The results of acoustics tests of different structure woven fabrics are presented. The researches were performed in the aeroacoustic anechoic chamber. Ten fabrics were tested (four of them with honeycomb 3D design) to check their acoustic properties. The tests were conducted inside lower and medium acoustical frequency zones. The presented studies showed that all fabrics with honeycomb weaves had much less attenuation than other fabrics, mostly due to less dense structures at higher thicknesses and more open internal structures. Having analyzed the obtained results, some comments are shown and possibilities of using such woven structures are proposed.

Utilizing textile-based acoustic materials can be considered basically from two points of view. First, it may be used as a sound absorbing material. Second, it may be used as a decoration that gives the surrounding area a new artistic appearance. To improve the acoustic possibilities of any woven fabric, it is necessary to study the influences of yarn characteristics and the internal structures of weave interlacement. To understand the impact of the yarn on the fabric, the samples were prepared using only polyester fiber as textured, twisted, and staple yarns. Regarding this experiment, the basic weave’s structure type, such as plain, rib, sateen, and twill, were used. Overall, 16 woven fabrics were prepared. The investigation was performed in the range of low to medium acoustic frequencies. The experiments were conducted in an anechoic chamber. Compared to other yarn types, fabrics formed from textured polyester yarn had higher sound absorption properties. Moreover, the observed results show that the different incidence angles of acoustic signals influence the measured sound absorption properties of a textile.

Detailed experimental investigations were conducted of the detailed flow structures in a model two-stage low-pressure turbine. The objective of this study is to gain more insight into phenomena affecting flow behaviour due to the indexing airfoil effects in multi-stage machines. To investigate the effect of the vane clocking on axial turbine efficiency and performance, an analysis of the experimental results of the steady and unsteady flow measurements throughout the flow field for different circumferential positions of the first stator is performed. Detailed flow pictures were measured for all measuring planes according to the radial and circumferential inter-row traversing. Aerodynamic measurements were compared to the turbine design speed and “classical” clocking position of the two stators. Herein, some steady and unsteady flow measurement results, and the external characteristics for different circumferential positions of the stator vanes are described. The experimental investigations presented in this paper were carried out since mid-nineties [1] on a 2-stage turbine research facility TM-3 at the Institute of Turbomachinery of Technical University of Lodz in close cooperation with Institute of Jet Propulsion and Turbomachinery of Technical University of Aachen, Germany.

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