Patent application describes an apparatus for monitoring the process of melt fiberization on spinning discs. The core of the apparatus is the method of flow field quantification by computer-aided visualization.
F.06 Development of a new product
COBISS.SI-ID: 13179931Doctoral dissertation considers velocity field of water flow at sharp-crested rectangular side weirs and their discharge coefficients for subcritical flow. This work focuses on experimental results, obtained at various physical hydraulic models. A visualization method is employed, which – in contrast to more common approaches – allows non-invasive quantification of velocity fields. These are measured in separate horizontal planes of observed flow. Determination of vector field of velocities is based on the analysis of films displaying the movement of inserted pollutant, e.i. particles, dye or electrolysisgenerated hydrogen bubbles. The method allows numerical calculation of components of velocity vectors with great spatial and time resolution. Results of measurements provide a new, more detailed insight into complexity of water flow at side weir, and – in contrast to one of the energy-approach assumptions – indicate the distinctively nonuniform distribution of considered velocities along the flow. Results are compared with published studies. As an additional contribution to science a new, phenomenological equation for a side weir discharge coefficient has been formulated on the basis of dimensional analysis and a power-law formulation. This equation is simple to use and is valid for fairly wide range of dimensionless parameters that give main geometrical and hydraulic characteristics of flow over side weirs.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 5862497On a model of a circular secondary settling tank the dissertation deals with typical flow structures that establish at twelve different combinations of hydraulic and solids loading. Another variable parameter beside the already mentioned were also solid particles that served as suspended matter. The first group of used particles was fine ground hazelnut shell that was available in two different compositions of grain size; the second group were glass microbeads in three different granulations. Three control experiments were conducted at neutral density conditions by introducing a dye. All experiments were filmed with a digital camera. By processing video clips of experiments an indicator of concentration in the inflow and in the vicinity of the effluent was captured by photogrammetric approach and data on flow field was obtained by computer-aided flow visualization. A repetition of the first series was carried out in order to collect samples of inflow and outflow suspension. A wide set of experiments with carefully chosen parameters enabled a systematic study of hydrodynamic phenomena in the sedimentation chamber. Flow field and clarification efficiency were found out to be closely related to the value of the densimetric Froude number Frd. All experiments exhibited trends of growing efficiency when values of the densimetric Froude number Frd were decreasing. A three-layer flow structure never occurred when the biggest particle granulation from glass microspheres and when coarse ground hazelnut shell was used. By the rest of the model particles a low value of Frd reflected in a formation of favourable three-layer flow structure, whereas the threshold value of Frd (when the value is exceeded, the three-layer flow does not develop) was independent from the type or size of the particles.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 6622817In this thesis, the process of mineral wool fiber formation from the melt spun by a spinner wheel is investigated. Due to restrictions in the study of the real process, melt fiberization is modeled on a single wheel spinning machine supplied by cold Newtonian liquids. High-speed camera visualization is employed to conduct the measurements in different operating points defined by the variation of the wheel rotational speed, liquid flow rate and physical properties. Results of the photographic material analysis are presented as the identification of the typical spinner operating regimes and as regression models for characteristic integral fiberization parameters such as the number, length and diameter of ligaments and related flow structures. Additionally, ligament growth kinematics is studied in conjunction with the hydrodynamic stability of fiberization. Based on the qualitative and quantitative analysis results of the process, operational characteristics are compared to other types of rotary fiberization devices and to known theoretical models of the relevant hydrodynamic phenomena. In relation to the undesired phenomena of the industrial spinner wheel surface abrasion and the unfiberized material formation, we investigate the mechanisms of the liquid film velocity slip against the wheel and the ligament end pinch-off, respectively.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 13812251