Jacek Sobczyk

Strata Mechanics Research Institute of the Polish Academy of Sciences in Krakow · Flow Metrology

This article presents an experimental stand for the generation of gas flows with very low velocities. The constant volume air flow was generated in the measurement area with the use of a Mariotte bottle and a water piston (water column in a tank). The air-flow velocity was determined from the change in the height of the water piston with time, whic...

This paper describes a study to expand the knowledge as to whether a thermal wave anemometer can be used to measure the velocity of flowing gases or gas mixtures in situ. For this purpose, several series of measurements were performed in laboratory conditions using both the previously used probe and other probes of similar design. The probes were n...

This paper presents the results of PIV measurements of turbulent airflow in a channel with a single ribbed wall. The rough elements had the form of evenly spaced trapezoids. The ratio of the height of a single rib to the height of the measurement channel was 0.1. The ratio of the distance between adjacent ribs to the height of a single rib (i.e., t...

This paper presents a method of measuring gas flow velocity based on the thermal time-of-flight method. The essence of the solution is an analysis of the time shift and the shape of voltage signals at the transmitter and at a temperature wave detector. The measurements used a probe composed of a wave transmitter and a detector, both in the form of...

Today, we are aware of the fact that a set of such parameters as relative humidity (RH) [%], temperature (T) [°C] and barometric pressure (p) [hPa], which determine microclimate in a given location, directly affect the condition of art objects, since they determine the speed of a large number of their deterioration processes. The list of parameters...

The experimental study with the use of particle image velocimetry (PIV) has been conducted to investigate the stability of flow around two identical square cylinders in tandem arrangement at a different Reynolds numbers. The important study parameter was the displacement of the downstream cylinder with velocity in range from Vc = 0.01 to 0.09 m/s....

The paper reports results of an analysis concerning the influence of a computational domain discretization method on the numerical stability of a model as well as the calculation error. The topology of a packed bed of a granular material consisting of granules contacting tangentially in one point makes the modelling of heat and mass transfer due to...

The conducted research, though still at the preliminary stage, is a step toward a better understanding of the flow phenomena accompanying hot-wire probes. For the flow in the vicinity of a wall, a potentially non-optimal case was analyzed – a single normal hot-wire probe oriented normally to the surface. According to the results, undisturbed flow,...

Computational domain discretization is the pre-processing stage in CFD analysis and it highly contributes to reducing the level of solution error as well as increasing the numerical stability of a model. The discretization of domain representing a packed bed of granular material is a demanding task due to the topology of the model consisting of sph...

This paper is about experimental study of air flow around two identical square cylinders arranged in tandem with the use of particle image velocimetry approach. Impact of progressive increase and progressive decrease in the spacing between centres of the cylinders (ranging from 2 to 9 widths of the cylinder) on a hysteresis limit were investigated....

The paper presents a simple method for determining the phenomenon of unsteady thermal effects in cooling of circular cylinder. The research has been undertaken in order to explain the thermoaerodynamic processes, which are characterized by the turbulent structure of the flow around a stationary rigid heated cylinder cooled by the oscillating flow....

Flow characteristics in vicinity of six circular cylinders aligned inline was investigated experimentally by means of PIV method. Experiments were conducted in a low speed closed circuit wind tunnel. Inflow velocity was 1.2 m/s which corresponds to Re=1600 based on the cylinder diameter. Spacing ratio between cylinders L/D was 1.5. Instantaneous an...

Preliminary experimental study of the flow field disturbance in the vicinity of single sensor normal hot-wire anemometer (SN) probe was carried out. Regular 2D particle image velocimetry (PIV) setup equipped with micro lens and distance rings was applied to measurements of macroscopic flow around microscopic elements. Experimental results revealed...

Flow characteristics in vicinity of six circular cylinders aligned inline was investigated experimentally by means of PIV method. Experiments were conducted in a low speed closed circuit wind tunnel. Inflow velocity was 1.2 m/s which corresponds to Re =1600 based on the cylinder diameter. Spacing ratio between cylinders L / D was 1.5. Instantaneous...

Preliminary experimental study of the flow field disturbance in the vicinity of single sensor normal hot-wire anemometer (SN) probe was carried out. Regular 2D particle image velocimetry (PIV) setup equipped with micro lens and distance rings was applied to measurements of macroscopic flow around microscopic elements. Experimental results revealed...

The aim of this work is the development of the lattice Boltzmann model for simulation of the mold filling process. The authors present a simplified approach to the modeling of liquid metal-gas flows with particular emphasis on the interactions between these phases. The boundary condition for momentum transfer of the moving free surface to the gaseo...

This paper presents the results of the preliminary experimental investigations of the disturbance of velocity field resulting from placing a vane anemometer in the analyzed air flow. Experiments were conducted in a wind tunnel with a closed loop. For the measurement process, Particle Image Velocimetry (PIV) method was used to visualize the flow str...

The present work analyzes the influence of seepage and desorption processes on the initial conditions of coal and gas mini-outbursts. A series of laboratory experiments incorporating coal briquettes and three different gases, namely carbon dioxide, methane or nitrogen were carried out. Experiments relied on mini-outburst inducing. Space and time pr...

The seepage of gas through coal and in particular through coal briquettes has already been a quite well known phenomenon. This also refers to its influence on certain initial conditions of coal and gas outbursts such as threshold values of so called gas stresses. In turn a detailed research on the influence of sorption processes on these conditions...

Certain laboratory tests require a gas source with a stable pressure. Commercially available gas pressure regulators address the above requirement. However, the accuracy of these devices is often insufficient and what is more, the market offer of accurate gas pressure regulators is limited. Moreover, the commercially available gas pressure regulato...

W pracy przedstawiono krótką analizę naprężeń gazowych, które powstają w brykietach węglowych podczas eksperymentów laboratoryjnych polegających na prowokowaniu miniwyrzutów. Za materiał badawczy posłużyła próba węglowa pobrana z kopalni „Zofiówka”, a użytym gazem był azot. Obok analizy porównawczej wyznaczonych maksimów globalnych naprężeń gazowyc...

This article introduces a project and some specifications of the capillary flow meter. The functioning of the presented flow meter is based on the measurement of pressure drop caused by the gas flowing through the capillary. The article includes in detail a description of the calibration process of the above-mentioned measuring device and presents...

Non-destructive research of historical objects makes possible to collect valuable information concerning technical construction and the state of preservation. Observations and analyses carried out in visible light, UV, infrared as well as under the impact of X-ray radiation provide an image of the object's surface and its inner structure. The outco...