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This article presents a description of design work for newly created centrifugal fans. This was done based on the example of an innovative solution that uses a change in impeller geometry. In the described solution, this is achieved by shortening and lengthening the impeller blades. The development of a technical solution with such properties requires a change of approach in the design process compared with classic solutions. Therefore, the following text describes this process from the concept stage to demonstrator tests. The principle of operation of such a solution is presented and the assumptions made based on analytical calculations are also described. The text also shows a 3D model of the centrifugal fan with variable impeller geometry, made with the help of computer aided design (CAD) tools. In the further part, numerical calculations were made on its basis. The finite element method (FEM) calculation made it possible to verify the structural strength of the project and its modal properties as well as to verify flow parameters, thanks to the use of computational fluid dynamics (CFD) calculations. The next step describes the procedure for testing centrifugal fans with variable rotor geometry, which is different from that of fans without this feature. The next part presents the results of research from the tests carried out.

The paper presents a method for checking the technical condition pipeline compensators and method of investigation during the research. This method is based on numerical calculations FEM and long-term measurement loads of temperature. In the whole pipeline installation there are three types of compensators: 1-lens compensator , 2-lens compensator, 3-lens compensator, which transfer loads at different levels. The aim of the analysis was to check the correct choice of compensators in each pipeline line.

The testing and inspection of fans is a crucial task at the stages of designing and prototyping as well as in terms of future exploitation. In case of machines performing rotational movement, the scope of research is very broad and concerns strength tests, vibration diagnostics, acoustic test, and flow tests. The article presents the issue of studying vibrations of chosen elements of a fan with special regard to the casing and flow tests of the fan itself. The tests were carried out both on the actual object and numerically.

Centrifugal fans are widely used in order to move air or other gases in ducts. As exact as possible manufacturing of fan is required in order to ensure long time of operation and desired flow parameters. In the article evaluation of influence of unevenly spaced blades onto flow parameters of impeller is considered. Thanks to usage of numerical simulation, few different configuration of blades inaccuracies could be compared with basic ideal case. Received results suggests that inaccuracies in circumferential blade spacing influences flow pattern across impeller and changes flow parameters of fan. It is interesting that in few cases efficiency of impeller is higher than in basic solution, but in fact such situation cannot been accepted since in these cases non-uniform fluid force distribution can cause higher vibrations of fan. In general, differences of efficiency are small what suggests that influence of unevenly spaced blades onto flow parameters can be in many cases neglected.

The modal analysis of technical objects undergoing variable load intensity is an important task, thanks to which the safety in terms of resonance vibration phenomenon can be measured. This paper concerns the aspects of testing the new WLS series fans, used for local mine ventilation, which provide safer underground conditions resulting in more efficient work. The use of numerical methods in the calculations of natural frequencies and the comparison of numerical and experimental results calculated with the use of operational modal analysis have been emphasized.

Operation of machines in resonance ranges is a great challenge for design engineers. The paper focuses on the analysis of centrifugal fan casing vibrations which during machine operation, particularly in unsteady states, are very strong. Within a series of investigations performed according to the experimental modal analysis natural frequencies of fan casing vibrations were specified. Additional numerical simulations helped to define theoretical values of the natural vibrations frequency and its mode shapes. The results were analyzed and the numerical model was adjusted. The information was later used in the analysis of vibration measurements in real operating conditions. The results achieved for a nine-blade impeller (new type) were compared to results of an old construction eight-blade fan impeller. New solutions, which shall facilitate casing operation beyond resonance frequencies vibrations areas, were proposed.

The condition of headframes in underground mines has a substantial effect on the proper operation and safety of hoisting equipment. One of the potential problems that might occur during operation is the tilting of these structures, which can lead to difficulties in operation and, in extreme cases, to failures. The paper presents an original method of evaluating the technical condition of headframes, estimating the remaining operating time and finding the causes of irregularities in the operation of this kind of structures. To show this, a series of experimental studies and structural analyses were conducted on a model headframe. Based on experimental tests and numerical calculations, the operational safety of the structure was established along with limit values of operational parameters and possible preventative measures were proposed.