In the paper, the authors refer to measurement of a car cabin heat load and indoor environment during driving in real traffic conditions. The primary aim was to obtain data for boundary conditions, model testing and results comparison of the 1D car cabin heat load model. The secondary aim was better understanding of cabin environment inside a car cabin under different operational conditions. As test vehicle Škoda Felicia Combi with dark blue painting was used and GPS data, parameters of ventilation, cabin environnment and ambient environment were measured. Measurements were preformed for summer, autumn and winter conditions including parking and driving test circuits around Brno. Driving circuit included driving in the city, out of the city and on the highway D1. and Obsahuje seznam literatury
Validation of a numerical simulation using experimental data is a necessary prerequisite for verification of proper use of numerical method. This article deals with a comparison of velocities as predicted by an idealized model of human upper airways during stationary inspiration for three different breathing regimes. For the purpose of this study, a model which includes a realistic geometry of the mouth cavity and glottis coupled with and idealized geometry of the trachea and bronchial tree up to the fourth generation on branching was made. Calculations were compared with experimental data acquired by Phase-Doppler Particle Anemometry (P/DPA) on the identical geometry. Velocity data were compared at three points in the trachea. Specific air flow characteristics are documented and discussed based on results of the numerical simulation of the velocity field. and Obsahuje seznam literatury
Deposition of fibers in human lungs is known as a health hazard. In-vitro measurements were performed with glass fibers in a realistic model of human lungs up to the seventh generation of branching to estimate the effect of fiber size and breathing pattern on fiber deposition. Deposited fibers were rinsed from the model segments and gathered on nitrocellulose filters. Phase-contrast microscopy with high resolution camera was used to capture images of filters with fibers. New software was developed for an automated image analysis and local deposition characteristics were calculated afterwards. The whole method proved to be a useful and valuable tool for the evaluation of fiber and particle deposition. and Obsahuje seznam literatury
Pressure-swirl atomizers are widely used in various combustion applications including aircraft jet engines. Spray characteristics, such as drop-size and velocity distribution have a principal influence on the combustion process. A number of studies have dealt with single-point laser diagnostic techniques, such as Phase-Doppler Anemometry, for spray measurements. An alternative approach is the use of a whole-field method - Particle Image Velocimetry (PIV). This contribution deals with investigation of spray characteristics of a spill-return pressure-swirl atomizer for a small-sized jet engine by means of PIV. The nozzle was operated on a cold test bench at atmospheric pressure and room temperature. Measurements were carried out in an axial section of the spray cone with various single-camera and stereoscopic PIV configurations. Results of out measurements provide a quantitative visualization of the spray flow fields in regimes based on the engine operating conditions. Comparison of velocity profiles obtained from the individual PIV configurations is presented and discussed. The pressure-swirl spray is recognised as an optically harsh environment for PIV due to large particle size range, high diameter-velocity correlations, strong velocity gradients and large velocity differences within an image, large variations in ‘seeding‘ concentration and out-of-plane particle movement. The PIV results comprise new findings to the complex 3D character of velocity field in the pressure-swirl sprays. and Obsahuje seznam literatury
The article presents a liquid film instability model designed using results of the set of CFD simulations. The governing equations of the model are derived using a linear equation of motion. The stability analysis is carried out by imposing a liquid surface disturbance which growth rate is investigated in dependence on the geometrical and physical configuration. The gas effect parameters, which are decisive variables in the model, are derived using results of the set of CFD simulations of turbulent flow in channel with wavy surface. The agreement between predicted and measured critical gas velocities and wavelengths in dependence on the liquid film thickness is very good. and Obsahuje seznam literatury
This work describes Large Eddy Simulation of backward-facing step flow laden with particles. The concentration of the particles in the flow is high enough for consideration of two-way coupling. This means that the particles are influenced by fluid and vice versa. The inter-particle collisions are neglected. The Euler-Lagrange method is adopted which means that the fluid is considered to be continuum (Euler approach) and for each individual particle is solved Lagrangian equation of motion. Particles are considered to be spherical. The simulations are performed for different volume fractions. The results are compared to the single-phase flow in order to investigate the effect of the particles on the turbulence statistics of the carrier phase. and Obsahuje seznam literatury