Motor-Generator For Swirl Turbine

Cílem této dizertační práce je navrhnout motor-generátor pro vírovou turbínu. Vírová turbína je poměrně nový typ turbíny vyvinutý na Odboru fluidního inženýrství Viktora Kaplana Energetického ústavu FSI VUT v Brně. Vírová turbína je navržená pro použití na malých spádech, kde mají klasické typy turbín buď špatnou účinnost anebo nejsou ekonomicky výhodné. Jako vhodná konstrukce pro motor-generátor byl vybrán synchronní stroj s permanentními magnety a axiálním tokem s bezželezným statorem. V rámci práce je proveden výpočet vlastností turbíny pro definovaný pracovní bod a vytvořen simulační model turbíny. Poté je již proveden samotný návrh motor-generátoru tak, aby optimálně splňoval vlastnosti turbíny. Celý návrh motor-generátoru je ověřen pomocí výpočtu metodu konečných prvků. Navržený stroj musí být schopen pracovat jako generátor i jako motor, pokud by bylo nutné použit turbínu jako čerpadlo.The aim of this doctoral thesis is to design a motor-generator for swirl turbine. Swirl turbine is a relatively new type of turbine developed at the Department of Fluid Engineering Viktor Kaplan Energy Institute FME BUT. Swirl turbine is designed for use on small head, where the classical types of turbines either poor efficacy or are economically disadvantaged. As suitable construction for the motor-generator was selected synchronous machine with permanent magnets and with axial magnetic flow with coreless stator. As part of the work is carried out calculating the properties of turbines for defined operating point simulation model of the turbine. After already made draft motor-generator to optimally meet the characteristics of the turbine. The complete design of the motor-generator is validated by calculating the finite element method models. Designed machine must be able to work as a generator and as a motor, if it was necessary to use a turbine as a pump.

Vibrodiagnostics Faults Classification for the Safety Enhancement of Industrial Machinery

The current digitization of industrial processes is leading to the development of smart machines and smart applications in the field of engineering technologies. The basis is an advanced sensor system that monitors selected characteristic values of the machine. The obtained data need to be further analysed, correctly interpreted, and visualized by the machine operator. Thus the machine operator can gain a sixth sense for keeping the machine and the production process in a suitable condition. This has a positive effect on reducing the stress load on the operator in the production of expensive components and in monitoring the safe condition of the machine. The key element here is the use of a suitable classification model for data evaluation of the monitored machine parameters. The article deals with the comparison of the success rate of classification models from the MATLAB Classification Learner App. Classification models will compare data from the frequency and time domain, the data source is the same. Both data samples are from real measurements on the CNC vertical machining center (CNC-Computer Numerical Control). Three basic states representing machine tool damage are recognized. The data are then processed and reduced for the use of the MATLAB Classification Learner app, which creates a model for recognizing faults. The article aims to compare the success rate of classification models when the data source is a dataset in time or frequency domain and combination.</p

Transition of cavitating flow to supercavitation within Venturi nozzle – hysteresis investigation

Cavitation is usually considered as undesirable phenomena. On the other hand, it can be utilized in many applications. One of the technical applications is using cavitation in water treatment, where hydrodynamic cavitation seems to be effective way how to reduce cyanobacteria within large bulks of water. The main scope of this paper is investigation of the cavitation within Venturi nozzle during the transition from fully developed cavitation to supercavitation regime and vice versa. Dynamics of cavitation was investigated using experimental data of pressure pulsations and analysis of high speed videos, where FFT of the pixel intensity and Proper Orthogonal Decomposition (POD) of the records were done to identify dominant frequencies connected with the presence of cavitation. The methodology of the high speed (HS) records semiautomated analysis using the FFT was described. Obtained results were correlated and above that the possible presence of hysteresis was discussed

Analýza zátěžného momentu asynchronního motoru

This paper is focused on the load torque evaluation of the induction machine. There is described the problem of load torque oscillations and its impact to other electromagnetic variables in induction machine. In this article, the issue of modulated stator current is resolved and behaviors of amplitude and phase modulation are separated using demodulation algorithms after that. Newly, the variable load torque is retroactively determined from coefficients of amplitude and phase modulation not from nondemodulated stator current frequency spectrum. At last, theoretically acquired knowledge is compared with real measurement and different values of amplitude and phase modulation obtained from the mathematical motor model and from the real measurement are discussed. In the future, this analysis can be used as a basis for online diagnosis of driven load.Tento článek je zaměřen na vyhodnocení zátěžného momentu asynchronního motoru. Je tu popsána problematika proměnného zátěžného momentu a její dopad na ostatní veličiny asynchronního stroje. Je zde řešena otázka modulace statorových proudů asynchronního motoru vlivem oscilačního momentu a pomocí uvedených demodulačních procesů jsou zde odděleny vlivy jednotlivých modulací a jejich projevy jsou zkoumány separovaně. Nově je proměnný zátěžný moment zpětně určován z koeficientů amplitudové a fázové modulace, ne z nedemodulovaného frekvenčního spektra statorových proudů. V závěru jsou porovnávány teoreticky získané vědomosti s reálným měřením a jsou diskutovány různé hodnoty amplitudové a fázové modulace získané z matematického modelu motoru a z reálného měření. V budoucnu může sloužit tato analýza jako základ pro online diagnostiku poháněných zátěží

Numerical simulation and experimental visualization of the separated cavitating boundary layer over NACA2412

Cavitation is physical phenomenon of crucial impact on the operation range and service lifetime of the hydraulic machines (pumps, turbines, valves etc.). Experimental measurement of cavitation is expensive and time consuming process, while some important characteristic of the flow are difficult to measure due to the nature of the phenomenon. Current possibilities of computational fluid dynamics provide a way for deeper understanding of cavitation which is important for many applications in the hydraulic machines industry such as expanding operation range or extending lifetime of the hydraulic machines. Simplified model consists of NACA 2412 hydrofoil with 8 degrees angle of attack fixed in between the walls of cavitation tunnel. Present investigation focuses on comparison of vapor volume fractions obtained by 3D CFD simulations and high speed visualization of the real cavitation phenomena. Several operating regimes corresponding to different cavitation numbers are studied with aim to assess the dynamics of the separated cavitating sheets/cloud

Numerická simulace a experimentální vizualizace separujíci se kavitující mezní vrstvy profilu NACA2412

Cavitation is physical phenomenon of crucial impact on the operation range and service lifetime of the hydraulic machines (pumps, turbines, valves etc.). Experimental measurement of cavitation is expensive and time consuming process, while some important characteristic of the flow are difficult to measure due to the nature of the phenomenon. Current possibilities of computational fluid dynamics provide a way for deeper understanding of cavitation which is important for many applications in the hydraulic machines industry such as expanding operation range or extending lifetime of the hydraulic machines. Simplified model consists of NACA 2412 hydrofoil with 8 degrees angle of attack fixed in between the walls of cavitation tunnel. Present investigation focuses on comparison of vapor volume fractions obtained by 3D CFD simulations and high speed visualization of the real cavitation phenomena. Several operating regimes corresponding to different cavitation numbers are studied with aim to assess the dynamics of the separated cavitating sheets/cloudsPublikace se zabývá dynamikou kavitace při obtékání hydraulického profilu NACA 2412 s fixním úhlem náběhu. Numerické výpočty byly porovnány s experimentálními výsledky