 S.
https://doi.org/10.3390/s18072136
Bilateral comparison for determining the dynamic characteristic values of contact thermometers in fluids. - In: Journal of sensors and sensor systems, ISSN 2194-878X, Bd. 7 (2018), 1, S. 331-337
https://doi.org/10.5194/jsss-7-331-2018
Evaluation of dry electrodes in canine heart rate monitoring. - In: Sensors, ISSN 1424-8220, Bd. 18 (2018), 6, 1757, insges. 12 S.
https://doi.org/10.3390/s18061757
Modular AUV system with integrated real-time water quality analysis. - In: Sensors, ISSN 1424-8220, Bd. 18 (2018), 6, 1837, insges. 17 S.
https://doi.org/10.3390/s18061837
An ADRC-based control strategy for FRT improvement of wind power generation with a doubly-fed induction generator. - In: Energies, ISSN 1996-1073, Bd. 11 (2018), 5, 1150, S. 1-19
https://doi.org/10.3390/en11051150
Precision structuring and functionalization of ceramics with ultra-short laser pulses. - In: Journal of laser applications, ISSN 1938-1387, Bd. 30 (2018), 3, S. 032501, insges. 7 S.
https://doi.org/10.2351/1.5040628