The article discusses the process of designing and testing as well as their results, carried out in order to increase the efficiency of axial fans, implemented as part of the European project INESI. Modifications of existing solutions based on rapid prototyping methods were presented. Scanning, FEM and CFD numerical calculations and 3D printing were used for that purpose. Rapid prototyping involved the use of a steel blade base and 3D-printed complex aerodynamic shapes that were bonded to create completely new blades. After their installation on the new rotor, enabling the angle of attack adjusting, a number of verifying tests of the fan were carried out. The solution was successfully tested and the results are discussed in the article.

This article presents a proposal for a wireless diagnostic system for checking the air tightness of the ventilation network. The solution is designed to increase crew safety in underground mining plants and increase the energy efficiency of the ventube ventilation system. The system is based on sensors measuring the pressure inside the ventilation duct in relation to the barometric pressure in the immediate vicinity of the duct. The flow of diagnostic data is based on a cascade transfer. The data from the first sensor are transferred successively to the last one. Based on the prior calibration of alarm thresholds in each device, the leakage or factor influencing the increase of air flow resistance is located. The article presents the genesis of the creation and discusses the principle and purpose of the system. In the following chapters, the progress of work related to testing the system in laboratory, industrial, and underground conditions at the Velenje Premogovnik mine (Slovenia) is presented. The authors analyze the test results and indicate the directions of possible further work on improving the system. The proposed leak detection system is based on a network of pressure sensors that communicate with each other to clearly pinpoint the leak location. The system has been designed for operation in underground mining plants with limited space.

The article discusses laboratory methods and the corresponding computational methods verifying compliance with the normative requirements regarding the lateral correction force of the powered roof support. The currently used flat model only allows for checking the normative requirement in relation to the sum of active forces of the correction cylinders installed in the roof support. Determining the required value of the active force of each cylinder is possible due to the simplified FEM model of a powered roof support, described in the research work, treated as a uniform weightless elastic body loaded with a concentrated force recreating the weight of the roof support located on an inclined longwall panel. The third analysed computational method involves determining the reaction in the four correction cylinders of the roof support, creating a spatial, statically indeterminate system of forces. It enables determining the range of variability of the response in the correction cylinders as a function of the distribution of floor pressure on the roof support base. The discussed computational methods were used to determine, for example, the lateral correction force of one of the types of powered supports used in a longwall panel inclined at an angle of 35°. The usefulness of the discussed calculation methods at various stages of the designing process of the powered support and its certification has been confirmed.