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Non-linear Vibration of Planar Case of Three-blade Bundle with Dry Friction Contacts
Šnábl, Pavel ; Pešek, Luděk ; Půst, Ladislav
Using dry friction couplings (so called tie-bosses) between the blades in turbine rotors can be used to suppress dangerous resonant vibrations of turbine blades and it has been studied on our institute on various models. Experimental setup of three-blade bundle was built along with bladed wheel. The first set-up of the bundle was with blades turned 45 degrees to the disc plane. In that case the deformation of the blades causes turning of the ends of tie-bosses and edge contact together with multi-directional slip occurs. The experimental set-up was simplified herein so that the blades are parallel to the disc plane and in-line slip occurs. Although single electromagnet was used to excite the system, the first mode of vibration with no slip in tie-bosses just occurred. In case of bladed wheel, all blades have coupling through tie-bosses with neighbouring blades which stiffen them and raise their eigenfrequency. In our case, a mistuning by reducing mass of side blades caused similar behaviour. Steel to steel contact pair was used for the first tests.
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Modern trends of using ceramic cores for aerospace and IGT sector
Karafa, Pavel ; Láník, Boris (referee) ; Tomek, Ladislav (advisor)
The bachelor thesis deals with the manufacturing process and applications of ceramic cores for use in investment casting foundries. These ceramic cores find use extensively in the aerospace and energy industries for the production of turbine blades, or sometimes to create cavities in castings, which can’t be created by other methods. A separate task of ceramic cores described in the work is to create cooling cavities inside the body of the blade to improve the working process of the turbine. Work on the introduction briefly describes the casting using the lost wax method, which the turbine blades are produced, then the materials, separate process for producing ceramic cores, removing them from casting and default application of kernels.
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Modern trends of using ceramic cores for aerospace and IGT sector
Karafa, Pavel ; Láník, Boris (referee) ; Tomek, Ladislav (advisor)
The bachelor thesis deals with the manufacturing process and applications of ceramic cores for use in investment casting foundries. These ceramic cores find use extensively in the aerospace and energy industries for the production of turbine blades, or sometimes to create cavities in castings, which can’t be created by other methods. A separate task of ceramic cores described in the work is to create cooling cavities inside the body of the blade to improve the working process of the turbine. Work on the introduction briefly describes the casting using the lost wax method, which the turbine blades are produced, then the materials, separate process for producing ceramic cores, removing them from casting and default application of kernels.
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Processing of undersampled blade signals
Balda, Miroslav
The paper deals with a method of processing samples of instantaneous positions of blades of a turbine wheel when passing along a sensor attached to the stator of the turbine. The signals are highly undersampled, since the natural frequencies of blades are much higher than the sampling frequency. The paper reveals the way of signal reconstruction based on a priory knowledge of the blade natural frequencies.
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