Torsional vibrations at guide-vane shaft of pump-turbine model

This article focuses on the problem of guide-vane vibrations of reversible pump-turbines, especially, in the pump mode. These vibrations are transmitted to the guide-vane shaft torque. The guide-vane vibrations are caused by the impeller exit flow, which has a turbulent and partly nondeterministic property. Experimentally determined flow velocities at the impeller exit are given. The mathematical models for theoretical torsional vibration prediction formulated using linear and nonlinear differential equations are presented. The results of theoretical calculations are compared with measurements results. The possibility of transferring the parameters from the model to the prototype is discussed

Cavitation Instabilities at the Entrance Pipe of Centrifugal Pump

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Zamenjava energenta v termoelektrarni

In Slovenia, approximately one third of electricity is produced in thermal power plants. Electricity prices have risen sharply recently. There are several reasons for this. One of them is the large increase in the price of CO2 coupons that thermal power plants have to buy, since they emit large amounts of greenhouse gas into the environment during the production of electricity. Emissions of the greenhouse gas CO2 are the result of burning fossil fuels, in this case coal. We want to use renewable energy sources to replace fossil fuels and reduce greenhouse gas emissions. More than half of Slovenia is covered with forest, and as a result, wood biomass energy represents a great energy potential. One possibility is the use of wood biomass in a classic thermal power plant for the production of electricity. This contribution presents the energy potential of Slovenian forests, before evaluating the replacement of the energy source in the existing coal-based thermal power plant with wood biomass. It has been discovered that there is enough wood biomass in Slovenia, and that all the electricity that is currently produced from coal can be produced from wood biomass. The cost of wood biomass is higher than the cost of coal. By changing the energy source, we save on the purchase of CO2 coupons. Therefore, the use of wood biomass represents an economically justified energy source for the production of electricity.V Sloveniji približno eno tretjino električne energije proizvedemo v termoelektrarnah. Električna energije se je v zadnjem času močno podražila – razlogov za to je več. Eden izmed njih je veliko povišanje cene emisijskih kuponov, ki jih morajo kupovati termoelektrarne, saj pri proizvodnji električne energije v okolje emitirajo izdatne količine toplogrednega plina. Emisije toplogrednega plina CO2 so posledica zgorevanja fosilnih goriv, v tem primeru premoga. Z obnovljivimi viri energije želimo nadomestiti fosilna goriva in zmanjšati emisije toplogrednih plinov. Več kot polovica Slovenije je pokrita z gozdom, zato energija lesne biomase predstavlja velik energetski potencial. Ena od možnosti je uporaba lesne biomase v klasični termoelektrarni za proizvodnjo električne energije. V tem prispevku predstavimo energetski potencial slovenskih gozdov in ovrednotimo zamenjavo energenta v obstoječi termoelektrarni na premog z lesno biomaso. Ugotovitve kažejo, da je v Sloveniji dovolj lesne biomase, da lahko iz nje proizvedemo vso električno energijo, ki jo sedaj pridobivamo iz premoga. Strošek lesne biomase je višji od stroška premoga, vendar z zamenjavo energenta prihranimo pri nakupu emisijskih kuponov. Tako je uporaba lesne biomase ekonomsko upravičen energent za proizvodnjo električne energije

Emergency gate vibration of the pipe-turbine model

The vibration behaviour of an emergency gate situated on a horizontal-shaft Kaplan turbine is studied. The analysis and transfer of the dynamic movements of the gate are quite complex. In particular the behaviour is examined of the emergency gate for the case when the power unit is disconnected from the system or there is a breakdown of the guide vane system at the moment when the maximal head and capacity are achieved. Experimental-numerical methods both in the time domain and in the frequency are employed. Natural vibrations characterize a first zone, corresponding to relatively small gate openings. As the gate opening increases, the vibration behaviour of the gate becomes increasingly dependent on the swirl pulsations in the draft tube of the turbine. Finally, the data transfer from the model to the prototype by use of the dinamic similitude law is discussed