Laboratory of Heat and Mass Transfer

Department:   Department D 2 - Thermodynamics
Head:   doc. Ing. Zdeněk Trávníček, CSc.

The laboratory encompasses expertise in heat and mass transfer, fluid dynamics and fluidics. Specific missions include passive and active control of flow and temperature fields, intensification of heat and mass transfer in forced convection (impinging and synthetic jets, wakes).
The laboratory is a trendsetter of modern and effective trends in the subject field, which are based on biomimetic principles: known and well-tried concepts of biological systems in nature are applied in technology to enhance human products.

Visualizations obtained in the laboratory:

Synthetic jets
Phase locked visualization and phase averaging of the velocity measurement
Credits:: J. Kordík, Z. Trávníček

 

Local heat transfer

Produced by (the above animated) synthetic jet. The experiment was carried out using the naphthalene sublimation technique in the field laboratory in Nový Knín. Using the heat/mass transfer analogy the experimental mass transfer data were transformed into the Nusselt number distribution shown in the figure.

 

Visualization of the von Kármán vortex street

at temperature T = 144.5°C, Re = 61
(a) Isothermal case T* = TW/T = 1.00
(b) Cooling of the cylinder (T*=0.70, Reeff=71) causes increasing of the vortex shedding frequency

 

Jet bistability

Two-slot impinging jet demonstrates bistability and hysteresis of flowfields: boundary conditions alone cannot determine the flowfield uniquely, because the flow pattern (A or B) depends on flowfield history. Flow field assumption (top figures) and confirmation by flow visualization (bottom figures).