National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Numerical simulations of aeroelastic instabilities in turbine blade cascade by modified Van der Pol model at running excitation
Pešek, Luděk ; Šnábl, Pavel ; Prasad, Chandra Shekhar ; Delanney, Y.
Apart from rotary test rig for evaluation of structural dynamics of the bladed wheels, the control flutter experiments has been performed on the linear cascade model in the subsonic wind tunnel in the Institute of Thermomechanics, of CAS, in Prague. These experiments are aimed at stability evaluation of the cascade at running waves or at stability limit testing by flow speed changes or by force impulses of blades. The onset of flutter and its spreading in the cascade are observed, too. The linear cascade model consists of five NACA010 blades. All the blades can be separately excited with electromagnetic torque excitation mechanism and all of them are instrumented to measure the aerodynamic moments which can be used to calculate the aerodynamic work. A more details about the linear blade cascade experimental set up can be found in [1-2]. To predict a dynamic behaviour in the blade cascade, we have been dealing with simplified theoretical modelling of the aeroelastic instability in turbine blade cascade [3-5]. Due to the application of the reduced cascade model consisting of simple elements – springs, rigid bodies, linear dampers – and aeroelastic forces introduced by analytical Van der Pol model, it facilitates to study the dangerous states of vibration of such complicated turbine parts [6-9]. This study is aimed at examination of aeroelastic instabilities of 10-blade cascade at running excitation that arises due to the wakes flowing from stator the blades to the rotating blades. They cause forced excitation in the narrow frequency range.
Excitation of rotor wheel blade resonant vibration by magnetic field
Vaněk, František ; Pešek, Luděk ; Procházka, Pavel ; Cibulka, Jan ; Vaněk, Petr
Development of excitation by magnetic field for a rotating bladed wheel were analyzed and tested on the model wheel of IT AS CR. Two solutions with permament magnets and electromagnets were considered. The new electromagnets UTM2 and UTM3 for the excitation in the Campbell machine were designed. Vibration phenomena excited by electromagnets were measured by strain-gauges and magneto-kinematic system VDS-UT.

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