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

Abstract

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.

Non-Linear Regression Models with Vibration Amplitude Optimization Algorithms in a Microturbine

“…Conventional models for the study of vibrations of a microturbine in different applications focus only in the dynamic model [ 9 , 10 , 11 ]. However, obtaining better energy management requires optimizing the efficiency of DER systems.…”

On the Use of Selected 4th Generation Nuclear Reactors in Marine Power Plants

“…The dimensions of the space for the drive depend on its power, thermodynamic parameters and the working medium [25]. It is also important from the operational point of view to ensure trouble-free operating conditions, i.e., among others, protection against propulsion vibrations [26], [27], and to ensure appropriate controls [28]. For the ships considered below, with the prospect of using the VHTR reactors, as in Fig.…”

Failure analysis of a high-speed induction machine driven by a SiC-inverter and operating on a common shaft with a high-speed generator

“…The influence of different rectifier topologies on a high-speed permanent magnet generator used in a micro-gas turbine distributed generation system has been studied by Qiu et al [27]. The design criteria, assembly practices and experimental analysis of the whole low-cost micro generation system with a high-power density microturbine has been discussed by Pottie et al [25] The investigation of dynamic properties of the microturbine with a maximum rotational speed of 120 krpm was shown by Żywica et al [37]. The dynamic analysis of 1 kW, 30 kW, and 700 kW turbines were presented by Breńkacz et al [5][6][7].…”