Vibration based diagnostics of the multi-stage microturbine operating in the medium-temperature ORC system

This article discusses a vibrodiagnostic system designed for the prototypical microturbine operating in an ORC-based power plant with an electrical capacity of around 100 kW. The first part of the article is devoted to the numerical analysis of the microturbine, which was conducted with taking into account the fact that the asynchronous electro-generator is connected to the microturbine shaft by a reduction gear. Based on the results of the analysis, the diagnostic system dedicated for the microturbine has also been developed. The second part of the article presents a vibrodiagnostic system in detail. The system with a dedicated measuring and monitoring software (developed using the LabVIEW programming environment) was described. The developed solution enables not only constant monitoring of the test object, but also protects the microturbine against propagation of damage and failure

Investigation of dynamic properties of the microturbine with a maximum rotational speed of 120 krpm – predictions and experimental tests

Advances in the development of analysis and design methods for fluid-flow machines have enabled both their multi-criteria optimisation and miniaturisation. To decrease the size of such a machine whilst, at the same time, maintaining its output power level, the rotor’s rotational speed needs to be increased. It is the reason for serious difficulties with respect to the rotor dynamics and the selection of a bearing system. This article discusses the simulation analysis and experimental research carried out on a prototypical microturbine, designed for use in a domestic ORC (organic Rankine cycle) cogeneration system. During the design process, the basic assumption was to develop a turbomachine, whose dimensions would have been as small as possible and whose output electric power would have been about 1 kilowatt. A supersonic impulse turbine, with a nominal rotational speed of 100,000 rpm, was used in order to obtain high flow efficiency. The maximum speed of the rotor was determined at a level of 120,000 rpm. The article presents the results of analyses made at the design stage and preliminary results of the experimental research. The numerical simulations covered the bearing system optimisation and the rotor dynamics analysis. Next, based on the outcomes of these analyses, a decision was made to use non-conventional gas bearings which are fed by the low-boiling medium’s vapour that comes from the ORC system. Within the framework of the experimental research, the dynamic behaviour of the turbogenerator was examined in terms of the rotational speed and produced energy. The performed measurements are proof of very good dynamic properties of the tested machine and after the research was over it was concluded that there were absolutely no signs of wear of the turbogenerator’s subassemblies

Investigation of dynamic properties of the microturbine with a maximum rotational speed of 120 krpm – predictions and experimental tests

Advances in the development of analysis and design methods for fluid-flow machines have enabled both their multi-criteria optimisation and miniaturisation. To decrease the size of such a machine whilst, at the same time, maintaining its output power level, the rotor’s rotational speed needs to be increased. It is the reason for serious difficulties with respect to the rotor dynamics and the selection of a bearing system. This article discusses the simulation analysis and experimental research carried out on a prototypical microturbine, designed for use in a domestic ORC (organic Rankine cycle) cogeneration system. During the design process, the basic assumption was to develop a turbomachine, whose dimensions would have been as small as possible and whose output electric power would have been about 1 kilowatt. A supersonic impulse turbine, with a nominal rotational speed of 100,000 rpm, was used in order to obtain high flow efficiency. The maximum speed of the rotor was determined at a level of 120,000 rpm. The article presents the results of analyses made at the design stage and preliminary results of the experimental research. The numerical simulations covered the bearing system optimisation and the rotor dynamics analysis. Next, based on the outcomes of these analyses, a decision was made to use non-conventional gas bearings which are fed by the low-boiling medium’s vapour that comes from the ORC system. Within the framework of the experimental research, the dynamic behaviour of the turbogenerator was examined in terms of the rotational speed and produced energy. The performed measurements are proof of very good dynamic properties of the tested machine and after the research was over it was concluded that there were absolutely no signs of wear of the turbogenerator’s subassemblies

Additively Manufactured Parts Made of a Polymer Material Used for the Experimental Verification of a Component of a High-Speed Machine with an Optimised Geometry—Preliminary Research

This paper describes a novel method for the experimental validation of numerically optimised turbomachinery components. In the field of additive manufacturing, numerical models still need to be improved, especially with the experimental data. The paper presents the operational characteristics of a compressor wheel, measured during experimental research. The validation process included conducting a computational flow analysis and experimental tests of two compressor wheels: The aluminium wheel and the 3D printed wheel (made of a polymer material). The chosen manufacturing technology and the results obtained made it possible to determine the speed range in which the operation of the tested machine is stable. In addition, dynamic destructive tests were performed on the polymer disc and their results were compared with the results of the strength analysis. The tests were carried out at high rotational speeds (up to 120,000 rpm). The results of the research described above have proven the utility of this technology in the research and development of high-speed turbomachines operating at speeds up to 90,000 rpm. The research results obtained show that the technology used is suitable for multi-variant optimization of the tested machine part. This work has also contributed to the further development of numerical models

Flow characteristics of an automotive compressor with an additively manufactured rotor disc

This paper presents the results of experimental research regarding the determination of the flow characteristics of the compressor of an automotive turbocharger with a plastic rotor disc. The disc was manufactured using the 3D printing technology called the multijet printing, which allows complex geometries to be printed with high precision. Currently, in addition to speeding up the manufacturing processes and reducing their costs, 3D printing technologies are increasingly seen as standard tools that can be used in the design and optimization of machine parts. This article is a continuation of research on the possibility of applying additively manufactured elements in turbomachines. The experimental research was carried out at high rotational speeds (up to 110 000 rpm), using the automotive turbocharger with two different compressor rotors (i.e. one aluminum and one polymer). The first chapters of the paper discuss the preparation stage of the research (i.e. the manufacture of the rotor, the test rig). Then, the experimental research and the flow characteristics are described. The results obtained for the two types of discs were compared with each other and the area of application of the additively manufactured rotor was determined. The rotor functioned properly in the range of tested operating parameters and the results obtained showed that the technology and material applied could be used in the optimization studies of the blade systems of high-speed fluid-flow machines

Zastosowanie metody wytwarzania addytywnego do wykonania panwi łożysk ślizgowych – badania wstępne

The paper presents the application of an unconventional method of manufacturing bearing sleeves as well as the carrying out of preliminary research in which the manufactured components were used on a real object. Additive manufacturing methods are increasingly being used, which leads to the rapid development of technologies and their applications. The MultiJet Printing technology was used in the research, which allows precise 3D printing of sleeves made of polymeric materials. The first part of the article deals with the selected manufacturing method and the preparation of a model. The study aimed at evaluating the usefulness of bearings manufactured using the 3D printing technology to support slow-speed rotors. The preliminary research described focuses on the study of operating parameters such as the moment of friction and the bearing node temperature as a function of rotational speed during operation. Experimental tests were carried out at low rotational speeds. This paper presents and determines the scope of the application of bearings manufactured using 3D printing technology.W pracy przedstawiono zastosowanie niekonwencjonalnej metody wytwarzania panwi łożysk wraz z przeprowadzeniem badań wstępnych z użyciem wykonanych elementów na obiekcie rzeczywistym. Metody wytwarzania addytywnego stosowane są na coraz większą skalę, co wiąże się ze znacznym rozwojem technologii i ich aplikacjami. Do badań wykorzystano technologię MultiJet Printing, pozwalającą na precyzyjny wydruk 3D panwi z materiałów polimerowych. Pierwsza część pracy poświęcona jest wybranej metodzie wytwarzania i przygotowaniu modelu. Celem pracy było określenie przydatności łożysk wykonanych technologią wydruku 3D do podparcia wolnoobrotowych wirników. Opisywane badania wstępne obejmują poznanie takich parametrów pracy jak moment tarcia oraz temperatura węzła łożyskowego w funkcji prędkości obrotowej podczas pracy. Część eksperymentalną przeprowadzono w warunkach niskich prędkości obrotowych. W niniejszej pracy przedstawiono i określono zakres zastosowań łożysk wytworzonych omawianą w artykule metodą wydruku 3D

VIBRATION ANALYSIS OF A TURBOCHARGER WITH AN ADDITIVELY MANUFACTURED COMPRESSOR WHEEL

This article presents the vibration analysis of a turbocharger, whose compression wheel was manufactured using a high-precision additive manufacturing technology. Currently, there are advance studies around the world for the development of parts of innovative fluid-flow machines using additive manufacturing techniques. The experimental research was carried out under conditions of reduced flow temperatures. The tests and the analysis were performed on a wheel manufactured using a 3D printing technology and on a conventionally used aluminium wheel. Apart from an FFT analysis of the vibration signal during machine operation, a machine run-up test was conducted (up to a speed of 105,000 rpm). The results showed the positive impact of the use of a plastic wheel on the dynamics of the system at a certain speed range, which might contribute to the development of a new method to optimise the geometry of flow systems in small high-speed turbomachines. A modified automotive turbocharger was subjected to experiments on a test stand

A Novel Measurement Approach to Experimentally Determine the Thermomechanical Properties of a Gas Foil Bearing Using a Specialized Sensing Foil Made of Inconel Alloy

Modern approaches dedicated to controlling the operation of gas foil bearings require advanced measurement techniques to comprehensively investigate the bearings’ thermal and thermomechanical properties. Their successful long-term maintenance with constant operational characteristics may be feasible only when the allowed thermal and mechanical regimes are rigorously kept. Hence, an adequate acquisition of experimental readings for the critical physical quantities should be conducted to track the actual condition of the bearing. The above-stated demand has motivated the authors of this present work to perform the thermomechanical characterization of the prototype installation of a gas foil bearing, applying a specialized sensing foil. This so-called top foil is a component of the structural part of the bearing’s supporting layer and composed of a superalloy, Inconel 625. The strain and temperature distributions were identified based on the readings from the strain gauges and integrated thermocouples mounted on the top foil. The measurements’ results were obtained for the experiments that represent the arbitrarily selected operational conditions of the tested bearing. Specifically, the considered measurement scenario relates to the operation at a nominal rotational speed, i.e., during the stable process, as well as to the run-up and run-out stages. The main objectives of the work are: (a) experimental proof for the described functionalities of the designed and manufactured specialized sensing foil that allow for the application of a novel approach to the bearing’s characterization, and (b) qualitative investigation of the relation between the mechanical and thermal properties of the tested bearing, using the measurements conducted with the newly proposed technical solution